APRS Digipeater Update

I am happy to announce that the digipeater project is coming along slowly but surely. I have run into some major hiccups along the way, moreover with the many USB devices I have been using and the poltergeist of RFI.

Long story short, the Pi can only handle so many USB hosts from the OTG cable, and with the tests that I've run, it can't be more than two it seems. The problem I have run into is using 3 devices at once - one for the GPS dongle, one for the audio card, and one for the FTDI chip to trigger PTT. I have used a cheapy USB hub but I haven't used anything else, which may solve my problem. If not, I haven't forgotten that the Pi has GPIO pins, which makes the Pi even more versatile. In fact, Direwolf natively supports GPIO PTT. This problem was solved by using a shorter USB extension cord of around 6 feet. The GPS dongle was originally running from a 12 foot cord. Shortening it seemed to help tremendously.

So, what's the plan now? For now, I have changed my plan of attack to exclude the FTDI chip and do PTT through GPIO. I will once again etch a PCB to do this using an optocoupler, though I'm sure it will be small enough. The Baofeng PTT works by connecting the shields of the mic and headphones connectors together. I have also figured out that the GPS dongle needs to be far away from the machine or outdoors for proper signal acquisition, so using a USB extension cord is a must.

Another problem is the soundcard. I have run into the issue where every time I key up the Baofeng, the audio card, as well as every other USB device, stops working. Sometimes it recovers and sometimes it requires a complete reboot of the Pi. This, obviously, will not work out in the field. To mitigate this, I think that this will require an external antenna farther away from the main system.

That's all for now, and unfortunately, until I get more time, this project will have to set on the back burner for now :(

All hope isn't lost, though. I can definitely still use this as an I-Gate since I have several VHF scanner sitting around, so for now, I think this is what I will be doing until I can get a definitive answer of what's going on.

UPDATE (1-11): IT WORKS! I bought some snap-on ferrites a while back and added some to the OTG cable and the soundcard. The Baofeng was also faced away from the Pi and the card. I do plan on using an external antenna as this will also help mitigate RF issues. So now, I need to finalize the audio cable and PTT circuit to get this on-air!