My experience with 2 different DigiPi builds

[Will KT5W]

I wanted to share my two DigiPi builds with the group or anyone who might be thinking about building their own DigiPi. I had different objectives for each of the builds, the first one will go in my vehicle to be primarily used on APRS. It is connected to an ICOM ID-880H via a mini din 6 cable to the packet jack on the back of the radio and powered via the OEM USB port in the vehicle (aftermarket ones in the 12v cigarette lighter are too noisy on 2m/70cm). When using APRS I just manually tune the radio to the APRS frequency and then connect my phone via Bluetooth and APRSdroid. I'm sure there are more elegant solutions out there and I will probably refine this one as I go.

This DigiPi is built on the Raspberry Pi 2W with a Fe-Audio soundcard from Budd Churchward (WB7FHC) and a Radio Interface Board (RIB) from Randy Robinson (N7EBB). The Icom ID-880H does not have a USB connection so I went with an external sound card and the RIB, the nice thing about this build is that I can also easily transition it to an HT via a TRRS cable and a portable power pack when leaving the vehicle. Due to space constraints on the board I used the 1.3" small screen. I still need to get a case for this DigiPi to protect it better. 

The second DigiPi is based on a Raspberry Pi 3B+ and the Fe-Audio soundcard. This DigiPi is usually connected to my Elecraft KX3 for digital modes on HF. I connect the Line In/Out on the soundcard to the Mic/Headphone jacks on the KX3 and then plug the USB CAT control cable into the Raspberry Pi. I had a spare USB GPS module laying around (Stratux GPYes) so I included that as well to use for location and time data. While not in the field I connect to the DigiPi via Wifi using a VNC and can remotely operate WSJT-X or any of the other programs. 

A couple observations about using the DigiPi with the KX3:

-Your log file for WSJT-X is located at ~/.local/share/WSJT-X/wsjtx_log.adi you can either use the Shell window or SSH into the DigiPi to access it. Be sure to periodically click the "Save Configs" button so that it will save your log. I also use the scp command to copy the log to my Windows desktop. 

scp p...@XX.XX.XX.XX:~/.local/share/WSJT-X/wsjtx_log.adi “C:\Users\YourUserName\Desktop" 

This allows me to sign and upload the logs to LOTW, etc. via my Windows computer. If you go to the field and operate, before you shutdown click on the "Save Configs" button and then when you get back home you can retrieve your logs from the DigiPi. 

-I ran into some issues with under voltage on the Raspberry Pi 3B+ which made it unstable. You can go to Shell or SSH and use the dmesg command to see if your power supply is providing enough amps. If it is not, you will see error messages about under voltage. For the Raspberry Pi 3B+ I need around 5V 3amps. 

-For the GPS module, if you go to Shell or SSH and type gpsmon it will bring up a text display and show you how many satellites your are tracking, your latitude/longitude, time, etc. To exit press CTRL+C. Very useful for checking the status of the gps module. 

-To see how your timing is doing you can use the chronyc tracking command to display your timing source and offset. If you're planning on using WSJT-X or any of the digital modes that are based on time slots you'll want to try to get as accurate a time as possible. If you don't want to go the GPS route I believe other folks have successfully used Real Time Clock (RTC) add on boards successfully. 

-To check how much of a load you're putting on your Raspberry Pi you can use the top command and see the CPU and memory usage. CTRL+C to exit. 

-You can check your wifi status using the iwconfig command. When I'm using a VNC viewer at home over my local network it helps to move the DigiPi around to get the best wifi signal/connection to cut down on latency.

-In WSJT-X v. 2.6.1 I had the best signal decodes on FT8 by using Decode>Fast and checking the box labeled AP. Depending on your radio setup you'll need to adjust the volume on the output and mic gain to get the best performance. I also regularly double click the Erase button to help speed up decode times, not sure if it really helps that much but it declutters the screen and helps me not get too distracted about the new DX station that just answered another caller.

73

Will

KT5W

[Craig]

Absolutely spectacular Will - thanks for sharing.  We desperately need information
like this in some sort of wiki so we can all learn from this experience.

Personally, for me, I LIIKE the PICTURES!   I'm not sure why, keep'm coming :)

You gave me some ideas for DigiPi 1.9-3, system-info is working, volume sliders,
and I like the iwconfig idea along with cgps/gpsmon.

great work!
-craig
KM6LYW

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[Craig Ellison]

Great info, Will.  There is tons of good stuff!
I'm going to print it out and keep it with me.

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