And The Meek (Signal) Shall Inherit The Earth: Testing Propagation With WSPR & FT8
So, you are looking at my latest ham radio acquisition, the WSPR Desktop Transmitter Model 80to10 by ZachTek. As always, I buy all of my own items and do not accept solicitations for product reviews. In fact, I really only talk about the things I own that I like on this blog for the most part. I placed the order for this in early July and a month later it showed up from Sweden. ZachTek clearly warned that this would be the case if I chose USPS (which I did) rather than DHL as a mail carrier. I was not in a hurry and I wanted to use my post office box.
So the WSPR unit is a black box device with a GPS antenna (with an SMA connector) hanging off one side and a RF antenna port with an SMA socket on the other. The GPS is critical for synchronizing the timing of the unit, and will also automatically populate the maidenhead grid location. A standard micro USB cable powers the transmitter (requiring 5V and 250mA) and programs/configures the onboard Arduino. Other than requiring a computer for programming, the WSPR transmitter can operate independently. The USB plug can be plugged into a computer, accessory battery, or a wall wort in the same manner as charging your cell phone.
I purchased, however, a device from Powerwerx, the USBbuddy, that converts 12V DC to 5V DC. The 12V end has Anderson Powerpoles, whereas the 5V end is a USB socket. This is to be able to easily power up the WSPR unit with the Bioenno 15AH LifePo battery that is a standard part of my portable radio gear.
I had to install device drivers in order to have my computer recognize the WSPR unit upon first use on my Windows 10 machine. The ZachTek WSPR Transmitter Configuration software is downloadable from the ZackTek website.
Programming the unit is a matter of picking the right COM port in the “Serial Port” tab, hitting connect, and watching the GPS graphic to make sure their is an appropriate signal quality for transmission.
Then move over to the “Boot Configuration” tab and whichever application you want the WSPR unit to perform on startup. I chose the WSPR Beacon, as I wanted to use this as a standalone device.
Finally, under the “WSPR Beacon” tab, select which bands that you would like to have the unit cycle transmission through and how many seconds you would like to pause for after transmission. The default pause is 480 seconds. Add your call sign, your reported Maidenhead grid square (“Auto” is fine), click save settings, and hit start.
That’s it! The Zachtek Desktop WSPR transmitter is now programmed to work as soon as you plug it in to a power supply and antenna.
So, I played around with the WSPR unit indoors for a few weeks. Then this past weekend was the 2021 August North American QSO Party SSB. AA1F and I had some big plans of camping and playing radio, but Hurricane Henri and all its hype closed down the Massachusetts State Parks. So instead of a low noise floor setting with lots of tall trees to set up dueling radios, we instead turned our Boston city backyard into Field Day.
The picture below is a representative of what we did for the 2021 August NAQP SSB. I did not take any actual pictures of the real contest day. Regardless, we set up that same ice fishing tent, plus a pop up tent, and ran a 40M OCF dipole along that privacy fence, and had my DIY 49:1 EFHW antenna with a 60 foot radiator on the other side of the yard. Overall, the tallest point of either antenna was under 10 feet. Obviously we are masters of the compromised antenna! And you can just imagine the noise floor in this neighborhood of triple deckers!
So during a dinner break around 5pm, I plugged the 49:1 EFHW antenna that I had been using into the WSPR transmitter for about 20 minutes. I transmitted WSPR on 40M, 20M, 15M, and 10M, as this is where the EFHW was resonant, and I do not want to transmit into a high SWR. My spots–or stations that heard my signal–are shown below. Many of my maps look different because I had to use different sources to acquire them, and I then had to use a photo editor to color them most effectively. The following map is from http://wsprd.vk7jj.com/.
Below is just a close-up of the United States portion of the the 49:1 EFHW WSPR spots in the original coloration. The yellow lines represent 20M and the green lines represent 40M.
The map below is of the 31 SSB qsos I managed to make (using the EFHW antenna) during the entire NAQP. Do not laugh at me! Each one of the qsos was hard fought given the state of my antenna! Most of those contacts were made on 40M, although I do have some 20M and 80M contacts as well. The map is from www.qsomap.org.
Here is my SSB qso map overlying the WSPR map. You can see how similiar the clustering of the red pins (SSB qsos) are with the yellow lines (40M WSPR spots). This visually shows that the WSPR propagation pattern and SSB propagation pattern of this antenna are indeed similar.
The following map (from WSPRnet.org ) is the WSPR spots on 80M, 40M, 20M, and 12M from the 40M OCF dipole antenna that AA1F was using. The WSPR transmitter ran for about 45 minutes.
And again a United States – centric view of those WSPR spots…
AA1F’s 36 qsos, made on 20M, 40M, and 80M, from the NAQP are shown below.
And now his SSB qsos are shown below overlying the WSPR spot map. All of these contacts were made with the 40M OCF dipole antenna. I think the similarity in propagation between the WSPR transmitter and AA1F’s SSB qsos, although expected theoretically, are quite uncanny to actually visualize.
So, although I did not do any real data crunching with this to show if the propagation between the SSB contacts and the WSPR spots were indeed statistically significant. I am considering this test to be a successful pilot on how WSPR can be used to predict propagation. There are many variables not accounted for here. Mainly, I mixed together all of the bands for both WSPR and SSB without really trying to separate anything out. The number of spots and contacts were rather small. The WSPR transmission occurred for only 20 to 45 minutes around 5pm to 6pm, whereas we made SSB contacts from about 3pm to 11pm, therefore time differences for propagation were not taken in to consideration.
There is a lot of talk on the radio forums about what weak signal work (like WSJT-X) is good for. WSPR is of course part of WSJT-X, as is the ever popular and controversial FT8 mode. It turns out that by enabling PSK Reporter on your WSJT-X software you can view a map of all of the stations that decode your FT8 transmission. Enabling PSK Reporter takes 3 steps in the settings menu of WSJT-X. 1) On General tab, enter your callsign and 6 character grid square. It probably is already there. 2) On Frequencies tab, specify your antenna (on a per-band basis). I skipped this step as I wasn’t sure what it meant. 3) On Reporting tab, check the “Enable PSK Reporter spotting box.” That is it!
Sit down and play some FT8. And then head over to the https://pskreporter.info/ , enter in your callsign and some of the other dropdown information, and take a peak at your FT8 propagation map!
So, in summary, I think these weak signal modes are a fun, interesting, and accessible way for hams to test propagation. I plan on doing a lot more work with WSPR and FT8 and my various antennas and operating situations, and I am particularly pleased with the Zachtek unit. I look forward to taking it out for some portable radio soon!
Enjoy,
KM1NDY