dec 16

Top 10 Amateur Radio Uses for the Raspberry Pi

Bron: hamblog.co.uk
The Raspberry Pi has proved to be a phenomenal hit with hobbyists around the world. Originally conceived to get children into computer programming, it was quickly adopted by hobbyists due to its cheap price and GPIO output pins. Indeed, initial demand was unprecedented and supplies were limited for some time after launch and this still continues after each new version is released.

It didn’t take long for the Amateur Radio community to see the potential in this little computer and sure enough we’re starting to see some really interesting uses coming to the fore.

The purpose of this article is to show you what can already be achieved and give you some ideas, rather than detail how to achieve each use! I’ve provided links against each use to help you take the next steps. Hopefully this article will encourage you to get started with the Pi.

This article is based around a presentation I gave to my local club (CDARS – Chesham & District Amateur Radio Society). You can download a PDF of the presentation here.

Introduction

The Raspberry Pi (in its various forms) is a credit card sized computer which costs very little, from £4 for the Raspberry Pi Zero (buy) to £30 for the top-spec Raspberry Pi 3 (buy). This cheap price in part helps makes the Pi a compelling platform for hobbyists looking to experiment with. In fact the Pi Zero is so cheap, it’s almost throw away (but that would be a shame!).

The Raspberry Pi doesn’t use a traditional hard drive, instead it uses SD cards to store the Operating System and software, this is also a very cheap form of storage!

Flavours of Pi

There have been several versions of the Raspberry Pi computer since initial launch, I’ve linked to the most recent versions below:

  • Raspberry Pi 1 (variants include: model A/B/B+)
  • Raspberry Pi 2
  • Raspberry Pi 3 (£30)
    • Top of the range Pi!
  • Raspberry Pi Zero (£4)
    • Almost a micro-Pi, very small, about the same power as the Pi 1, but super cheap and small!

The Operating System

First thing you need to know is that the Raspberry Pi doesn’t use Microsoft Windows, this is for several reasons, not least due to cost. Instead it uses the Linux operating system, if you’re not amiliar with this, Linux is Open Source (free), runs 90% of the world’s fastest supercomputers and has a large community of developers and resulting software (all of which is again free).

If you have ever used an Android or Amazon phone or tablet you have already used a ‘distribution’ of Linux, but you probably never realised!

There is a distribution of Linux especially for the Pi called Raspbian and this comes with enough software to get you started.

GPIO Pins

Now we get onto one of the main reasons the Raspberry Pi has been so widely adopted by hobbyists, the General Purpose Input Output Pins (GPIO). Depending on the version of Pi you get they will have anything from 26-40 GPIO pins onboard.

This is what gives us the physical interface between the Pi and the outside world, because it allows us to connect a very wide range of sensors/devices and breakout boards. These devices can collect information and can be controlled by software (which you can install or even write) on the Pi. Suddenly the potential for real world ham radio applications seems endless!

Pi HATs (Hardware Attached on Top) are specially designed bits of hardware which can be purchased and plugged straight into the GPIO pins. These are pre-assembled and are designed to be the same size as the Pi to make mounting easier.

 

Top 10 Amateur Radio Uses

Now I’ll take a look at my favourite amateur radio uses for the Raspberry Pi, these are listed in order of my priority order.

1. Decoding Data Modes

The Raspberry Pi can use the audio input from an external USB sound card to decode digital modes. In fact you can install the popular FLDigi software on the Pi to decode a wide array of data modes including RTTY, PSK and CW to name a few.

This is probably the first project I would recommend to people dipping their toes in the world of Pi, in fact you can even buy SD cards with Raspbian+FLDigi pre-installed from Mike Richards G4WNC. This is a great way to get started quickly.

Once you’re decoding signals on the Pi, you can take it up a notch and start spotting the received signals to the Reverse Beacon Network via the Internet. This is easily done within the FLDigi configuration.

People are experimenting with the Pi and rig control to allow for TX as well, although this is not something I have experience of just yet.

 

2. Remote Software Defined Radio (SDR)

That’s right, you can set-up (probably) the cheapest SDR receiver using a Raspberry Pi, USB soundcard and a RTL Dongle (~£10). You can receive between 25MHz up to around 1800MHz using this dongle, not too shabby. Attach this to a discone antenna and you’ve got a very capable scanner!

You can run the popular SDR# (pronounced SDR Sharp) software under Raspbian to make this a reality.

What’s more, is that the Pi and dongle can be remotely located and accessed from the comfort of your desktop/laptop/tablet device in your home. You of course need to connect your Pi to your home network somehow, you have two choices here either using a WiFi (separate dongle needed) or via Ethernet cable. I would recommend the hardwired cable route if possible to minimise drop outs.

Once again Mike G4WNV sells pre-built SD Cards with everything you need to get started, just add a Raspberry Pi and an RTL dongle (who doesn’t have one knocking around the shack?).

 

3. WSPR Transmitter

The Pi is quite incredible in that you can press the GPIO pins into outputting RF between 0-250MHz. Suddenly we have a capable LF/MF/HF/VHF WSPR transmitter! The Raspberry Pi has a reference crystal on board which allows for this, although it will need to be calibrated within the WsprryPi software to ensure it’s precise enough for WSPR.

The Pi provides around 10mW of output, so not a massive amount of RF, but enough for the WSPR beaconing mode. One important note is that it outputs a square wave which necessitates a low pass filter. You will also want to use a regulated power supply with it to ensure additional frequency stability.

A WSPR beacon for an outlay of £4 (assuming Pi Zero)? Amazing!

 

4. Amateur Satellite Tracking

This is probably the easiest Raspberry Pi project you can undertake. Install the GPredict software on your Raspberry Pi and you have a very capable satellite tracker, allowing you to track every conceivable satellite across the world in real time.

It allows you to filter the type of satellites you can track, this is where you can just select the amateur radio satellites you’re interested in working and see in real time which of the birds you can work through.

Of course the next step is to interface the Raspberry Pi with your antenna controller and start tracking the sats in real time, now there’s a thought!

 

5. Digital Voice (DV) Hotspot

Turning the Pi into a DV (Digital Voice) hotspot has proved to be another popular use of the Pi by amateurs. There are a number of dongles and add on boards which allows you to turn your Pi into an access point into the D-STAR, Fusion and DMR networks.

The Pi bridges the gap from RF to the internet, without you requiring any local repeaters that support DV to be in range.

There are currently two commercial add-ons that will add DV support to your Pi:

This is a great use for a cheap Pi computer, now you can join the digital voice revolution without waiting for your local repeater technology to catch up!

I’ve not tried this yet, but hope to set one up soon so I can make use of my rigs D-Star and Fusion capabilities.

 

6. APRS I-Gate

You can turn the Raspberry Pi into a APRS (Automatic Packet Reporting System) Digipeater to track the positions of amateurs and indeed yourself. When you connect a HT to you Pi you can receive packets from the radio and send them onto the APRS-IS (internet based APRS network) and vice versa.

Good instructions for setting up a RX only APRS I-Gate can be found here.

7. ADS-B Flight Tracker


Using the PiAware software you can now track real time ADS-B (Automatic Dependent Surveillance – Broadcast) flight tracking information from aircraft.

This allows you to track the aircraft in your area and track their progress in real time, pretty cool! I live not too far away from London Heathrow airport so there’s always a lot of planes to track, which you can see in the screenshot here.

You will require an SDR dongle (cheap £10 RTL TV dongle will do) to receive these and a suitable antenna for the 1090 MHz signals.

See the PiAware setup instructions or for a more convenient option see Mike G4WNC pre-built SD cards.

8. Rotator Controller

This is not one I’ve tried, but some intrepid experimenters are using the Raspberry Pi to control their antenna rotators. Check out the PiRotator project.

 

9. Retro Gaming Machine

Ok, the last two aren’t amateur uses for the Raspberry Pi, but they do rank as many people’s favourite uses for this great little computer!

The Pi can be easily turned into a retro arcade machine to play all of the classic games from your youth.

The RetroPie project gives you everything you need to run games from a whole host of different gaming platforms. I’ve tested ZX Spectrum and SNES games and these run very well!

The Picade (£180) gives your Raspberry Pi a quality arcade cabinet complete with retro controls, this is super cool, but I can’t quite make the jump to spend £180 on it.

10. Media Centre

You can turn the Pi into a complete media centre, capable of playing a dizzying array of video file types stored locally on a hard drive and even allows you to stream video using popular services such as YouTube, Netflix and Amazon Prime Video. Of course as the Pi has an HDMI output you can connect this straight to your TV.

The software is known as Kodi (previously XBMC) and can run a myriad of add on applications to add a ton of functionality. I’ve used various incarnations of this software for about 10 years now (on other non-Pi platforms) and found it very good.

The Future of Experimentation?

I believe that we’re now in the transition period in amateur radio, moving from the traditional home brewing and into the future of computer/RF augmentation. The Hybridisation of these technologies allows for a lot of interesting new areas in our hobby, we’re already seeing this in the rise of SDR radio.

The Raspberry Pi and Arduino revolution are leading the way at the moment and the limits are only your imagination in what can be done.

This new part of our hobby has a lot of scope for bringing in more of the Maker community into our hobby and will inject new ideas and passion, that is much needed.

Conclusion

Hopefully this article has given you a taster of some of the amateur radio uses of the Raspberry Pi and given you some motivation to get one and give some of these a go. It’s a very versatile computer and for an outlay of £4 you can’t really say no!

The Pi Zero is particularly interesting and I’m sure we will see more from this extremely cheap and small computer in the future. Keep your eyes peeled!

Have you found additional amateur radio uses for the Raspberry Pi? Let me know in the comments.

dec 16

The Future of Amateur Radio is Software

Bron: faradayrf.com
The future of amateur radio will be built on its software and supported by hardware. Amateur radio operators will continue to solder components together and string up antennas, but this will be a means to an end for most people. We’ve seen incredible performance increase in hardware by moving towards software defined radios, yet this change has not drastically affected how the radios are used. Hardware is smaller and more accessible than ever before. This has created an opportunity for technology to start changing how we use radios. The change is starting to focus on us, the operators, and software will be the catalyst.

FaradayRF Firmware screenshot

FaradayRF Telemetry firmware radio code.

Change Is Good

There will always be resistance to change. The “know coders” and “real radios have knobs” camps will always have an opinion. Ham radio has been and always will be a medium to explore. Instead of complaining about change, many of us are building digital communities of like-minded people. Radio amateurs who find WSPR and FT8 fascinating are pushing its use for keyboard to keyboard operation. Communities such as FaradayRF are putting the idea of keyboard to keyboard communications into question, pushing forward towards more automation. Ham radio operators are experiencing a paradigm shift within the hobby. Amateur radio isn’t just about real-time communications anymore; experimenters are building interconnected digital infrastructures to serve the wider community. The hobby is about to explode with growth directly from software and hardware platforms waiting to be implemented as tools from the radio amateur’s toolbox.

Networking operations within ham radio allows each station to become larger than itself. Imagine real-time authentication of QSOs using digital signatures. Silence on many of the
microwave bands could be filled with activity as digital networks are much more suited to these bands. Microwave operation is difficult with point to point contacts but perfect for networking short hops between larger collections of stations. Even data mining operations within the bands and using the analytics to gain useful insight into the hobby would be fascinating. Improved sensor telemetry also allows ham radio to be on the forefront of citizen science.

A Connected Medium For Exploration

Ham radio is no longer just about making the contact. Instead it’s changing into an incredibly useful medium for fun, education, and experimentation just like it always has been. Simply, we always viewed the hobby as a means to communicate when the hobby is even more interesting if the communications become the enabler of even better technology. Software glues hardware and adventures together. Our hobby provides us the opportunity for adventure, linking distant stations together. This is why the future of ham radio is software. Embracing this change will grow not only the technology in amateur radio but the strength of our community.

dec 14

RFinder M1 – A Review By N8EFJ

Hi I’m N8EFJ Bob from Toledo Ohio,
I work at a commercial 2-way radio shop in Toledo and have been there since 1982 in this profession. I have been a ham since 1995.

This is my review and explaination of the RFinder M1DU analog/DMR 2-way radio and android cell phone as I understand it. I have the 440 to 480 Mhz version.

First of all it is in my opinoin a software defined radio run by the mini computer called a smartphone.
It is currently running android 6.0 and who knows it might be upgraded to 7.0 someday.
I have the (Nova launcher) app launcher overlay with customizeable icons and gestures to fully customize the user interface of the phone.

As a cell phone the RFinder does a pretty good job utilizing the AT&T network in the USA and does run and support the LTE or 4g network connection. Voice quality is as good as many other cell phones.
I also run the Zello PTT app for ptt radio like calls to friends over the network just as many cell phone users can do, talking quality in this mode is great also. The cellular signal quality is as good as many high-end cell phones if not better in many cases for calls and network connectivity.

Now for the meat of the review – the 2-way radio portion.
With the RFinder app up and running and connected to the internet, the repeater list is constantly updated following your current GPS location and displaying all the repeaters in your area as long as they are coordinated and the proper information is listed with the coordinatiog body of the repeater. You can set the distance of the listing from your location in the settings menu and what bands are listed as well.

Much of the information Rfinder gets is also outside of those bodies scouring the web to fill in any missing information to provide the user with the most up to date listings, such as frequencies, “pl” and “dpl” tones, echolink information, system fusion information, DMR color codes and talkgroups, IRLP connections and many more.
This information list is worldwide, so no matter where you go you should have the repeater list for your location.

So just by selecting a repeater in your area and touching the corresponding talkgroup desired, in the case of DMR and then touching send to radio. The software sends the information to the radio module thus programming it for what you selected. You are now ready to start talking on the system selected, it’s just that simple.

The RFinder application is constantly being updated by Bob Greenberg and his engineering staff, They actually listen to their customers and implement some of the changes requested.
If there is a problem, just simply report it to RFinder and they will shortly in many cases have it fixed in the next release of the App. Some releases are 2 in one week.

After all it is a software defined radio! Problems can be easily fixed and new features added. As the movie producers say (we’ll fix it in post).

The radio performance in as good as many other DMR radios I have used. These results were attained from my 2 service monitors – the Aeroflex 2975 for analog testing and the 2017 Aeroflex 8800SX for digital testing.

The results of my particular radio are as follows – – –
Receive sensitivity is .20 microvolts for both analog and DMR. The Transmit deviation on analog is 2.2 khz for narrow, 4.2 khz for wideband. The TX power out is 3.2 watts for high power on analog, 3.9 watts for DMR on high power. Low power is 1.9 watts for analog and 2.0 for DMR. DMR bit error rate was 0 or .1 % at worst.

In high RF environments I do not get much intermod as with cheaper radios, that have not much in the way of front end filtering. After all I do work in the 2-way service environment where often times I’m up at a site with many repeaters on the roof or tower sites where intermod is a known problem with cheaper radios.

I mostly use low power to conserve battery and the local repeater (N8EFJ) is no more than 5 miles away centered in the city roughly.
I did switch to a Motorola XPR6550 whip antenna for the radio as the performance and match is slightly better than the stock antenna.
Speaking of battery life, it comes with a 6200 mah battery thats 6.2 amp-hours, more than enough for a day of use. But if you have the gift to gab and somehow you do run the battery down…. you can buy a second battery and just swap it out. I mean it’s not like many phones that have a permenant battery in it, this one is removable /swapable.

This has been my independant review with the RFinder radio/phone set, and yes I did buy one in May of 2017.
I personally met Bob Greenberg at the FortWayne Indiana hamfest in November 2017, He is a great guy, very helpful and informative.

I hope you find some of this information useful, and if I left something out please add to the review!

73, God Bless