MotoTRBO audio complaints

[samsharpe]

I have a large user base of XPR portables. They are set up on several digital talkgroups going through a TRBO repeater. Most of the guys sound ok but the ladies sound really bad. We have some real soprano voices and they sound like they are getting clipped when they speak or like the vocoder translates their high frequency voices into lower frequencies and you can't understand them at times... It reminds me of the old analog music synths where you could slide a translation function across a SAW waveform.

We've tried the digital audio gain settings since the last firmware release, but that didn't improve anything. We've also tried turning privacy on and off with no difference in quality. Can anyone think of anything else to try? Is there perhaps something in CPS that I'm overlooking?

[wavetar]

Out of curiosity, are these UHF units, or VHF? We've had no issues to speak of thus far with UHF systems, but the one VHF customer we have has had lots of different issues ranging from warbling/distorted audio to intermittantly missing transmissions in known good signal areas...big time PITA.

Todd

[samsharpe]

Well thanks for responding Wavetar. They're on UHF.

[wavetar]

Not sure if there's anything you'll be able to do to help your issue. It's a well known issue with some vocoders that in optimizing the algorithm for what's considered "standard" voice, that a small percentage of voices (typically women's) fall out of the range & do not translate very well across the radios.

[Vercomm]

Hey Todd,

I'm looking at moving a customer over to a TRBO system using VHF. They will be using 90% XPR4450's with GPS active. Good idea or bad?? Will I be getting numerous calls about poor audio and missed radio calls? Currently this customer uses a simplex VHF system. I do have demo repeaters and mobiles for them to try before they decide to move to TRBO or not.

Any thoughts??

[john9912]

There were some audio problems reported when mixing 1.5 version firmware with older firmware versions . I'm not saying this is your problem but, make sure ALL radios AND repeater have the newest firmware...

[wavetar]

I think you'll be ok with the mobiles. The range in TRBO is actually quite impressive with the mobiles. It's looking like the main issue with our VHF customer is inside buildings with the portables. It's well known that VHF isn't great for building penetration, but I would've expected things to be better in TRBO mode...and it kind of is, yet with drawbacks. Often the radios will work where analog didn't, but the higher bit error rate resulting from poor VHF penetration means the audio quality varies quite a bit, depending on how well the vocoder's predictive algorithm fills in the blanks. It also means you can have a strong signal within a building, but the quality of it may cause the BER to rise to the point the radio doesn't even unmute! This is where the analog radios would have an advantage...you might get some static, but it would get through. This is how it's been explained to me by the M engineers, at least. It's still an ongoing case, so we'll see how things shake out.