Pro-96 won't mute after receiving digital signal

[rescue161]

I'm having trouble getting this scanner to mute and resume scanning after it receives a digital signal on a conventional frequency.

It's not squelch/white noise that I hear after a transmission, it sounds like a full quieting signal. If I turn the squelch down, the rushing squelch/white noise comes through and then once I turn the squelch back up, it scans normally.

If I hit any button during this failure to mute, it resumes scanning as normal.

I've used a few different radios to test it with, all with the same results.

Does this scanner need to go back, or is this normal?

 

[loumaag]

Scott,

Does this happen if you are just monitoring signals or does it happen only if you key up a radio very close to the 96? If it happens only when you key up a radio close by the scanner, might I suggest that instead of messing with the scanner, you shut the radio off. It sounds more like once open, the scanner is locking on something locally. To answer your other question, no it isn't normal, but I would eliminate other possiblities before I blamed the scanner, as this is a problem I have never heard mentioned before.

 

[rescue161]

I've reset the scanner per the instructions.

I've also gone through all of the "Startup Keys".

The DSP tests fail! When I press "0" at the welcome screen and then press "TEXT" and then enter, I get the following message with white noise:

"DSP Test FM 868.5125 10u 1kHz @3.6kHz Press Enter"

Upon pressing "Enter", I get:

"DSP Test 1 Freq / Amp1 FAILURE CL to EXIT"

Any thoughts?

 

[loumaag]

I've reset the scanner per the instructions.

I've also gone through all of the "Startup Keys".

The DSP tests fail! When I press "0" at the welcome screen and then press "TEXT" and then enter, I get the following message with white noise:

"DSP Test FM 868.5125 10u 1kHz @3.6kHz Press Enter"

Upon pressing "Enter", I get:

"DSP Test 1 Freq / Amp1 FAILURE CL to EXIT"

Any thoughts?

Yes, don't press 0 during the welcome screen. :lol:

Seriously, that test cannot be done without several pieces of service equipment including a signal generator attached to the antenna. It isn't there for the user. Go back to my last post. I really don't think anything is wrong with the scanner. Test your test first.

 

[rescue161]

Well, I went down the road while listening to a digital frequency (wife talking on one of my radios). - Same problem.

I've also noticed that the problem only goes away when a sound is emitted from the speaker, i.e. when you press a button and a "key-press" beep is heard. If you single-press the light key, the problem is still there, but if you hold the light key down and the beep is heard, the scanner mutes.

Just for fun, I re-loaded the DSP to see if that helped. - It did not.

There are no digital systems here for me to monitor, so I'm stuck using my Astro Sabers or my XTS5000. I'll let it ride if you think it may be something in the Motorola radios programming. They all mute with no problems though.

 

[Forts]

I have seen this as well on conventional P25 channels. I've been listening to a conversation, then it just sounds like 'dead air' basically... or an open Mic. I usually just hit scan to send it on it's way again. I've only had it happen maybe one or two times a week so I'm not that concerned about it, but it sounds like you have a worse case of whatever it is.....

 

[rescue161]

Well, I've come to the conclusion that it only refuses to unmute while in "Paused" or "Manual" mode. It will not unmute the "dead air" sound until another sound is heard over the speaker.

Upon investigation, I found out that while in scan mode, this does not happen. I still hear the "dead air", but after a delay of a few seconds, it starts scanning again.

I also found out that when the display changes to "Dg" while in "Paused" or "Manual" mode, it will stay in "Dg" mode until 1) it hears an FM signal or 2) you manually intervene and hit a button on the CP.

I guess that's the way they made it, but it sure sounds like a glitch to me. I'm just going over this thing with a fine-toothed comb just because I haven't bought/had a scanner since I bought my BC235XLT back in 1997. Before that it was my Pro-2006 that I bought new in 1992. I'm very familiar with Motorola radios, hence my confusion when the scanner doesn't perform just like the Motorolas.

 

[loumaag]

Well, I've come to the conclusion that it only refuses to unmute while in "Paused" or "Manual" mode. It will not unmute the "dead air" sound until another sound is heard over the speaker.

This was the key. You actually have probably given the key to what a lot of people have been complaining about over in the Pro-2096 sitcky thread in reference to a "hum" being emitted. (Who'd a thunk we had to get the answer from a guy on assignment in Rota, Spain. :shock: )

Anyway, I did a little experiment here. Since one of the local towers of the TRS I monitor has only 3 channels, I put my Pro-96 in "Manual" mode on one of the voice channels, this shows a "MO" in the upper right hand corner "FM" would be the equivelant if I wasn't using a Trunking channel for the test. Being held on the channel of course it changed to "DG" when someone talked. When they cleared the channel and there was no longer any carrier on the frequency, the "DG" stayed up in the corner and for a timed 30 seconds it sounds like there is a "hiss" coming from the speaker. If I had to guess, I would say that whatever DSP logic gets engaged on a digital signal detect, continues to operate for a while and that it is being reflected in the audio circuit. Interestingly enough, while there is RF on the signal, that "hiss" is not there, it only appears after the carrier drops.

Now as to the 30 second timing; I cannot say with assurance that this is due to the timing in the scanner. I can only say that is what it appears, the reason is the TRS here "cycles" idle transmitters every 60 seconds, which means during idle times the controller tests each transmitter every minute to make sure it is still working by keying the transmitter, this causes the scanner to drop out of DG mode in any case. But the 30 seconds is a good guess, as the hissing goes away and the scanner is still in DG mode when it does, so I guess someone someplace with a conventional Digital system might be in a better position to make that determination.

Scott, as for your particular situation, as you point out, this doesn't happen if the radio is in scan mode, so that is the easiest solution for you. Even if you are only scanning one channel, the radio will kill its "digital DSP search" when it goes back into scan mode.

Good catch.

 

[rescue161]

LOL, Yeah, maybe they'll "fix" it in the next firmware or DSP upgrade.

I knew there was something wrong.

Upon retesting, mine does not drop at 30 seconds, not even a minute. It continues until a sound is heard. I actually let it sit for more than 5 minutes and it was still "hissing".

I guess it really isn't too bad as the scan mode seems to "fix" the problem, but hopefully they'll fix it.

 

[JamesO]

Interesting catch!

I have both a PRO-96 and a PRO-2096.

My PRO-96 does what Lou states, when in manual mode I have 30 seconds of hiss after a transmission ends, but I never really noticed it, it is not so obvious on "MY" PRO-96. Not sure if the 30 seconds is the unit going into Power Save mode?? Cannot remember how the power saver mode operates on the PRO-96. I need to try the same set up with external power and see what happens?

Now my PRO-2096 seems to hiss for a much longer time period, did not get a chance to time it, but it is more than 30 seconds, probably will not fully "MUTE" at all?

Note, both scanners have the same program loaded and were on the same channel in "manual" mode. If I manually advance a channel, with the up or down button, both the PRO-96 and PRO-2096 immediately "MUTE".

Now one thing my PRO-2096 will do that my PRO-96 will not, while in "manual" mode, is allow me to manually open the squelch. I realize that you will not be able to manually open the squelch on a channel programmed with tone squelch. Note I am in "manual" mode not "pause" mode on a TG.

I remember things seemed to have changed when I did the upgrade from the original factory DSP load on the PRO-96. I remember after the DSP upgrade, I noticed I could not manually open the squelch most of the time, but on closer comparison, the PRO-2096 can have the squelch opened manually on anything that is not programmed with tone squelch. The PRO-96 has since had the CPU upgrade and nothing changed with the new CPU and the RS Techs sure did not pick up on this "Mute" issue to manually opening the squelch issue.

Seems that these radios have a logic issue with the "Mute" function for the AF amplifier circuit?? Not sure what is up with the PRO-96 inability to manually open the squelch??

Luckily, both my scanners AF circuits are fairly clean and the hiss is not very noticeable. It will be interesting to see if anything becomes of this issue over the long run.

JamesO

 

[rescue161]

Note that I'm NOT monitoring any trunked talk groups, only conventional frequencies.

The only problem is with digital reception.

Receiving an analog frequency proves to NOT cause this problem.

I wish there was a digital TRS here to test my findings. The only TRS here is not digital and is VERY sporatic in that I can here it on limited occassions. It is very strange because when I hear it, it's VERY strong, but like the wind, it disappears and can not be heard for days and sometimes weeks...??? It's almost like a "mobile" TRS. It's in the High 460's MHz range, but that's getting off the subject.

 

[unitcharlie]

scott: i did an experiment tonight.... the kentucky state police use digital but they are a multi-cast system--there are freqs scattered thru the post areas for dispatch and talk-around", essentially a "conventional" system using apco 25... when the dispatcher started talking on one of their freqs i paused the freq using "manual" and programmed the same freq into my 92.... the "dg" stayed in the upper right hand corner while they were talking, then held for about five seconds while the radio unkeyed...but there was a barely audible hiss.... the 92 had the robotic sound while the radio was keyed and then silence when the freq cleared... but the hiss continued until there was a new transmission or i pressed another key... i have version 1.2 with the digital gain on.... i will have to wait for monday to check one of the local digital trunked systems....

 

[Voyager]

scott: i did an experiment tonight.... the kentucky state police use digital but they are a multi-cast system--there are freqs scattered thru the post areas for dispatch and talk-around", essentially a "conventional" system using apco 25... when the dispatcher started talking on one of their freqs i paused the freq using "manual" and programmed the same freq into my 92.... the "dg" stayed in the upper right hand corner while they were talking, then held for about five seconds while the radio unkeyed...but there was a barely audible hiss.... the 92 had the robotic sound while the radio was keyed and then silence when the freq cleared... but the hiss continued until there was a new transmission or i pressed another key... i have version 1.2 with the digital gain on.... i will have to wait for monday to check one of the local digital trunked systems....

The 'robotic' sound is likely the hang time on the P25 repeater. They send a tail of 'no audio (read: no data) and just the sync signal for a second or two after the transmission ends.

The PRO-96 doesn't fully mute the received signal when it receives a data (P25) transmission. It's the same on the 2096.

I too had a hum on my 2096 until I switched from the supplied wall wart to a real power supply (Astron). After I switched, no more hum. So, I think the hum issue is different from the problems described above.

HOWEVER, I also tried the same thing and have the same symptom as Lou and JamesO - my Dg stays on indefinitely after receiving a digital signal, but there is a low level squelch noise on after the digital signal disappears while on MANUAL mode. I can't say I've noticed it hanging on any conventional P25 channels, but the hiss is definitely there on my '96 (F1.1/U1.2)

My 2096 has the same symptom, but never seems to 'time out' on its own while on MANUAL. It's been going for several minutes now. While scanning the P25 channels, it is not hanging on the channel and seems to mute fully when it starts scanning again. Same with scanning on the '96.

I suspect what we are hearing is the audio amp failing to shut off. It makes sense that there is a timeout on the '96 (due to battery power) but not on the 2096.

Joe M.

 

[unitcharlie]

i was on battery power when i did the experiment....

 

[Voyager]

i was on battery power when i did the experiment....

Note that the PS issue was the HUM - not the hiss you reported.

Joe M.

 

[unitcharlie]

my bad... too much sleep and not enough coffe while reading the early morning posts....