Strange waterfall

YelloEye

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Alright, so after buying a pair of GMRS radios, I decided I also wanted to get into watching radio overall and snagged an RTL-SDRv3 so I could decode digital, look at ADS-B, get ISS and NOAA pictures, etc. Man there's a lot. Anyway, ran across a couple of these weird moving transmissions. No voice that I heard so might just be interference, once it stopped all I heard was static. But from my time in the military I also recalled hearing about frequency hop transmissions. The image below probably isn't that, but I did see what I think was freq hop up on the 70cm HAM band which I thought was odd.

Is this freq hop or just some weird interference? Is this what freq hop would look like?

1628107445515.png
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Update. At least some of these are just the tuner trying to keep up with me scrolling through the bands. But that back and forth graph pictured was me being stationary for a bit IIRC.
 
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spinner55

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The band is shared with the military. Mainly radar - wait till the President comes to town. See how much interference you get from E3-AWACS aircraft. "The 420-450 MHz band is a shared frequencies with Radiolocation. (US government / Military)"
 
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YelloEye

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The band is shared with the military. Mainly radar - wait till the President comes to town. See how much interference you get from A3-AWACS aircraft. "The 420-450 MHz band is a shared frequencies with Radiolocation. (US government / Military)"
That sounds exciting. I'll have to make sure to monitor that when it happens. For now just enjoying watching GMRS traffic, heard people chatting on the travel tone not associated with a known GMRS repeater. Guessing they're just traveling in a group down the freeway as I lost them pretty quick. I do hear a station identifier on that freq pretty regularly though it's registered on a different tone.
 

spinner55

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That sounds exciting. I'll have to make sure to monitor that when it happens. For now just enjoying watching GMRS traffic, heard people chatting on the travel tone not associated with a known GMRS repeater. Guessing they're just traveling in a group down the freeway as I lost them pretty quick. I do hear a station identifier on that freq pretty regularly though it's registered on a different tone.

Radiolocation is the primary user - ham are secondary. Which means hams cannot cause harmful interference to primary users. Now if you live near the Canadian border. There are sections of the band that hams cannot use. Think 420 to 430 if I remember are used for commercial users.

Here is a link to the 420-450 federal band plan.

220 / 440 / 900 are shared bands with US government. The only reason will lost 220-222 MHz was the government removed some operations from it. Then the FCC gave it to commercial users - bad move for a great band.

Take care
Spin
 

YelloEye

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I'm chalking up my original waterfall as just being me scrolling back and forth faster than the tuner could keep up with.

Ran across a +DMR stream today which was neat. No idea who operates there, will have to look it up. Chatter was hard to understand.
1628200106708.png
 

Token

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Alright, so after buying a pair of GMRS radios, I decided I also wanted to get into watching radio overall and snagged an RTL-SDRv3 so I could decode digital, look at ADS-B, get ISS and NOAA pictures, etc. Man there's a lot. Anyway, ran across a couple of these weird moving transmissions. No voice that I heard so might just be interference, once it stopped all I heard was static. But from my time in the military I also recalled hearing about frequency hop transmissions. The image below probably isn't that, but I did see what I think was freq hop up on the 70cm HAM band which I thought was odd.

Is this freq hop or just some weird interference? Is this what freq hop would look like?

View attachment 185357
Post automatically merged:

Update. At least some of these are just the tuner trying to keep up with me scrolling through the bands. But that back and forth graph pictured was me being stationary for a bit IIRC.

No, that is not freq hop of any kind. Below are a few videos form my YouTube channel with Freq Hop signals in them.

In this case the freq hop burst starts with some kind of MFSK, and into the hop. Note that this video is on HF, not VHF or UHF, but you can still get the feel for it. The majority of the videos on my channel are HF stuff.


The below video is a different freq hop signal, again on HF. The stuff of interest is the periodic hits spread from 8050 kHz to 8150 kHz. You can hear it in the audio as periodic and repeating tick / pop sounds.


The below video is interesting to me because it is freq hop it is not digitized, not encrypted, narrow banded, and you can clearly hear the intelligence on the hops.


This last one is VHF. This is US mil, known to hobbyist as "waterdrops".


T!
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The band is shared with the military. Mainly radar - wait till the President comes to town. See how much interference you get from A3-AWACS aircraft. "The 420-450 MHz band is a shared frequencies with Radiolocation. (US government / Military)"

I assume that is a typo and you mean the E3 Sentry. Another airborne radar you will run into in the band is the one on the E2 Hawkeye. I really need to grab some samples of those to put on the YouTube channel.

T!
 
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jestric

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....

I assume that is a typo and you mean the E3 Sentry. Another airborne radar you will run into in the band is the one on the E2 Hawkeye. I really need to grab some samples of those to put on the YouTube channel.

T!

AWACS is the name of the specific system installed in the E-3.
 

Token

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AWACS is the name of the specific system installed in the E-3.

Yes I am ... ahhh .... reasonably familiar with AWACS. My comment was to the quote "A-3 AWACS aircraft". That is why I said "I assume that is a typo, and you mean the E-3 Sentry". I assumed he typoed E-3 to A-3.

Just FYI, the E-3 radar and the E-2D radar are fairly similar, and both eat up the 70 cm band occasionally.

T!
 

rwsmith123

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Here's a little video clip of a strange waterfall I saw:

Back of the local Target after a torrential downpour!!

Sorry, couldn't resist :)
 

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