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Trunk-tracking Scanners FAQ

 Trunktracking Scanners

Question: What is trunktracking and where can I get more information?

Trunktracking is the hobby of using a scanner to follow conversations on a trunking communications system. Trunking systems let a large group of 2-way radio users (or even different groups of 2-way radio users) efficiently use a large range of frequencies. Instead of selecting a specific frequency for a transmission, the user simply selects a talk group. The trunking system automatically transmits the call on the first available frequency and also sends (on a different frequency called a data channel) a code that uniquely identifies that transmission.

Since the trunking system might send a call and its response on different frequencies, it is difficult to listen to trunked communications using a regular scanner. Trunking scanners let you select and monitor the data channel frequency sent with a 2-way radio transmission, so you can hear the call and response for that user and more easily "follow" the conversation.

You can access additional on-line information on Trunk-tracking at:

Please note, this internet site is not affiliated with RadioShack Corporation and off-site information is neither created, maintained nor verified by RadioShack Corporation. Responsibility for the content rests solely with the page owner.

For more detailed information on trunktracking, see our Guide to Trunktracking Scanners.

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Question: How do I convert EDACS SYSTEM ID format (decimal to AFS)?

Our scanners use either decimal format or decimal and AFS format. You can convert decimal EDACS IDs to the AFS (Agency-Fleet-Subfleet) format as follows:

The example below starts with the Decimal ID 0586.

  1. Convert Decimal to Binary
    586 decimal = 01001001010 binary
    ID's are 11-bit binary. If you get a binary that isn't 11 bits, just add leading zeroes until you get 11 bits.
  2. Split the binary as follows #### / #### / ###
    0100 / 1001 / 010
  3. Convert each GID to decimal
    04 09 2
  4. Format as ##-###

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Question: I can't scan an EDACS system, and I know the frequencies are right.

With an EDACS system, the frequencies have to be in a particular order. Also, unless indicated otherwise in the scanner's manual, you should not mix other frequencies in the same bank as the EDACS frequencies. We do not have information on the correct order for specific EDACS frequencies.

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Question: Why does my scanner take so long to pick up data channels?

You are probably operating in a fringe area for the transmission. You would need to improve the signal strength, either by changing locations or using a larger antenna.

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