Audio Stuttering

M6XCX
Posts: 9
Joined: Sat Jan 11, 2020 5:34 pm
Location: Berkshire, UK

Audio Stuttering

Post by M6XCX » Thu Jan 23, 2020 10:10 pm

Apologies if this has already been discussed, but having read through many posts I haven't come across it.

I get a lot of audio stutter when receiving DMR on my OpenGD77 from my MMDVM hotstpot, but not on my Anytone UV878.

I've tried turning calibration off and that hasn't made any difference, and I've used three different OpenGD77 firmware versions, including the latest from yesterday.

It's probably something I'm doing, but can anyone shed any light on what, please?

Other than that, it's a fantastic firmware and so much more user friendly than the original. 8-)


Thanks,
Tony.

VK3KYY
Posts: 1656
Joined: Sat Nov 16, 2019 3:25 am
Location: Melbourne, Australia
Contact:

Re: Audio Stuttering

Post by VK3KYY » Fri Jan 24, 2020 12:27 am

This has been reported by a few people, but I've not personally heard it

Which version of the firmware are you running. The last couple of versions have improved audio buffering which seems to give some improvement in the audio for some people.

Can you take a video of the problem showing the whole radio, so we can see if the green led flashes etc when the audio drops out.

User avatar
m1dyp
Posts: 335
Joined: Sat Nov 16, 2019 8:03 am
Location: Hertfordshire, U.K.

Re: Audio Stuttering

Post by m1dyp » Fri Jan 24, 2020 3:50 am

i had 'stuttering' when using a dvmega blue stack (not as bad with 'no inband data turned on)
as soon as i switched to pi zero w / mmdvm its all good
problem solved here, just a standard install of pi star, no offsets, it even works when i cross mode from dmr to fusion
73 de Ken :D

VK3KYY
Posts: 1656
Joined: Sat Nov 16, 2019 3:25 am
Location: Melbourne, Australia
Contact:

Re: Audio Stuttering

Post by VK3KYY » Fri Jan 24, 2020 3:55 am

m1dyp wrote:
Fri Jan 24, 2020 3:50 am
i had 'stuttering' when using a dvmega blue stack (not as bad with 'no inband data turned on)
as soon as i switched to pi zero w / mmdvm its all good
problem solved here, just a standard install of pi star, no offsets, it even works when i cross mode from dmr to fusion
Some of the original DVMega problems were caused by the calibration table bug, but that would only apply to the Tx.

I think Bud W0RMT/VK3BUD can lend me his DVMega, but possibly its not a DVMega issue at all.

I've also had reports that Duplex MMDVMHotspots have the same problem, so I'll try putting my duplex HS back into Duplex mode (as currently its in Simplex)

User avatar
m1dyp
Posts: 335
Joined: Sat Nov 16, 2019 8:03 am
Location: Hertfordshire, U.K.

Re: Audio Stuttering

Post by m1dyp » Fri Jan 24, 2020 4:07 am

yeah i have read about loads of problems with the duplex ones so i'm sticking to the singles :D

i have an early dual band mega but even with the latest firmware 3.26, it's still not right on dmr
73 de Ken :D

M6XCX
Posts: 9
Joined: Sat Jan 11, 2020 5:34 pm
Location: Berkshire, UK

Re: Audio Stuttering

Post by M6XCX » Sat Jan 25, 2020 9:22 am

Thank you both very much for the quick replies.

I have created the video (after what seemed like ages waiting for someone to more than just key up!), and uploaded it my google drive. Hopefully the link will work... https://drive.google.com/file/d/1ak-hKd ... sp=sharing

In terms of what I'm using...
- oGD77 version from Jan 22 2020
- AnyTone UV878+ (which is next to the GD77 but has no stuttering)
- Jumbospot MMDVM running Pi-Star v3.4.16 / Dashboard 20191220 (I believe it's simplex hardware and Pi-Star is set in simplex)

Let me know if any other info would help, and thank you in advance for your problem solving skills!

F6GVE
Posts: 43
Joined: Sat Nov 16, 2019 8:52 am

Re: Audio Stuttering

Post by F6GVE » Sat Jan 25, 2020 5:25 pm

Roger, this video perfectly illustrates what I have with my 2 opendGD77 too.
It is exactly the same "noise"

I tried to calibrate my GD77's as better as possible. I use three Jumbo spots (not dual), GD77 hotspot, and this is exactly this noise.
It seems less frequent when listenning my local repeater (Motorola TX+RX)

This rarely happens with one GD77, let's say once every 5 mn, and is more frequent with the second one, roughly once every 2 mn

Luc

User avatar
m1dyp
Posts: 335
Joined: Sat Nov 16, 2019 8:03 am
Location: Hertfordshire, U.K.

Re: Audio Stuttering

Post by m1dyp » Sat Jan 25, 2020 7:32 pm

hi, i find that different dmr radios act differently, for example, my gd77 will sound fine but my md380 will break up, if i adjust the offsets to suit one, the other plays up.

now i only use one radio on the same hot spot that has been configured for that radio, seems they don't like sharing :roll:

i found this somewhere but i cannot remember where, it 'may' help

Most of the boards I've been getting lately have required adjusting the offset to function properly on DMR. Many boards are shipped with a sticker on the bottom with the required offset. These are usually pretty close. There is however a way to get this more exact and specific to your radio.
MMDVMcal

Luckily there is a utility built in to Pi Star that enables you to tune your offset. All it requires is pen and paper, a calculator and a little time.

Step one is to gain ssh access to your Pi. The easiest way to do this is go to "Configuration" then click "Expert" then "SSH Access" and log in with pi-star and your password.

Next set your radio to VFO Digital mode at 433.000mHz TS1 TG9

Then go back to SSH and type "sudo pistar-mmdvmcal" this will start the calibration program. Type "m" this sets a 1031 Hz test tone. Next press the "space bar" to start transmitting. You should hear the test tone on your radio at this point. Next press the "f" key repeatedly until the radio goes silent. After that press the "F" key multiple times until the tone comes back. Write down the frequency at which the tone comes back. Now you have to go the opposite way. Press "F" until the tone stops followed by "f" and write down the frequency where the tone comes back again. Next subtract the lower frequency from the higher frequency of the two you just wrote down. Divide that number by 2 and add the result to the lower frequency. Now the difference you get from 433mHz is your offset.
To sum up
sudo pistar-mmdvmcal
m
space bar
f (repeatedly until you lose the tone)
F (repeatedly until the tone comes back)
F (repeatedly until you lose the tone)
f (repeatedly until the tone comes back)
subtract lower frequency from higher frequency
divide that number by 2
add the result to lower frequency
find difference between result and 433mHz
Once you have your offset you have to set it in Pi Star.

You'll need to go to your pi-star dashboard, then "Configure" and "Expert" Now click on "MMDVMHost" Scroll down to "Modem" and enter your offset in RXOffset and TXOffset. Don't forget to click "Apply Changes"



Still having trouble talking to your hotspot?

The above method will usually get you close enough but if it doesn't there is a method to tune your hotspot for a minimal BER.

First, set your radio to 433.000mHz Talk Group 1 and Color Code 1.



Next, use the same command in SSH to start mmdvmcal "sudo pistar-mmdvmcal" then press "b" to start the BER tuning program. While pressing the PTT on your radio press the "f" key or "F" key to adjust the frequency until you get the smallest BER you can achieve. However far off you are from the starting frequency of 433mHz is what your RXOffset should be set to.

Tip: These are the instructions for DMR. When you start the mmdvmcal program it displays a list of codes for other tests and other modes you can test.


good luck
73 de Ken :D

User avatar
YT5HOK
Posts: 123
Joined: Sat Nov 16, 2019 11:36 am
Location: Belgrade, KN04FR

Re: Audio Stuttering

Post by YT5HOK » Sat Jan 25, 2020 7:38 pm

Marko

User avatar
m1dyp
Posts: 335
Joined: Sat Nov 16, 2019 8:03 am
Location: Hertfordshire, U.K.

Re: Audio Stuttering

Post by m1dyp » Sat Jan 25, 2020 7:44 pm

thank you, i'm getting old and forgetful :D
73 de Ken :D

Post Reply