TRX-2: Need help with receiving dmr con+

[phil81]

Hi all,
I'm trying monitor a local bus service which comprises of programming of tgid's and rid's. They work on con+ system over 2 sites. First I just programmed all the freq's in one site (trunk radio system) so could just scan everything, also made another v-scan folder with the sites separate and lcn's in correct order with all the tgid's and rid's duplicated for both sites.

If I had nothing to compare it to , I would think it's working fine. However I have it runing side by side with a bcd536 programmed up exactly the same , in the same environment. I would say 30% of the time I miss the start or the end of the conversation and the odd time the completely miss it compared to bcd536. Then other odd times it will pick up the conversation and the uniden hasn't but no where near as much as the trx-2 recieving. Its there any fine tuning I need to do or settings I'm missing?? Please let me know what I can do to try resolve this problem.

Regards
Phil

 

[Ubbe]

When a user release his PTT the Whistler scanner starts to scan all frequencies you have set for that site and hunt for the talk group to get active again during the delay time.

What you should do are to have all sites separeted so it only scans one sites frequencies when searching for a TG as that will be much quicker than to scan all frequencies. Then you should not miss the beginning of conversations.

Set all TGs and IDs delay to 5-10 seconds. Then you will follow all conversations to the end.

Don't set the squelch level any higher than 10.

I have several DMR radios, a BCD536 and a TRX-2 scanning pretty much the same DMR systems and I would say that the TRX-2 receives 95% of conversations and the BCD536 90% if I set system hold to 3 sec on the Uniden. The TRX-2 have a poorly working squelch so it doesn't open up on weak signals, which is neccesary as it doesn't do digital decode if the SQ is closed, and the BCD535 just skips over active conversations when it feels like it and needs the control channel data to be decoded during a long hold time.

/Ubbe

 

[phil81]

Thanks for tips Ubbe,
I have set the delay to 5.5sec and squelch to max, and can report it has made quite a difference. I find having 2 sites (one 5 ch the other with 8ch) opposed to having individual sites for every frequency, works better for me. Does the dwell time setting need adjustment for more fine tuning? will it make any difference ?

 

[Ubbe]

As I understand the TRX scanner it scans all frequencies of one site when it reaches a DMR system and if one frequency opens the squelch it will decode the data. If the data says that it is an active TG where someone are transmitting it will check if the TG matches any of those programmed and in that case starts monitoring it. If the data says that a TG are in idle state it will ignore it and check the next frequency and eventually go to the next site.

If you set a longer dwell time it will check all site frequencies over a longer period of time and any TG's in idle state might get active with conversations and also the chance of hearing the start of a dispatcher call increase, but then the risk of missing calls in other systems also increase. It's a balance that you have to make and normally you use deafult and only increase dwell on those systems that are important to you.

As soon as the TRX scanner monitors a call the dwell is ignored and it's the TG delay that are used for the remaining time on that site. When that delay runs out it scans thru the remaning sites for active calls and then leave that DMR system.

/Ubbe