Many thanks to Conrad (N2YCH) who shares the following field report:

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QRPppppp….WSPR

By: Conrad Trautmann (N2YCH)

WSPR, or Weak Signal Propagation Reporter, is a digital mode you can select within WSJT-X. You can use the data that’s generated by the WSPR network to check your own antenna’s performance for transmitting and receiving and also to see what paths are open by band at a particular time of day from your QTH. Recently, I’ve been using WSPR to improve my own antenna systems and to help reduce local noise sources.

Originally developed by Joe Taylor, K1JT, an approximately two minute QRP transmission contains the originating station’s call sign, the maidenhead grid locator and the transmit power level being used. Stations typically use 250mw up to 5watts when they send these signals. WSJT-X allows you to select how often you want to send this transmission and what bands to transmit on. There’s an embedded schedule in WSJT-X that allows “band-hopping” for stations using a multiband antenna to transmit on different bands. When not transmitting, it listens for and decodes other stations transmitting and can post “spots” of those stations to the WSPR network database.

Here on QRPer.com, Thomas, K4SWL posted in this field report what the various flavors of QRP power levels are…

• QRP: 5 watts to 1 watt (for some contest 10 watts = SSB QRP)
• QRPp: Less than 1 watt to 100 mw
• QRPpp: Less than 100mw

Did you know that there are more than 3,000 WSPR HF beacons running on all of the amateur bands all over the world at QRP power or less? Many are running 250mw or less. If you open up WSJT-X and select the WSPR mode, you’ll see that the pull down for power levels give you these options:

• 37dbm = 5w
• 33dbm = 2w
• 30dbm = 1w
• 27dbm = 500mw
• 23dbm = 200mw
• 20dbm = 100mw
• 17dbm = 50mw
• 13dbm = 20mw
• 10dbm = 10mw
• 7dbm = 5mw
• 3dbm = 2mw
• 0dbm = 1mw

You could transmit your own beacon if you choose to using WSJT-X. You can also receive many of the 3,000+ beacons that are on the air right now if you wanted.

Why, you ask?

Let me tell you about the WSPR journey I’ve taken over the past few months and how what I’ve learned has benefitted me, my station and my antennas. Here’s how extreme QRPpp signals can help all of us.

I’m an avid digital operator, and I’ve tested many of the digital modes that WSJT-X, FLDigi, VarAC and others have to offer.

WSPR (Weak Signal Propagation Reporter) is a program embedded as a mode in WSJT-X and you can set it to transmit at the various power levels I listed above and band hop to different bands if your antenna can support those frequencies. When it’s not transmitting, it will receive and post the beacons it hears to the WSPRnet.org web site. For anyone familiar with pskreporter.info, WSPRnet.org is similar in that it provides maps of where and when “spots” are received and the relative signal strength the signals were when received by station, the mode and frequency.

After setting my station to transmit and receive on WSPR and looking at my spots on WSPRnet.org that were reported by receiving stations over the previous day, it was a thrill to see my 250mw signal making it out all over the world. Amazing actually, that such a small amount of power could travel that far. 250mw to Antarctica? That’s pretty good.

I bought a QRP-Labs QCX transceiver and the external companion GPS clock, which supports running WSPR transmission stand alone, without tying up a computer. Then I learned about the Sotabeams WSPRLite Antenna Tester (a 250mw WSPR transmitter) and the various WSPR transmitters offered by ZachTek which can also run without needing a computer.

My goal was to have WSPR beacons transmitting on as many bands as possible. Combining them into a single, multiband antenna posed its own problems, which is a topic for another article. However, all of these solutions just transmitted. I was hoping to also be able to receive and post spots as well.

Then, QRP-Labs (shout out to Hans Summers) came out with the QDX and then the QMX, both of which connect to a PC and are controlled by WSJT-X to do the band hopping transmitting and receiving. Like FT8, WSPR does depend on timing to work best, so using an external GPS clock for the QCX or connecting a QDX or QMX to a computer that can get it’s time from the internet can help keep the transmission cycles in sync with the receiver sites for best reception results.

This is cool stuff, but still, what’s the point? That’s when a friend I made in the WSPR community, Tom, WA2TP pointed out how to use all of these beacons to improve my station’s receiving capabilities. I have a good HF receiver and a dipole antenna and a hexbeam on a rotor and I figured I was good to go. I was making contacts without any problems. Tom told me this: “It’s all about the noise.”

He recommended using a wideband SDR called a Kiwi that can view the entire HF spectrum from 0 -30MHz on a waterfall at one time. My ICOM IC-7610 can connect to a PC and work with HDSDR software which has a waterfall, but it will only show you the spectrum of the particular band you’re on, not the entire HF spectrum at once. The Kiwi shows the entire spectrum from 0 to 30 MHz and when set up just right, you can see noise in there…a lot of noise, emanating from all sorts of things.

If you’re trying to receive a 250mw WSPR beacon signal transmitting from Australia, the noise from the after-market, wall-wart switching power supply connected to your cell phone charger a few feet away from your antenna could be way noisier and will blank that VK beacon right out. Your antenna and ability to hear distant signals is only as good as how low or quiet the local QRM is that we all have to deal with.

So began my hunt for noise, with a lot of guidance from folks with experience at it.

My success at eliminating the noise was being measured by where I placed on the WSPR Top Spotters leaderboard.  It’s a record of how many beacons you receive and spot/post by band and is updated daily at 0000 UTC.  It allows you to sort by distance and received signal strength, which is helpful. As I found and eliminated my local noise sources, I was able to hear more beacons from further away, thereby improving my receive capability. When I began in May 2024, I was ranked at 62nd of the top 200 WSPR receive sites.

I could write up an entire post on the various noise sources I found and how I tracked them down, but I’ll save that for another time. I will share a few highlights…

• I own a Tesla. Tesla recommends you leave your car attached to the charging cable when it’s parked. I always left it plugged in. Guess what? When it’s plugged in, the on-board AC to DC inverter runs all the time, even if it’s not charging, creating S5 or more noise on 40 meters. All of 40 meters. See the photo below. The yellow and orange bars to the left are the local broadcast band AM stations. The bright green bar about one third of the way over from the left shows the noise generated after plugging the Tesla in and it’s not even charging.

• I have a Sonos speaker in my garage. It’s unplugged now because it was creating noise up and down the entire band
• I had a USB powered LED light strip mounted over the top of my IC-7610. It created huge S7 spikes all over 20 meters. I didn’t see them when I was running FT8, but once I viewed it on the waterfall, there they were. You may have guessed that the light strip is no longer plugged in.
• I discovered that the window air conditioner I use in my ham shack creates a ton of wideband noise at 10 meters. Adding snap on ferrite cores over the power cord suppressed the noise.
• Common mode noise being introduced on the RF cable coming from the antenna to my house was creating noise in the waterfall and also detuning the antenna. A 1:1 balun between the antenna and the line at the antenna end is a must to isolate the antenna from the cable to keep that noise at a minimum.

There are more stories and most of the noise was self-inflicted, meaning it was my own equipment creating it. Maybe more experienced hams are reading this saying most people should know this stuff already, but until someone showed me the right tools and how to use them, I didn’t even know where I should look or even that I had a problem.

Each time I discovered a noise source and eliminated it, no matter how low or small it was, it helped my WSPR beacon receive statistics. Think about it, if I can reliably pick up those 250 mw VK-land beacons 16,000 km away, I should be able to hear anything, anywhere provided the band is open. Having a good, sensitive, selective radio and a fantastic high gain antenna can’t eliminate the S5 inverter noise coming from the car in the garage.

Some sources of good advice on tools to use and how to chase down and isolate noise in your shack can be found here at KA7OEI’s blog. I personally used the TinySA and active antenna and built a loop as suggested to locate my noise sources.

Remember how I was trying to run WSPR on multiple bands at once? I was surprised to learn that there are a few WSPR skimmer software applications that you can connect to a Software Defined Radio (SDR) to listen to all bands (or almost all, depending on your make and model of SDR) simultaneously and post results to the spotter sites. The one I’m using is a Linux application called WsprDaemon. I’m a Microsoft windows guy, but I learned enough Linux with the help of the internet and ChatGPT to muddle my way through repurposing an old PC to load and run Linux Ubuntu server. Actually, I started with a Raspberry Pi, which will work, but I quickly determined that it was underpowered and I abandoned that early on.

From there, following the installation instructions on the WsprDaemon site worked for me. Other applications you can use to do this include the Airspy HF+ Spyserver, Kiwi SDR’s built-in WSPR extension, SparkSDR and CWSL_DIGI.

Try an internet search for these for more information. Being able to see your reception on more than just one band at a time will help you determine what frequencies your antenna is optimized for and also give you an at-a-glance look at “how are the bands doing right here at my QTH, today.” I’ve decided against more than one 10 meter POTA activation and activated on 20 meters instead knowing that my home WSPR receive station was hardly hearing anything at the high frequencies. If it can’t pick up the beacons, then it’s unlikely I’ll have success making a meaningful amount of contacts. You can use VOACAP or dxmaps.com to see this data as well, but this is a real time report on how things are performing right at your house or receive site.

Another thing WsprDaemon can do is allow you to connect more than one radio at a time and upload only the best signal report from multiple radios tuned to the same frequency at once. I’m using this to have multiple antennas aimed in different directions feed two radios to get both North and South and East and West antenna coverage. Once you have two radios connected, you can conduct antenna tests against yourself to see which antenna will be better to use than another, by band. There’s a very inexpensive SDR model called the RX888 MKII that you can buy for less than $200 that will monitor all of the bands from 2200 meters to 6 meters when connected to WsprDaemon.

The RX888 SDR – Up Close Photos | The SWLing Post

Once my local noise sources were resolved, I turned my focus to the antenna performance. I began experimenting by changing which antenna was feeding the main receiver and seeing how my receive performance compared to other receive stations in my area.

The top spotters site will allow you to sort by grid square, so you can do that comparison. There’s also a number of great reports you can view at wspr.rocks. I’ve tried all of my antennas and the best performer so far is my 80 meter Buckmaster OCF dipole.

Even with good performance from that antenna, I was still not keeping up with other Top Spotters. I was getting a fraction of the number of stations on 40 and 20 meters that some of the others were. I will point out that where you’re located geographically on earth can have a lot to do with how many stations you can receive. I’m in a pretty good spot here in the Northeastern, USA. But I was still not doing well compared to other stations in my general vicinity.

That’s when I decided to add a second receiver and run my other antennas into it to compare how they worked.

I have a 200’ non-resonant dipole antenna oriented East to West that does nearly as well as the OCFD which is oriented North to South. Adding both of these into WSPRDaemon, my 20 meter spots started coming up. I was picking up beacons on one and not the other and vice versa.

After a lot of testing, I determined that while EFHW antennas have their place for certain applications, they are noisy compared to the dipoles. This is not new news to anyone who knows antenna theory, but I can confirm it in practice. I tried the amplified magnetic loop antenna with hopes that it could outperform the OCFD on the low bands, but it didn’t. The OCFD won every time. I also tried a tuned 20 meter dipole at 30’ on a temporary mast oriented in different directions and the OCFD beat it as well.

WSPR QRPpp beacons transmitting from all over the world have helped me to eliminate my local QRM, determine what my best antennas are and how to orient them for the best reception I can. It was fun to learn the linux commands and to see WsprDaemon begin posting the spots. Finally, it was satisfying to see my station climb up the Top Spotters leaderboard as I made those changes and improvements.

Recently, I took my WSPR receivers offline to operate as K2D for the 13 Colonies Special Event the first week of July. It was the first time I had gone on the air since I began the WSPR testing.

It felt as though my radio had been supercharged; I was receiving stations from Asia on 20 meters during the day that I would normally only see during the gray line hours. There was no doubt that the work I did to improve my WSPR reception had paid off while running FT8 and FT4 for the special event.

To conclude, I’ll end by repeating the good advice my friend Tom gave me…”It is all about the noise.”

73

Conrad, N2YCH