Help with SSTV PTT Activation on 2m HTs with DigiPi

[David]

Hello,
I’m experimenting with SSTV on 2m using the DigiPi SSTV option and could use some help troubleshooting a PTT issue. My setup includes:

• Hardware: DigiRig Mobile with the appropriate cables for each radio, Raspberry Pi Zero 2 W running DigiPi 1.9.4
• Radios tested: Tidradio H-8, Yaesu FTM-510, Yaesu FT-70D
• Software: QSSTV on DigiPi for SSTV

I believe I can decode SSTV signals on the HT, as I see noise on the waterfall, indicating audio input is working, but I haven’t fully tested decoding yet. However PTT isn’t activating for transmission. Other digital modes like APRS, Winlink work fine and trigger PTT as expected on these radios.
My goal is to demonstrate to new Technician-level hams in our local club that they can explore digital modes like SSTV on 2m with affordable gear (e.g., Tidradio HT, DigiRig Mobile, Pi Zero). I’m particularly interested in decoding SSTV images from ISS passes, which are typically on 2m, and showing new hams how they can also send SSTV to each other with the right setup. Since SSTV is more common on HF, I’m wondering if there’s a specific configuration tweak needed for 2m HTs.

Has anyone successfully run SSTV on 2m with a similar setup? Any tips on configuring QSSTV or DigiPi to ensure PTT activation? I’d also love advice on other digital modes suitable for Technician hams using HTs and DigiPi to help introduce them to the fun of digital. As mentioned I seem to have APRS and Winlink working so far on 2m HT. I will explore the HF side as well to show some of the General class members how this can work for them too.
Thanks for any insights or suggestions!
73,NI7RODavid

[David Cottee]

Great work on the APRS and Winlink operations.

The configuration setup is a little different, but you should be able to get it to work.  The help file is quite good.  Transmission setup in qSSTV is a bit clunky, requiring a bit of learning to get the templates and stock images going, and the input /output audio levels right too.

You might need to use the special serial port option with RTS and ttyUSB0 rather than Hamlib control for the Digirig.

The radio club here (VK2) runs a SSTV net on the 2 metre FM repeater on Tuesday nights.  Great for testing, don't have to deal with the vagaries of the ISS. Not sure about your area, but you could start one up I guess.

So the WSJTX module for FT8 and WSPR works on VHF, but needs SSB modulation, so won't be useful for most HTs.  However the FLDigi module can use 8PSK mode for high speed data transmission on VHF/UHF FM.  I have no experience in this, but it looks very interesting.

73 David VK2VJ

[Craig]

Hi David,
 
sstv on vhf isn't something I've tested, but sounds interesting.

qSSTV can only use hamlib for ptt, not GPIO.

However, you can run "rigctld -P GPIO -p 12" supposedly, then configure
qsstv to use the hamlib rig-control interface.


if it helps,
-craig
KM6LYW

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[David]

Good morning,
After more testing this morning, here’s where I’m at. The HTs (Tidradio H-8 and Yaesu FT-70D) are still struggling with the DigiRig Mobile. They seem to receive fine, but PTT is finicky. Sometimes it holds on after a transmission, or it fails to activate entirely. When PTT fails, receiving stops working until I restart the DigiPi.
On the other hand, my Yaesu FTM-510 plays nicely with the DigiRig Mobile so far. It’s using the 10-pin data port cable, and I haven’t had issues triggering PTT (knock on wood). Thanks to David VK2VJ for suggesting I switch to /dev/ttyUSB0, that was the trick for getting SSTV working smoothly on the FTM-510.
I’ll keep troubleshooting the HT side and appreciate any tips on resolving the PTT issues. Thanks for the help, everyone!
73,
NI7RO
David

[Craig]

these are classic symptoms of RF on the audio/ptt/ground cables... crash after first transmit, stuck-on first transmit.

ferrite beads are required on all cables, especially with HT's, that have no other ground but the pi

If you click SysLog, you might see complaints about USB errors and "EMI" interference.  Pi's shutdown
their USB ports if RF is too intense.

try relocating your antenna way too... lower power, just to test

-craig
KM6LYW

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[David]

Thank you for the help so far from both Craig and David.

Update: 

So I have successfully done APRS, Winlink, and SSTV now from the Yaesu - FTM510 and the Tidradio H8. 

The Yaesu was easy for Winlink and APRS, and once I adjusted the "ttyS0" to "ttyUSB0" in the SSTV configuration like David suggested, the Yaesu was doing SSTV just fine (have not decoded; need a club member to test sending me something).

The HT was a bit tricky, but after putting some ferrite beads like Craig suggested on both ends of the USB cable, it started playing nice. I have now got it doing APRS sending and receiving, Winlink, and sent an SSTV image today. It did need the same ttyUSB0 setting like the Yaesu.

I think possibly (knock on wood) things seem to be working. Now I need to set up a demonstration for my local club member to show some of the new Techs what they can do with just a few tools.

Thanks again!

73

NI7RO

David

[David]

I will try again as my last message seems to have been deleted.

I was trying to give an update and let people know what worked so they could benefit from it, hopefully.

First, thank you for the help, Craig, and David. Between both of your suggestions, I believe things are working now.

For the SSTV, changing ttyS0 to ttyUSB0 seemed to be the ticket. After that, it worked.

After adding the ferrite beads to both ends of the USB cable, I was then also able to keep the PTT from getting stuck on.

I have now successfully been able to send SSTV, APRS, and Winlink from the HT. For receive, I have tested Winlink and APRS but need another local ham to send me something on SSTV to decode.

I am excited to show the club this setup and hope they will be able to start playing with digital modes!

Thanks again for the help.

73

NI7RO

David

On Friday, September 5, 2025 at 9:28:07 AM UTC-7 km6...@gmail.com wrote:

[David Cottee]

Hi David and all,

What is really cool is the DRM digital mode of SSTV available on qSSTV on the digipi.  Although designed for HF, there is no reason it could not be used on VHF/UHF as it has a 2.5kHz bandwidth setting.  The quality of the images is quite spectacular, as it has builtin error correction.  Uses a variant of the Digital Radio Mondiale encoding.  Length of the transmission varies with the image size (which is selectable) and the mode options.  There is a Windows EasyPal programme for non-Linux/digipi users, with which I am unfamiliar.

There is quite a bit of activity on 7058kHz LSB in VK.  

Cheers,

David VK2VJ

On Wednesday, September 3, 2025 at 10:59:24 AM UTC+10 dcha...@yahoo.com wrote:

[David]

I am having fun decoding the SSTV ISS event this week. Running the DigiPi on a simple HT and coax to a Jpole that is mounted outside. 

I will have to look through the group to see the best way to get the images off the DigiPi sd card once the event is over. 

Now I know I can both send and receive SSTV though on 2m setup.

73

NI7RO

David

[Craig]

great fun with the ISS!

you'll find the images on digipi using sftp or scp (filezilla?) at /home/pi/.config/qsstv

make sure you press [save configuration] on the DigiPi home page to commit
any images to the SD card.

-craig
KM6LYW

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