Learning digital scanning

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chaser3007

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I have had scanners just about all my life. But; I am lost when it comes to this digital stuff. Can anyone give me a newbie's understanding of this side of scanning? All the stuff about talkgroups, programming via your computer. Hmmm I am not stupid but .... Also; I live in VA where I have APCO25 system for Fairfax County, Montgomery County all use this Motorola Project 25 trunked system for all public safety communications and DC uses an ASTRO Trunking System. Most talkgroups on this system are P25 digital. So; if I buy a scanner that says it's APCO25 will it work for this P25 and so on? I am really looking forward to getting back into the world of scanning so any info is appreciated.
 

gmclam

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Happy New Year and Welcome to RadioReference.com !!!

I have had scanners just about all my life. But; I am lost when it comes to this digital stuff. Can anyone give me a newbie's understanding of this side of scanning?
I look at it this way; you have AM, FM and digital. that might be oversimplistic, but that's a good place to start.

All the stuff about talkgroups, programming via your computer.
Talkgroups (TGs) are like an "extension phone" on a PBX phone system. A big company might have 10 incoming lines, but 100 extensions. While only 10 people can talk at the same time, that is all that is usually needed.

TGs are not specifically related to "digital". TGs come in to play with "Trunked Radio Systems" (TRS). Scanners made so far can only handle 3 different types of TRSs; Motorola, EDACS & LTR.

In the old days we had 8 or 16 crystals controlling our channels. We pretty much could remember those channels. Then scanners became programmable; and before trunking they were about 200 channels and still not hard for most tru hobbysists to remember. But with 500+ channels and trunked systems with another 100+ TGs, remembering the codes became tough.

So someone came out with "alpha tagging". Basically being able to add a TEXT phrase for each channel. Now instead of programming 1000 frequencies, there are also 16000 characters for the alpha tags. Too much to do realistically by hand. Computers make it a whiz.

Hmmm I am not stupid but .... Also; I live in VA where I have APCO25 system for Fairfax County, Montgomery County all use this Motorola Project 25 trunked system for all public safety communications and DC uses an ASTRO Trunking System. Most talkgroups on this system are P25 digital. So; if I buy a scanner that says it's APCO25 will it work for this P25 and so on? I am really looking forward to getting back into the world of scanning so any info is appreciated.
When it comes to digital TGs, there will be a "mode" indicator next to each ID in the database. If the mode is "A", it is analog. If the mode is "D", it is digital. If the mode is "E", it is digital encrypted and can not be monitored.

Assuming the TGs can be monitored, the next step is having a scanner which can "track" them during a conversation. What happens is that each new transmission is typically assigned a new frequency. So if you're using an old non-trunk-tracking scanner, you can pick up the individual transmissions, but you won't get the IDs and the scanner won't follow it from frequency to frequency.

There are some systems out there which can not be tracked and some which can not be scanned. Hopefully someone from your area will chime in and answer that part of your question.
 
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