What is this wideband signal at exactly 432MHz?

Need help installing or figuring out something about your SDR? Ask here.
Post Reply
Ben321
Posts: 33
Joined: Wed Feb 15, 2017 9:52 am

What is this wideband signal at exactly 432MHz?

Post by Ben321 » Fri Jul 26, 2019 9:35 am

It's a little over 1 MHz wide and appears to use AM as its modulation, and it appears to have either 2 or 3 subcarriers. If 3 subcarriers, they appear to be using FM modulation, with the lower 2 having a wider bandwidth than the highest one. If 2 subcarriers, the lower one appears to be FSK modulated between 2 widely spaced different frequencies, while the higher subcarrier appears to be FM modulated.

If anybody can help ID it, that would be great.

Here's a screenshot of the signal.
Image

Username
Posts: 494
Joined: Sun Oct 09, 2016 7:27 am

Re: What is this wideband signal at exactly 432MHz?

Post by Username » Fri Jul 26, 2019 11:01 am

Where are you from?
And it look like Noise for me.

Ben321
Posts: 33
Joined: Wed Feb 15, 2017 9:52 am

Re: What is this wideband signal at exactly 432MHz?

Post by Ben321 » Fri Jul 26, 2019 7:31 pm

Username wrote:
Fri Jul 26, 2019 11:01 am
Where are you from?
And it look like Noise for me.
I live in Seattle, WA.

I thought that maybe since it had a carrier at a very specific frequency (exactly 432MHz), and also is extremely stable (no jitter in the carrier frequency at all), that maybe it was some kind of GPS calibrated transmitter. And that would mean it was likely some kind of utility signal that is mission-critical and requires extremely precise timing.

Username
Posts: 494
Joined: Sun Oct 09, 2016 7:27 am

Re: What is this wideband signal at exactly 432MHz?

Post by Username » Fri Jul 26, 2019 7:53 pm

Maybe. But just a Spike with nohting on it could be anything or nothing.

Ben321
Posts: 33
Joined: Wed Feb 15, 2017 9:52 am

Re: What is this wideband signal at exactly 432MHz?

Post by Ben321 » Sat Jul 27, 2019 5:19 am

Username wrote:
Fri Jul 26, 2019 7:53 pm
Maybe. But just a Spike with nohting on it could be anything or nothing.
Notice the signals to the left and right of this "spike" that clearly are subcarriers, which are AM modulating the carrier (which is at exatly 432MHz)? That's not a spike, that's a carrier signal of some kind. And the total signal takes up about half the bandwidth of the 2.4MHz passband.

Username
Posts: 494
Joined: Sun Oct 09, 2016 7:27 am

Re: What is this wideband signal at exactly 432MHz?

Post by Username » Sat Jul 27, 2019 10:15 am

I NEVER saw any AM Signal above 136 who is the Air Band.
Oke oke maybe some Weather Station use AM Bursts.

It lust just like Noise sorry for that. I have a lot of this Spikes here.

Post Reply