Transmitter Software Capabilities and Issues (Jessie)

[KenW6HHC]

Hi Dave G8GKQ,

OK...good to know that it already on your "track down list".
I can certainly live with the quirk...now that I understand it. I just need to use PTT first to bring-up-the repeater....and from that point on, ViewFinder video will work OK.

I was a bit concerned that this may only occur when using the DATV-Express board as the modulator. But, you made it sound like that this also occurs with Portsdown modulator board.

Thanks for the info and all your efforts.......de Ken W6HHC

[KenW6HHC]

Hi Dave G8GKQ,

I noticed a very repeatable jump in video latency occurs while in the CAMPEG-2 camera mode and using the DATV-Express board as the modulator. My tests were all performed with FEC=1/2 and SR=1000 and SR=2000 with the same results.

Transmission
Duration............ Video latency
1) <55 minutes.......1.5 seconds (very acceptable)
2) >65 minutes......12.5 seconds

The Video latency returns to 1.5 seconds if I stop the transmission, pause, and then start to transmit again.

This probably is a very low priority issue since most DATV QSO transmissions do not last 60 minutes...only perhaps videos clips and slide-shows, and the jump in latency would be difficult to notice after it occurred.

...de Ken W6HHC

[G8XZD-TV]

This probably is a very low priority issue since most DATV transmissions do not last 60 minutes...

...de Ken W6HHC

You've never watched a G4KLB over then

[G8GKQ]

Ken

Thanks for the info. That's a bit worrying as one of our future applications for the Portsdown is repeater streaming, 24/7. I'd be interested to know what happens at the 2 hour point - it might help track down the cause.

Dave, G8GKQ

[KenW6HHC]

Hi Dave,

I will run a two hour test today to see if the addition video latency continues or increases, etc.

73...de Ken W6HHC

[KenW6HHC]

Hi Dave G8GKQ,

There were no further video latency changes after 1 hour. I ran tests to just over four hours.
As a reminder to readers...the jump in video latency occurs while in the CAMPEG-2 camera mode and using the DATV-Express board as the modulator. My tests were all performed with FEC=1/2 and SR=1000 and SR=2000 with the same results.

Transmission
Duration................... Video latency
1) <55 minutes................1.5 seconds (very acceptable)
2) >65-to-115 minutes......12.5 seconds
3) >125-to-235 minutes.....12.5 seconds
4) >245 minutes..............12.5 seconds

The Video latency returns to 1.5 seconds if I stop the transmission, pause, and then start to transmit again.
I can NOT test to see if this video latency quirk also occurs with a Portsdown modulator board in a set-up? My first suspicion is RPi-3 code (maybe kernel...maybe FFMPEG encoding not behaving correctly)?? BTW...the VIEWFINDER video displayed on LCD never is impacted....the touchscreen latency always stays around 1.5 second.
...de Ken W6HHC

[G8GKQ]

Hi Ken

Thanks very much for doing these tests - they help a lot. I'll take a look at the problem as soon as I can.

Dave

[i2NDT]

Hi Dave!
I have my RPI+SD card (by BATC) and Waveshare screen (nothing else) all connected together. everything is ok as I can transmit (ugly mode and paternaudio) and I see the carrier on my SA.
I am able to go back to stand by mode touching the hidden TX button and than I can change all parameters. so all "buttons" work except the RX one! when I touch it the screen freezes...and I have to reboot to be able to control the touch screen again.
I have also updated to the latest software release but no improvement. than, tampering with my SSH terminal (pibootstrap) by mistake I also updated raspian jessie...but again no improvement!

i2NDT Claudio

[g0mjw]

I think I have seen this too - however, unless you have a receiver plugged in there isn't a lot of point in the RX button. Might make sense to disable it's function if no receiver is detected.

Mike

[i2NDT]

actually if I plug in a RTL dongle the RX button works! the RX screen shows something similar to the constellation pattern...but I do not understand it's purpose!