Arduino Class Libraries for WSPR and SiLabs Si5351 Clock Generator IC

My first attempt at writing an Arduino sketch that transmitted a WSPR message using an AD9850 DDS Signal Generator module, whilst successful required the WSPR message to be generated using the WSPRcode.EXE and then manually edited into the Arduino Sketch before compiling the code.  Ideally, I'd like to be able to read the position and time from the NMEA string from a GPS, encode the message and then transmit it automatically - OK there are niceties such as a User Interface and LCD to contend with! 

Looking back at the Etherkits website, they appear to have a module available which has an SiLabs Si5351 Clock Generator mounted into a breakout, as do Adafruit, however they also supply an easily integrated Class Library.  Until a recent C# online course at work, I didn't really understand what C++ classes did and how to use them, so it's  time to experiment as I've got the example code to compile without error.

I've also got some building to do as I've got some QRP Labs low-pass filter modules to build for 5 and 10 MHz together with a Kanga / M0XPD Si5351 Shield for the Arduino. 

Raspberry Pi WSPR Transmitter

Sometimes several things come together that make a really easy project...

Having read several copies of the Official Raspberry Pi Magazine, I was intrigued that one of the issues this magazine actually gave away a Raspberry Pi Zero on the front cover in the same way that computer magazines in the 90's used to have CD-Roms and floppies on the front!

The current incarnation of the Raspberry Pi Zero W has onboard WiFi and Bluetooth networking and with the addition of a Raspberry Pi Stem becomes a complete OTG (On the Go) USB stick - ideal for working away in Lancashire without the need to cart a mouse/keyboard/monitor up to your hotel room!  You can even get a 3D printed case online for a few pounds...

Then I found WsprryPi - a WSPR transmitter that uses the Raspberry Pi's onboard frequency generator to transmit WSPR and uses NTP (Network Time Protocol) to discipline the oscillator frequency - all that is needed is an external Low-Pass Filter and you have a little transmitter.

Enter Language Spy with a neat little filter module.  I managed to get one for 17m (another one of my favourite bands) before the stock ran out.  

The Raspberry Pi output pin is a square-wave switched from 0V to 3.3V and therefore is approximately 1.65V RMS, there are obviously losses in the low-pass filter as the higher harmonics that make up the square wave are lost, however I measured the output at approximately 0.9V(RMS) into a 50Ω load

This works out to approximately 10 mW (or 10 dBm) so QQRP.

Unfortunately a recent upgrade to Windows 10 appears to have broken the raspberrypi.local shortcut, so whilst the board still works, the OTG capability doesn't and a mouse and keyboard are needed once more.  

Further Adventures in QRSS...

Having decided to buy the Yaesu SCU-17 USB Sound Card Interface for the FT-817, which  provides a dedicated USB sound card, serial port and PTT switching etc.,  I tuned my receiver to 10.13870 MHz and shortly afterwards received an off-air signal from IK2CMN over several minutes (as shown in the WSJT waterfall display below).

Setting my own callsign was a doddle and shortly afterwards I managed to get the OpenBeacon to transmit "G0VRM IO93QT" in QRSS into the dummy load, however it's not quite as clean as the off-air signal.  Following the instructions, I uploaded a WSPR string and it worked first time!

Notice that there are two entries for G0VRM, however one is 35 dB down and is probably some oddity of the radio being so close to the transmitter, although it appears to be very stable!  Looking promising, however connecting the beacon to an external antenna via a Z-match proved to be unsucessful.

Adventures in QRSS

Whilst wandering around the 2016 G-QRP Convention at Rishworth with Richard G0GLZ, I spotted a box on one of the stalls, and having talked to the stallholder established it was a QRSS (very slow Morse) beacon transmitter that had at one time been used in Senegal in West Africa.  At this point I decided that perhaps this project wasn't for me, it was promptly bought (partly on my behalf) by Richard G0GLZ - I did consider "The one that got away" as the title of this entry...

Although the manufacturer appears to have retired the OpenBeacon kit and have removed it from their website, the documentation and driver software are still available from http://etherkit.github.io/openbeacon_landing_page.html.  As the name suggests, the OpenBeacon is an open-source beacon transmitter that is capable of transmitting a variety of modes which include QRSS, DFCW, Sequential Multi-tone Hellschreiber and WSPR.

The first challenge for this project was the installation of the unsigned driver software under Windows 10 Advanced Boot Menu, which required a change to the startup settings in order to disable Driver Signature Enforcement, several reboots later with the driver successfully installed, I was then able get the settings showing the previous callsign of 6W7RV.

Looking up the locator IK14LL on http://qthlocator.free.fr/index.php, it appears to be almost as West as it is possible to be and still be in Africa; and from the QRZ.com database, the callsign once belonged to a holiday rental "shack" located in a Wildlife Reserve with its own lagoon and Baobab forest (sorry, no pictures I'm afraid).

Finally, back to my own shack, after connecting the beacon up to a 50Ω dummy load (a BNC thin-wire Ethernet terminator in its previous life) and was able to hear the beacon transmission on my FT-817.

Arduino WSPR Beacon

The idea of building a stand-alone WSPR beacon came about after I built the Silicon Labs si570 based USB-Controlled Synthesizer several years ago and struggled to find a real use for it and was hoping this might be supported in the WSPR software.

Last year I ordered an AD9850 module from eBay and following the example from the web of "Testing an eBay AD9850 DDS Module with Arduino (N8RO)" was able to make it work.  Shorly afterwards I built the Kanga / M0XPD DDS shield and found George M0GEO had already written a WSPR beacon.

Over the last few evenings whilst working away I have combined the two and managed to get it to transmit a message to my FT-817 and decode it using my PC.

Nerds who will change the world

(Letter published in RadCom, March 2015, p12)

I'm sure many of us watched the recent Royal Institution Christmas Lecture "Sparks Will Fly", presented by Danielle George the Professor of RF Engineering at Manchester University with great anticipation.  Over the course of three hours, she instilled into her young audience into thinking about "How the spark of your imagination and some twenty-first century tinkering can change the world".

I have followed these lectures for many years, and cannot think of any that have had more relevance to amateur radio, and after reading the article in the Guardian newspaper back on 19 August 2014 that described the series that promised to usher in a "new era of home experimentation", I was expecting to see some amateur radio involvement and content in the lectures.

I was very surprised to see that there was no mention of the series in RadCom or on the RSGB website in the lead up to Christmas, and was somewhat dismayed when there was no amateur radio content whatsoever.  This was evident when she opened her second lecture on communications with the question "With the ability to make video calls to anyone, anywhere, where could I possibly call that would amaze you?", and then showed a staged contact with the International Space Station using her iPhone.

I therefore feel that I must ask the question if anyone from the RSGB knew about these lectures and attempted to get involved?  If not, then this is particularly worrying when the board has selected 'Youth' as its focus for the future, and the involvement in such a high-profile event would have kick-started any planned activities.  And more so, does this also indicate that today's amateur radio is no longer relevant to University Science and Engineering Departments?

This brings me onto the subject of "tinkering" mentioned in the lecture series.  As many of you are aware, there is currently a peak in public interest in coding on such platforms as the Raspberry Pi and Arduino through the Maker movement, with many entry-level projects in magazines involving the use of radio technology such as RFID and ZigBee, to control home appliances.  I must ask two further questions?  Why aren't we promoting amateur radio as the enabling technology for schools STEM projects (Science, Technology Engineering and Mathematics) such as High Altitude Balloons, and where is our equivalent of the Raspberry Pi that encourages people to tinker with amateur radio?

Meanwhile, the RSGB recently expressed its desire in its long-term plan that Members should "not be seen as nerds" and completely misses the zeitgeist for young people with scientific interests, who see this a badge of honour, and may well become our future engineers and scientists.

Whilst I can see that refocusing its strategy might present problems with the business model of the society, as it would have to look beyond it's consumer electronics focus and the revenue it brings from advertising, and enter the world described by Professor George, who ironically sees us as "coming through a period where everything was a black box, and people are starting to tinker again like the old ham radio enthusiasts"...

I must therefore ask the final question:  Who is going to represent the technical future of our hobby?

Pi in the Sky!

The new Pi-in-the-sky board add on the new Raspberry Pi Model A+ is a complete telemetry module for High Altitude Balloons. It is a brilliant example of using amateur radio as the "Enabling Technology" for demonstrating Science, Technology, Engineering and Mathematics (STEM) for young people.

Even though we aren't officially allowed to do it under the terms of our licence, it gets around this loop-hole by using a licence-free 433 MHz module similar to those used in car key fobs, and to decode the signal all you need is a very cheap TV dongle and some clever software!