Ham Radio Field Computer for Off Grid Comms

Field computers are used primarily for data modes operations, either fixed station or in the field. The channel made heavy use of the Raspberry Pi early on. It was cheap, painfully “fun” to configure, but wasn’t without its challenges. Later on, the channel migrated over to the Microsoft Surface for data mode communications. The Microsoft Surface has simplified my field radio kit, making deployment faster and more effective. In the future, I’d like to see us move towards an Android-based field computer. This is in its early stages, but it looks like there is some movement, in that direction. Time will tell!

Rugged computers or?

There are lots of different opinions about rugged computers. I think yes, a rugged computer is a good things. However, rugged computers can be difficult to power, too heavy for portable work, and often more of a pain in the ass than they are worth. Yes, rugged is a good thing! Just be careful which obne you choose. Currently, my primary field computers are both Microsoft Surface Go models. These are not rugged, but do a good enough job for my current needs.

An Android OS Field Computer

The ultimate goal for man-portable off-grid ham radio is portability. One of the most portable of devices available today, are Android-based smartphones and tablets. These are smaller, lighter, and very capable for off-grid ham radio data modes. The problem we have is a limited number of Android apps in the Ham Radio space.

For emergency communications and preparedness,  there are two very important Android apps, recently published. The first Winlink app for Android was released in late 2022. It’s called WoAD which stands for “Winlink on Android Devices”. WoAD is a very capable Winlink client,  capable of running ARDOP sessions,  Packet Sessions, Robust Packet Sessions,  and Winlink telnet sessions.

Another Android app relevant to the emergency communications and preparedness communities is APRSDroid. APRSDroid is an APRS client, primarily used on 2M VHF. What you probably didn’t know is APRSDroid also supports Robust Packet and HF APRS.

HF APRS is generally used on the 30M band, on frequency 10,147.30 USB. At the moment, APRSDroid makes use of a Robust Packet TNC running in KISS mode, to send and receive APRS position reports, send and receive APRS messages,  and plot APRS station reports, on graphical maps.

Where APRS range on VHF can be measured in tens of miles/kilometers, HF APRS range can be measured in hundreds or thousands of miles/kilometers. This range is achieved with little or no intermediate infrastructure!

Winlink and APRS are two of the most critical tools in our emergency communications toolbox. I’m grateful they’ve come to Android OS.

Ham Radio with a Microsoft Surface

Microsoft Surface Go 2/3 Tablet

As mentioned in the video Saying Goodbye to the Raspberry Pi some time ago, I have migrated to a Microsoft Surface for Ham Radio Data modes. The primary reason for the move away from the Raspberry Pi, was reducing the number of unique items carried, to make it useable in the field. Sadly, the Raspi was too complicated, had too many components, and was too fiddly to configure. There are circumstances where a Raspeberry Pi could do well. Scroll down the page for my Raspberry Pi research, field testing, and findings.

At the time of this post, I already had two Microsoft Surface Tablets. One was the Microsoft Surface Go 2, the other Microsoft Surface Pro 3. For this project I decided on another Microsoft Surface Go 2 (LTE variant), running a LITE & stripped down version of Windows. More on the OS later on.

I purchased to Microsoft Surface Go2 LTE because it has a built-in GPS. This was a hard lesson learned with the Icom IC-705, which doesn’t allow access to its internal GPS telemetry, over its wireless connection. The GPS is an excellent addition to the kit, when our radios don’t have them built-in. can use an internal (or external) GPS for sharing our position, mapping, time synchronization, … Seemed like the internal GPS on a Surface would be a win, so I headed to ebay to find a second hand Microsoft Surface Go2 LTE, and actually found one. With the internal GPS, Winlink, JS8Call Tools, Robust Packet and all the other telemetry using modes I use, now all can get location data from the internal GPS, on the Microsoft Surface Go2 LTE.

Why not a Surface Go 3?

Short answer, I’m usually on a tight budget! Being on a limited budget, the cost of a Surface Go 3 LTE brand new, was hard to justify. The Surface Go 2 LTE with an M3 CPU has better performance than my Pentium Gold Surface Go 2 model, and is easier to find second-hand. My Pentium Gold Surface Go 2 has worked flawlessly for ham radio data modes, blogging, and tutorial screen capture, … I am updating this article on that machine right now! These are not gaming computers, but ridiculously capable for ham radio. If you choose a Surface Go 3, I would suggest the LTE/i3 variant with built-in GPS and more ram (just to be sure).

Why a Microsoft Surface?

Finally, the following video explains in easy to understand terms, my justification for switching over from a Raspberry Pi, to a windows based machine. I do have a raspberry pi based tablet which might fit the bill for many of you. Unfortunately, it required more time to prepare, test and document. It would certainly reduce our budget but unfortunately, would increase our headaches. If your heart is set on a non-Microsoft machine, I would suggest a Debian based Linux tablet or laptop (even a Surface running Linux).

For everything you’d ever want to know about using a Microsoft Surface Go for Ham Radio, please read this post.

Microsoft Surface Go & Icom IC-705
Microsoft Surface Go & Xiegu x6100

For more Microsoft Surface posts on this site, click here:

Microsoft Surface Go & Icom IC-705

Raspberry Pi

Unless your heart is truly set on a raspberry pi, I would suggest skipping the raspberry pi as it can become a complete waste of time, compared to other solutions. It is cheap to start with, but quickly becomes a money pit to make it into a reliable field computer. As a cheap desktop computer for FT8 or JS8Call, go for it. For portable work off-grid, think hard!

The Raspberry Pi is a budget friendly cult platform, often used for off grid computing, and/or off grid communications. On this page you’ll find various tutorials, helping to build a Raspberry Pi, which is more effective off grid. We will also show you various examples using the raspberry pi for off-grid communications.

Although I promoted the Raspberry Pi for some time, it ultimately became an unreliable money pit.Yes at its core, it was cheap, and lightweight. Sadly, uncommon tasks were a constant challenge! Documentation was almost always outdated and worse, a challenge to sort through and find. Still, when it worked, it worked well!

Before going any further down the Raspberry Pi Rabbit hole, I would suggest watching this video. As mentioned earlier in this article, the Raspberry Pi is not without its challenges. That doesn’t make it bad, but it can be challenging to deploy effectively, without a bunch of hands on fiddling.

The previous video titled Ultimate Raspberry Pi build for ham radio, we discussed the strategy an off grid Raspberry Pi field computer, for portable ham radio field communications. In the following video, we’re taking that Raspberry Pi field computer to Lapland just above the Arctic Circle, to put the Raspberry Pi powered portable ham radio station, to the test.

Unfortunately it’s not possible to test the Raspberry Pi field computer, without putting the entire portable ham radio Field Station to the test. This adds the necessary context, when demonstrating off-grid Communications in the field with the Raspberry Pi. That means we’re going to test the Raspberry Pi field computer, the qrp go kit, the effectiveness of a Raspberry Pi JS8Call combination for off grid ham radio communications, the shelter, heat source, do some cooking, as well as all the things that go into amateur radio field communications in winter, and above the Arctic Circle.

In addition to information on this page, there’s also a plethora of information about the Raspberry Pi, posted on oh8stn.org.

Tutorials

Until recently, rig control over wifi network has been a challenge. Recently, John N0JDS broke me down and made me take another look at the FLRig developments. I was happily surprised to find the FT-891 almost fully supported. This means complete touchscreen control over my VNC client. The UI is still suffering, but its totally useable.

Screen sharing over wifi is another benefit of integration of the raspberry pi with our amateur radios. In the following post, we can see my Yaesu FT-891 and raspberry pi, being remotely accessed by 3 different mobile devices, while in use as a desktop.

RTC Install and configuration. The next in more recent tutorial was adding a real time clock, to the Raspberry Pi. One of the ways the manufacturers of the Raspberry Pi keep costs down, it’s by omitting components which aren’t necessary for efficient operation. This leaves the end user responsible for adding components to the Raspberry Pi, allowing it to meet the needs of their particular project. In practice I didn’t need the real time clock since the GPS worked flawlessly however. If it’s important to have a redundancy plan, in case GPS access for some reason was denied. It was also wise to have a redundancy plan for what could be a very real possibility, where both internet and GPS satellites were inaccessible. In this scenario, we would rely on the Raspberry Pi real time clock. In this video we install, configure, then field test the Raspberry Pi, using amateur radio data Communications on HF. The field test was completely off-grid.

WinLink and PSKMail email are important tools in the ham radio and preparedness communications communities. In this post, you can see PAT WinLink running on my raspberry pi. It appers the project has been abandoned, but it is a workable solution for the raspberry pi powered amateur radio station.

Is it possible to run two unique audio interfaces on the Raspberry Pi, on two seperate apps e.g. FLDigi & Dire Wolf? Answer, absolutely! The raspberry pi 4b is a powerful platform. With adequate cooling, the RPi 4 can easily run two different apps, with two unique audio streams, cat control, … provided the apps are running on seperate workspaces.

In the field

In this video, I take the Raspberry Pi to the field near the Arctic Circle. The goal was to understand the possibility of using a Raspberry Pi, to power a data mode, portable ham radio station in the field. It is a rather Antiquated video. It does show where we came from, and what we were trying to achieve.

Hardware solutions

Over the past couple of years, we’ve tried a few different Hardware Solutions to get the Raspberry Pi off grid. The PiJuice hat was the first. Unfortunately it kind of created just as many problems as it solved. Like many of the solutions we see on this page, they need some time to mature.

NW Digital Radio DRAWS: https://oh8stn.org/blog/2018/11/18/digi-mode-ham-radio-hat-for-raspberry-pi/

DRAWS Hat. NW Digital Radio calls it a Digital Radio Amateur WorkStation Board for the Raspberry Pi. I think Digital Radio Amateur Workstation System would be more cool, but i’ll take it. I was pretty stoked about this board when it came out. The belief was, integrating the Raspberry Pi with a field radio will be easier than ever. Fewer cables, no cable mess, and a clean installation. The hat integrates a GPS, Real-Time clock, dual audio interfaces, and external power regulation. If ever configured correctly, it will solve lots of problems.

Some operators seem to have been able to make it work. I on the other hand was never happy with the support, setup complexity, or the performance on HF digital modes. I’m hoping this was just a matter of letting the product mature, before I get back to it. I stopped working with the product after being incredibly frustrated with all these things. I haven’t given up, but they’re certainly should be an easier way to deploy this device for the end user.

Here are the two videos I did on the draws hat. I’ll come back to it, once it matures.

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The entire Ham Radio with a Raspberry Pi playlist:

Mentioned in the latest video

AmRRon Setup Scripts for Raspberry Pi
https://gitlab.com/amrron/setup-scripts

73
Julian oh8stn
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