As I mention in my “About Me” page I’m a long-time amateur radio operator. Ham radio for many might be thought of as an anachronism in the times of cell phones and internet. If you picture modern ham radio as just two operators “ragchewing” on a weird sounding single sideband transmission, you have hardly scratched the surface.
For plenty of reasons, I have largely worked on digital modes and what is known as QRP. Which in layman’s terms means low transmitting power (and to some extent inexpensive) equipment. While around as an operating option since about 2009, Weak Signal Propagation Reporting (WSPR) finally made it into the news last year in a big way, and it is one of the digital ham modes I operate. I’ll explain why in a bit.
What is WSPR? It is a narrow band, slow speed digital mode that is a transmission consisting of a call sign of the sender, the station’s Maidenhead grid location on earth and the transmitter power. This is a beacon sent out only to see where it might be received – there is no “2-way” communication but for the aggregated reception reports created by receiving stations published on the web.
WSPR was produced by Joe Taylor, a ham operator (K1JT) and Nobel Physics prize winner. In the past, he’s developed other transmission and reception methods to help with moonbounce and meteor scatter radio work.
My beacon transmits sporadically day and night using 200 milliwatts – on 40, 30 and 20 meters (essentially a spot on the 7MHz, 10MHz and 14 MHz ham bands). Your typical Class 2 bluetooth devices use 2.5 milliwatts of transmitter power, going at best 30′. But my 40 meter WSPR transmission can make it across the Atlantic depending on conditions! Here is a map of my 40m beacon one recent evening.
A you can see, my signal was heard to the mid-west and all the way to Europe! As I’m sending several different amateur radio band beacons here is what my map looked like on Friday evening, January 14:
So what purpose does this serve besides some bragging rights for operating a QRP digital mode? For one thing, this mode provides valuable radio wave propagation testing on a real time basis on shortwave bands. But another use is what made the headlines: predicting where a lost airliner might be found!
Think of each brief beacon “hop” as a digital tripwire. If something passed through its path the propagation would be “disturbed.” This disturbance along with some others in the same general region could be used to track locations of the object that made the changes in signal. All of the beacons are stored in a database, so a researcher can go back and recreate conditions that existed in the region at the time of interest. And an aerospace engineer in Germany did just that for the missing Indonesian MH340 plane: https://hackaday.com/2021/04/24/wspr-may-hold-the-key-to-mh370-final-position/
Will it be where he predicted? Stay tuned (sorry about the pun) – perhaps we will find out in 2022!