Uneven audio on astro systems

[PhillyPhoto]

One of the counties near me is on a 3600 baud UHF smart zone system, and I've been monitoring for a while and noticed certain units audio is louder when they talk than everyone else. I figured it might just be their system since it's UHF and almost everyone else around is 800 mhz, or because I was listening on a scanner. Then last week I went out to Detroit, MI and was hanging out at the fire house and noticed the same anomolies occuring on their 9600 baud 800 mhz system. So my question is, does this issue have to due with programming of the radios, or is it a malfunction withing certain radios, since it's happening on two different types of systems on two different bands? I'm not sure if this is because of the "audio gain" options or not.

[mr.syntrx]

I hear that around here all the time, with users on a mixture of identically programmed XTL5000 and XTS5000 radios with the same firmware versions. I'm guessing it's just something to do with the way the vocoder responds to different voices.

[Bruce1807]

Thats actually a a fact on things.
When the early TBRO came out my old boss in the UK said great but it wouldnt work with an Irish accent.

[Jayce]

I've noticed a big difference in the audio between analog and digital talkgroups. The digital ones are definitely louder. There is a setting in the XTS's to balance digital/analog audio but I haven't noticed a great deal of difference.

[sparks5011]

There is a programming adjustment in the radio to set AGC levels. As it comes from the factory it is disabled. When properly programmed it will limit the louder speaking users to a programmed level, and its supposed to help bring up the audio on the softer speaking users. Sometimes it works, most of the time it doesn't. I've heard it pump up background noise (engine roar, sirens, air horns etc.) to the point you couldn't understand the person speaking into the mike. The wonderful world of digital !

[Pj]

There is a SRN out, that states turn on AGC, set the levels to 0, but the total output to +6.

[Rayjk110]

Hmm...AGC should help, but - I guess they'll have to get the radios upgraded to support AGC, if the problem in the first place is an older host/dsp rev issue, which in that case won't support AGC then....if that makes sense.

[DPL]

I don't actually own any Astro radios myself, but on the scanner I hear the same uneven audio problems on the local digital system. Some groups of users I know for a fact are using AGC, and I still hear people who sound like they are going to blow out my speaker if I don't turn the volume down.

[Pj]

SRN 1370

Radios for this to work are:

Astro Spectra
Host 11.01.01/DSP 7.03.90/CPS 1.0/RSS 8.5

XTS3000/Astro Saber
Host 7.01.01/DSP 7.03.09/CPS 1.0/RSS 8.5

XTS2500/XTS5000
Host 1.04/DSP 1.04/CPS 1.01

XTS3500
N/A

There are very similar firmware releases for the ASTRO25 XTS3k/Saber/Spectra's.

[PhillyPhoto]

SRN 1370

Radios for this to work are:

Astro Spectra
Host 11.01.01/DSP 7.03.90/CPS 1.0/RSS 8.5

XTS3000/Astro Saber
Host 7.01.01/DSP 7.03.09/CPS 1.0/RSS 8.5

XTS2500/XTS5000
Host 1.04/DSP 1.04/CPS 1.01

XTS3500
N/A

There are very similar firmware releases for the ASTRO25 XTS3k/Saber/Spectra's.

So does that mean if the radio was older firmware, you get the loud audio?

[Pj]

It means that the AGC feature is not available in those radio's with lower or 512k firmware.

What the SRN essentially states, it "flattens" the audio from the radio. If you have a loud talker, it brings down the audio, and likewise for a soft talker.

On non-AGC radios, if you talk loud or soft, it will be very noticable.

Either way, it must be enabled in CPS/RSS. It is not enabled by default.

I forget what site, but there was a very good example of this with a LAPD chase with an air unit. The field units (don't know if AGC is implemented fleetwide at LAPD) sounded pretty level, but the helicopter was def loud.

[PhillyPhoto]

OK, but in the end there's nothing a receiving radio or scanner can do to limit the volume being received? That sucks, oh well.

[bellersley]

That isn't totally true. Some scanners and radios have AGC for RX. It is MUCH better if the transmitting radio has AGC enabled as well, but having it enabled on RX does make a signifigant difference. I tried that SRN on my radios before and it makes a world of difference.