In this issue of T&E, I have asked my friend Marty Buehring (KB4MG) to talk about why he loves WSPR, and what benefits you will realize as a ham utilizing WSPR for a variety of analytics. Marty has spoken about this topic before, but this is the first time he's laid it all out in print (and we have a Part Two coming soon). I'm proud that we were able to attract this caliber of content for our QRZ readers. Please remember -- T&E is a great location for anything you've been wanting to write about for an amateur radio audience. In today's column, I've shared a few comments (and copy-edited the piece to fit the column), but Marty is our WSPR expert and author. He will be present in the Forum discussion that follows in order to answer your questions, something that normal print publications can't do. Instant communication with the author of a tech article? Another benefit of the digital age! -- Dave W7DGJ

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From Marty Buehring (KB4MG):

Have you ever wondered what this “whisper” mode is all about and what it’s good for?  You are not alone. Many hams have never considered how it could be used to enhance their stations. In this issue, we will introduce applications that will help answer questions like those. Weak signal beacons like WSPR can be very useful for many things!

Would you like to check propagation in real-time using your antenna, or easily compare antennas and understand their radiation patterns? Forget complicated Smith Charts, as WSPR works real time and provides satisfying detail. While anyone who builds antennas can get on the air and ask their QSO buddies for signal reports, the result won’t equal the ease of using this remarkable tool.

Those who receive and decode a WSPR station leave behind what we call a “Spot.” These Spots get saved in a central database and it is those Spots and their associated maps that one can use to determine how signals are propagating at your station.

There have been many articles published about how to install, setup, and get basic information from WSPR but no much about the practical applications. Of course, we can only cover the basics, but this will be a good starting place for you to investigate further. Amateur Radio is about learning and discovery and WSPR will add a new skill to your tool box.

Practicality of WSPR Mode

You may not be immediately comfortable with the topic of “weak signals,” especially if you have a linear amplifier and regularly transmit at full legal limit. If that’s the case, you’d wonder, “What could less than half a watt do for me?”

For a QRP operator, however, it’s apparent immediately. Striving to make contacts using 5 watts or thereabouts, that ham has a better appreciation for what can be done with low power. Let us warn you right now, it’s amazing how far WSPR will reach. We’re talking here about signals between 10mW and 5 watts, and they will go all over the world. 

WSPR uses techniques pioneered by communication theory and deep space exploration to make use of very weak signals. The receiver is paired with some sophisticated software that employs coding to ensure a successful reception of the message. In fact, the coding used allows a 200mW WSPR transmitter to have the punch of 1000 watts of SSB on the receiving end.

Considered another digital mode, WSPR uses FSK modulation and is part of the WSJT-x suite. This article will not discuss these details, but we will provide a few references for your further study in Part Two and in the attached forum discussion thread.

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There are two parties required for this mode to work. If we have WSPR transmitters sending data, somebody has to be there to receive it. There are many weak signal enthusiasts across the globe that monitor the WSPR frequencies -- many with automated equipment running almost all the time. This data is collected and uploaded to a database maintained by WSPRnet.org. At the time of this writing almost 1700 receivers were reporting WSPR data and almost 3700 transmitters were in use.

Our figure below shows the main dashboard for General WSPR Stats on wspr.live. The Spots saved range in the millions. They gather this data from the WSPRnet database and then do analysis on it for us. We benefit from the many graphs and maps that they provide us for free.

Transmitters send their location (grid square), callsign, and the power of their transmission in dBm. The receivers in turn collect this data and upload it into the WSPRnet database. This database can be useful for understanding your antenna performance and

real time propagation.  In this article and in Part Two, we’ll mention several different use cases for this mode.

The three most popular uses for WSPR are Antenna Performance, Antenna Comparisons, and Propagation . . . these are the best ways to experiment with WSPR and learn more about your station. We'll talk about Antenna Performance in the current article, leaving Part Two to discuss the remaining use cases.

Use Case 1 – Antenna Performance

We all wonder about the performance of our antennas. Many hams say that there is too much emphasis on finding the perfect SWR or the best coax cables, and not enough on actual on-air performance. In reality, any antenna system with a reasonable match near 50 ohms will radiate RF energy. The questions we'll want to answer from there are:

• Is my antenna tuned good enough and working for what I want to do?
• Where is my signal going? ( ie. Radiation pattern)
• Based on our current band conditions, am I making contacts where I think I should?

Before running WSPR, ensure that all the obvious trouble spots (resonance, coax, connectors etc.) have been checked and that your antenna is ready to accept some RF. Once you have what you think is a working antenna, it’s time to try it out. I’m sure you’ll get on the air and ask for radio checks, but the WSPR approach will tell you much more than a string of 5-9’s.

First, a brief word on setup . . . There’s been a lot published and on YouTube about setting up WSPR with either your rig or a standalone device. (Personally, I like the WSPR transmitters from sources like ZachTek, QRPLabs, and TAPR. Dave (W7DGJ) relies on his ZachTek and has written about it here.) I prefer this approach as well because I can keep my rig turned off and just deal with a little device instead. Make sure that if you are using a larger transceiver that you back the power down to as low as it will go. 1 watt is perfect . . . any more and you could overwhelm that WSPR frequency.

You’ll first want to know where your signal is going. Though you won’t find WSPR receivers in any dense grid, there are usually enough listening so that you can get a very good idea of where you are being heard.

This map in figure 2 shows my 20-meter signal at 200mW. Impressive for such low power, but that is the way WSPR works. This answers the question “where is my signal going.” It’s been heard all over the States, in Africa, the South Pacific, Alaska and Australia. (DJ: My little ZachTek puts out a quarter of one watt and I regularly am heard at the South Pole!)

The results shown in Figure 3 give you a closer view of the same data, where you can begin to see an antenna pattern based on the contacts closest to the antenna. Based on my antenna height, and the vertical or horizontal orientation, stations closer to me are likely inside my Skip Zone. In the figure, you can see an antenna pattern emerging based on a close up of my local contacts. This map is from a service called WSPR.rocks, which is maintained by Phil Barnard (VK7JJ) in Tasmania. It’s a great site, and you should take time to explore. There are a lot of resources there to analyze your data, and many ways to look at the data -- including an export to Google Earth. I have drawn lines to connect the contacts closest to me and it has a specific pattern that roughly corresponds to my antenna coverage.

Figure 4 to left is the Radiation Pattern generated by WSPR.live showing azimuth. It looks very similar to my drawing. Now I know which directions my antenna is radiating. Though this is no guarantee I can talk with a particular station, I now know that my antenna will reach there with the current propagation conditions.

You may notice a strong NULL at the 92° to 130° azimuth. Turns out that I do have problems with that direction!  It could be simply that there are not any receivers in that area, or that they are inside my Skip Zone. However, it is rare for me to have any DX contacts at that azimuth as well, which warrants me looking more carefully at my antenna. This is perfect example of how WSPR can help identify possible antenna issues. You can quickly learn what adjustments to make to ensure the pattern you expect, and then quickly recheck with another WSPR run.

You can also get a Performance Summary on WSPR.rocks. Select Charts and Performance Summary. Spot Quality is a measure of how well the signal is received.  This data can be useful in understanding your “localized” pattern and coverage. The best quality is a spot that was received over the greatest distance at the lowest power and with the best signal-to-noise ratio. If you ran WSPR on multiple bands, that would show up here and be represented as the best combination of spots. This is part “antenna performance” but also depends a lot on propagation conditions.

As you can tell, this valuable resource (WSPR) has a lot to offer. it's an inexpensive investment that can be a fun practice all in itself or one that can be useful to you as you fine-tune the antennas in use at your shack. In Part Two, we'll go into some other great applications of this remarkable mode.

73, Marty Buehring KB4MG

with Dave Jensen, W7DGJ

Biosketch: Martin Buehring was first licensed in 1966 originally as WN9WEX. He operated CW on Heathkit and Hallicrafters equipment. When college came along, amateur radio went on the shelf; however, the ARS strongly influenced Marty to pursue a degree in electrical engineering. After graduation he worked for Motorola on diverse projects using microprocessors. He later moved onto Signetics and ultimately to Mentor Graphics, where he worked as an applications engineer and manager until his retirement in 2022. He was licensed again as Amateur Extra in 2013 as KB4MG and is the President of the Cherokee Amateur Radio Society in Woodstock, GA. He operates SSB, FT8, and has a WSPR listening station.

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