The WSPRlite from SOTABeams is an ingenious solution to a problem that you never realised

existed. That is, is it possible to package a transmitter and hardware/software into a tiny pocketable package that allows you to put out a WSPR signal (Weak Signal Propagation Reporter) wherever you are in the world?

The WSPRlite transmitter is just that and so incredibly small, measuring just 40 x 50 x 10mm, it can easily fit in the palm of your hand.

The WSPRlite is powered by a 5V USB supply, using a current of about 150mA maximum. This means that you can power it from a Powerbank-type 5V rechargeable battery for many hours, if not days. One thing to watch out for is make sure the Powerbank doesn’t switch itself off if it detects low or no current. I have a number of these, collected as free corporate gifts over the years, and one was found to be unsuitable for this reason.

The frequency range of the WSPRlite is 160m to 20m, although an external low-pass filter is recommended for use below 10MHz. Note that 60m is not currently supported. SOTAbeams, which manufactures and markets the WSPRlite, offers a suitable low-pass filter kit for 40, 80 and 160m for £24.50 inc. VAT. The company, which specialises in equipment for Summits on the Air (SOTA) and QRP enthusiasts, also has a selection of leads and adapters suitable for the WSPRlite, including the micro USB lead that you will need to program it.

The real power of WSPRlite comes when it is paired with SOTAbeam’s online data analysis system called DXplorer.net, which allows you to compare and graph different WSPR signals. But more of that later.

What is WSPR?So, firstly for new amateurs, what is WSPR, or Weak Signal Propagation Reporter?

WSPR (pronounced ‘whisper’) is a Frequency Shift Keying (FSK) mode that uses software designed by Joe Taylor, K1JT, a Nobel Prize-winning Princeton physicist and originator of the WSJT and JT65 weak signal software.

First released in April 2008, WSPR uses a transmission mode called MEPT-JT – the MEPT standing for Manned Experimental Propagation Transmitter.

WSPR uses FSK with a very small shift (you can just detect a slight ‘warble’) and occupies a bandwidth of about 6Hz. This means that many stations can be fitted into the 200Hz WSPR window.

Stations running WSPR automatically send out a beacon signal on a given frequency. Each transmission lasts for just under two minutes.

When your usual WSPR system with your transceiver is not transmitting it is actually listening for these WSPR beacon signals. If it hears one it logs it and sends the details via the internet to http://wsprnet.org/

WSPRnet then logs your information and even displays it on a map, with a line showing the paths between the transmitting and receiving stations. It also logs the received signal/noise ratio, any drift, the grid locators of the transmitter and receiver and calculates the bearing and distance between the two stations.

WSPR isn’t a two-way communication mode as such in that you don’t hold conventional QSOs. It is a beacon system for low-power transmitters.

The only problem is that to use WSPR you normally have to tie up your radio transceiver and a computer running the WSPR software. WSPRlite gets around this by combining a 5-200mW transmitter and the digital hardware in a single lightweight package.

How do you use it?Using a simple USB computer interface, you program the WSPRlite box with your callsign, QTH locator (just four digits, not six), band, percentage time it will transmit (it defaults to 20%) and power level. It also automatically generates a URL link to your data on the DXplorer.net site.

The configuration software is downloadable from www.DXplorer.net and versions are available for Windows Vista, 7, 8 and 10. It won’t run on Windows XP or Mac OS. A Linux version is said to be coming.

Once programmed, the WSPRlite no longer needs the computer to operate. Just disconnect it from the computer and connect it to a USB power supply (eg 5V Powerbank), press the ‘sync’ button two seconds past the start of any even minute, and off it goes.

Note that some users warn against using a mobile phone charger as your 5V supply as this can introduce ripple into your transmission.

WSPRlite will then make regular transmissions that are automatically received by stations around the world. These stations send their reports to the central WSPRnet.org website where you can see where your signals are reaching within seconds.

The unit only has two connections – a female SMA for the antenna and a USB

Review

WSPRlite

42 June 2017

SOTABeamsfrom

The tiny WSPRLite transmitter.

Steve Nichols, G0KYAinfotechcomms@googlemail.com

p42_44_wsprlite_radcom_june17.indd 42 10/05/2017 08:51:28

Review

42 June 2017

socket for the power. It also has a red/green status LED (light emitting diode) that can tell you various things, such as when it is transmitting, when it is about to transmit and whether you need to program it. A single button is used with an accurate clock to synchronise the transmissions so that they occur on the even minute.

Please note that you must have an antenna that has a standing wave ratio (SWR) match below 3:1, and preferably better than 2:1. The unit’s power output is

so low that it won’t trigger an automatic ATU (antenna tuning unit), so it is best to match the antenna with your normal radio and ATU first – or make sure you are using a resonant antenna with a low SWR.

One issue was that 20m propagation was so bad during the test period that I wasn’t being picked up anywhere at first!

But after a couple of cycles, lo and behold I was picked up in Madrid, Spain by EA1CDV, a total of 1412km, and by UB1NDF in Russia, at 2265km, both on 200mW. Then

I was picked up in Sweden by SA2BRJ and EB5DQ in Valencia.

But this is just the start. The DXplorer.net software (which is free to use for 12 months after you have bought a WSPRlite, and £19.95 per annum thereafter) can help with a lot of analyses.

For example, you can plot the maximum mean (average) distance you are being heard against time for periods from one hour to 30 days. Or you can view this information in a table.

You can also plot the stations that have heard you on a great circle map with your QTH (location) at the centre. It can also compare your results with any other station. Hovering over the colour-coded spots tells you the received signal-to-noise ratio and the distance.

As someone who has used WSPR extensively to test antennas you can quickly see the benefits of DXplorer.net. Transmitting for 15 minutes with one antenna and then switching to another will give you some graphs of their relative performance and directionality. You can, of course, do this with the raw data from WSPRnet.org, but DXplorer.net makes it quicker and easier to accomplish.

UsesThe uses of WSPRlite and DXplorer.net are only limited by your imagination. Antenna comparisons are an obvious one, but they can also be used for propagation studies. The small size of the unit means you can set up a WSPR beacon anywhere in the world.

Or you can leave it running in the shack and spot short-lived HF openings that you

A DXplorer.net map comparing signals from two stations.Comparing the distances covered by an antenna at G0KYA and another at G4ZAY.

June 2017 43

A WSPRlite unit showing DXplorer.net working on a tablet. Courtesy SOTAbeams.

p42_44_wsprlite_radcom_june17.indd 43 10/05/2017 08:51:38

Review

44 June 2017

might otherwise miss. A whole Facebook group (with more than 600 members) has evolved that is devoted to uses for WSPRlite and DXplorer.net.

Above all, the WSPRlite transmitter means that you don’t need to tie up a computer to run a WSPR beacon. Once programmed, the WSPRlite unit is totally self contained.

TX Factor and YouTubeMike Marsh, G1IAR tries out the WSPRlite in episode 16 of TX Factor, the only TV show dedicated to all things radio. Not having a lot of real estate for antenna erection Mike uses

a vertical on HF and it seems to work OK, but he is keen to find out exactly how well it performs and which directions and bands it favours. Find out how easy Mike found the WSPRlite to get up and running and just how far the 200mW signal gets from Mike’s East Devon QTH. Is his antenna really any good for DX? The results are quite surprising!

TX Factor Episode 16 will be available to view from 19 May at www.txfactor.co.ukTX Factor is sponsored by the RSGB and ML&S.

Michael, G0POT has produced a 13-minute YouTube video that explains the WSPRlite very well indeed. If you are

interested in buying one after reading this feature it is worth watching the video to get a better idea of what it is and what you can do with it.

Other amateurs are using it to test antennas and better understand propagation, such as the C6APY DXpedition mentioned in the box below.

The WSPRlite costs £59.95 including VAT, and includes a one-year subscription to DXplorer Premium worth £19.95. It can be bought direct from www.sotabeams.co.uk or call SOTAbeams on 07976 688 359.

Our thanks to Richard, G3CWI at SOTAbeams for the loan of the review model.

C6APY DXpedition

The C6APY DXpedition to the Berry Islands, NA-054, in March (M0IDA, M0VFC & M1ACB) used a WSPRlite to monitor band conditions in a very effective and efficient way to plan band changes while keeping their three radios fully active on the open bands. The WSPRlite was powered by a small USB battery, which ran for at least two days before needing a charge, and was easily moved to different bands and antennas during the island activation.

The pictures below show DXplorer.net screenshots from C6APY showing WSPR spots and 10MHz band (30m) WSPR activity using a quarter wave vertical with elevated radials close to the beach.

The seven day DXpedition worked a total of 9072 QSOs, 6110 of which were unique callsigns. The breakdown over the bands they used was 177 QSOs on 80m, 1091 on 40m, 1345 on 30m, 4563 on 20m, 1513 on 17m, 360 on 15m and 23 QSOs on 12m. Other interesting statistics show that most contacts were with North America (5177 QSOs) followed by Europe (3587 QSOs), there were much fewer contacts with South America (137 QSOs), Africa (116 QSOs), Oceania (30 QSOs) and Asia (25 QSOs).

Just as an aside, the DXpedition made 40-odd QSOs using the FO-29, SO-50 and AO-85 satellites. They used handhelds with Arrow portable antennas for the FM satellites. On FO-20 they used an unusual setup with an Elecraft K3 and 2m transverter for the uplink and a FUNcube dongle for the downlink, both with separate Arrow antennas and separate operators.

p42_44_wsprlite_radcom_june17.indd 44 10/05/2017 08:51:45