Searching for Milcom Activity
From The RadioReference Wiki
Milcom frequencies are not published by most governments. Activity is usually found by searching the 225-400 MHz range, and then identifying what you hear on a consistent basis. So, searching this range is a good place to start.
Searching large ranges of frequencies is easy with a Software Defined Radios using plugins like Frequency Manager Suite. This is impractical for a scanner simply because they can't scan as fast as a SDR. A better technique is to break up this band into a number of search ranges for more efficient searching. One way to break up this band is:
- Search range 1: 225 - 275 MHz
- Search range 2: 275 - 325 MHz
- Search range 3: 325 - 380 MHz
You can further divide these chunks into smaller ranges to suit your receiver's search abilities. Also, milcom aircraft communications use a 25 kHz interval. This is important; setting your step size to 25 kHz allows for faster searching and reduces the chance you'll miss a comm (smaller step sizes means longer searches). This thread contains ready made, bulk frequency files in various formats
Logging your Milcom Hits
Before long, you will accumulate a large number of milcom frequencies. However, not all of these frequencies will be active all the time, especially if you're not located near a region with a high amount of milcom activity. For example, NORAD frequencies may only be active during certain exercises, as opposed to aerial refueling which happens on a more regular basis.
Logging your milcom activity can help you identify the frequencies that are more common for your area. You can do this if you have software that supports frequency logging for your receiver. Log the milcom hits on your programmed frequencies on a daily basis, over a period of a week or 2 (or longer). After a while, you'll accumulate a set of "primary" milcom frequencies for your area. The same technique can be applied to searching as well.
Along with logging, recording activity is a convenient way of capturing what you hear for later review and retrieval. We have several packages compatible with many different scanners in the Recording Software and Tips and Radio Control Software articles for software and various hints and problems with feeding your scanner audio to your PC.
You should be aware that many older GRE/RS scanners cannot scan and log or record - it's simply not in the firmware to allow for this function. Exceptions include the RS Pro-2052 (which has Uniden firmware), It should be noted that both GRE and RS have left the scanner market (the GRE scanner web page is still around as of this writing, but for how long, it's impossible to say), so any support for these radios may be hard to come by.
The 380 - 400 MHz Range
While aero operations and other modes can be heard here, various military and federal users have established APCO-25 trunked systems in this band. Software Defined Radios should be able to handle this with software like UniTrunker or SDRTrunk. See the Trunked Radio Decoders article for more information.
Scanners, however, are a different matter. Support for 380 Mhz trunking didn't start until Uniden released the BCD396T and GRE produced the PSR-500. Scanners older than this will be unable to trunktrack in this band. This includes Radio Shack's Pro-96 and Pro-2096, along with Uniden's otherwise popular BC796D, BC785D, BC296D and BC250D. GRE's PSR-300 and PSR-400 are also incapable of truntracking here. Most all of the newer scanners (including those by Whistler, which bought out GRE and RS's designs) will be able to trunktrack here