piHPSDR and tx latency

["Christoph v. Wüllen"]

Dear HL2/pihpsdr users,


Now I have also encountered the problem, that TX occasionally looses PTT
(„tx relay chatter“). I only saw this with WSJTX, never with CW. The
PA temp was way below critical values, so I suspect a TX-IQ-FIFO
underrun.

To address this, I have updated my version of piHPSDR (github.com/dl1ycf)
to set the „PTT hang“ and „TX latency“ times to fixed values
(PTT: 5 msec, TXlatency: 30 msec) and did not see the problem again.

Note before piHPSDR did never set these values so the default ones
were active.

Still no support in the GUI to adapt these values, but this is
seemingly better than the default values.

If others have seen the problem as well, does it improve?

Yours,

Christoph DL1YCF.

[ron.ni...@gmail.com]

I you run a long sequence of network Pings from your PC to your HL2, what's the peak variation in Ping round trip latencies you see?  If your network's max UDP latency variation is greater than the HL2's default latency, that can cause Tx relay chatter.  I see that problem on a lot of WiFi network connections.

73,

Ron

n6ywu

[Steve Haynal]

Hi Christoph,

Did you see this problem with the latest stable gateware, 20201212_72p8? That gateware increased the TX buffer latency to 20ms and PTT to 12ms based on some feedback from SDR Console users.

73,

Steve

kf7o

On Wednesday, January 27, 2021 at 11:00:05 AM UTC-8 "Christoph v. Wüllen" wrote:

["Christoph v. Wüllen"]

No it was the gateware installed when I got the device, AFIK 7.1

But I shall try to use these values (20 msec / 12 msec) in pihpsdr
and see if they also work. Probably a good idea anyway to set
these values in piHPSDR since this makes it work independently
on the gateware default settings.

I did not dare to increase beyond 30 msec because I faintly remember
that there is a 5-bit-overflow with older gatewares.

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[Steve Haynal]

Hi Chistoph,

The newer gateware also doubles the buffer size, you can go up to I think 70-80ms if I remember correctly.

73,

Steve

kf7o

[Erwin]

Dear Christoph,

By chance I saw your post. Currently, I am experiencing "tx relay chatter" with deskHPSDR. Could you reveal where in the code I can adjust the "PTT hang" and "TX latency" times? I assume this will not be very different in deskHPSDR compared to piHPSDR.

Thanks in advance.

Best ragards,
Erwin

Op woensdag 27 januari 2021 om 20:00:05 UTC+1 schreef "Christoph v. Wüllen":

[Darek Zarzycki]

I solv this problem by hardware 

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