BECAUSE WE'RE ALL ABOUT RADIO
Radio station programming/content that is in Arabic.
A reduction in the signal strength of a radio signal that is caused by refraction within the Earth’s ionosphere.
Abbreviation used for the Adult Contemporary format of music. You can usually think of this in relation to radio stations that play “the best hits of the 70s, 80s, 90s and today” or the many popular “Chuck FM”/’Bob FM” formatted stations (“we play everything”). Many of those are adult contemporary. You can also think of music you might hear in a grocery store or in an office. Normally, you are hearing adult contemporary.
Shorthand method for notating ‘advertisement’. Can also use “Cmrcl” for commercial.
An abbreviation for the continent of Africa
Along with Morning Drive, this is one of the most listened to periods of time for a radio station and typically runs from roughly 3pm to 7pm local time. Coined as this is the period of time when most listeners are commuting from their jobs back home. Depending on the format of the radio station, this can be an excellent time to be able to pull an identification for received stations – especially since this usually also coincides with local sunset/grayline skip enhancement (at least most of the year). Stations that are formatted primarily in News/Talk (especially those with high power) are more likely to have regular traffic/weather updates and these almost always contain some sort of identifying information (“traffic and weather together on the 8s” or “traffic and weather every 10 minutes” are common marketing tools used by stations to lure listeners – but it also works for DXers!)
A commonly used measure of geomagnetic activity (solar/sun activity) for AM Dxers. The a-index values range from 0 and 400. A low value generally indicates good long-distance AM radio reception. However high A-index numbers can also be a reflection of strong aurora conditions. For mid-latitude DXers, this can me that stations to your North which usually dominate a frequency will be degraded in signal quality (or absent altogether) which allows for reception of stations further to your South (in the northern hemisphere, the inverse is true in the southern hemisphere). During strong “aurora nights” in the northern hemisphere, reception of stations into Central and South America is possible with relative ease. There are many web sites which gather this and other solar indicator values as an aid to DXers (see the General DX area of the DX Central Links page).
This refers to the strength or height of the radio wave. The more amplitude, the stronger the signal is as it exits the transmitter.
Amplitude Modulation (AM)
This is the method in which AM radio signals are generated. This means that in an AM signal, it is the amplitude of the carrier wave that changes. This is as opposed to an FM signal where it is the frequency of the carrier wave signal that modulates (changes). This term can also refer more loosely to the mediumwave band (which ranges from 530-1700 kHz in the Western hemisphere or 531-1702 in the Eastern hemisphere).
Depending on your point of view, this is either the component you use at the receiving end to pull in transmitted signals or the component used to transmit signals to receivers. Antennas can come in many sizes and shapes and their design is largely influenced by the frequency you are trying to receive/transmit.
Refers to the manner in which a transmitted signal propagates from the transmission tower/antenna into its surrounding area. Radio stations can have a large variety of antenna patterns depending on their class, frequency, power and location. Some can be non-directional, meaning their signal radiates in a near perfect circle with the transmitter location as the center point; they can be directional, meaning their signal will favor certain directions (lobe) and be designed to not radiate in others (null). The FCC authorizes and enforces antenna pattern usage for radio stations in the United States.
An abbreviation for the continent of Asia
A feature found on many communications receivers, software-defined radios (SDR) and some portables that allows the listener to reduce the overall signal coming through the radio and out of the speaker(s). Measured in decibels (dB). It is often favorable to attenuate/reduce the amount of gain coming into the radio, especially when very strong radio stations are being received (such as local stations in your area) to allow for other stations to be heard.
All-Time New One (ATNO)
Commonly used in the amateur radio community to indicate a station worked from an all-time new country for that particular DX (the first station they have worked in that country). Can also be used in AM/FM DX to indicate a station received for the first time for a DXer from a new country, state or even a station logged for the very first time. The latter is most commonly used when a DXer has lived in multiple locations and is logging a station for the first time from any location.
This may refer to both the visual display of aurora borealis at or near the northern/southern poles. In DX and radio terminology, auroral conditions can commonly be observed during periods of high solar activity. During strong aurora conditions (usually measured by high A-index values) the ionosphere absorbs radio signals in high northern/southern latitudes. This allows signals generated closer to the Equator to be heard, with less interference from usually dominant stations.
Automatic Gain Control (AGC)
This is a feature found on many desktop communications receivers, software-defined radios (SDR) and even some portables. AGC essentially tries to even out the volume of the received signal, making it easier to listen to. Essentially, the weaker the signal the more gain is applied to bring the audio level up while stronger stations have little to no gain applied (or even lowers the gain). You will hear/see terms such as AGC Fast or AGC Slow. These just refer to the reaction time of the circuitry in adjusting the gain and both are useful in certain situations.
An abbreviation for “BALanced to UNbalanced”. Refers to a device that allows for coupling of a balanced and unbalanced antenna wire. Most commonly used to join a copper wire antenna (such as a random wire “longwire” antenna) with a coaxial cable. This can be very useful when constructing longwire and other copper wire antennas, where there is a desire to still use a coaxial cable as the feedline coming into the radio.
The defined spectrum of frequencies. This can include examples such as the AM/mediumwave band, the HF band (where amateur radio and shortwave radio transmissions are found, starting at 1.8 MHz (1,800 kHz) and the VHF/UHF bands (where FM radio, NOAA weather radio, Amateur Radio, police/fire/EMS and other transmissions can be heard).
For DX purposes, this usually will refer to a list of radio stations commonly heard under normal conditions using your normal DX equipment. It is typically useful to conduct bandscans, notating each station heard, during the various times of day (sunrise, daytime, sunset and nighttime) in order to establish which stations are normally heard at a location. This makes identifying unusual conditions or new stations much easier, since you have a baseline “normal” to work from.
Can refer to the width of the frequency range(s) covered by a receiver, the frequency range of an antenna used for reception, the amount of frequency space occupied by a transmitted signal, or the frequency range defined in a software-defined radio (SDR) for reception. In SDRs, bandwidth is extremely important, especially when attempting to record all or parts of the AM or FM bands as it will determine how much of the band you are recording. In antennas, it is also a very important element in determining the effectiveness of the antenna for the frequency range you are trying to receive.
A station (commonly found below 520 kHz, among other frequencies) that is used for navigational purposes for aircraft and nautical vessels. Transmissions can be in many formats, though most in the sub-520 kHz frequencies will transmit a three-letter callsign in morse code/CW. For DXers, these can often be used to gauge propagation to show where signals are coming from and how strongly.
A type of antenna that is used for transmitting or receiving. Normally, a beam consists of a beam (a piece of metal/fiberglass, etc. that runs the length of the antenna) and two or more elements (mounted perpendicular to the beam. Each element’s width will usually shorten towards the front of the beam). With a beam, energy is focused in a specific direction. Not used commonly in AM DX (due to the size that would be needed for a beam at that frequency range) but are very commonly used in FM DX. DXers are interested in two specific measurements when it comes to beam antennas: gain and front-to-back-ratio. The higher the gain, the more boost in signal level the beam antenna will give you. The front-to-back ratio is a measurement of directionality, by measuring the signal levels both in the direction of the beam (front) and those opposite (behind). The higher the front-to-back-ratio, the more directional an antenna is which allows for a DXer to narrow their focus to a specific area for reception.
Invented by Harold Beverage in 1921, beverages are extremely long antennas used in AM DX that provide a DXer with very low noise, high directionality and significant signal gain, when compared to other antenna options. Beverages are normally placed 6-8’ off the ground and generally run for lengths of 500-1000 feet! They consist of a wire, a balun (on one end, where the feedline comes in) and a terminating resistor (on the opposite end) as well as a ground rod on both ends. For those that have the real estate, this is the ultimate in AM DX antennas, especially if you are able to have multiple beverage antennas oriented in multiple directions! Sometimes shortened to Bev. Antenna.
Shorthand abbreviation for the Business programming content of a radio station. Can include both stations primarily formatted for business-related talk (most usually related to stocks/stock market but can also include discussions for business owners, around finances, etc.) or BIZ-related content during a specific period for a station.
Refers to station advertising breaks that occur around :30 past the top-of-the-hour. Many stations will provide an identification during this commercial break and some will even include traffic and/or weather updates during this time. These breaks almost always have at least some local advertising as well. All-in-all, BOH (starting at :25 after and running through :35 after) is a fantastic time to try to identify a received radio station. BOH is the common way to notate this time period in logbooks.
BroadCast Band (BCB)
A commonly used abbreviation for the AM/mediumwave band.
A station that charges (brokers) slots of time (either fully or only part of their schedule) to individuals or groups to use. Can include religious programming, infomercials, ethnic programming, specialty music or anything that the purchaser wants to use (within station guidelines, of course).
Shorthand abbreviation for Country and Western music. This can include many sub-formats of the larger C&W genre. Some stations will focus more on “New country” (artists/songs that are currently on the charts), “classic country” (artists/songs that were big between 1970 and the mid-1990s) and bluegrass (found heavily in the Southern United States and is identifiable by the instrumentation used which often includes a banjo and no drum set). Stations will usually self-identify which subset of the genre they focus on.
Shorthand abbreviation for the region of Central America
Radio station programming/content that is in Chinese.
Callsign/Call letters (Cls)
The identifier used by most radio stations and usually granted to a station by some sort of governing body within their country of origin. In the United States, callsigns are assigned by the Federal Communications Commission (FCC) and consist of 3-4 letters that start with a K or a W. While there are exceptions, most stations with a callsign beginning with a W are east of the Mississippi River while most stations that start with a K are located west of the Mississippi River. Notable exceptions include KYW (1060 kHz, Philadelphia, PA) and KDKA (1020 kHz, Pittsburgh, PA) which both received their callsigns before the K/W designator was based on location.
The unmodulated signal of a radio transmitter.
Shorthand abbreviation for Contemporary Christian Radio. This can include contemporary Christian music (although this can sometimes be notated as REL/AC). CCR can also include Christian talk content as well (Where REL/AC is entirely music).
The unmodulated carrier frequency of a FM radio transmitter.
Central Daylight Time (CDT)
Time zone in North America that is UTC -5 (five hours behind UTC time). Only used during “daylight savings” periods from early spring to late fall.
Central Standard Time (CST)
Time zone in North America that is UTC -6 (six hours behind UTC time). Only used outside of “daylight savings” periods from late fall to early spring.
Shorthand abbreviation for Contemporary Hit Radio programming content of a radio station. This constitutes your Top 40 radio station, playing the current hits of the day that are on the Top 40 charts. While very prevalent on FM radio, there are some AM stations which still carry this format. Station imaging is very ‘young’ sounding, on-air personalities usually have a ton of energy.
Shorthand abbreviation that refers to station programming that is in the Classical Music format. This can include orchestral music, operas etc.
An illegal, unlicensed and otherwise unauthorized broadcasting station, usually broadcasting music. Also commonly referred to as a pirate.
Class A (AM)
Refers to an AM radio station in the United States that operates unlimited time on a clear channel and is designated to serve both a primary and secondary service area that covers an extended amount of distance. The primary service area is protected from interference from stations both on the same and adjacent frequencies. The secondary service area is protected from interference from stations on the same frequency. A Class A station must not use less than 10 kw and no more than 50 kw.
Class B (AM)
Refers to an AM radio station in the United States that operates unlimited time and is designated to serve only a primary service area that covers an extended amount of distance. A Class B station is authorized to use a minimum power of .25 kw with a maximum power of 50 kw (10 kw for those stations located within the ‘expanded band’ from 1610-1700 kHz).
Class C (AM)
Refers to an AM radio station in the United States that operates unlimited time on one of the designated “local channels” (1230, 1240, 1340, 1400, 1450, 1490). Class C stations are authorized to use a maximum of 1 kw and operate mostly with non-directional antenna patterns.
Class D (AM)
Refers to an AM radio station in the United States that operates either daytime-only, limited time or unlimited time with a nighttime power that does not exceed .25 kw. Class D stations operate with daytime powers not less than .25 kw and no more than 50 kw. Nighttime operations of Class D stations are not afforded protection and must protect their signal from interfering with all Class A and Class B operations during nighttime hours.
Clear channel station
Refers to an AM radio station in North America that receives the highest amount of protection from interference from other radio stations, especially during nighttime hours. Clear channel stations can often be heard for thousands of miles across a vast area of the country or even continent. Protection is both guaranteed and enforced through treaties or statutory laws.
Shorthand abbreviation to refer to station programming in the Classic Rock format. This genre of music is expanding with each passing year, but generally refers to music made in the 1960s-1980s and is generally oriented around guitar-based music (Pink Floyd, Led Zeppelin, later Rolling Stones, etc.)
Shorthand abbreviation for commercial/advertisement.
Sometimes referred to as a ‘general coverage’ receiver. These are often larger receivers built specifically to be used for receiving distant radio stations. As such, they are mostly designed to be desktop models (although some do have the ability to be used portably). They will often include connections for at least a coaxial cable feedline from an antenna (some times more than one) and will often also include a connection for a wire feedline (such as from a longwire antenna). They will often include coverage from longwave frequencies (usually 100 or 150 kHz, sometimes lower) all the way through 30 MHz (although some will extend into at least a portion of the VHF frequencies). Prior to software-defined radio, these were considered the top-of-the-line options for serious DXers. While still in use and available today, many DXers are starting to lean towards SDRs for their capability and flexibility.
A term used on antenna coverage maps for AM and FM radio stations. There are three contours: Local, Distant and Fringe. The contour is determined by engineering data from the FCC. For AM radio, contours are determined by the station’s transmitter power, it’s field strength pattern, the frequency of the station and the ground conductivity of the local area. For FM radio, contours are determined by the effective radiated power (ERP) of the station and the antenna height above average terrain (HAAT) which is calculated by determining the average ground elevation in all directions from the transmitter site between 1.5 and 10 miles away. For AM radio, contours are based on predicted 2.0 (local), 0.5 (distant) and 0.15 (fringe) mV/m signal strength of the ground wave signal. For FM radio, contours are based on predicted 60 (local), 50 (distant) and 40 (fringe) dBμ signal strength area.
For DXers, this is interference from stations located on frequencies adjacent to the desired/received signal. For example, if you have a local station on 1450 kHz and are trying to receive DX on 1440 kHz, your local station will often cause co-channel interference (also known as “splatter”) on your desired frequency. There are many methods you can use to reduce or even eliminate co-channel interference, including use of loop or other directional antennas, phasers, moving to Upper or Lower Sideband, reducing gain, filters, etc. Also, the more selective a radio is, the less vulnerable it is to co-channel interference.
Coordinated Universal Time (UTC)
Formerly known as Greenwich Mean Time (GMT). This is the time at the prime meridian (0° longitude) which passes through the city of Greenwich, United Kingdom. UTC is the standard time used by DXers around the world to notate time. Can also be referred to as zulu time (as in 1800 zulu or 1800z).
Critical Hour (CH)
In the United States, the FCC defines this period as the two hours that follow local sunrise and the two hours prior to local sunset. Since propagation during these periods may be a mixture of both groundwave and skywave, stations may have to reduce from their daytime power or change their antenna pattern to prevent interference with other stations. However, it allows certain daytime-only stations the ability to add additional time to their broadcast day by extending prior to and after local sunset.
Shorthand abbreviation for continuous wave which also refers to a carrier wave or unmodulated radio wave. Most commonly, CW is used to refer to transmissions made in morse code. It may also refer to the CW mode found on many communications receivers/transceivers.
Shorthand abbreviation for “conditions”. Often used to refer to the propagation characteristics of the radio bands during a DX session. Examples of use can include: “aurora cx”, “There were really poor cx on AM last night”, “strong cx to the upper Midwest”, “tropo cx”, etc.
Refers to an AM radio station that only broadcast between local sunrise and local sunset. These stations are becoming fewer and fewer as many stations are broadcasting 24-hour schedules with greatly reduced power and altered antenna patterns at night to prevent interfering with other stations.
A measurement of signal strength. Often used on signal meters on communications receivers, software-defined radios (SDRs) and portable radios. Can also be used in measurements for antennas such as antenna gain; a measurement of attenuation (the amount of the signal attenuated); volume or loudness of a sound, etc. Generally speaking, the more decibels/dBs measured, the more of the signal/volume, etc is going to be there.
Digital Audio Broadcast (DAB)
A digital radio system run by the World DAB Forum. Commonly used in the United Kingdom and other European countries.
Digital Signal Processing (DSP)
A feature found in many communications receivers, software-defined radios (SDR) and some portable radios. Can also be found in some external units (a piece of equipment solely used for DSP). The received signal is put through digital processing to make it easier to hear, reduce co-channel interference and other techniques.
A type of antenna optimized for the band/desired frequency. A dipole is generally 1/2-wavelength long, consisting of two 1/4-wavelength wires oriented in opposite directions and connected in its center to a feedline (usually by use of a balun). Signals arrive at the dipole perpendicular to the orientation (so if the two wires are pointing towards north and south, the dipole will receive signals best from the east and west). For a dipole to be most effective, it should be more than 1/2-wavelength above the ground Given the extremely long wavelength of frequencies in the AM/mediumwave band, this makes dipoles an inefficient antenna for AM reception (though they can be used to good results).
On a radio station coverage map, the distant contour is the area between the local and fringe countours, that is considered to be able to be received by listeners. For AM radio, the distant contour represents the predicted 0.5 mV/m signal strength of the ground wave signal. For FM radio, the fringe contour represents the predicted 50 dBμ signal strength area.
The lowest region of the ionosphere (roughly 25 to 50 miles / 50 to 90 km above the Earth’s surface). Mostly fades away after sunset (although there can be remnants of it that remain in some areas) Caused by the heating of the sun during the daytime, the D-layer absorbs signals that are transmitted generally below 7 MHz, including AM radio signals. This is why during the daytime, the predominant form of propagation for AM radio is Groundwave propagation. The D-layer builds up at sunrise (general starting a few hours before local sunrise) and then begins to break down during sunset (starting generally 2 hours before local sunset). This is part of the reason why sunrise/sunset periods can produce such unique propagation that cannot be found during daytime or nighttime DX.
Shorthand abbreviation for distance (originated as the telegraph abbreviation for ‘distant’). Also refers to the hobby (DXing) where the hobbyist (a DXer) is trying to receive (or contact, for Amateur Radio operators) distant radio stations. How one defines “distant” is completely subjective (many AM and FM radio stations that one will log are relatively close in geographical terms).
Shorthand for DX Expedition. Essentially any time a DXer travels from their home location in order to remove themselves from noise, have more room for antennas, or improve receiving conditions (especially to particular geographic areas or even parts of the world), it is a DXpedition. Some DXers go to great expense to plan extravagant DXpeditions on remote islands, desolate mountaintops, national parks, or seaside locations – all in the name of DX!
A special transmission – often organized by one of the DX clubs – that both allows the transmitting station to test or calibrate their equipment, while also making them easier to hear for DXers. DX Test will normally not contain standard programming, but rather test tones, the station’s call letters transmitted in CW and sometimes even unique programming to make them stand out (such as brass band marches, world music, or comedy recordings). DX Tests are generally run very late at night and often over weekends when there are fewer listeners. They are fantastic ways to pick up a new state or new country, even!
Radio station programming/content that is in English.
A layer in the ionosphere just above the D-layer (at an altitude of 55 to 90 miles / 85 to 140 km above the Earth’s surface). Normally fades away after sunset and can either absorb or reflect radio signals (depending on the frequency), This is the layer of the atmosphere where sporadic-Es (Es Skip) will occur. Originating in the upper regions of the HF-band, strong Es skip can travel into the FM radio band and even higher frequencies, allowing for reception of stations thousands of miles away within the VHF and even UHF bands.
Eastern Daylight Time (EDT)
Time zone in North America that is UTC -4 (four hours behind UTC time). Only used during “daylight savings” periods from early spring to late fall.
Eastern Standard Time (EST)
Time zone in North America that is UTC -5 (five hours behind UTC time). Only used outside of “daylight savings” periods from late fall to early spring.
Effective Radiated Power (ERP)
The output of a transmitter (in watts) multiplied by the amount of gain supplied by the antenna. Used by the FCC in determining antenna contours for FM radio stations in the United States.
Shorthand abbreviation to refer to Ethnic programming on a radio station. Many times, this will be programming catered to a specific audience that has a large population in the area (such as ETH: Korean or ETH: Russian). However, there are stations that run programming that covers multiple ethnicities.
Shorthand abbreviation for the continent of Europe
Shorthand abbreviation for the Easy listening programming content of a radio station. Often called “middle of the road” this can be instrumental or non-instrumental music that is non-aggressive or invasive. Widely used in offices, elevators, grocery stores, etc. When instrumental, it is often referred to “beautiful music” or even “muzak”. Singers of the genre can include Frank Sinatra, Dean Martin, Bing Crosby, Tony Bennett. Very similar to the NOS format.
Radio station programming/content that is in French.
The upper layer of the ionosphere above the E-layer (at an altitude of 90 to 400 miles / 120 to 1500 km above the Earth’s surface). This is the layer responsible for most long distance radio reception below roughly 30 MHz (although F-layer skip is possible in FM DX). During the day when the sun heats the Earth’s atmosphere, (especially during the summer months) the F-layer splits into two components: F1 and F2. At night, after the sun sets, those two components merge together into a single layer and then separate again after sunrise each day. The high altitude of the F-layer and the fact that it reflects mediumwave signals is what allows for such long distance reception during the nighttime hours.
Shorthand abbreviation for the agricultural programming content of a radio station. This can include agricultural report segments or a station entirely formatted for agricultural talk. Can be commonly found in the Midwest of the United States (states such as Nebraska, Iowa, Kansas, etc.)
Federal Communications Commission (FCC)
This is the government entity that administers licenses and governs broadcasting in the United States.
The cable that connects an antenna to the radio. In most cases, these will be some sort of coaxial cable (RG-6 Quad-Shield or RG-8 are popular choices for receiving antennas) or even straight copper wire (not all receivers/radios are able to support a direct connection to a wire, so in these situations a Balun is needed to couple the wire with a coaxial cable).
A feature found in many communications receivers, software-defined radios (SDR) and some portable radios that allows a DXer to restrict certain frequencies from passing through the audio circuit into the speaker. This provides a DXer the ability to narrow the bandwidth of a received signal to reduce or eliminate noise or co-channel interference, thus allowing better DX reception.
Refers to a typically normally lower powered FM radio station (but more power than an LPFM) that relays content from a sister AM or FM radio station. These stations usually have unique callsigns (instead of a three or four-letter designation, they will have a callsign formatted as W###XX, such as W234DG). You will hear these stations identified only with their call letters as the top-of-the-hour legal ID, usually, such as: “You’re listening to 680 WAAA, Anytown, W234AK, 98.9, Niceville.” You can even find some stations where they have their own little internal network of multiple AM stations and multiple FM translators, making for quite a mouthful during the legal ID!
A measurement of the number of complete cycles per second for an oscillating current; measured in Hertz (Hz) although n the early days of radio, this was measured in cycles. As such, vintage radios and publications may refer to kcs rather than kHz. A complete cycle of a signal is said to have 1 Hz. As you rise in frequency, units of Hz incorporate the metric system nomenclature. Therefore kilohertz (kHz) represents thousands of cycles per second, megahertz (MHz) represents millions of cycles per second, and gigahertz (GHz) represents billions of cycles per second
Also, from the frequency of a signal we are able to determine the wavelength of that signal. This is helpful when building antennas that are to be suited for specific frequency ranges. To determine the wavelength of a signal, divide 300,000 by the frequency in kilohertz and this will find the wavelength in meters (e.g. 300,000 : 1,450 kHz = 206.9 meters).
As an example, a dipole antenna is constructed of two 1/4-wavelength wires in opposite direction, mounted a full 1/2-wavelength off the ground. This means for a dipole antenna built for 1,450 kHz, it would need to have two wires of 51.7 meters (169.62 feet) in length, mounted 103.45 meters (339.4 feet) off the ground.
Frequency Modulation (FM)
The method by which FM radio signals are generated. Through this method, it is the carrier frequency which is modulated (changed) as variations in strength of the modulated signal occur (a louder signal such as music will modulated a different carrier frequency than softer content such as spoken word). This term can also be used to refer to the FM radio band which can be found between 87.5 and 108 MHz in the majority of the world (although in Japan, the FM band runs between 76 and 90 MHz).
On a radio station coverage map, the fringe contour is the outermost area that is considered to be able to be received by listeners. For AM radio, the fringe contour represents the predicted 0.15 mV/m signal strength of the ground wave signal. For FM radio, the fringe contour represents the predicted 40 dBμ
signal strength area.
Radio station programming/content that is in German.
An increase in the strength of the signal being received. This can be achieved a number of different ways such as the gain introduced by certain types of antennas (beams for example for FM DX), by the directionality of an antenna (turning a loop or beam to increase signal from a certain direction while decreasing signal from other directions) or artificially through pre-amplifiers the boost the incoming signal (but also any present noise in the signal) to make it more readable (listenable). Gain may also refer to RF Gain, which is a feature on many communications receivers, software-defined radios (SDR) and some portable radios. In many listening conditions, RF gain (often measured in dB) will be set at standard level (which can vary by radio). It can often be desirable to “back off” this gain to prevent overloading or to let dominant stations be easier to hear when a large number of stations are present on a frequency. This is especially helpful on “graveyard”/local channels.
Refers to changes within the geomagnetic field that surrounds the Earth. These are the result of solar wind which originates with the sun and blasts the Earth with plasma carrying electrical energy. Some of the types of activity that can be present include solar storms, auroras, coronal mass ejections, solar flares and more. Activity is measured on a constant basis by ground monitoring stations as well as satellites in orbit around both the sun and Earth. The activity is organized into five classifications: quiet, unsettled, active, stormy and major storm. Activity operates on an 11-year sunspot cycle and during the peak of that cycle, geomagnetic will normally intensify for a period of time. One indicator that scientists use to gauge solar activity (and therefore geomagnetic activity) is sunspots. Higher sunspot numbers can be very favorable for some radio frequencies but determinantal to others. For mediumwave DX, the lower the solar activity the better for most listeners. FM DX can be susceptible to interference during periods of high solar activity.
The magnetic field in and around the Earth that protects the planet from solar storms and radiation. As solar wind and other energy from the sun interacts with the geomagnetic field, it will bend, fluctuate and change. This interaction is part of what you see on display with the Northern and Southern lights as well as what causes changes to radio propagation.
Global Radio Guide (GRG)
Published twice a year by Gayle Van Horn/Teak Publishing. The GRG basically continues the tradition of the Monitoring Times frequency section (long considered the TV Guide of radio) and has expanded it further. Contains detailed information of international shortwave broadcasters’ schedules and frequencies (including both English and non-English broadcasts). Also includes international mediumwave information as well as equipment reviews and feature articles.
Shorthand abbreviation for Gospel programming content of a radio station. This can include stations which normally carry a different format (such as C&W) but during certain time periods (such as Sundays during the morning or early afternoon) they carry religious programming. Gospel formatted stations traditionally will fall into two camps: GOS, which carries religious sermons (often Baptist) and gospel music and UC: GOS, which carries religious sermons and music targeted at African Americans. GOS stations may use slogans such as “Joy” or “The Word” while UC: GOS stations will often use slogans such as “Praise” or “Victory” (though sometimes these slogans can be used interchangeably between the two formats). Note that GOS and UC: GOS stations are typically quite different from REL stations. REL stations tend to be more reserved, many spoken word educational programming (bible lessons, etc.) and music is more traditional in nature. Both GOS and UC: GOS stations will often have much more passionate sermons and spirited music.
Generally refers to the period around sunset/dusk when the D and E-Layer of the atmosphere start to break down and the F-Layer begins to merge. Because of this activity, radio stations are able to propagate much further than they had during the daylight hours. This is commonly referred to as “Grayline Enhancement” or “Grayline skip” by DXers. As the solar terminator (the line between day and night) move across the planet, each station within that grayline area gets a bit of a boost in their signal. Because of this, DXers will sometimes park their receivers on a single frequency (1570 and 1580 kHz have always been very popular for this technique) to hear all of the stations that rise up due to the enhancement and then fade out after they enter nighttime. It can also be used to refer to the same type of period in the morning during sunrise, although it is more commonly used to refer to sunset enhancement/sunset skip DX.
Great Circle Path
The shortest distance for a radio signal between any two points on the Earth, taking the planet’s curvature into consideration. Used mostly for identifying signal paths “across the poles” for international DX.
Greenwich Mean Time (GMT)
The former term used for what is now known as Coordinated Universal Time (UTC).
An electrical connection to the Earth, usually through a copper rod. For DXers, they are used to ‘ground’ an antenna or radio equipment. This allows two things: 1.) a small amount of lightning protection (by directing the charge into the ground rather into the home) 2.) reduces noise on an antenna.
For DXers, this typically refers to the extent by which the surface of the Earth is able to conduct radio signals in an efficient manner. Since radio signals are electromagnetic, they follow the same principle as anything electrical in nature. They travel much further over conductive surfaces than they do non-conductive surfaces or insulating surfaces. As such, the more conductive the surface is between your receiving location and the transmitting location of a radio station, the stronger that signal will be at your location as there has been less loss of the signal as it travels over the Earth’s surface. This most noticeably will impact the ground wave signal of an AM station. The absolute best ground conductivity can be found over salty water. This is what makes coastal locations fantastic for DX, as the signal is able to travel much better over saltwater than it does any other type of surface. In the United States, the FCC has completed thorough studies of ground conductivity for the entire continent and a US ground conductivity map can be found in the AM Links portion of the DX Central links pages. Ground conductivity maps for other parts of the world do exist and we will be looking to add those as well to our links section.
Ground wave propagation
Refers to the radio signal that travels directly across the surface of the Earth (as opposed to the skyward portion of a signal that is either absorbed or refracted by the ionosphere). Ground wave is the primary propagation method found for daytime transmissions in the mediumwave frequencies. The distance a ground wave signal can travel is limited and is influenced greatly by the conductivity of the ground/soil found on the surface. The more conductive the surface, the further a ground wave signal can travel. The best conductor of ground wave signals is salty sea water. As such, coastal locations often make fantastic places to DX as signals with a direct salt water path between the receiver and the transmitter will be enhanced by the conductivity of the water.
Height Above Average Terrain (HAAT)
A measurement used by the FCC in conjunction with station power to determine the antenna contour of a broadcasting FM radio station. Expressed as the antenna height above an elevation average, which is calculated by determining the average ground elevation in all directions from the transmitter site between 1.5 and 10 miles away.
One complete cycle of the radio wave per second
A high-pitched whistling sound caused by two carriers interfering with each other. The pitch of the whistle depends on the frequency difference between the two carriers. On AM radio, a het is a fantastic way to identify trans-atlantic and trans-pacific signals. This is because stations in North and South America are separated by 10 kHz while Europe, Asia and Africa all use 9 kHz spacing. Because of this difference in spacing, stations that are within 1-3 kHz from each other will normally cause a het to be heard, alerting you that a station is being received on a “split” frequency outside of your normal frequency spacing. An example of this for US DXers is 890 kHz and the het produced by Algeria’s Chaine 1 on 891 kHz. An example of this for European DXers would be 1089 kHz, which is normally TalkSPORT in the United Kingdom, however U.S. stations on 1090 kHz such as WBAL in Baltimore, Maryland can cause a distinct het to be heard. Hets are fantastic propagation markers to know when DX is coming in from across the ocean!
High Frequency (HF)
The portion of the radio spectrum that lies above the mediumwave bands. Generally speaking, HF starts at 1.8 MHz (1800 kHz) and runs through 30 MHz (although some consider the 50-54 MHz frequencies of the amateur radio 6-meter band to be part of HF as well, while others contend it classifies as VHF). On HF, you will find heavy usage from amateur radio, international shortwave broadcasters, the ‘tropical bands’, utility communications (essentially anything that is not broadcast or amateur including military communications, transoceanic airline communications, maritime communications, some satellite communications (including weather fax) and much, much more), time stations (such as WWV in the United States and CHU in Canada)
Normally, this will consist of the call letters of the station (for those that use them) and are most frequently noted at the top of the hour. In the United States, all radio stations are required by law to provide a full “legal ID” in English which consists of their Call Letters, immediately followed by the community or communities identified in the station’s license. The only thing allowed to be presented between the call letters and location is the frequency and/or the licensee information. This must be presented on-air as “close as possible” to the top of the hour” in a “natural break in program offerings.” A legal ID in the United States might read: “This is 680 WAAA, Anytown. An Anytown Radiocasting radio station.” Most DXers consider it to be in poor form to add a radio station to one’s logbook without hearing some form of positive identification (normally, the call letters).
The opposition against the flow of electronic current and radio energy that an electronic component or circuit presents. Impedance is measured in ohms. For optimum performance, the impedance of a receiving antenna, the feedline and the antenna connector on the radio should be approximately equal. Impedance mismatches will degrade the performance of the receiving equipment.
Electrically charged and Ionized layers forming a portion of the upper atmosphere of Earth (can be found between 40 to 400 miles or 50 to 600 km above the Earth’s surface), where it merges with the magnetosphere. It is also the portion of the atmosphere which has the most interaction on radio signals in either absorbing, refracting or reflecting them back to the surface. Composed of multiple layers, each with their own characteristics.
Intentional interference caused to radio signals to prevent the intended audience from receiving the signal. This is commonly played out when there are adversarial political relationships such as between Cuba and the United States, between North and South Korea, etc. This can also be done to block programming a government considers contrary to their broadcasting standards such as in the 1960s and 70s the efforts of the British government to jam the transmissions of offshore pirate radio stations.
Radio station programming/content that is in Japanese.
A unit of measuring frequency equal to 1000 hertz; Frequencies for stations in the AM/mediumwave bands are usually expressed in kHz.
A unit of measuring power equal to 1000 watts; The transmitter power of AM and FM radio stations are usually stated in kilowatts and in watts for very low-power stations.
A measure of short-term changes in geomagnetic activity with values that range from 0 to 9; the mid-latitude K-Index is released every three hours. Since K-index is a much more short-term measurement than the longer term A-index, a high K-index is usually a predictor that that A-Index will be going up soon. Like with the A-Index, there are many web sites which gather this and other solar indicator values as an aid to DXers (see the General DX>Solar Conditions area of the DX Central Links page).
A specific type of SDR that is commonly used by DXers for their online capacity, as they are able to be streamed online. This permits a DXer to stream a Kiwi SDR from anywhere around the world to observe radio conditions at that location. This is especially helpful when trying to hone-in on a particular station by trying to find a Kiwi SDR located near the target station. As an example, one night, I was trying to tune in a station located in Venezuela on 780 kHz. By using a Kiwi SDR located on the island of Bonaire (right next to Venezuela) I was able to verify that the programming content I heard on my radio was indeed coming from the Venezuelan station. The proliferation of streaming online receivers has made it possible for DXers to DX virtually from anywhere both as a research and DX aid as well as to answer the age-old question, “I wonder what DX would sound like from….”!
Radio station programming/content that is in Korean.
Shorthand abbreviation for Latin America
In the United States, every radio station is required by law to provide a ‘full legal ID” at the top-of-the-hour (as close as possible to the beginning of the hour, during a natural programming break). This legal ID must be in English and must include the station call letters and city of license with nothing else between them (with the exception of the operating frequency). During sports broadcasts, network announcers usually indicate they are going to “pause for 10 seconds for station identification, this is the _______ radio network”. This is when you should hear the station ID (hopefully, unless the person running the board at the station is not paying attention). Outside of the US, there are varying requirements for providing identification (if there are any at all).
In a general sense, refers to any frequencies below the MW band (below 530 kHz). Many non-directional beacons used for aircraft and ship navigation can be found here. There are an increasingly smaller number of broadcasters that can be found here from 153 - 279 kHz, primarily originating n Europe, the Middle East, Central Asia and Siberia. However due to the high costs of transmitter and antenna maintenance, these stations are becoming increasingly less common.
An antenna made up of traditionally copper wire (though other wire can be used) and of varying lengths. The longer the better to achieve sufficient signal strength and directionality. Differs from a Beverage in that there is no grounding or terminating resistor at the terminating end of the antenna. Shorter antennas are much more unidirectional however less efficient. For most DXers, including the author, this is the first antenna many of us were able to use, stretching a run of copper wire (can be found at most hardware stores in the wire section) out of a window and into and through a nearby tree.
A directional antenna consisting of loops of antenna wire forming a round or rectangular figure. Sizes can vary from small, indoor desktop loops, larger 4-6 foot (1-2 meters) loops on a stand (can be used indoors or outdoors) and larger outdoor loops (such as the W6LVP or Wellbrook ALA-1530 magnetic loops). Loop antennas can either be tuned (which involves tuning the loop to the desired frequency to provide adequate amounts of gain to the inbound signal) or untuned (for more broadband use, though usually requires some sort of pre-amplifier to boost signal strengths to a usable level). Due to the figure-8 receiving pattern found on loop antennas, the main benefit of a loop antenna is the ability to turn the loop to achieve acceptable boost in signal strength from desired stations or (and this can be the more effective option) to “null” or eliminate undesired signals (including local stations, routinely heard stations and noise). Loop antennas receive along their axis and null to their broadside. So, a loop antenna which is oriented to the north and south would favor signals from those directions while attenuating signals from the east and west. Magnetic loops especially are susceptible to having their antenna pattern altered by anything metal so it is best to have them mounted as far from your home as possible.
Lower sideband (LSB)
Used widely in AM/mediumwave DX, this is the lower sideband of a transmitter’s carrier. Many communications receivers, software-defined radios (SDR) and even some portable radios have this feature. If you were looking at a signal on a spectrum display or waterfall on a software-defined radio (SDR), this would be the signal to the left of the carrier frequency of an AM radio station. Can be used to great effect to reduce or eliminate co-channel interference from stations above the desired frequency. For instance, if you have a local station on 1450 kHz, and are trying to DX on 1440 kHz, you can engage the radio’s LSB to narrow the bandwidth of the received signal to only the part of the signal found below the carrier frequency. In many cases, this can greatly or entirely reduce co-channel interference.
Shorthand abbreviation for a low power FM radio station. These are specifically licensed radio stations in the United States and many other countries that serve very specific location/regions. Often referred to as microbroadcasting. Coverage areas of LPFM can sometimes not extend past a few blocks in a city environment.
Local Sunrise Time (LSR)
Defined as the time in a given location which constitutes sunrise. Used in the application of Pre-Sunrise Authority and Critical Hour privileges for radio stations in the United States. Also used in determining sign-on times for stations that are Daytime-only. In the United States, since sunrise times can change daily, the FCC uses the sunrise time from the 15th of the month, adjusted to the nearest quarter hour. So, a local sunrise that occurs at 07:41 on the 15th of the month, the actual LSR of the station would be 07:45.
Local Sunset Time (LSS)
Defined as the time in a given location which constitutes sunset. Used in the application of Post-Sunset Authority and Critical Hour privileges for radio stations in the United States. Also used in determining sign-of times for stations that are Daytime-only. In the United States, since sunset times can change daily, the FCC uses the sunrise time from the 15th of the month, adjusted to the nearest quarter hour. So, a local sunset that occurs at 5:41 on the 15th of the month, the actual LSS of the station would be 5:45.
Maximum Usable Frequency (MUF) Based on propagation, represents the highest frequency allowing for DX reception/transmission. For FM DX, it is a reflection of band openings especially as it relates to Sporadic Es skip. As an Es opening intensifies, the MUF increases, eventually reaching the FM band.
Radio frequencies found between 530-1700 kHz (in the Western hemisphere) or 531-1611/1702 kHz (in the Eastern hemisphere). Only stations licensed by their country’s government body for radio licensing are permitted to transmit on these frequencies. Mediumwave (or Medium Wave by some) is the more commonly used terminology used outside of the United States. Within the United States, this band is most commonly referred to as the “AM” or “AM Radio”.
A unit of measurement of frequency equivalent to 1,000,000 Hz or 1,000 kHz. This is the primary frequency unit used for FM radio frequencies.
A unit of measurement of power equivalent to 1,000,000 watts. There are some stations in Europe and Asia that have powers in this range, though they are not as common as they once were.
Meteor Scatter (Ms)
A propagation commonly found in VHF frequencies and therefore used with FM DX, by which FM signals are refracted through the ionized trails of meteors entering the Earth's atmosphere. Can last anywhere from milliseconds to several minutes.
Can refer to the transmission method of a transmitted signal (such as AM or FM) but also can refer to the receiving mode within a communications receiver, software-defined radio (SDR) or portable radio (AM, FM, LSB, USB, SSB).
The term used for the addition of information to an electronic signal by changing the carrier. In AM and FM radio, this is through changing the amplitude of the carrier (Amplitude Modulation or AM) or the frequency of the carrier (Frequency Modulation or FM). This additional information is the actual programming content of the station and can include music, voice and sounds/tones.
Like Afternoon Drive, this is one of the most listened to periods of time for a radio station and typically runs from roughly 6am to 9am local time. Coined as this is the period of time that most listeners are in their vehicles commuting to their jobs. Depending on the format of the radio station, this can be an excellent time to be able to pull an identification for received stations – especially since this usually also coincides with local sunrise enhancement. Stations that are formatted primarily in News/Talk (especially those with high power) are more likely to have regular traffic/weather updates and these almost always contain some sort of identifying information (“traffic and weather together on the 8s” or “traffic and weather every 10 minutes” are common marketing tools used by stations to lure listeners – but it also works for DXers!)
Mountain Daylight Time (MDT)
Time zone in North America that is UTC -6 (six hours behind UTC time). Only used during “daylight savings” periods from early spring to late fall.
Mountain Standard Time (MST)
Time zone in North America that is UTC -7 (seven hours behind UTC time). Only used outside of “daylight savings” periods from late fall to early spring.
Shorthand abbreviation to refer to music.
Shorthand abbreviation for the continent of North America. Can also refer to National Anthem (NA). In the United States and many other countries, radio stations will sometimes play their national anthem at signoff, at sign-on or sometimes both. Hearing a national anthem is a really fantastic way to help identify a station that you are hearing.
A grouping of radio stations around common programming content. This can be anything from a music station that is part of a news network (national or sometimes state/provincial networks), a station whose format is entirely reliant upon a network (such as a sports formatted station carrying ESPN or other nationally syndicated network content), it can be a sports network that carries a particular sports teams’ games/matches (such as Premier League, National Football League, etc.) or it can even be a network that delivers a specific radio program (Coast-to-Coast AM, Rush Limbaugh, Focus on the Family) that a radio station can broadcast on their channel. Networks usually will have “network” breaks which consist of a combination of network advertisements (carried to all stations down “the line”) and slots for local advertisements (so that a station can sell advertising time on those specific programs). Network content can be tricky to navigate for a DXer, as being that they are often nationally or regionally syndicated, and can go for long stretches without any chance for the carrying station to provide an identification, a DXer can spend a large amount of time on a single frequency, chasing a single station waiting for them to ID. This is especially true during overnight and weekend periods. The proliferation of software-defined radios (SDR) has helped to circumvent this issue by allowing DXers to fast-forward/rewind through content that does not contain identifying information.
Noise blanker (NB)
A feature found in many communications receivers, software-defined radios (SDR) and some portable radios that helps to reduce or eliminate electric pulse noise from a frequency.
Shorthand abbreviation that refers to Nostalgic programming on a radio station. Similar to EZL, although the genre has shifted a bit to include softer hits from The Beatles (think Yesterday), Michael Buble, Pat Boone, Tony Bennett, Louis Armstrong, Harry Connick Jr. Often referred to as “Adult standards”.
A feature found in many communications receivers, software-defined radios (SDR) and some portable radios that allows a DXer to filter certain frequencies that are unwanted from the signal path. This can include heterodynes or even specific frequencies within the programming content (low frequencies, for example). Some receivers/SDRs even have what is known as an Auto Notch Filter (ANF) which will try to eliminate unwanted signals on its own. Many a DXer tuned to a frequency looking for heterodynes from trans-oceanic DX only to find none were there and only later realizing it was because they had their Auto Notch Filter on and it was suppressing those hets from being heard!
Shorthand abbreviation for News programming content on a radio station. This can either be the primary format of the station (as in a News/Talk station) or simply a news update on any station (such as a primarily music formatted station that is doing top-of-the-hour network news).
Shorthand abbreviation for the continent of Oceania.
Shorthand abbreviation that refers to Oldies programming on a radio station. This is often music from the late 1950s to late 1970s from such artists as The Beatles, The Beach Boys, The Rolling Stones, Buddy Holly, Motown artists, etc. There can be some crossover between this format and NOS or CLR in some stations. Oldies stations will often brand as such (“Oldies 92.5”) or carry verbiage such as “Good time oldies”.
Refers to a software-defined radio (SDR) that has been made available to stream online. One of the more popular SDRs for this is the Kiwi SDR and one of the more popular sites to browse available streams is SDR.HU. With this technology, it is possible for a DXer to pull up a receiver that is located close to a station they are trying to target for reception to confirm programming details. It also allows a DXer to take a virtual DXpedition around the world any time they want! The proliferation of SDR technology and online streaming has been one of the biggest advances in DXing in the last 30 or more years!
Refers to a period where there is better than usual propagation conditions to a certain area. For instance, on the East Coast of the United States, one can have an opening into locations such as Europe, Africa, South America, etc.
Pacific Daylight Time (PDT)
Time zone in North America that is UTC -7 (seven hours behind UTC time). Only used during “daylight savings” periods from early spring to late fall.
Pacific Standard Time (PST)
Time zone in North America that is UTC -8 (eight hours behind UTC time). Only used outside of “daylight savings” periods from late fall to early spring.
When a station’s programming is simulcast on more than one frequency at a time, a DXer can use those other transmissions to establish a parallel to confirm receipt of the original station. This is commonly used when identifying Cuban radio stations as their national networks will often transmit on many different AM radio frequencies. For instance, Radio Progresso transmits on 640 kHz as well as 890 and 900 kHz as well. Therefore, if you are hearing Spanish programming content on 640, you can check to see if you are hearing that same content on 890 and/or 900 kHz. If so, you have established that the 640 content is parallel to 890 and 900 kHz (written as //890 and 900). This can also be used when comparing a transmitted signal’s programming with that of an online Web stream of a station’s on-air programming. Web streams are often delayed from the on-air signal anywhere from 2 seconds to a minute or more, but you can still use this method to great effect to confirm the identity of the station being received. A word of caution, though. Syndicated network content does not make for a good source of confirmation, as that same content can be found on any station carrying that particular network. For instance, a station running ESPN sports programming would sound like any other station on that frequ3ncy that is also running ESPN sports programming. Also, note that many stations will run special web stream-only advertising during commercial breaks, so advertising may sound different on on the Web stream when compared to the on-air signal.
A device that combines the signals received on two different antennas, and then allows the user/DXer to adjust the level (or amount of signal) and the phase of the incoming signals in order to develop a steerable null. What these means for the DXer is that by using a phaser, you can null out strong local stations to DX what is left on the frequency without them, or to reduce or eliminate co-channel interference to allow for better DX on those adjacent frequencies. You can also use a phaser to null or boost desired signals on a frequency (even those that are not overly strong), in effect allowing you to steer the antenna pattern created by the combination of the two antennas.
An illegal, unlicensed and otherwise unauthorized broadcasting station, usually broadcasting music. Also commonly referred to as a clandestine.
Refers to whether an antenna transmits/received from a horizontal or vertical position. If a transmitting antenna is in one polarization and the receiving antenna is in the opposite polarization, the receiving end will notice a significant loss of signal strength. There are antennas that are ‘circularly polarized” which contain both horizontal and vertical polarized elements to rectify this situation.
A smaller receiver that can be used portably. Often will have an option to allow it to run on batteries. Some portable radios only cover AM and FM frequencies only, while others can include shortwave frequencies and even VHF aircraft frequencies. Most will have a built-in ferrite rod antenna that is used for AM radio reception. These antennas are normally mounted within the radio so that it is parallel to the horizontal orientation of the radio. As such, you can turn a portable radio along this horizontal axis and it will act in a manner similar to a loop antenna. However, the signals come in to the ferrite rod broadside to the antenna. That is to say, if the radio is oriented horizontally, the two ends are the nulls, while the signals are coming in perpendicular to the radio itself. For shortwave, FM/VHF reception, most portables will include a telescopic whip antenna. Many DXers, this author included, have used portable radios to great effect in logging large numbers of AM and FM radio stations including non-domestic ones! They are a great balance of price and performance for any DXer, especially those new to the hobby!
Radio station programming/content that is in Portuguese.
Short for: pre-amplifier. A feature found on some communications receivers, software-defined radios (SDRs), some receiving antennas, and is sometimes found in external equipment that can be purchased separately. A preamp boosts weak signals, however it is important to remember it will also amplify noise and interference
Normally found in an external unit that can be put in-line between an antenna and a radio, it allows a DXer to tune a receiver’s amplifying circuitry for increased sensitivity on a desired frequency range. Much like the tuning function on a tunable loop antenna, a preselector allows you to essentially add an additional “tuning” to the receiver to the desired frequency, which boosts its ability to pull in weak signals.
The process by which a radio wave or radio signal travels between the transmitting location and the receiving location. There are many different methodologies by which this can occur in both AM and FM DX.
Pre-Sunrise Service Authorization (PSRA)
Authorization from the FCC for daytime-only stations in the United States to sign on at 6 AM local time, even if this is prior to their local sunrise time. This is due to the fact that during certain times of the year, sunrises happen later, thereby cutting short the amount of time – especially during morning drive – that a station can be operational. PSRAs are a way around this for stations to provide programming content to their communities outside of the time that would be normally allotted to them, due to varying sunrise times in winter.
Post-Sunset Service Authorization (PSSA)
Authorization from the FCC for daytime-only stations in the United States to sign off at 6 PM local time, even if this is after to their local sunset time. This is due to the fact that during certain times of the year, sunsets happen earlier, thereby cutting short the amount of time – especially during afternoon drive – that a station can be operational. PSSAs are a way around this for stations to provide programming content to their communities outside of the time that would be normally allotted to them, due to varying sunset times in winter.
Public Service Announcement (PSA)
A commercial aired by a radio station for a non-profit organization or for a government program. Normally “public service announcement” will be explicitly mentioned, most will also mention “the ad council” as well. PSAs can be national, regional and even local in nature. If you hear a PSA that mentions a specific US State, for instance (i.e “the Missouri Association of Broadcasters,” “the South Carolina Department of Transportation” ) that can be a huge help in identifying which station you are hearing.
Shorthand abbreviation for ‘program’. This will usually refer to a specific program within a block of programming (i.e. the Rush Limbaugh Program, the Bill Davis Coach’s Show, etc.).
A series of 2-3 letter codes, each starting with the letter Q, that began in use with the telegraph industry. The codes are used as shorthand for commonly used phrases. Examples include QTH for location, QRM for man-made interference and QSO for conversation.
In addition to top-of-the-hour and bottom-of-the-hour, the quarter hour periods (at :15 and :45 after the hour) are also when many stations will take an advertising break and therefore can be a time when a station may identify. Even if the station does not complete a full ID with call letters, they may present some other sort of identifying information such as a branding slogan, local advertisements (with local business names, phone numbers and addresses) or weather forecast. In addition, since the FCC rounds sunrise and sunset times to the nearest quarter hour, stations that are daytime-only may be noted signing on/off during these times which can also present a fruitful opportunity to try to catch an identification.
A Q-code which dates back to the days of the telegraph, which stands for man-made interference. For AM/FM DXers this can be things such as television, electrical noise, etc.
A Q-code which dates back to the days of the telegraph, which stands for natural interference. For AM/FM DXers, this can be things such as lightning (which AM radio is much more susceptible to), atmospheric noise and noise created by the sun (especially during summer months).
A Q-code which dates back to the days of the telegraph, which stands for “I confirm reception.” For AM/FM DXers, a QSL is a written confirmation received from a radio station in exchange for a reception report sent by the DXer that contains programming details. This QSL serves as verification that the DXer did in fact hear that station. DXers have collected these QSLs since the early days of radio. Though not as common as in past years, stations can and do still send station stickers, coverage maps, advertising rate sheets and other promotional materials to DXers who send reception reports.
A Q-code which dates back to the days of the telegraph, which stands for location. For AM/FM DXers this will normally mean their home location where their commit the majority of their DX. It can also refer to the location of a DXpedition or other non-home location where DX can occur. Also, it can refer to the location of the transmitting station.
Radio Data System (RDS)
Digital text information that is embedded in the transmitted signal of an FM radio station. Radios that have RDS-enabled will display this information to the listener. Each station has a unique PI Code (which is searchable on sites such as the WTFDA database for North American stations) which will display with other RDS information sent by the station. Each station is different but usually will send data such as call letter/slogan or other identifying information, title/artist of the song playing or program information. Can be a HUGE help in rapidly identifying an FM DX station that is being received.
A written description of program details gathered by a DXer and sent to a broadcast radio station in hopes that the station will verify those details in the form of a QSL card or letter. Reception details should include specific information about programming content, specific verbiage used and any other identifying characteristics that will demonstrate reception of the station in question (phone numbers, addresses, local business/advertiser names, weather forecasts and especially any station branding or verbiage during identifications).
Shorthand abbreviation that refers to Religious programming on a radio station. This is a very broad term that can encompass many different variations of programming. It can be used to indicate content that is educational in nature (bible teachings and other discussion-based programming), call-in religious shows, sermons and music. However, in most cases, there is a distinct difference between REL and GOS content.
Radio Frequency (RF)
The oscillation rate of electrical or electromagnetic energy that is found between approximately 20 kHz and 300 GHz. These frequencies are the rate at which an oscillating current (created by information from a transmitter) can radiate from a conductor (antenna) and into the surrounding air (and into the ionosphere) in the form of radio waves.
A control within a communications receiver, software-defined radio (SDR) or portable radio that controls the amount of sensitivity of the radio. The more sensitive it is, the more it is capable to pull in weak signals. However, in the presence of strong signals (such as a single local station or multiple strong stations) it can be beneficial to reduce the sensitivity of the receiver in order to allow signals to rise and fall individually and make them easier to decipher.
Radio station programming/content that is in Russian.
The shorthand abbreviation for receiver/receive.
Software-Defined Radio/Receiver (SDR)
A device that contains the necessary circuitry to decode inbound radio signals, often over a large frequency range, that is then interfaced with a computer and special software. SDRs will have connections for at least one antenna and require an interface software (much of which is available at no cost) to act as an interface with the SDR device. Most SDRs simply connect via USB connection to a laptop, tablet or desktop computer. SDR pricing can range cost-effective options to much more sophisticated and expensive systems with integrated software. Some of the benefits of using an SDR over a traditional communications receiver or portable radio include: the ability to record or schedule recordings of part of or even entire radio bands, extensive filtering and digital signal processing, radio signal visualizations through waterfalls and spectrum displays, the ability to stream SDR receptions over an Internet connection for remote listening capability, the ability to grab screen captures of SDR receptions for documentation or even posting online. The SDR community Is an ever-growing one and new uses and capabilities are being discovered and implemented all the time. Just in recent years, the technology has advanced to allow the performance of smaller, low-cost SDRs to actually rival that of much more expensive and less flexible communications receivers.
Refers to the ability of a receiver to reject signals that are being received on frequencies adjacent to the desired frequency. Measured in decibels (dB). The more selective a receiver is, the more capable it will be at rejecting co-channel interference, as well as being less subject to spurious signals caused by overload from strong local stations.
Refers to the ability of a receiver to receive weak signals and measured in microvolts (mV). With sensitivity, the lower the number, the more sensitive the receiver is. Receiver sensitivity is only part of the equation though when trying to pull in weak signals. The sensitivity of your antenna, the noise at your location, co-channel interference and ground conductivity are just some of the other factors that can impact the ability
Colloquial term used by DXers and amateur radio operators to refer to the room where they house their radio equipment.
Generally speaking, it is the part of the radio spectrum located anywhere between mediumwave and VHF (most commonly 1.8 MHz to 30 MHz). It also is commonly used to refer to the portion of the HF frequencies where one would typically find international shortwave broadcasters (or specifically, the DX of international shortwave broadcasters).
Shortwave Listener (SWL)
Another commonly used term/abbreviation (the abbreviation is the more commonly used) for a shortwave DXer.
Shortwave Listening (SWLing)
Another commonly used term/abbreviation (the abbreviation is the more commonly used) for shortwave DXing.
In Amplitude Modulation, where the carrier wave is at the center of the signal, there are two sidebands on either side of that carrier wave. These sidebands essentially contain half of the information contained within the radio signal (half of the voice, music, sounds, etc.). As such, a sideband refers to a portion of the modulated carrier that is either above or below the center carrier wave. The portion above is referred to as upper sideband (USB) while the portion below is the lower sideband (LSB). By switching to USB or LSB, one can often reduce or even eliminate entirely co-channel interference from local and other strong radio stations.
Single sideband (SSB)
Modulation that removes one sideband and the carrier and transmits only the remaining sideband. This is opposed to an amplitude modulation (AM) transmission in which both sidebands are used to carry a message. SSB (either upper or lower) is a popular transmission method of Amateur Radio operators as well as maritime and aviation transmissions over HF frequencies.
A system used in reception reports by DXers to indicate signal strength (S), interference (I), noise (N), propagation (P) and overall quality (O) of the reception on a scale from 1 (lowest) to 5 (highest). More commonly used by shortwave DXers, but the principles can be applied for AM and FM DXers to better understand the characteristics of the signals they are receiving.
A more simplified version of SINPO to rate reception quality in reception reports. Values are given for signal strength (S), interference (I) and overall quality (O)
A radio station that is in the same or nearby market and owned by the same owner/licensee. Some sister stations will relay/re-broadcast programming on a part or full time basis. This can also be referred to sometimes as a “station group”, especially when there is a combination of AM and FM translators being used.
Used by DXers in general to talk about long distance propagation. Specifically, refers to when a signal travels from the transmitter up to the ionosphere and back down to the Earth. It is called skip because the signal “skips” off the ionosphere and over the area between the transmitter and where the signal can be received again.
Sky wave propagation
The type of propagation being described when radio signals are propagated by refraction in the ionosphere, making one or more “skips”.
What DXers call the meter on a receiver which indicates signal strength.
When there is activity on the surface of the sun, such as solar flares or sunspots, these can cause high levels of radiation to leave the solar surface and travel through space. This activity can have impacts on radio frequency propagation through the interaction of the energy with the Earth’s ionosphere.
An 11-year cycle in the frequency and number of solar active events and sunspots. The downward period of the solar cycle which leads to the solar minimum, is when geomagnetic activity is at its lowest. The upward period of the solar cycle, which leads to the solar maximum, is when solar activity is at its lowest. After several very active solar cycles, Cycle 24 which began in 2008 and has now technically ended, was known for being largely one of very quiet solar activity. There are signs that the transition to Cycle 25 was underway as of late 2019/early 2020.
Measurement of the radio emission from the sun, used as an indicator of overall solar activity.
The period during the 11-year solar cycle in which the highest amount of solar activity occurs. Cycle 24 had a “double peak” maximum in 2011 and again in 2014. The maximum for Cycle 25 should occur sometime between 2023-2026.
The period during the 11-year solar cycle in which the lowest amount of solar activity occurs. In Cycle 24, this occurred in 2009 and again near the end of the cycle in 2017-2019. For Cycle 25, you can likely expect Solar Minimum conditions from 2020-2023 and again from 2027-2030.
In the upper portion of the HF bands and into VHF/UHF frequencies, Sporadic E (or E-Skip as it is most commonly referred) is a phenomenon of random areas of ionization (commonly referred to as clouds) occurring in the E-layer of the ionosphere that allows refraction of frequencies much higher than would normally behave in this way. The summer months are the peak time of the year for E-skip propagation, with a second, smaller peak in early winter. For locations at or very near the equator, equatorial E-skip can last throughout the year peaking around mid-day. This propagation method is used by FM DXers for long-distance FM reception, with reception distances often approaching or exceeding 1,000 miles (1600 kilometers).
Shorthand abbreviation that refers to Sports programming on a radio station. This can refer to a station that is carrying sports programming at the time (such as a game or match) or a station whose primary format is sports. For sports-formatted stations, this can take the form of call-in sports talk shows, host-driven sports discussion shows, live sports broadcasts and replays, and team specific sports content (coach’s shows, pre and post-game shows). In the United States, most sports stations will primarily use syndicated network content (such as that offered by ESPN, Fox Sports, CBS Sports, etc.), though there are some stations that host their own full schedule of self-created sports content (bigger stations such as WFAN-660 New York, for example). Sports stations that carry syndication will usually air sports news/highlights at the top of the hour and randomly throughout the hour. Often during sporting events in the U.S., stations will “pause 10 seconds for station identification” at least once an hour (usually as close to the top-of-the-hour as they can).
A feature found in most communications receivers, software-defined radios (SDR) and in some portable radios that mutes the receiver until the signal strength exceeds a predefined level. This level is set by adjusting the ‘squelch knob.’ For the purposes of AM/FM DX, it is usually something that a DXer would use, it is more often used in the VHF/UHF frequencies on scanner radios (those that are used for monitoring police, fire and EMS transmissions).
Radio station programming/content that is in Spanish. In the United States, even those stations that are formatted entirely in Spanish are required to provide a legal ID at the top-of-the-hour in English.
The period of time starting two hours prior to and lasting until two hours after local sunrise when there is enhancement for signal propagation due to the grayline of the rising sun. This is also when daytime-only stations are signing back on for the day.
The period of time starting two hours prior to and lasting until two hours after local sunset when there is enhancement for signal propagation due to the grayline of the setting sun (this is because of the erosion of the D and E-layers of the ionosphere as well as the merging of the F1 and F2 layer into a single F-Layer that radio signals are now able to bounce off of for greater distance reception). This is also when daytime-only stations are signing off for the day.
A visible area of darkness on the surface of the sun because it is cooler than the surrounding surface. Sunspots can be a visual indicator of solar activity. The more visible sunspots, the more active the sun is, generally speaking (during a solar maximum is when one would generally see the highest concentration of sunspots).
A daily measurement of sunspot activity (R), defined as R = k (10 g + s) where s = number of individual spots, g = number of sunspot groups, and k is an observatory factor.
Time Check/Time Announcement (TC)
Term and abbreviation/shorthand used for when a radio station will verbally give the time on the air. This is most commonly done during the top-of-the-hour and during morning/afternoon drive periods. An example would be “You’re listening to 680 WAAA, Anytown. It’s four o’clock.” or “It’s 4:15, time for a check of traffic and weather together every 15 minutes on newsradio 680 WAAA.”
Television Interference (TVI)
Interference/noise noted on the mediumwave frequencies (FM is less prone) due to oscillations within nearby televisions. Older Cathode-ray-tube (CRT) TVs were much more prone to creating this type of interference than newer televisions are, although plasma screen TVs are still notorious for creating this noise.
When a DXer did not during their DXing session hear a definitive station identification or other definitive information to positively identify a station they are receiving, but they believe they have narrowed down the station, they will mark the log as ‘tentative’ in their logbook. This usually appears as “WAAA (Tent)”. It is often recommended for a DXer to keep a list of these tentative stations handy so they can revisit them at a later time to try to pull a definitive identification so they can update their logbook.
Shorthand abbreviation that refers to Talk programming on a radio station. This can refer to a station that is carrying talk programming at the time (such as a call-in show or talk radio program) or a station whose primary format is talk. While there are exceptions, talk-formatted radio stations are almost always marketed as a News/Talk station. This means that in addition to the talk radio programming, they also provide news updates at the top-of-the-hour and likely throughout the hour (most would even have a news staff at the station to provide local news as well). The vast majority of talk radio programming is syndicated nationally or at least regionally, though there are some stations that have their own local talk show hosts that deal with local news/issues. Great times to try to find an ID from one of these stations is at the top and bottom-of-the-hour and during the quarter hour advertising breaks.
The beginning of a new hour, in DX terms this usually starts 5 minutes prior to and ends 5 minutes after the new hour begins. This is when the vast majority of radio stations will self-identify, normally with their call letters (if they use them) and any other branding information. In the United States, stations are required to provide a full “legal ID” that consists of a station’s call letters and city of license (must be together, although they can provide the frequency between these two, but that is pretty much it). The legal ID in the US must be completed in English and must occur “as close as possible” to the start of the new hour (during a ‘natural programming break”). Outside of the US, there are varying dfegrees of requirements for identification (if there is any at all) but the top-of-the-hour is usually the best bet for hearing a station ID. This is also when stations will generally include news updates, weather forecasts, traffic updates, sports headlines, etc. All of these will normally include some sort of station branding to aid in identifying the station.
Shorthand abbreviation used for the traveler’s information programming content of a radio station. This can refer to Traveler’s Information Stations (TIS) which provide traveller’s advisory information (often near airports or theme parks, for example), stations formatted exclusively for tourists with information on tourist destinations (similar to what you might find on the TV in a hotel) or specific content oriented towards tourists (tourist attraction promotion, discussion, etc.).
Transequatorial Propagation (TEP)
A form of FM DX propagation by where signals cross between locations across the equator. Most prevalent during periods of high solar activity in the evenings, allows for reception of stations 3000-4000 miles (4800-6400 km) from the reception location.
Traveler’s Information Station (TIS)
In the United States, these are stations usually found new airports, theme parks or other tourist attractions or on stretches of highway. They are typically using very low power (sometimes, anywhere from a couple of hundred milliwatts up to no more than about 10 watts) that provide recorded loops of traveler’s information. This can be “highway advisory radio” with information on highway conditions (such as ramp closures, rest area information, etc), relayed NOAA weather radio forecasts, tourist attraction information (hours of operations, parking information, etc.) and other information directed entirely to travelers. Normally, these can be found on either 530 or 1610 kHz, although they are able to be on other frequencies.
Tropospheric Ducting (Tropo)
The propagation of frequencies above 30 MHz via bending through temperature inversion layers and along weather fronts in the troposphere, the lowest part of the atmosphere. This type of propagation happens regularly in coastal regions but can happen inland as well. FM DXers can use Tropo (sometimes called Tropo enhancement) to receive stations from 200 miles away or more, but rarely approaching or exceeding 1,000 miles (except in rare very strong tropo events).
Used by a DXer when they have programming details but were unable to identify the station they were receiving. Unlike Tent, a DXer will use UNID when they have no lead on which station it could be. An example one might see/use would be “580 – UNID – 3/16 at 0100 UTC – Heard fast-talking man in SS mentioning “Radio Victoria” several times at the top-of-the-hour before going to SS mx. Can find no Radio Victoria or anything close on 580 anywhere online.”
Upper sideband (USB)
Used widely in AM/mediumwave DX, this is the upper sideband of a transmitter’s carrier. Many communications receivers, software-defined radios (SDR) and even some portable radios have this feature. If you were looking at a signal on a spectrum display or waterfall on a software-defined radio (SDR), this would be the signal to the right of the carrier frequency of an AM radio station. Can be used to great effect to reduce or eliminate co-channel interference from stations below the desired frequency. For instance, if you have a local station on 1450 kHz, and are trying to DX on 1460 kHz, you can engage the radio’s USB to narrow the bandwidth of the received signal to only the part of the signal found above the carrier frequency. In many cases, this can greatly or entirely reduce co-channel interference.
Radio stations or transmission other than broadcasting or amateur stations. These are not transmissions targeted or serving the general public but are very popular among DXers such as marine, air traffic and military communications.
Very high frequencies (30-300 MHz)
Shorthand abbreviation for a verification (QSL) signer
Known as the distance between identical points in adjacent cycles of a waveform radio signal. Wavelength is inversely related to the frequency so the higher the frequency of the signal, the shorter the wavelength. Wavelength and frequency can be counted as follows: divide 300,000 by the frequency in kilohertz and you get the wavelength in meters (e.g. 300,000 / 1700 kHz = 176 meters).
Shorthand abbreviation for the World Radio TV Handbook. Published annually, this is one of the gold standard publications for DXer use. Has information on radio stations from around the world including those found on both mediumwave and shortwave. Also has equipment reviews and feature articles of interest to DXers and broadcasters alike.
Shorthand abbreviation for weather. This is most often used by DXers to indicate when a station gives a weather forecast on the air or talks about weather during programming content.
Another term used to indicate the “Expanded Band” of the mediumwave band. This is an addition to the traditional AM radio band introduced in some countries in the mid-to-late 1990's (1610-1700 kHz in the Western hemisphere, 1611-1702 kHz in the Eastern hemisphere).
Highly directional antenna type used by FM DXers consisting of a dipole connected to the receiver and two additional elements, a slightly longer reflector and a slightly shorter director. Directionality is in the direction of the director.
An amateur radio abbreviation for "best regards" however it is widely used among all DXers.
Shorthand abbreviation for indicates a parallel frequency (see Parallel)