This is the FAQ section of
The Broadcast Archive

Maintained by:
Barry Mishkind - The Eclectic Engineer
Last Update 11/8/05

A glossary of miscellaneous broadcast terms:  

(See one missing? Share the information!!)


Conelrad - (CONtrol of ELectronic RADiation) 

A "over the air" system to provide warnings and information in case of national emergency. In use form 1951 to 1963. More info here.


Most oldtimers will use this term instead of Hertz, as in kilocycles or Megacycles. This has nothing to do with bicycles. The term was changed to honor Henrich Hertz, whose experiment proved the "wavelike" nature of radio signals.

Directional Antenna

Beginning with WSUN/WFLA in 1932, stations began to use multiple towers to "protect" other stations on the same frequency. Similar to algebra, using different ratios of current and phase angle of signal, the power would "add' or "cancel" in certain desired directions.

In the early days, stations were built and the "reduced" signal observed on the desired angle. The station would then operate with the same "parameters" on a regular basis. Later on, as portable equipment came into use, a number of measurements could be made on each "radial" from the transmission site, to "prove" the shape of the directional array.

"DX" and "QSL"

These terms started as Morse Code "words." DX is an acronym for "distant" and refers to stations distant from the listener. Many DXers send letters to the stations they hear, requesting QSL, or "reception" cards. These cards are then used to verify the listener has heard the station. In the 20's and 30's, stations often sent stamps (not unlike postage stamps) to be placed in a book "collecting" the stations heard. EKKO was one prominent stamp company.

EAS - Emergency Alert System

This system, introduced in the US on January 1, 1997, was to replace the EBS with a more resilient and flexible system that would have fewer "errors" and more information to pass along. 

EBS - Emergency Broadcast System

This system replaced the Conelrad emergency system in 1963. At first, it used carrier interruption to alert monitoring stations, but this gave way in the 1970s to the familiar "two tone" alert signal. With weekly test activations, "This is a test .... " became a regular feature of programming, and the bane of Program Directors.

EKKO Stamps

A series of stamps sent out to listeners who reported hearing a station. Very popular in the 1920s and 1930s, the EKKO Company in Chicago, IL, manufactured both the stamps and albums for saving them, selling the former to radio stations and the latter to listeners. Similar stamps were produced by the Bryant Company, also in Chicago. .

ENG - Electronic News Gathering

The procedure of collecting news and feeding it back to the studio by electronic means. Often these crews are identified by their vans, with a hydraulic piston microwave antenna system to relay back to the main station, but also can include satellite trucks and even just a car with a portable tape recorder, either audio or video.


kHz is an abbreviation for kiloHertz. The term Hertz, named for the inventor, refers to the number of times an electrical signal of alternating current "crosses" the "0" line and changes from positive to negative and back to positive. Human hearing is nominally in the 50 to 15,000 Hertz range. A kiloHertz is 1000 Hertz (15,000 Hertz = 15 kHz). Frequencies above about 100 kHz are said to be in the "Radio Frequency Range" as they are used for transmitting sonic or digital information.


MHz is an abbreviation for MegaHertz, mega taking the meaning of 1 million. So 1,000,000 Hertz = 1 MHz.


Many sources claim this to be an early telephone company term, which referred to remote broadcasts as those "Not Emanating from the Main Office." Many older consoles have this label to the selectors and pots used for remote broadcasts. On the other hand, the name of the captain from 20,000 Leagues Under the Sea may be a good clue. Nemo in Latin means "no name" or "no man."

"PSA" (later PSRA)

Dan Strassberg reports: I don't know when the FCC instituted the current system of PSRAs for AM daytimers (and also for full-time AMs that don't like their night DA patterns). My guess is that it wasn't until sometime in the late '60 or early '70s that the FCC added the requirement for a special pre-sunrise authorization document (the PSRA) for stations that wanted to run a different power and/or pattern than their normal nighttime facilities during the hours between 600 AM local time and sunrise (whenever sunrise was later than 600 AM local time).

In fact, I remember that it took a few years after the PSRA system started before the kinks in the timing were worked out, because the original rule specified 600 AM local STANDARD time, which meant that in certain parts of the country, a PSRA didn't allow a uniform year-round sign-on time--which was the main object of PSRAs. The solution was to replace the regulation's reference to local standard time with a reference to local time. This change also solved (after the fact) a problem created in the 1973 energy crisis, when daylight-savings time was put into effect throughout the winter. That winter, some stations that weren't eligible for PSRAs were allowed to sign on an hour before local sunrise--initially with 50W. I remember that WLIB New York City (then a 10-kW directional limited-time station, which normally operated from New York sunrise to Fort Wayne IN sunset) complained that, even with its directional signal, which was designed to protect WOWO from daytime skywave and deliver a strong signal to the east over New York City, it couldn't be heard in Manhattan from its Jersey Meadowlands location with only 50W. So the FCC increased WLIB's emergency pre-sunrise power to 214W.

Before PSRAs (originally called PSAs because there were no PSSAs, that is, post-sunset authorizations), Class IB and Class IIID stations were allowed to begin using their normal daytime pattern and power at 400 AM local standard time unless another station claimed that such operation caused objectionable interference.

The PSRA moved the 400 AM power-change/sign-on to 600 AM but limited the power to the lesser of 500W or a lower power based on a formula that was intended to prevent objectionable interference to Canadian stations and in some cases to US Class I stations. PSRAs enabled a few Class IID stations located east of the dominant co-channel Class I station and within the class I's 0.5 mV/m 50% skywave contour to sign on at local sunrise for the first time, but often with reduced power. Some other Class IIDs in the same situation did not benefit because they had always been allowed to sign on at local sunrise with full daytime facilities. Many Class IID stations located west of the dominant Class I were finally allowed to sign on at local sunrise at the dominant station but usually with less than their full daytime power. Until the advent of the PSRA, the early sign on for such stations was reseved for a few legacy stations on the west coast, such as KFVD (now KTNQ), KFAX, and KXL.

Eventually, the PSRA system was applied to full-time stations, many of which found that operating between 600 AM and sunrise with their day patterns and only 500W permitted them to cover their markets better than they could when running the night pattern and higher power until sunrise.

There were other wrinkles, including a short period when some US stations were allowed to run pre-sunrise powers higher than 500W if the station they were protecting was in Canada and the formulas indicated that a power between 500W and the normal daytime power provided adequate protection.


Post SunSet Authority.  Started in198x, this permitted daytime stations to stay on in the evening, with a series of power levels specified from sunset to late night. Some stations got more than enough power to be useful. Some got as little as a watt, into a directional array. Perhaps the lowest power authorized (it likely was not used) was 0.6 watts.  A much better deal for some stations than others.

QSL Cards

QSL cards are usually postcards with a station's call sign and data. These are sent to listeners who report receiving a station. Some stations will actually send a letter on station letterhead, others will send various combinations of information and maps.

RPU - Remote Pick Up

An RPU system is used by radio and television stations to get programming back to the studio from a "remote" broadcast. This may be a news story, sports event, or "personal appearance" at a clients business. RPU frequencies normally run in the 160 or 450 MHz band, TV in several GHz bands.


SCA is Subsidiary Communications Authority or, in other words, an audio subcarrier on a main station, usually FM. For many years, this was the way Muzak was distributed. Today, many private services can be found on SCA channels, from foreign language programming to radio reading services for the blind.


A simulcast is when two stations run the same program at the same time in the same city. This was common practice in the early days of FM, when stations tried to save money by running the same material on AM and FM. In an effort to reduce the spectrum waste and promote variety of programming, on October 15, 1965, the FCC made a ruling demanding that at least 50% of all programming on each station be "original." The practice has been revived in recent years as station groups try to use multiple stations to cover some growing markets. WTOP in Washington, DC, for example bought an AM and an FM in the suburbs to carry their signal. (According to some reports, the simulcasts can reach more people than the original station!)

STL - Studio to Transmitter Link

The term is usually used to refer to a microwave link, most often in the 950 MHz range. However, technically, it can refer to the phone line or any other method of getting the program from the studio to the transmitter.


Your brother wears dresses. 

TRL - Telemetry Return Link

Also called TSL or Transmitter to Studio Link. This term refers to methods used to get meter readings, status and alarm settings, and other information back to the studio from the transmitter site. Often in the 450 MHz range, these links can be used with a "control link" on the STL to eliminate the need for phone lines to the transmitter site.