It's all about the Software

Hi All

I am trying to find a way to solve an issue I am having,

My setup is a Adam Pluto Controlled by SDRconsole and I am running JTDX and JTsync on my PC

Now when I sync the time on the PC to the server I am seeing the FT8 stations have a dt between 0.8 - 1.1

I can then Sync that to 0.0 using JT Sync,

Problem is that my TX time is off it will now be +1.2 compared to my RX

That is getting near the point of not being decoded on the other end,

So basically why am I seeing a difference between RX and TX sync and is there anything I can do to solve this,

FT8 isn't too bad but I find that I can not work stations unless I spend some time with a the online SDR on another PC and mess with the time sync to get my signal to decode,

I have no issues using FT8 on HF and I have a good understanding of the JTDX software as I make thousands of QSO's per year on FT8,

If anyone can offer any advice that would be great,

Thanks
Trevor
EI2GLB

For best timekeeping use Windows NTP:

https://www.satsignal.eu/ntp/setup.html

I hope that helps....

73,
David GM8ARV

EI2GLB wrote: Sun Nov 10, 2024 8:20 pm

My setup is a Adam Pluto Controlled by SDRconsole and I am running JTDX and JTsync on my PC

Now when I sync the time on the PC to the server I am seeing the FT8 stations have a dt between 0.8 - 1.1

Thanks
Trevor
EI2GLB

Trevor, I wonder if you are overthinking this issue? I just went on FT8 on 40m to check, and I immediately see dt on received stations between 0.2 and 1.1. That is very common. I think you are assuming that everyone else is correct when in fact I regularly see FT8 received stations timing all over the place.

You only need to be sure that your own TX is on time, and this should happen automatically just by syncing your PC to a reliable NTP server. I'm in the UK so I use the NPL NTP server ntp2.npl.co.uk. Also I make sure my PC syncs more regularly than once a day even though it possibly does not need to. I think every three hours or so. You can adjust the interval between syncs by a Registry value. Not sure right now which one but it's all findable on Google.

To set NTP server:
https://www.windowscentral.com/how-mana ... windows-10

If your RX stations dt is almost always never less than 0.8 (and I'd check quite a few times to make sure) then maybe you have some sort of delay somewhere in your audio system from RX to the software? Check any VAC settings (if used), and look up articles about audio latency on Google.

Also to avoid buffering issues in any part of the chain make sure that all devices in your audio chain are set to the same 48kHz sampling rate. By default many systems or parts are set to 44.1kHz. SDRC in particular needs you to make sure all audio connections/devices in and out are at 48kHz. This is very important.

To check the sample rate and other settings of all your audio devices in Windows, bring up the Windows "Run" dialogue (press Windows key on keyboard then type Run and the Return) and type mmsys.cpl in the Run window to bring up the Audio Devices panel, then check the Properties in each device for 48kHz etc.

73

Max

Transmit latency may be a problem with SDRs and buffering that is needed to avoid drop outs and such - unless JTFX FT8 can compensate for the buffer latency. Computations do not happen instantly.

{o.o}