Fully assembled KiwiSDR and Beaglebone SBC (Single Board Computer)

Our very own WebSDR

I think most members are aware that we now have a WebSDR available to us (a link to which is available at the bottom of the website homepage). What you may not realise is that it's temporarily installed at my home while we test out suitable antennas, and then look to get the whole shooting match installed either at the club shack, or if that proves problematic, at a secondary location which is both RF-quiet and has a good internet uplink.

I'll be posting three or four articles on how the whole project comes together to provide a useful addition to our shack, and I'll write them in the style of a retrospective guide for those that come after us and who are seeking guidance. The implementation has certainly proved to be popular with members so far, with all four available access slots filled up every weekday lunchtime. On several occasions, I have been unable to snag one for myself, and if that trend continues we do have the option of allowing eight concurrent users, though only two of those eight will get the full graphical 'waterfall' experience. The rest just get an audio interface.

For this first instalment, I'll detail the physical build so that you can get a feel for what it looks like in the raw. I'll also cover the initial setup process and explain some of the difficulties I encountered along the way. The next article will give an overview of the back-end software configuration so that you can see some of the flexibility we have in that regard.

Other articles may cover wideband antenna testing, and possibly one on how to actually use it once you've loaded the webpage into your browser. That last one may just end up being a talk at the club or over Zoom, and would be a very high-level walkthrough to enable everyone to have some fun with it, regardless of experience. Most of you will already be well beyond that, I suspect.

Hardware - What's in the Box?

I purchased the KiwiSDR in kit form from Mr Lynch. I'd have been happy to have sourced it from anywhere, but they happened to be by far the cheapest. I also picked up a 5V power supply while I was at it (1.5A, although owners in the know often recommend a modified 3A Raspberry Pi item). You can also get a really nice aluminium enclosure, but it's around £45, and is not in stock anywhere that I could find. Thankfully the kit comes with an adequate DIY acrylic case which turned out to be fine as long as you don't plan to throw it around too much.

The included Acrylic enclosure - suprisingly sturdy once assembled

The box contained nearly everything you need to get started, and contrary to the instructions, the two main parts (the little BeagleBone computer board, and the KiwiSDR radio board) were already mated together via a subset of the GPIO pins. I pulled them apart again for the photos below.

There is lots of information on the BeagleBone computers at beagleboard.org. They've made several variants of this developer-focused board over the years, but apparently all the KiwiSDR kits come with the later BeagleBone Green (BBG) which is good news as these all include 4GB eMMC flash memory. The Green board (Green, as in the colour of the screen-printed background) is actually a Seeed Studio collaboration - an evolution of the original BeagleBone Black, and made possible by the open-source hardware philosophy much loved by the maker community.

The 4GB of memory is important, because ultimately it'll give us an upgrade path to Debian 10.x (Buster) from Debian 8.x (Jessie) which is now unsupported and therefore effectively a burning platform.

Beaglebone SBC

Beaglebone SBC Underside

KiwiSDR RF Board

In an attempt to avoid letting the magic smoke out, I read all the info on the maker's website which proved very useful albeit a little bit daunting for a complete newbie. I needn't have worried, as most of the scary situations that beginners seem to find themselves in are as a result of just diving in and not reading up on the basics first.

Turns out that as long as the two boards have been connected together correctly, you can pretty much just plug in the various cables and then watch it all power up.

The only pre-requisites for a successful first boot appear to be a reasonable internet connection and an existing DHCP server set up on your network. The Beagle will need the latter to establish an IP address for itself, as you can't easily set this up manually until after it has performed a software update. You can change it to a static IP address once it's up and running, which is what I did. I like to know where my flock are at all times.

I built and tested the device before attempting the enclosure assembly. This seemed sensible in case there were any issues encountered, and because although I read the instructions before starting, I'm only human, and the case is boring!

I'm going to suggest that a logical pre-power-on procedure would therefore go something like this:

1) DON'T INSERT THE SD CARD. There is an Micro-SD card included in the kit, and a corresponding slot on the BeagleBone. It's for emergency recovery only, and is not needed unless you really know what you're doing, or the support guru on the official forum suggests it's a good idea. I'm going to guess that the Micro-SD card contains the self-same v1.2 image that's already pre-loaded onto the device.

2) Connect some sort of reasonable HF antenna (via adaptors if necessary) to the RF ANT section of the KiwiSDR board. There is a standard screw-terminal block for a High-Z antenna wire and ground, but I did what most people will do and connected a 50Ω coax-fed antenna to the commonly-found SMA socket. No antenna is supplied in the box.

Make sure you pick the correct SMA socket though, because there are TWO on the Kiwi board. The other one is for a 3.3V GPS antenna. The silk-screen printing on the board and the manual clearly identify which is which.

3) Connect the above mentioned GPS antenna, if required. The kit comes with a neat little GPS antenna, so although the whole thing is going to live under my desk for the time being, I connected it up even though it has no possibility of seeing clear sky in this location. I wanted it to be detected during any automatic software update and to have its driver correctly installed. Its presence gets flagged for inclusion on the receiver list at kiwisdr.com as well as being used in actual TDOA directing-finding functionality. More on that another day.

KiwiSDR Antenna Connections

4) Plug in an Ethernet cable. Thankfully there is no WiFi capability on-board. Good old-fashioned copper twisted-pair technology for solid reliability and bandwidth. Woe betide anyone who thinks it's a good idea to use a cheap WiFi bridge as a permanent solution. My experience of these is mixed to say the least. The other end of your cable is obviously going into your router, network switch or whatever. This isn't a networking tutorial, though it might turn into a bit of a networking anecdote later on. An Ethernet cable is not supplied either, though I'm sure you have a whole bunch of them in those otherwise empty boxes up in the loft.

KiwiSDR Power, Ethernet and USB Ports

Now before we reach 5) Connect power supply, get yourself ready for bed, or find something else to do which will keep you completely occupied for at least two hours. You are NOT going to want to interrupt the initial start-up process until it completes normally, and it's almost impossible to resist the temptation to power-cycle your new toy every five minutes if you're just sitting there staring at it.

5) Connect power supply. Yes, you can do it now, as long as you definitely read and understood 1) DON'T INSERT THE SD CARD

Most, if not all BeagleBones which come in the Kiwi kits are pre-loaded with a Debian-based operating system which is ready to go out of the box. I have a feeling that my retailer of choice had performed this step on my behalf. The initial startup process (assuming you have an active internet connection) will soon sniff out the latest version of the Beagle/Kiwi software on Github and go get it. It will then compile everything on your device and then reboot itself. As mentioned, the pre-loaded version is v1.2 but the latest version (at time of writing) is v1.544, and there is no comparison. Security issues alone mean you must upgrade, but functionality is massively improved too.

If everything has worked as it should have, your KiwiSDR is now available on your local network. You can probably find it at:

my.kiwisdr.com

or

kiwisdr.local:8073

...if you're lucky.

I just dipped into my router's admin pages and found it's DHCP IP address, and then added the port number :8073.

Your admin page can then be found at yourlanip:8073/admin

Relevant password information can be found at kiwisdr.com.

I'm not going to cover the dynamic DNS setup, because either you know how to do this already, or you're going to do some research online and work it out. The Kiwi group used to offer a reverse-proxy solution, but no longer. Fortunately though, there is a DUC (Dynamic Update Client) included in the (downloaded) software and accessible via the Kiwi admin panel. Unfortunately, it only allows configuration of services from no-ip.com (so you can select a yourname.ddns.net:8073 address). Annoyingly, no-ip nag you to death every 30 days on the free version, so I used my own script instead of the regular DUC so I can peacefully enjoy the free services offered by duckdns.org.

You're also going to need to do some port forwarding on your router. You probably know how that works. Just set up a virtual server, where you map an external port number to your newly-assigned static IP address (you don't have to go static, but it's much easier IMO) and internal port number, then tell it to use the TCP protocol.

You can find generic information on how to perform these last two steps all over the place, including the manual for your router hopefully.

Once you've got everything working, you can go back to the acrylic enclosure build. Instructions are included, and are generally OK, except that the position of the USB port printed on the acrylic base panel doesn't correspond to where it is on the BeagleBone (in my version at least) and the photos are lousy and lack detail. Top tip: the bottom acrylic sheet (and yes, you will need a hairdryer and some serious patience to get the protective film off) goes on the UNDERSIDE of the metal side panels and not INSIDE, or you simply won't have enough clearance to get the paired boards underneath the slide-in top sheet. You'll also have to separate the Beagle and Kiwi to bolt it all up and then get the enclosure push-pins in place which hold it all together (remarkably well). Be sure to push the GPIO pins fully home between the boards too, otherwise clearance will once again be an issue when assembling.

I've made all that sound like a bit of a nightmare, but in reality it's really straightforward and fun if you take your time - especially if you've done this kind of thing before.

Next Time...

What happens when all of this goes to hell in a handcart, how to fix it, and how to finally get yourself some much needed alone-time with your new KiwiSDR.

Berni M0XYF

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