amateur radio – Richard Mudhar

HP Stream 11 lives again with Xubuntu

I bought this must’ve been 2016. It was a bad move from the get-go, because the hard disk is only 32Gb. And it had Windows 10, and 32Gb is only just enough to get Windows on. Pretty soon I had to use an outboard hard drive to be able to update windows, and by about 2019 even that didn’t work. It’s a shame, because it’s otherwise serviceable, but totally non-upgradeable – the ‘hard drive’ is an eMMC soldered to the board. It lasted me three years. I did like the light weight and silent operation, but the overall gutless performance and slower and slower startup was bad.

I could use a linux laptop

I had been tinkering with a Raspberry Pi4 for amateur radio field use, but wrangling a Pi in the field for things like SOTA is a mess, because a Pi plus all the odds and sods you need to make it work is a collection of parts flying in loose formation, and unlike a DC3 they don’t always work well together. It’s bad enough connecting the computer to the radio via analogue audio connectors ¹, having to connect the Pi plus screen to a Bluetooth keyboard plus some sort of battery to USB-C power contraption gets a bit much in the field although it all works fine on the bench. I had already run the FLdigi and WSJT-X software on the HP Stream in Windows so I knew it was capable of decent performance, better than the Pi4 which struggles a bit to decode WSJT-X in a reasonable time.

However, I had heard bad things about trying Linux on the HP stream, because the Wifi card is very proprietary. The Ubuntu drivers seem to have fixed that now

It was surprisingly easy to load once I quit trying to install on the UEFI BIOS. I uses Xubuntu LTS 20.04, downloading the iso and putting this onto a USB stick using balenaEtcher. I found the install instructions for Xubuntu hard to find and sketchy, but they are good enough to feature this hint

If you don’t already know how to install Xubuntu, then please read this great tutorial, which applies as much to Xubuntu as to Ubuntu.

which is indeed great, and took me from there. But first I had to switch off the UEFI BIOS. It’s not that obvious to me what advantage UEFI gives me with a machine with a whopping 32Gb of disk space which is far from the 2Tb limit UEFI is supposed to fix, so legacy is fine with me.

A disadvantage of linux on a laptop, apart from the general gangly geeky oddballness of linux on the desktop as opposed to on the server is battery life is not optimised so well.

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Raspberry Pi 4 with touchscreen and FLdigi

I got a new Raspberry Pi v4 and the official touchscreen. The aim of this is to be able to run FLdigi and WSJT-X¹ in a portable setup. Also to stop FLdigi getting hopelessly confused on my main PC – with two sound cards already adding a third sound card as interface for the radio meant portaudio, whatever that is, gets hopelessly confused on Windows and loses touch with the hardware intermittently.

Setting it up was surprisingly painless – blow a new 16Gb SD card with Raspbian, connect screen to the 5V and 0V on the GPIO and the ribbon cable to DSI. Normally you then have to remember to add the empty file ssh to the boot partition with the PC so you can talk to the damn thing, and perhaps wrangle the wireless config if the Pi doesn’t have Ethernet.

With the touchscreen I didn’t need all that. Although I started it up on ethernet, the onboard Bluetooth meant I could connect a Bluetooth keyboard using just the touchscreen, and then set up the wifi in the usual way. The touchscreen needs a reasonably firm press, this is no responsive smartphone screen, and being so small it is sometimes hard to get the right target, even with a conductive stylus, particularly as I set the font size a little smaller to use the screen area more. Continue reading “Raspberry Pi 4 with touchscreen and FLdigi”

Sainsonic AP510 APRS tracker experiments

I bought an AP510 some time ago, at the time results were disappointing, but the firmware has improved over the years. Using 20141215 I was getting signals out to about 8 miles from the typical white stick omnis like Diamond X50, and up to 20 miles from near Chagford on Dartmoor when it was mounted in a backpack. As you can see from the header picture, I had a great RF takeoff and not much vegetation in the way from pedestrian height 😉

Thank you G6SQX and G0MAS for running high performance APRS IGates! The difference in performance with the antenna taped to the fibreglass shell at the back of my campervan is visible in the paucity of reports near G0MAS around Uffculme, range was only a quarter of that as a pedestrian. Despite having steady power and a USB lead as a counterpoise to the aerial. Maybe taping the aerial to the fibreglass detuned it, this thing is marginal enough at 1W output.

My track and the stations G0MAS and G6SQX it reached

Some of the idea of getting this was to play with radio on the hills so it’s good that it performs better in pedestrian mode. I’d like to have a better feel of why exactly that was.

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The Sainsonic AP510 APRS tracker can work well

As long as you recognise that the stock antenna is truly dire. And you’re prepared to fiddle a lot to get the AP510 and software going. This is not something that works out of the box. As supplied from Ebay in April 2016 the firmware of this didn’t match the software, in fact the firmware was too old. Cue much frustration and turning off and on to try and get it to talk. No dice.

Sainsonic AP510 description

Do what this guy says he has a treasure trove of the files in the links to the youtube post. It worked for me. I had to flash the firmware before my box would talk to the Sainsonic config software, and without doing that this device is no use at all.

Now if you can get an integrated GPS, APRS tracker, 2m rig for £78 it’s a great deal, if you can’t configure it it’s a rotten deal. But it worked for me in the end. There’s much to like, it’s small, it has its own battery, the price is right etc. There are things not to like – the male SMA on the board. SMAs are fragile, that pin is gonna break after about 500 cycles, which is why it’s nice to have the plug on the cable or the rubber duck aerial so you get to change that rather than the rig. Oh and the USB connector is a 3.3V RS232 connector, not a USB connector, though it can use a mini USB connector to a normal USB outlet to charge.

So I configured it and fired it up and it sort of works, well, out to about 200m for a J-pole vertical in my loft. Now I admit a J-pole with its somewhat live coax even after a CM coax choke doesn’t belong in the cluttered environment of the loft and I’ll change it for a Diamond X-30 or the like outside at some point, but I have a receive igate on it and it serves other mobile APRS stations okay enough, and serves me up to about 500m in the town with a Kenwood THD7. Continue reading “The Sainsonic AP510 APRS tracker can work well”

GPS serial receiver for Kenwood TH-D7

press the pos button while GPS data is running at it will show you the locator,and lat/long, the degree and decimal points flash on reception. With an unlocked GPS it is lat/long of 0

This project is to make something that used to be common – a GPS receiver with serial data output. Modern APRS handhelds like the THD72 have GPS on board, but my Kenwood TH-D7 is from the turn of the century and doesn’t have onboard GPS. I used to pipe the output of a handheld GPS into the serial port. That worked fine, but in the field it’s a drag to use a handheld GPS tethered to a rig. Every time you want to put something down or set the rucksack down you end up with a knitting session on the cables. This is why they invented Bluetooth, and one option I considered was running a little Bluetooth receiver to a Copilot BT GPS. Trouble with the Copilot is how do you recharge it in the field, and I need to pick off power from somewhere to run the Bluetooth receiver. So I still get cables to the rig and another battery to manage 🙁

Most handheld GPS receivers like my Garmin Vista HCx have moved on to USB serial interfaces now, whereas the 1990s vintage Kenwood TH-D7e uses 4800-n-8-1 RS232, which is what GPS units chucked out in those days. Early THD7s had a problem reading the serial stream since NMEA 0183.3 superseded 0183.2 for the reasons described in the Potator article. I assumed my unit was one of these, so I constructed the Potator, but while the rig worked through it, it also worked without it, so I was lucky and dispensed with that 🙂

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Revisiting Amateur Radio

I took my Radio Amateur’s Exam (RAE) in 1978 – I’d been interested in electronics as a child but I was never going to be able to afford any gear, I thought a technical interest would add a little bit of colour to my application to do Physics at Imperial College. My grandfather had been a radio amateur and he gave me an old homebrew crystalled 2m AM rig. But when I fired it up and my Physics teacher who was a radio ham looked for the signal at his home about 500 yards away there was nothing there, and I didn’t have the skill or gear to know what to do. I had a multimeter but no ‘scope. I could do the RAE, with a general electronics background and revising the licensing terms on the train up from southeast London to City and Guilds which was taken in what the University College London building in Malet Street. Imposing joint, I think it looked like this.

Somewhat doctored form of my old RAE ;) — Somewhat doctored form of my old RAE 😉

I got into Imperial. Didn’t do anything with the pass for over ten years until I came to Suffolk, and there were a few radio amateurs in the group I joined, and I got my amateur licence in 1991 – next year I will be eligible for the QCWA 😉 Initially I used a modified Tait PMR rig on 2m, but getting crystals cut got old quickly because it was dear. I then bought a secondhand FT290. However, I was living only 15m above sea level in the town, and I never got my head round all this propagation malarkey, and not having Morse meant I had to stay 6m and up ISTR. I stuck with 2m and I was never going to be doing this working the world thing without HF[ref]I’ve simplified things a lot – I had technical and engineering skills but no talent for operating[/ref], and was always a second class licensee ‘cuz only Real Men used HF.

The Internet and Amateur radio

Packet radio and the early TCP-IP over KISS modems was interesting and how I learned some of how routeing went. Then the Internet happened and basically ate amateur radio’s lunch, well, what was left of it after GSM mobile and SMS became widespread. It’s difficult for anybody born after 1990 to realise just how poor communications were, but in the end when you want to just get in touch then a modern mobile phone has solved most of the problems amateur radio had uniquely addressed, if we leave out the self training and experimentation lark. Amateur radio had been doing okay with data communications and packet AX-25, but then that Berners-Lee chap invented the Web, and broadband showed up. It looked like game over, and, well, as for so many people, life and work kinda gets in the way.

A different era, and different applications

Recently I had a use for APRS, and I take another look and I like what a new generation have done with amateur radio, they’ve grabbed it by the short and curlies and dragged it into the 21st century, working with modern networking and tech rather than harking back to the golden days of Morse and tubes. I have nothing against Morse or tubes and indeed now that I don’t have to pass Morse to get on HF I am messing about with it.

I read James M0ACQ’s blog about how he went from a standing start to Full Licence in a year. Not only is he doing good stuff with it and indeed some things I may take a fancy to, but there seem to be others doing more with it.

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