Batboard

What would cause an XPR 4550 (in analog) to receive choppy audio while other (lower quality) radios have a clear signal.

The problem started after norrowbanding.

The radio was bench tested and is working perfectly.

The signal is a provided by the state for Ambulance/Hospital communications and the state engineers are also trying to figure it out?

We are all scratching our heads?

Thanks!

noloflashradio wrote:What would cause an XPR 4550 (in analog) to receive choppy audio while other (lower quality) radios have a clear signal.

The problem started after norrowbanding.

The radio was bench tested and is working perfectly.

The signal is a provided by the state for Ambulance/Hospital communications and the state engineers are also trying to figure it out?

We are all scratching our heads?

Thanks!

Not enough details. Is this a repeater output? Is the transmitter sending CTCSS?

Has the transmitter been looked at with a service monitor for both frequency and deviation? Was the radio actually narrow banded and measured with a service monitor, or was it just changed with the software and the tech walked away?

What frequency band are you using?

How strong is the signal into the XPR4550?

The details might not seem important to you, but can tell the whole story if they are there.

Jim

The signal is from the repeater. It is CTSS but I have changed the receiving radios to CSQ and the problem stays.

The engineers responsible for the repeater have done some spectrum analysis and tested the XPR mobiles and they think the problem may be that the XPR's are too good and their signal is not but still surprised it's only there radios having a problem.

UHF 460 range.

Signal is very strong and close by.

Ok, have you check frequency error? Deviation? Bench testing the radios only points to the problem being with the infrastructure and not the subscribers. I wouldn't be scratching my head until I verified the infrastructure was in good working order.

My older narrowbanded analog stuff is very tolerant of any overdeviated signal - a 4KHz dev signal is received perfectly OK on a 12.5KHz spaced/ 2.5KHz dev narrowbanded channel.

However, my digital stuff (using analog mode) will not accept even a very slightly overdeviated signal without causing choppy audio.

Maybe the repeater deviation is slightly too high?

A quick check might be to test the XPR receiver using 20 KHz spacing/ 4KHz dev and see if the received audio sounds OK (although it might sound a bit quiet)??

When I hear about choppy audio in narrowbanded receivers, I think transmitter deviation. Time to check system deviation.

Thanks for the replies! They have been forwarded to the repeater's engineer.
I tried to reprogram the radio to Wide to test but the new MOTOTRBO software doesn't allow reverting to narrow( I may be able to get the bypass from Moto). I can try to change the deviation and see if that helps. Since I am not responsible for the infrastructure all I can do until that's fixed is try and find a workaround on the 'subscriber' end to make it work.

noloflashradio wrote:Thanks for the replies! They have been forwarded to the repeater's engineer.
I tried to reprogram the radio to Wide to test but the new MOTOTRBO software doesn't allow reverting to narrow

https://www.p25.ca/threads/3495-MotoTRB ... on-removal

Read this thread. It works perfectly with CPS 9.0. GARY

Thanks!

Problem solved...infrastructure was still wideband...even though they thought it was changed!

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It's a miracle I tell you. Simply a miracle.

Bill_G wrote:It's a miracle I tell you. Simply a miracle.

It's not everyday that you can remotely figure out what is wrong with a radio system. But this one seems to be right on. Good going radio techs. Who do we send the FCC after?

Jim

Jim202 wrote:

Bill_G wrote:It's a miracle I tell you. Simply a miracle.

It's not everyday that you can remotely figure out what is wrong with a radio system. But this one seems to be right on. Good going radio techs. Who do we send the FCC after?

Jim

It came from all that experience moving customers to NB. I learned pretty quick to do the base stations and repeaters first. At the very least, turn the base station dev down so that the dispatchers sounded good after you touched a mobile. Like g8tzl wrote above, the dual mode (digital/analog) radios have a steep cut in their IF filtering that really makes WB sound terrible. Almost any make/model (MOT, Kenwood, Icom) of wide/narrow analog only radio could tolerate some wide rx, but the dual mode models all got choppy. You couldn't understand a thing. It made the transition a little bumpy, but if you hustled, you got through it in a couple long days. On the plus side, a Trbo or NXDN mobile made it easy to find the subscribers that had been forgotten in the process. It was amazing how many portables guys had pack ratted away that didn't show up for months after we had NB'd their system. On the other hand, Quantar and MTR repeaters became the great equalizers. Everybody passed through them just fine wide or narrow. Go in wide, come out narrow. Couldn't tell the difference.

Yes, you guys are great...thanks for the help
As far as who needs "going after..." that's for me to know....(but it's one of 50;-))

His punishment is 40 lashes with a wet noodle

escomm wrote:His punishment is 40 lashes with a wet noodle

Think a better punishment is to be on call for the next 3 months straight. Maybe while driving to the customer at midnight, that person can think about this over and over and over till they learn do it right the first time. Don't take for granted that someone else made the change.

Jim