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Milcom Receiving Equipment

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Revision as of 15:30, 26 November 2020 by Ka3jjz (talk | contribs)

The VHF/UHF Milcom Receiver

A receiver for monitoring VHF and UHF Milcom must cover, at a minimum, the 225-400 and 138-144 mhz ranges. Mil flights sometimes also use the civil air band (118-136 mhz) range. With the exception of the civil air band (where AM mode is the norm) and the VHF Low/162/406 Mhz bands (FM), either AM or FM mode transmissions may be heard in these ranges, so the ability to change mode independent of the frequency being received is very important.


If you are using a scanner, one with a fast scan rate is necessary when scanning a large number of milcom channels. Most milcom aircraft communications are short in duration, and after a while you will be accumulating and scanning a large number of frequencies. What qualifies as a 'fast' scanner is subjective. As an example, the Uniden BC780XLT is a popular mil air scanner which can scan 100 channels per second.


Good sensitivity in the above frequency ranges is a must. You will be receiving milcom aircraft signals originating from hundreds of miles away, and they can be relatively weak. Dynamic range (resistance to overloading) is also important, particularly if you live in an urban area. This will help you avoid hearing signals such as FM and TV where they don't belong. It's not unusual to find that you need to add filtering for FM or TV frequencies. This is very much determined by your local RF environment, and should be considered on a case by case basis.


Software Defined Radios

This is easily the king of the hill. Very fast searches and flexibility are just two attributes; in addition you can get a RTL-SDR for next to nothing. See our Software Defined Radios article for a great deal more on this subject, including links to applications and plug ins.


Hobby level SDRs have a serious fault with overloading. Most simply don't have enough filtering in the front end (or any at all) to prevent FM, TV and other signals from intruding.


Widebanded Radios

Scanners

This is where milcom scanning started, and still has a large base today. Various models can be found on the Uniden Scanners and Whistler Scanners pages. Be sure to check their specifications carefully - older models such as the BC796D can't trunktrack in the 380 Mhz band, where many bases have installed Project 25 systems. Some can't change the mode indepedent of the frequency (for example the 138 Mhz band is set for FM mode and it can't be changed).


While Radio Shack Scanners and GRE Scanners are an attractive alternative, keep in mind that both companies have left the scanner market. Therefore getting any servicing might be very difficult. In general, these scanners have more issues with overloading than the Unidens.


Each of these manufacturers are extensively covered in the RadioReference forums. Be sure to ask your questions there.


Antennas

Antennas for milcom cover a large amount of frequencies. Sometimes (especially in urban areas) this can contribute to hearing signals where they don't belong, especially when using radios (or even SDRs) with poor resistance to overloading. Additional filtering is often required in these situations. See our Scanner Accessories page for links for various kinds of filters


Here are a few examples of widebanded antennas. See our Scanner Antennas page for antenna links as well as coax suppliers.

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