TRX-1: Hytera XPT on TRX-1 and BCD436HP

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kh6sz

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This problem has really got me stumped. Recently one of the casinos on the coast here switched from conventional to Hytera XPT. Here is a link to the FCC license info:

ULS License - Industrial/Business Pool, Trunked License - WPHV318 - GRAND CASINO HOTEL BILOXI - Frequencies Summary

I found out that 5 frequencies are activem and programmed them in conventionally and in a MotoTrbo Trunk network on my 436 and also programmed them into my TRX-1 in a DMR system. I was several blocks away from the site today (at another casino) and had both scanners monitoring it at the same time for several hours. When I got home, I reviewed the results and found that on the 436 Mototrbo trunk it picked up nothing (expected because no LCN's are entered yet), and the conventional gave me several talkgroups (Numbers from 3-13).

Then I reviewed the TRX-1 and it gave me talkgroup numbers from 4194307 through 4194315. The User ID numbers for both radios were the same, in the 1100-1300 range.

Is the reason for the difference because of the way I programmed them, or does each radio handle the talkgroups in a different way? This is the first system that was different between different scanners. Any help would be appreciated. Thanks!
 

slicerwizard

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Scanner manufacturers haven't figured out how to properly handle XPT.

Let's see, 4194307 in hexadecimal is 40 00 03; there's your talkgroup 3.

4194315 is 40 00 0B; B=13; hello talkgroup 13.


Protip for any scanner manufacturer out there: XPT talkgroups only use 8 bits; when monitoring an XPT system/channel, decode talkgroup fields accordingly. And XPT signals can be recognized by looking for Hytera's MFID as well as Hytera's XPT-specific messages. It's not like you have to decode the messages, just acknowledge their presence.
 

kh6sz

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Scanner manufacturers haven't figured out how to properly handle XPT.

Let's see, 4194307 in hexadecimal is 40 00 03; there's your talkgroup 3.

4194315 is 40 00 0B; B=13; hello talkgroup 13.


Protip for any scanner manufacturer out there: XPT talkgroups only use 8 bits; when monitoring an XPT system/channel, decode talkgroup fields accordingly. And XPT signals can be recognized by looking for Hytera's MFID as well as Hytera's XPT-specific messages. It's not like you have to decode the messages, just acknowledge their presence.

Thanks so much Slicerwizard.
It looks like the 436 is converting the talkgroups fine, but the whistler just left it as is. I don't think there is any settings in the ez-scan program to correct that, but I'm just putting something like '4194315 CH 13' for the alpha tag so I can compare radios.

I haven't tried using DSD+ FL on the system yet, will have to fire up the laptop and give it a try next time I'm over that way. Thanks for the great explanation, even I understood it!
 

slicerwizard

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No prob, happy to help. Looks like you're handling it as best you can for now.

BTW, I suspect that that 40 might be something similar to a home repeater ID (like LTR uses), but one would need to find a multi-channel XPT system where groups were homed across several channels; group calls would tend to be carried on their home channels, allowing one to deduce how home channels are encoded into the various messages, what each repeater's channel ID was, and so on. If XPT does use home repeaters, then that repeater ID would have to be part of each true group ID, e.g. something like 1-13 instead of just 13. More stuff for the scanner manufacturers to figure out and get right.
 
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