An unusual new way to combine hobbies

Hi,

Completely new, and have had my R&S up a couple of days, and still learning. Today, I got the opportunity to capture something on both the Shake and Boom side that I thought was interesting. I was listening to something with headphones on, and completely missed a low Helicopter flyover till my youngest daughter tapped me on the shoulder and asked if I’d seen the large black helicopter. Intrigued, I opened up my Automatic Dependent Surveillance Broadcast (ADSB) system, which I have on another standalone RPi, and there was indeed a low flyby from a US Customs and Border Patrol Sikorsky S76B leaving the FBI facility about 20 miles from here:

That got me wondering what the Shake and Boom saw, and it appears I captured the flyover on both, and was able to extract some data from each showing the approach, flyover, and passing, including what I think are plots of doppler:

I think it’s pretty neat that I can combine both of these interests and derive interesting data within just a few days. The RShake is a great device! At the least, I know the signature of the S-76B now for the future!

Regards,

Bob

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Having done some passive sonar work earlier in my Navy career to track submarines, the s-curve on your plot is a classic doppler shift. Fun fact, if you know the fundamental frequency that the aircraft is putting out, you can do some math to calculate it’s speed and distance relative to your sensor. This is still one of the primary techniques used to passively track submarines.

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Really cool insights. Since, I have captured quite a few more, and the S-curve appears with each pass, different depending on speeds. Thanks for sharing.

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