X days Off Grid Radio & Raspberry Pi Prerequisites

Hello Operators

At the time of writing this, it’s just about time to head out on one of the X days off grid excursions. My radio uses a headless Raspberry Pi for digital Communications. This allows me to have the same user experience connecting with my radio, regardless of the tablet or laptop I’m using access it. I very much like the idea of connecting to the radio, so I view the radio and the Raspberry Pi as a single integrated system.

When operating from home, my Raspberry Pi , tablet, or laptop all use the Wi-Fi network from home. As an interim solution, I used a 4G Wireless Wi-Fi router to create that Network away from home. Naturally getting rid of the 4G Wireless Wi-Fi worker for field work is a priority.

My buddy Jordan KN4CRD, sent me this easy-to-follow tutorial. It allows us to set up a dynamic access point for the Raspberry Pi when away from our home network, I’ll explain.

Normally my Raspberry Pi (when operating from home), is accessible to other devices in the same network, from the Wi-Fi access point in my home. That allows connections to it using a VNC client. The tutorial Jordan sent me does a few very cool things.

  1. When I’m home, ut attaches to my home Wi-Fi network and bridges it, so I still have internet when I’m attached to the VNC client..
  2. If it doesn’t find that Network, which means I’m away from home or the network is down, it creates its own network with the built-in Wi-Fi adapter on the Raspberry Pi.
  3. It also creates its own DHCP server to hand out IP addresses to my tablet or laptop, so that I can connect over VNC client to my Raspberry Pi powered radio.

Here’s the link to creating an access point on your Raspberry Pi.

The other thing that was required was a very accurate clock on the Raspberry Pi. Some digital modes are dependent upon clock accuracy. Normally we achieve that accuracy from time servers while connected to the internet. Unfortunately with the X days off grid series, it would be ridiculous to use the internet to synchronize my clock, considering the series is entirely about communications off grid. 😀

To circumvent the problem of not being connected to the internet, I’ve decided to use a ublox GPS dongle.

Here’s a blog post that wrote with instructions for setting up the GPS dongle as the nmea source to synchronize your clock. If you happen to be connected to the internet it will also use time servers from the net. If you’re out in the field away from internet access, it’ll simply use the nmea from your USB GPS.

Setting up a USB GPS as a nmea Time server for your Raspberry Pi clock .

Finally, after the plethora of things I had to do for when link, updating my Raspberry Pi, setting up the GPS, access point,… Was one thing I needed to do before I could pack up the station. That is actually making a clone of my SD card. This way if something happens out in the field my SD card is corrupted or destroyed, I have a bootable backup to restore it to where it was after I’ve made all of these configuration changes.

If you haven’t already seen the trailer for The X days off grid series they look.

Rock and roll guys

Julian oh8stn

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