Nanook

nanook@friendica.eskimo.com

Owner of Eskimo North

Network posts

P.O. Box 55816

Shoreline, Washington, USA

https://www.eskimo.com/~nanook

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Nanook

4 years ago

(Shoreline, WA, USA)

Nanook
4 years ago — (Shoreline, WA, USA)

Wierd Signals in the 82-88 Mhz Range

Starting last night I began receiving strange signals in the 80-88Mhz region of the spectrum on my SDR. If I use FM demodulation, I hear a strong 60Hz component and a very weak voice. These signals are numerous across this range, most are short lived (a few maybe 10 seconds but some persist). These frequencies used to be occupied by television channels 5 and 6 but they've been moved to UHF. This is just outside of Seattle, Washington. These are extremely unstable in terms of frequency, I would suspect some CB'ers linear had a bad parasitic oscillation if it weren't for them being so numerous across the 80-88Mhz and they go right up to 87.9 Mhz but do not encroach on the 88-108Mhz broadcast band which suggests they are very intentionally generated. Any ideas?

Christian Bredlow likes this.

in reply to Nanook

BR 549 ☎

in reply to Nanook 4 years ago

72–76 MHz: Radio controlled models, industrial remote control, and other devices. Model aircraft operate on 72 MHz while surface models operate on 75 MHz in the USA and Canada, air navigation beacons 74.8–75.2 MHz.

in reply to Nanook

BR 549 ☎

in reply to Nanook 4 years ago

crappy cheap Chinese quadrotor toys?

in reply to Nanook

Nanook

in reply to Nanook 4 years ago

Whatever these signals are they arrived virtually overnight. Also, don't think 60Hz or voice components can be explained that way.

in reply to Nanook

BR 549 ☎

in reply to Nanook 4 years ago

Triangulate . . one of the fun things I did with my Dad 50 years ago was transmitter hunts with the local ham club. One of the last ones I went on was done with a 2m transmitter. It was more of a challenge than the earlier 10m hunts, they were using a horizontally polarized antenna, and 2m bounces off of all sorts of stuff that 10m would just go around.

in reply to BR 549 ☎

Nanook

in reply to BR 549 ☎ 4 years ago

@BR 549 ☎ Computer is not portable and antenna not very directional.

in reply to Nanook

BR 549 ☎

in reply to Nanook 4 years ago

Dad made a portable 10m receiver that we once used to win the hunt -- it consisted of a copper loop, a variable capacitor, a diode, and a phone jack. portable handheld, back in the days before there was digital anything -- when we got close enough, the loop could carried on foot, listening on a pair of war surplus headphones.

in reply to BR 549 ☎

Nanook

in reply to BR 549 ☎ 4 years ago

@BR 549 ☎ This is near enough the FM broadcast band that you'd need something a bit more selective. And the 60Hz modulation component would make it hard to differentiate between normal power line harmonics.

in reply to Nanook

BR 549 ☎

in reply to Nanook 4 years ago

the little loop receiver is obviously only good for AM radio. and because all the hams were either at the hiding place or looking for it, there was nothing else on the 10m band that day 😉 fun times.

yeah, I know, to locate the signal you describe, you'd need better gear. two or three receivers, and precise timing info, or so.

in reply to BR 549 ☎

Nanook

in reply to BR 549 ☎ 4 years ago

@BR 549 ☎ If you look at the waterfall display and the IF display you can see most of them are highly intermittent and wander all over hell and back. This would seem to make it near impossible to track with any equipment. If I were bent on fucking with the FCC this would be ideal.