I recently spent some time in Central Pennsylvania at my daughter’s house. Since I was going to be there a while, I brought along my Raspberry Pi hotspot. While I’m not really active in digital voice modes (or any voice modes, for that matter), there are a couple of DMR nets I like to check into each week. 

One issue I ran into in the past, is that my hotspot refuses to connect to their Wi-Fi network. Their Wi-Fi SSID has both an apostrophe and a space in it, so I’m guessing that’s the issue. I could have connected the hotspot directly to their router via an ethernet cable. Because of their router’s location, I would have had to move some furniture and put the hotspot in an awkward location. So, this time around I brought a little travel router to try another approach. 

Back when I was working, I had a TP-Link Nano router that I took on business trips. Typically, I would connect it to an Ethernet port in my hotel room to create a personal Wi-Fi network for my laptop and phone. A while back, I upgraded to the newer (and faster) TP-Link TL-WR802N travel router. I don’t travel nearly as much these days, so the new router hasn’t seen much use.

I brought the travel router along on this trip to create a wireless bridge from the house’s Wi-Fi to my personal Wi-Fi. The router’s Wi-Fi network has an SSID that my hotspot likes. I haven’t used that mode much, so I had to resort to the user manual to refresh my memory on how to set this thing up.

Actually, it was pretty easy to set up. It was simply a matter of connecting my laptop to travel travel router’s Wi-Fi to access the admin functions. From there, I set it up in the “Hotspot Router” mode. Then, I scanned to find the house’s Wi-Fi network and logged into it.

Testing the internet connectivity with my laptop, the speed looked good. I had previously added my travel router’s SSID and password to the hotspot, so soon after powering up I was hearing the sounds of DMR coming from my HT. This configuration worked great, and I successfully checked into a few nets during the week. 

The next time I go out there to visit, I’ll just need to power up the router and the hotspot, and everything should work. (Knock on wood)

No ground-breaking technological advances here. I just love when a plan comes together. 

73, Craig WB3GCK

[Disclaimer: I have no monetary interest in this product, and there are no affiliate links in this post. I’m just a satisfied owner.]

Back in 2020, I started fooling around with digital voice modes. I don’t really use them a lot, but there are a couple of DMR nets I like to check into each week. I recently started using the WPSD software instead of the Pi-Star software I had been using on my two hotspots. Just for the heck of it, I wanted to try upgrading the old Raspberry Pi Zero board on one of them to something more capable.

According to the documentation, WPSD was never written for single core processors, like the old Pi Zero W board in my hotspot. The developer recommends a Pi Zero 2 W or better. While it will work on a single core Pi, it runs slower—I can attest to that. I also noticed that CPU utilization was well over 100% at times. With its quad core processor, the Raspberry Pi Zero 2 W is supposed to be five times faster than its single core predecessor. So, I was hoping to see some general performance improvements and faster boot-ups after this upgrade.

In the interest of full disclosure, I’m no Raspberry Pi expert—far from it. I had to do some online research before launching into this. It looked simple enough; the Pi Zero 2 W board is a drop-in replacement for the original Pi Zero board, so it seemed simple enough.

I bought a Pi Zero 2 W board on Amazon for about $28 (US). The board didn’t have the header pins installed, so I bought some. I bought a box of 40-pin headers for less than $10 (US). I now have more of them than I’ll use in my lifetime. 

I took advantage of a rainy Sunday to do the upgrade. First, I needed to install headers on each end of the Raspberry Pi’s GPIO area. The two headers had two rows of five pins each. With the help of an Xacto knife, I snapped the pieces I needed from one of the (many) 40-pin headers I now own. With my aging eyes, I needed to use a lighted magnifying glass to do the soldering. To avoid melting the plastic, I allowed some cooling time after I soldered each pin.

From there, it was a simple task to disassemble the hotspot, swap boards, and put it back together. I estimate that the hardware part of the upgrade took all of about 20 minutes. 

I had previously burned the WPSD image on a new Micro SD card, so it was ready to go. When I inserted the card and powered up, the hotspot booted up in a minute or two. After importing a backup WPSD configuration file and doing a couple of tweaks, the hotspot came to life. Success!

The performance improvements were immediately obvious. The dashboard and configuration web pages were much more responsive, and the CPU load typically stays under 20%. It’s been running for a week now, and it’s been rock-solid. Since this upgrade went so smoothly, I went ahead and upgraded my other hotspot. That one was just as easy and is also working great.

For you Raspberry Pi power users out there, this is pretty trivial stuff. Yeah, I guess it is. But it was an easy and fun little project, and I learned a bit about Raspberry Pi boards in the process.

73, Craig WB3GCK

Taner Schenker (DB1NTO), der Entwickler des PicoAPRS, hat mich via Twitter auf das Projekt „Android Codec2 Walkie-Talkie“ aufmerksam gemacht.

ATTENTION! NOW YOU CAN MAKE DIGITAL VOICE TALK WITH YOUR PICOAPRS! Thanks to sh123! Install codec2_talkie apk from GitHub https://t.co/PLy0x4yO1z set your PicoAPRS to TNC mode and connect with your smartphone via USB cable. That's it
Both have to set the same baudrate in the app pic.twitter.com/xG5EZ1ZeJB

— Taner Schenker (@PicoAPRS) December 8, 2020

Dabei handelt es sich um eine minimalistische Android-App mit der man mittels AX.25 digitalen Sprechfunk betreiben kann. Die App verbindet sich via Bluetooth oder USB mit einem KISS-TNC. Über das am TNC angeschlossene Funkgerät können dann Codec2-Audioframes, welche in KISS-Frames eingekapselt sind, versendet werden.

Die App bzw. Codec2 ändert nichts an Modulation oder sonstigen Parametern. Es hängt alles vom verwendeten Funkgerät ab.

Laut Entwickler sollen sich AFSK1200, GMSK 9600, LoRa, FSK, FreeDV und weitere Modulationen verwenden lassen. Einzige Bedingung ist, dass verwendete Funkgerät muss via KISS ansprechbar gemacht werden.

Laut dem GitHub-Repository funktioniert es mit dem PicoAPRS und mit den kleinen LoRA ESP32 Modulen, die Bluetooth integriert haben.

Das Projekt befindet sich in einem recht jungen Stadium sieht, aber vielversprechend aus.

Ich werde das in den kommenden Tagen mal mit unterschiedlichen TNCs und LoRa-Modems durchtesten. Über die Resultate berichte ich dann hier im Blog.

Weitere Infos zu dem Projekt gibt es bei GitHub und im Forum unsigned.io

Das Bildmaterial in diesem Artikel wurde mir von Taner Schenker, DB1NTO zur Verfügung gestellt.