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Comment by marricks | Hacker News Reader

Does anyone have more information in this WSPR system? I’m not certain how someone could have access to enough stations to pick up enough stray radio signals to detect a flight path. It sounds very intricate.

Edit: sounds like it’s based off of amateur radio operators https://en.wikipedia.org/wiki/WSPR_(amateur_radio_software)

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I'm also interested in learning about how this can be used for tracking.

From the paper [1]:

> The method is based on pattern recognition of anomalies in the radio transmissions between stations in the global WSPR network in the received signal-to noise ratio (SNR) and/or the drift of the received signal when compared to the transmission frequency. These anomalies in transmission links may be due to a number of causes, including an aircraft crossing the transmission path.

That's pretty vague, but it's a start.

[1] https://www.dropbox.com/s/tvtfw14tfyfljie/Global%20Detection...

It's based off of amateur radio yes. As a ham this is actually really really cool. A Raspberry Pi is able to transmit detectable WSPR off of it's 10dBm output from the GPIO and an antenna if you have a callsign and want to try it.

There is a database & map of current WSPR activity on all amateur bands. I frequently use it for propagation indicators.

https://wsprnet.org/drupal/wsprnet/map

This is the article that underscores much of this work on tracking: https://www.dropbox.com/s/w43gu64vn7jvmxm/Using%20the%20WSPR...

Quite fascinating.

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