Ionosondes (Chirpsounders) on the Shortwave Bands

[spongella]

If you've ever heard a quick "zwoop" sound in your headphones while on HF, you might have been hearing an ionosonde or chipsounder. It's a system of determining ionospheric conditions using a transmitter and receiver. These ionosonde transmissions look like the picture below, an angled straight line going up the band. Some travel quite quickly and can be somewhat jarring when listening on HF. This one was seen using a HackRF one, but any SDR dongle will allow you to "see" one.

 

[RONZ]

Have you ever did the same thing on CHU Canada?

 

[lfp302]

I used to hear something that sounded like a bank of airplane propeller engines. It was usually on multiple bands. Maybe 400 HZ or so. Always wondered what that was.

 

[spongella]

Have you ever did the same thing on CHU Canada?

If you are referring to 3.330 MHz no I have not specifically looked at that frequency. Ionosondes are all over the HF band though, even up in the CB band.

 

[spongella]

I used to hear something that sounded like a bank of airplane propeller engines. It was usually on multiple bands. Maybe 400 HZ or so. Always wondered what that was.

Might be Stanag 4285 - check this site for all types of digital sounds: www.sigidwiki.com/wiki/Category:Military