Motorola ASTRO XTS/XTL programming question

[Hexem]

Hi all, apologies if this post is in the wrong section. I have used the search function which did not return any results.

I've been programming my (and others) xts and xtl series radios for a number of years now (from the old DOS system to the new CPS) and one setting in the programming alludes me.

I our area we can still rx NSW Police chatter on the digital network. No encryption yet. Anyway, When receiving the local NSWPol communications (in digital) when the operator sends out priority (1 and 2) call alert beeps, the radio (xts and xtl series) does not receive the beep as an audible tone, rather a garbled tone mixed with the digital. I've been informed that the single or double beep should be loud and clear like it use to sound when it was in analogue.

I've tried many different combinations in the software, from Squelch type, Rx options, ASTRO, Mixed etc, digital modulator type and Rx unmute rule. The console operated beeps (tones) are washed out in the digital rx audio.

Can anyone shed some light on this or point me in the direction of a post which covers this issue please?

P.S. I'm using ASTRO CPS R20 for xts5k and xtl and CPR R05.03 for xts3k.

Cheers
Hex

 

[Mars]

If the dispatcher is sending an analog alert-tone through the DIU or through the MCC7500, etc (on a new system), it will always sound like crap because the tones are analog, being encoded with IMBE, which was never meant to encode those audio frequencies.

If they're sending out call alerts, it's likely as a group call. The radio will beep and the dispatch can then talk. Radios can be configured to utilize minimum volume levels for the alert tones. This way if a user has their volume turned down, the tones will still be loud and clear.

Finally, updating the firmware to latest versions may help with certain audio issues.

 

[tsunami_australia]

Hey Hexem, Mars. Yes the VKG tone sounds like crap over digital radio and I think Mars might be on the money with the analogue tone generator. If it were a group call there should be no tone via MDC1200 as far as I'm aware over P25. I have my XTL5000 set to decode groups etc and read the radioID (assuming it is still done via MDC) and I've never had a beep.

There is 3 parts of stuff all you can do about the tone. It sometimes on my radio in the car sounds like the warbley crap you get on fringe reception (codec issues in re-assembling the tone I'm sure).

Not sure if you are aware Mars, outside metro areas VKG (NSW Police) have been shifting to P25 clear over voting for anything in the future . I get some interesting noises at times and the same crappy tone decode (though not quite as bad as the XTL5000) using DSD+ on the desktop computer using an old Pro2039 200ch scanner (dinosaur). The same results via a realtek USB tv tuner using SDR.

 

[Hexem]

Mars,

Sorry for the late reply. Thanks for your information, as mentioned by tsunami the tone we believe is an analogue tone single pitch and can be a short or as long as the operator wants it to be. A mate of mine in the job confirmed with me that he receives the tone/beep loud on his portable at work so it might be the way the comms centres are sending the tone out (digital or in the clear analogue).

tsunami, there is an online P25 digital scanner running up your way which when the priority calls go out (1 or 2 beeps) it is a clear tone not a warbled tone mixed in with the digital. My XTL5000 sound the same as the portable.

Cheers
Hexem

 

[MattSR]

NSW Police are sending the analog alert tones out through a DIU3000. I have compared this on multiple receivers and the break up is occurring on the transmit side - i.e. it's totally to do with the analog tones going through IMBE and getting mangled in the process.

Not much you can do about it

It sometimes on my radio in the car sounds like the warbley crap you get on fringe reception (codec issues in re-assembling the tone I'm sure).

Kind of - xMBE codecs can only encode a limited number of "frequency bands" - say you put a 1006Hz tone through the codec, it will get encoded as the nearest possible tone - which I think in this case is 1011Hz. The problem is that the codec sometimes has trouble deciding exactly which frequency band the source tone resides in and can chase its tail with the internal pitch tracking algorithms etc which results in an audible "breakup" - the codec is trying to decide exactly what frequency the source is. This isn't a problem with voice as voice pitch changes constantly so as the voice frequency moves between these frequency bands, there is a small step which is called Quantization. The fact that the voice is moving quickly masks this to the human ear, but when the BER is high or there is a glitch, it is this Quantization that makes digital audio sound robotic.

Cheers,
Matt

 

[tvsjr]

We have several systems around here doing the same thing. My city still uses QC2 for station alerting and volunteer paging, but they simulcast this out their 700 P25 phase 1 system as well. It results in some very interesting warbly audio... even better when the VHF radio hits on the VHF side and the 700 radio hits on fire dispatch simultaneously in the truck!

 

[tsunami_australia]

- xMBE codecs can only encode a limited number of "frequency bands" - say you put a 1006Hz tone through the codec, it will get encoded as the nearest possible tone - which I think in this case is 1011Hz. The problem is that the codec sometimes has trouble deciding exactly which frequency band the source tone resides in and can chase its tail

That makes a lot of sense, so it works like band pass filters per-say where it matches the closest modulatable tone.. Also since most spoken words are short you wouldn't get to notice it I'd imagine. The human voice sounds very different over digital due to the selection though.

Hexem, forgot to mention it's not just 1-2 beeps. I've heard 3 before but rarely, generally officer down or in strife.

As for the online scanner, if it is coming from Port Macquarie, they are still AFIAK working 78mhz WFM for the moment but have P25 off Middle Brother for both Oscar (Kew north) and November (Kew south). Oscar and Papa seem to be 100% joined at the hip now so it is Kew to the border and on a quite night they link O+P with N and makes for a noisy night (VERY big area, like ALL NSW east coast and mountain range north of Newcastle up to the border, say 9hrs drive from southern to northern boundary for the non local folks).

 

[MattSR]

That makes a lot of sense, so it works like band pass filters per-say where it matches the closest modulatable tone.. Also since most spoken words are short you wouldn't get to notice it I'd imagine. The human voice sounds very different over digital due to the selection though.

Correct - Pitch Estimation algorithms form a large part of the xMBE code - that's why it's called Multi-Band Excitation - it measures the energy in each frequency band and maps each band to a function of the Nyquist rate (8kHz for IMBE)

 

[Hexem]

Is there a Display Light Time option for XTL5000 with W3 HHCH (same as for XTS portables)?

I've checked the usual locations in the CPS and not having any luck. I'm guessing you can't set an off time.

Cheers