Sending Christmas Greetings to the ISS

There was much media coverage in the UK of the “Santa pass” (Telegraph, Daily Mail) The International Space Station passed over the UK in the late afternoon and early evening on Christmas Eve and around 17:20GMT promised an especially bright display in the dark skies. So imaginatively we were asked to observe and imagine that the bright moving point of light was actually Santa off delivering his presents.

As luck would have much of the UK had a crystal clear sky and I even managed to get my 80 plus year old Mother-in-law out in the garden to watch the spectacle. She was impressed and it was great to overhear lots of excited children coming out in the nearby homes to watch Santa as he flew overhead.

Back in October 2013 after becoming a newly licensed radio amateur I managed to send APRS packets to the International Space Station which were digipeated and received back on earth by other operators. Back then I used a lowly Baofeng UV5R handheld and I decided to repeat the exercise this time using the FT857D (this time running around 20W) to talk to Santa!

The computer I used back then has been decommissioned so on the laptop I installed the UISS program from ON6MU which makes easy work of APRS to the ISS and instead of the cumbersome AGWPE I used the excellent soundcard modem from UZ7HO.

I attempted to send a message on the pass at 15:43 but failed completely, discovering I’d got my soundcard incorrectly set up. I corrected this and left the autobeacon mode running in UISS during the Santa pass and checking back much later could clearly see I’d sent and had a message repeated back from the ISS.

Checking the ariss website ( I could see the repeated message had been received by another station and my position was showing up on the map (M0NRD)

I have successfully done it again today on Christmas Day! As the raw packets below confirm.

M0NRD>CQ,RS0ISS*,qAR,DM2RM:73' Happy Christmas from Andrew IO93OB
M0NRD>CQ,RS0ISS*,qAR,MB7USS:=5304.08N/00048.47W-73' Happy Christmas from Andrew
M0NRD>CQ,RS0ISS*,qAR,HG8GL-6:73' Happy Christmas from Andrew IO93OB

It was a nice achievement and another nice Christmas present was achieved early this morning while running WSPR on 40m, managing to get received in New Zealand

Anyway enjoy the rest of the festive season and I wish you all the best in 2015

Using the Ultimate3

I have dusted off the Ultimate3 QRSS beacon kit that I built earlier in the year while a foundation licensee. Having progressed to a intermediate licence I can now operate something I’ve constructed.

Until now it has been attached it to a dummy load with the FUNCube Dongle Pro+ SDR in close proximity as a receiver for experimental purposes.

One unresolved issue was it being consistently off frequency. The DDS modules used are prone to temperature fluctuations and component variances so the Ultimate 3 has the option of using a GPS module to provide both an accurate time source and an accurate 1PPS input which can be used to self calibrate. Except in my case it had proved to be unreliable.

I am using one of the inexpensive GY-GPS6MV2 modules containing the U-Blox chipset I posted about previously with the additional tap off to provide the 1PPS TTL signal.

Initially the GPS module was connected in close proximity to the Ultimate3 but struggled to maintain lock probably due to interference from the DDS module. Even when lock was achieved the calibration never seemed to work. I posted a question on the yahoo support group and from the answers I verified the calibration setting were correct so the only likely culprit was the quality of the 1PPS signal.

The serial NMEA sentences and the 1PPS signal from the GPS are likely to be required in other planned projects, such as an ‘shack clock’ and a GPS disciplined frequency standard. So I decided to put the GPS module  into a waterproof housing that can fitted on the shack roof in clear view of the sky and away from any potential interference. A multi-cored cable supplies power and the TTL RX/1PPS signals being fed back to the bench.

Sourcing an inexpensive weatherproof enclosure (£2) and waterproof cable gland were straightforward enough. I mounted the GPS module on a piece of strip board and replaced the on board LED with one mounted in the enclosure so I easily determine if the GPS had achieved lock, since it only flashes when it has. The LED is sealed with epoxy resin. It should be noted that the outputs of the U-BLOX chip are only rated at 10mA so bear it mind when selecting an LED and calculating the current limiting resistor. The connecting cable is some surplus unscreened alarm cable fitted with a couple of ferrite clamps.

The GPS now has no trouble achieving lock and quickly sets the Ultimate3 clock. Researching the 1PPS problem I hadn’t come up with anything definite, as the signal looked okay on the oscilloscope. But I decided to fit a 10K resistor pull up resistor between the 1PPS output and the 3.3V supply on the GPS module. If this actually made the difference I have no idea but the Ulimate3 now successfully calibrates the DDS using the GPS.

At the moment I have configured the beacon to run WSPR and I have been spotted by other operators. Initially I wasn’t getting much RF out of the device and it turned out to be a combination of poor connection caused by me not removing the enamel properly on a toroid winding and an iffy antenna connector. Both have been corrected and now get a measurable deflection on the SWR/Power meter. With the additional of a second power amplifier FET it is around 200-250mW.

I purchased the Ultimate3 with a low pass filter for the 40M band and while I have had some European spots the results have been a little disappointing. 40M has turned out to be almost unusable at my QTH due to QRN/M so not sure if that is having an effect, also the antenna I have isn’t naturally resonant on 40M so is going through a tuner which will certainly be introducing some losses, without the tuner the FETs get very warm!

With this in mind I have purchased some additional LPFs for the 30M and 20M bands and the LPF relay switching board for the Ultimate 3 so can try/run multiple bands.

Datamode Interface built

This weekend I finally got around to sorting out my digital/data mode interface for the Yaesu FT-857D.

To transmit and receive digital/data modes you need to connect the radio audio in/out to the computers sound card in/out, the computer then runs the necessary software to encode/decode the signals. I want to try out WSPR, PSK, JT65 and some SSTV for starters I have spent too long just receiving and decoding…

There are a number of inexpensive commercial interfaces available, but many of them use the same basic design originally intended for eQSO/Echolink operation. I nearly succumbed but I had built an eQSO interface many years ago when using PMR446 and had most of the parts to build another.

I nearly took the easy route and got a commercial one since connecting up some home built circuitry to a £20 hand held is slightly less daunting than plugging it into an expensive rig!  My original interface has been modified and reused over the years and was a bit of a mess, but being brave I decided I could tidy it up and I couldn’t really damage anything if I took my time… actually the truth was I discovered I didn’t have the necessary optocoupler IC so couldn’t build a new one just yet…

A simple internet search for digital/data mode interfaces will bring up a great deal of information, schematics and ideas for home brew solutions. The basics can be found here for example.

The simplest form of interface is just a simple direct lead with the transmitter operating in VOX mode. However levels can be a problem as the line/speaker output from a computer can be too high for a transmitters microphone input. Also connecting a radio to a computer directly can lead to problems with ground loops and interference.

The computer can be made to control the Push-To-Talk (PTT) on the transmitter using a serial port with the software controlling one of the handshake lines (RTS/DTR) Some data mode software support CAT to allow control of the PTT as well as tuning the transmitter, but the serial port method is more universal.

The preferred interface, and the one I had built isolates the computer from the radio by using two audio transformers and an optocoupler. There is no direct connection between the two devices so keeps interference to a minimum.

I could have used the microphone and speaker output on the radio, but the FT-857D has a convenient data connector on the back. This is a 6-pin DIN socket as used by older (PS/2) computer keyboards/mice. Note the diagram shown in the FT-857D manual (as below) is the view as you look at the socket.

FT-857D Data connector as in the manual

The connector has two “data” outputs but they are simply fixed level audio outputs from the receiver. The one of interest for most modes is the 1200 baud output (the 9600 baud output is more akin to a discriminator tap and is only of use for FM packet) There is a data-in (TX-audio) and a PTT control line.

Like many people I initially thought I could cut a lead off a mouse/keyboard and repurpose it, however I discovered most only use four wires and they don’t use the necessary pins! You might be lucky especially with older keyboards or alternatively if you have an old keyboard extender cable they usually have all six wires present. Alternatively the plugs are readily available from the likes of CPC/Farnell.

I had a hunt around in a junk box and located a suitable keyboard extender cable. I chopped off the useless end and metered out the pins to identify the appropriate wires. Remember when looking at the plug the pins are swapped left-to-right compared to the diagram which is the socket view.

Well here is the insides of the interface.. and as you can see I completely failed to tidy it up! Not my best work, but I did put it in a new box and I did tape up all those unused wires!

The messy internals of the interface

One annoying issue I had was the audio from the computer wasn’t getting to the radio, it worked and scoped out okay when out the box, but in the box it stopped working. I suspected a bad solder joint and redid them all, but still showing the same intermittent issue. I did notice flexing the board slightly out the box cause the fault and soon located a track on the vero-board which appeared to have a hairline crack, I couldn’t see anything obvious but a wire soldered along it cured the issue.

It looks better with the lid on..

I soon had it connected up and fired up WSPR

Computer, radio and interface

It was straight forward setting up WSPR to use a combination of CAT for tuning and the RTS PTT control and soon had some encouraging results, in fact these are some of the spots of my 5W signal on 10m/20m and 30m, I was grinning from ear to ear!

10M Spots

20M Spots

30M Spots

I had simply set up the FT-857D for basic USB transmission, however it does have a dedicated DIG mode, the manual refers to setting it up for RTTY/PSK, I very briefly had a go with PSK31 and Digipan and was successfully decoding signals and put out a few CQ calls (again on 5w) but got no immediate response. However checking PSK Reporter later it seems I had been heard by VC3S, OH1FOG and ES1JA maximum distance was around 3260 miles

Looking forward to spending some more time experimenting with the data modes.

Cheap GPS module

Several of the Arduino projects I have been experimenting with have used a GPS module to provide accurate time and/or location information and in the case of the QRSS/WSRP QRP beacon a highly accurate GPS derived 1 second pulse is used for frequency calibration. A number of people have enquired about the GPS module I am using.

Most GPS devices have a limit on the altitude they work at, normally 60,000 feet or less. This is a legacy of the now defunct CoCom (Coordinating Committee for Multilateral Export Controls) restrictions. For my HAB project this restriction needs to be disabled and the GPS must be switched into ‘flight mode’ In the HAB community the favoured devices are made by U-BLOX

Therefore when I was sourcing a GPS I had search specifically for a inexpensive device using a U-BLOX.

The GY-GPS6MV2 as supplied

I soon found something called a GY-GPS6MV2, it appears to be a generic design and is readily available on eBay from suppliers in China, Hong Kong and Singapore and can be purchased at the moment for around than £10 (approx $15) including postage!

It is also available from domestic suppliers but often at a much more inflated price, but you don’t have to wait several weeks for them to be delivered.

There are many other GPS modules available but this module seems to be one of the cheapest available. it is often listed as a NEO6MV2 GPS Module Aircraft Flight Controller.

The module consists of a small PCB 25mm x 35 mm size with a separate ceramic antenna connected by a small lead which is 25mm x 25mm in size. The Antenna is quite heavy and isn’t suited to Pico HAB payloads but for other uses is more than satisfactory.

On the board is a small button-cell battery to provide backup to the GPS chip and a small EEPROM connected to the GPS chip which I believe can store configuration(s). I haven’t used it myself just using the module in it’s default set up at the moment. For a schematic click here

The board has four connectors VCC, GND, TX (Transmit) and RX (Receive) and can be powered by the 5V supply on Arduino boards since it has a small regulator to provide the 3.3V needed. 

In most projects all that is required is data out of the GPS. The GPS TX (data out) being connected directly to the microcontrollers RX (data in) The (0V and 3.3V) level shift of the signal is compatible with the TTL input of the microcontroller.

The GPS by default will start up and output standard NMEA sentences at 9600 Baud, until GPS position lock is achieved the NMEA sentences won’t have a long/lat location. The module also has an LED which will start flashing once a lock is achieved.

There is no direct connection for the highly accurate 1PPS (pulse per second) signal that can be used for frequency calibration, but the flashing LED is driven by pin 3 of the GPS module which is the 1PPS (pulse per second) signal required.

The 1PSS signal, like the TX is either 0V and 3.3V, in order to use it a small lead will need to be soldered onto the board, either directly onto Pin3 of the GPS chip, or alternatively on to the small current limiting resistor used by the LED, as indicated below.

Showing the GPS 1pps points

Ultimate3 QRSS Beacon kit built!

At the start of the year I did some experimentation with cheap DDS modules based on the Analog Devices AD9850 connected to the Arduino board, making a rudimentary WSPR transmitter prototype.

My current licence restrictions prevent me using anything home-brew for transmitting except for commercial kits. So I ordered an Ultimate3 QRSS beacon kit from Hans Summers (G0UPL) thinking that it would be okay. I subsequently learned that any commercially available kit must satisfy IR 2028 which is all a bit vague and unclear but sadly I don’t believe this particular kit does.

All was not lost, building this kit should more than satisfy one of the practical assessments of the intermediate examination, which will get me around this problem.

The Ultimate3 kit is extremely popular and so I had to wait a little for delivery and it arrived on Friday. After the last few weekends of non-radio activities I had planned to get my antennas backup and do some proper operating. Like many people I had been forced to take everything down due to the barrage of storms and high winds the UK has been experiencing recently.

A tidy workbench

Saturday saw no let up in the wind, so I decided to spend a few hours building the kit instead.

The instructions were extremely clear and straight forward and soon had it built up, though it is high time I invested in new soldering station. I have a basic Antex 25W iron. I cannot remember exactly when I brought it but it is well over 10 years ago.  It was more than adequate to build this kit and for soldering connectors but I could do with something adjustable and more comfortable.

Taking shape

The only issue I had was winding the first toroid, 25 turns later I realised I had wound it the wrong way round so the leads didn’t line up with the holes in the PCB. I could have made it fit but nope I will do it properly so I unwound it and did it again.

I also made the mistake of not scraping the enamel off the toroid wire and tried the heat it and bubble it off method, except I think my iron just isn’t hot enough so ended up using a piece of wire wool to remove the enamel.

Lessons learned I soon had the other three toroids correctly wound and wire prepared for the low-pass filter board.

Close up of the LPF

   A final visual check and powered it up and it worked first time!

All built
It works!

Setting it up

Full of confidence I grabbed my trusty GPS module which has been pressed into service on a few Arduino projects including the HAB project. Quickly soldered some connecting wires and powered everything up.. all was well or so it seemed when the display suddenly went blank, backlight was on, just no characters.

Pressing the button I occasionally got some random characters and a flashing cursor! I de-soldered the GPS and still nothing. I suspected the display was faulty but trying it on the HAB prototype board confirmed it was okay. I checked the display connector continuity and everything appeared okay.

Out with the oscilloscope I started probing, everything checked out. Crystal was oscillating and data pulses on the display control lines. Then I checked the supply pin on the display and it was only reading 4.1V, this under-voltage would explain the odd display behaviour.

PSU output was 5V, micro-controller was 5V, DDS module had 5V. All very puzzling till I removed the DDS module and spotted a discoloured track on the PCB, touching it with a screwdriver and the lacquer fell away revealing a tell tale scorch mark, somehow I had made a nice resistor!

Burnt track to right of micro-controller

A quick wire link soldered in place and everything was back to normal.

What caused it? Checking the de-soldered GPS connecting wire I spotted a stray single strand of wire on the ground wire. I suspect this must have shorted to the adjacent 5V line and since I was using a nice beefy ex-PC PSU as a bench supply it had popped the track without the hint of a flicker. The GPS has been rewired properly and is working nicely, now to connect a dummy load and experiment some more.

Sunday was a lovely day, wind dropped so antennas have been put back up and I took the opportunity to tidy up the installation a bit. I also dug out an old fibreglass pole to put the M0CVO HW-20HP back up. I didn’t get to do any operating in the end as by the time I had done this and made up a couple of decent patch leads it was time for roast beef and all the trimmings and an evening in front of the TV.

The HW-20HP back up

Putting PL259 and N-Type connectors on coax is also part of the intermediate assessment, so perhaps I should have videoed making up the patch-leads as proof 😉

FUNCube Decode Issues

I had a pleasant surprise last week at the AGM/Prize giving evening of the South Kestevan Amateur Radio Society (SKARS) being awarded the Most Promising Newcomer!

I also had a small write up in Tim Kirby’s (G4VXE) VHF/UHF section of the February issue of Practical Wireless about my I-Cube1 reception which I have mentioned on here before.

I haven’t progressed very far with my Arduino projects. There has been a set back in the plans to build and use an Ultimate3 QRSS kit. I had incorrectly assumed as it was a kit being sold commercially that it would satisfy my foundation conditions. However I have been advised that Foundation license holders may use radio equipment constructed using commercially available kits which satisfy IR 2028 which is all a bit vague and woolly, but I don’t believe this particular kit does.

There is a simple solution, I will just have to take my intermediate assessment and exam at the first opportunity!

I have been doing a little WSPR spotting, getting some nice spots.

Over the Christmas/New Year period I have neglected the FUNCube-1(A073) satellite and was slipping down the telemetry upload rankings, sad I know!

Now I have got back the upstairs ‘shack’ I set up my original FUNCube Dongle on the laptop running the dashboard application continually to capture/decode the telemetry using the loft mounted discone. I took the opportunity to upgrade to the latest version 8.14 of the dashboard software, however something was amiss when checking the statistics I was only adding the odd frame here and there, sometimes not making a single decode during the high power daylight passes.

I switched back over to the newer FUNCube Dongle PRO+ running my main PC, which I had also updated to the version 8.14 dashboard and saw the same behaviour, rather than getting daylight decodes of 30+ frames I was just getting the odd 1 or 2.

My first thought it was an antenna or interference issue, but checking the SDR waterfall the signal is still very strong with little QRM. Suspecting a software issue introduced by the update I checked the FUNCube forum and found a thread which appeared to confirm my suspicions.

I have a number of discussions on twitter with various people including David Johnson (G4DPZ)  an AMSAT-UK Committee Member and one of the developers of the FUNcube ground segment. David kindly performed an analysis of one of the passes yesterday where I managed just 2 frames, and from the results it does appear to be an issue at this end, rather than issue with the spacecraft.

I have uninstalled v8.14 and put back on an earlier version of the dashboard (v8.09) and thanks to a windows update last night have also performed a full reboot!

There was a good pass this morning at 62 degrees maximum elevation (to the east), followed by a lower pass at 22 degrees elevation (to the west so not so good) and it seems things have improved managing 68 and 17 frames respectively. So could this be an issue with the latest dashboard?

If anyone has suffered similar performance fall-off, or indeed not suffered any issues then please add some feedback to the FUNCube forum.

My copy of Radcom arrived but didn’t have much time to read it..

The culprit! 😉

Arduino, WSPR and AD9850 DDS experiments

Happy New Year!

Christmas is thankfully behind us so I can get back to what I enjoy doing once I have reorganised my workshop.

As you know I am currently developing a potential High Altitude Balloon (HAB) project and have been experimenting with the Arduino microprocessor platform and have constructed a basic prototype.

With the arrival of the GPS module(s) I have had it successfully working and even took it out for a test walk in the local area, receiving the data and uploading it to the UKHAS habitat system.

NERD-1 and Boris have just been for a walk, first time NERD-1 has had proper GPS and running on batteries. #hab
— Andrew Garratt M6GTG (@nerdsville) November 23, 2013

This project has revitalised my interest in ‘hobby electronics’ and I have ideas for a number of other Arduino based projects and have been splashing out on components from eBay. Just before Christmas I purchased an Arduino Mega board, this has more I/O pins than the current Uno and specifically some extra hardware serial ports.

Do any internet search for Arduino based amateur radio projects and it will results in numerous mentions of projects using ultra cheap DDS modules based on the Analog Devices AD9850/AD9851 chipsets.

DDS means Direct digital synthesiser and is a type of frequency generation which can be used for creating arbitrary waveforms from a single, fixed-frequency reference clock. Read the Wikipedia page for more details.

In a nutshell the AD9850 is a chip that under microprocessor control can produce a sinusoidal wave from about 1hz to 40mhz. In other words it is an accurate microprocessor controlled VFO (Variable Frequency Oscillator) or signal generator.

VFOs are the main building blocks of radio receivers and transmitters, so not surprisingly a lot of projects have utilised these modules, rather than the traditional means. Intrigued I ordered a couple of these modules for the pricey sum of £3.50 each!

Using information on George Smart’s (M1GEO) website and Simon Kennedy’s (G0FCU) blog  I quickly had a simple WSPR beacon running!

Experimenting with Arduino and AD9850 DDS and GPS unit..
— Andrew Garratt M6GTG (@nerdsville) December 29, 2013

The Arduino uses the GPS module borrowed from NERD-1 for accurate time and then controls the output of the AD9850 DDS to generate the WSPR signal.

Before anyone panics I know at the moment I only hold a Foundation Amateur Licence so the construction of homebrew transmitters isn’t allowed. This ‘beacon’ has no power amplifier and the antenna consisted of an inch or so of wire on the DDS output. I was able to verify the operation using my SDR receiver in the same room.

Construction of commercial kits is allowed under my licence so I have ordered a Ultimate3 QRSS kit from Hans Summers for the pricely sum of £17.50! This uses the same DDS module and same microcontroller as the Arduino.

In the meantime there is also more information and ideas on Eugenr Marcus’ (W3PM) webpage about the use of these DDS modules, including making frequency reference sources and calibration using the GPS module.

My new year resolution is to get my Intermediate Licence as soon as possible..  but it has been great to get down to some proper experimenting…

Cannot beat a picture of an oscilloscope to look techy.. my DDS experiments continue…
— Andrew Garratt M6GTG (@nerdsville) January 1, 2014

WSPR using a FUNCube Dongle PRO+

For sometime I have been using my FUNCube Dongle Pro+ SDR as an HF receiver station for WSPR, so. I thought it was about time I posted something.

By its very nature radio propagation isn’t totally predictable so someone transmitting can never know exactly where their signal will be received. There is whole science behind radio propagation prediction and amateur radio operators are always on the look out for openings or skip conditions for DX communications. To aid operators a number of propagation beacons exist, usually operating in CW mode transmitting their identification (call sign and location). Some of them use frequency shift keying and some transmit signals in digital modulation modes.

While invaluable operators have to actively receive and monitor these signals and what they really want to know is how their signal is getting out to the rest of the world. This is where the WSPR system comes into its own. The WSPR system uses a protocol which probes these potential propagation paths using low-power QRP transmissions.

WSPR (pronounced “whisper”) stands for “Weak Signal Propagation Reporter” and is a computer program that enables amateur radio stations to participate in a world-wide network of low power propagation beacons. The station transmits beacon signals and receives signals from other stations operating in the same amateur band. These stations then upload ‘spots’ that they receive in real time to a central website enabling operators to find out where and how strongly they were received, and can view the propagation paths on a map.

It is also possible to operate a receive only station uploading ‘spots’ to the same website, all that is required is a receiver capable of receiving single side band transmissions and feeding the resultant audio into the WSPR program where it is processed. The WSPR program was written by Joe Taylor, K1JT.

These “whisper” signals are often barely audible but their presence can be detected by the WSPR program using signal processing. The WSPR signal uses frequency shift keying (FSK) with a very small shift and a very slow data rate. The signals bandwidth occupied is only about 6 Hz so many stations can operate within the 200Hz WSPR window without interference. WSPR transmissions are encoded to carry a station’s callsign, grid locator, and transmitter power in dBm. The program can decode signals with S/N as low as -28 dB in a 2500 Hz bandwidth.

Each transmission lasts for just under two minutes, and starts at the beginning of each even-numbered minute. Therefore it is vitally important that transmitters and receivers are synchronised, so one of the fundamental pre-requisites of success with WSPR is an accurately-set computer clock. This is achieved by using internet or GPS time synchronisation methods.

Setting Up

This diagram shows the set up I am using at the moment. I have a long-wire antenna connected to the FUNCube Dongle Pro+. I am using SDRSharp (SDR#) to operate the FCDP+ and the resulting audio output is then used as the input into the WSPR program.

I am using SDR# but any suitable SDR program could be used, I have used SDR-Radio and HDSDR but I have found the SDR# program uses less resources on my ageing PC.

Routing the sound output from one program to be the input into another can be problematic and depends on the soundcard and its driver, you might be lucky and have a ‘stereo-mix’ or ‘what-u-hear’ option to use the main sound card output as a recording input, or alternatively you will need to use something like virtual audio cable VAC.

Since the WSPR signal is very narrow band it is desirable that your receiver is accurately calibrated. Most SDR program that support the FUNCube Dongle PRO+ allow a correction setting so that the tuned signal is at the correct frequency, the use of beacons, repeaters, time signals or broadcast stations is an excellent method to set this correction if required.

You will need to download the WSPR program from the current stable version is WSPR-2.11. The installation is straightforward and when you start the program a window will appear that looks like a command prompt, don’t close this window, it will give important debug messages if there problems. Then the main console window will open along with a window where you set the station parameters.

Don’t worry about the Callsign and Grid locator at the moment, the first thing to do is select the correct audio in source, the rest can be ignored as it relates to a transmitter and I am describing how to set up a receive only station.

Firstly slide the Tx fraction (%) to zero, since you won’t be transmitting and make sure the upload spots is unchecked at the moment, then select the appropriate band you wish to receive. Then set the appropriate dial frequencies in your SDR receiver program, this is shown in the window and your SDR program will need to operate in USB, with a bandwidth of 2500Hz.

The current WSPR dial frequencies are (MHz)
0.136, 0.4742, 1.8366, 3.5926, 5.2872, 7.0386, 10.1387, 14.0956, 18.1046, 21.0946, 24.9246, 28.1246, 50.293, 70.091,144.489

I suggest you turn off any AGC and any filtering in the receiver, uncheck the idle box in WSPR and then wait for the next ‘even’ minute at which point the program should show receiving, alter the sound level so the Rx Noise is ideally around 0dB, but it will work between -10dB and +10dB.

When the two minute interval is over a segment will appear in the waterfall in the top panel and the program will decode any WSPR transmissions received, you will see them as lines in the waterfall as the above image shows. Any successful decodes will appear in the bottom panel.

Once you have got it working, the next thing is to register on the website for a SWL callsign, mine is G-SWL10 you will also need to know your grid-locator, you can find this easily using

Once registered then putting the data into the station parameters and checking the upload spots will send your spots to the website database, where you can view your spots in the database and on a map, the map at the top shows my spots on one day this week on 20m, getting stations from Australia, the Far East and the US as well as Europe.

Some important things to note are ensure you computer clock is accurately set, if it is wrong you will be out of sync and decodes won’t happen and ensure you are tuned to the correct frequency as you have set the WSPR program otherwise spots will be reported for the wrong band.

It is a fascinating activity and even as just a receiver you are offering a valuable service to amateur operators.