There may be occasions when the reader is on-scene at a location, and need to determine the extent of radio frequency spectrum usage. Elements of interest may include fixed, mobile, and portable assets over a typical frequency range of 25 MHz. To 1.3 GHz.The following article is an example of the material that will be appearing in future issues of Signal-3. Subscription information for the new digital format is available at:
In the United States, OSINT can be used 99% of the time to determine the frequencies licensed at a particular location. The primary source is the FCC General Menu Reports page on the Internet. From there, the researcher can enter in latitude and longitude coordinates to get a listing of all FCC licenses in a given location. This will not account for Federal Government radio transmitters, amateur radio repeaters, or transmitters that are unlicensed for whatever reason. It also will not tell the researcher what frequencies are actually actively transmitting at the location. To determine that, the researcher will need to conduct a field exercise.
The most common tool used for on-site frequency determination is a police scanner with nearby signal detection capability. They are known by the trade names “Close Call” (Uniden/Bearcat), “Signal Sweeper” (Whistler), and “Signal Stalker” (Radio Shack). For the purposes of this article, they all function in the same manner and are referred to as “CC/SS.” With a Radio Shack #20-032 Magnet-Mount Scanner Antenna (or similar unit), the operator should be able to receive transmissions from a tower location at line of sight distances of up to one mile with the scanner's CC/SS function. Busy frequencies will be detected in short order. Less active ones will take longer. Some CC/SS scanners have an auto store feature that will automatically record CC/SS hits into memory. A scanner with said function could be left in a hidden location and recovered at a later time. The disadvantages to using a CC/SS scanner are:
1. The operator is limited to the frequency coverage of the scanner itself.
2. The operator will be unable to detect certain digital signals.