BIG AM signal

[SpaceForceCmdr]

Any idea what this huge AM signal could be? It's right next to a regular station, but it doesn't sound like anything intelligible.

 

[Boombox]

What does it sound like? Have you tried using a portable AM radio to see if it picks up the same signal?

 

[a417]

was this crossposted to reddit?

 

[SpaceForceCmdr]

I'll post a vid with sound later, but if I recall, it just sounds like noise.

Yeah, I think I posted to this to reddit a few days ago. It seems weird that it's such a wide signal, but I'm new to all this stuff.

 

[studgeman]

Granted it doesn't look like the FM version, but any chance it might be HD radio?

 

[SpaceForceCmdr]

Maybe. Weird thing is, most of the signal seems to be around 1155, which wouldn't even be a station here. Don't they go in 10 khz increments?

 

[studgeman]

HD radio would be directly adjacent to the main channel as it is a "sideband." At one point there used to be digital only AM. Its a little bit of a stretch thinking HD radio, but other than localized interference I am at a loss for other obvious signals. Other areas of the world use DRM (Digital radio monodial) Really just kinda brainstroming here.

 

[SpaceForceCmdr]

I just looked up a list of stations around here, and it looks like WCUE Family Radio is at 1150, and then there is a Detroit station at 1130. Maybe the 1150 one is just very powerful?

 

[SpaceForceCmdr]

Another thing, someone on reddit mentioned a powerful station in Detroit. It's WDFN, and transmit power is 50,000 watts, which is 10x stronger than WCUE.

 

[a417]

That is not an HD Radio signal. The first time you see one, you will have that signal burned into your brain. It's very distinctive. That looks like local interfererence to me...

 

[Whiskey3JMC]

Turn the RF gain down a bit, does the inclining slope go down at all? I'd hazard a guess and say RFI from a nearby electrical source. Simply turning on fluorescent lighting or opening my refrigerator in my house causes undesired effects from my SDR on AM

 

[SpaceForceCmdr]

FWIW, here's a short clip:

If I turn the gain way down, the inclining slope is still there.

 

[a417]

That's almost assuredly a local RFI source.

Are you running this on a laptop? If you are, knock off the power to your house for a couple of seconds and see if it's within your walls or in your neighborhood.

 

[SpaceForceCmdr]

I'm normally on my desktop, but I could try it out on my laptop. I'm not really that concerned with it. I wasn't planning on listening to this station anyway, but found it peculiar.

 

[a417]

I'm normally on my desktop, but I could try it out on my laptop. I'm not really that concerned with it.

No, but you don't know if that's not also throwing a spur somewhere else on your local spectrum. I mean you did post it in multiple places...so, give it a try?

 

[krokus]

Any updates?

 

[SpaceForceCmdr]

Well, I'm using an Airspy HF+ Discovery now, and this is what it looks like. The slanting part is gone, but it still looks a bit odd. I can listen to a station at 1100, and one at 1140, but that whole area in between is just garbage.

 

[SpaceForceCmdr]

and here it is if I switch to my MLA-30 loop

 

[majoco]

Have you looked for any harmonics or sub-harmonics? Some time ago there was quite a strong whistle on one of our lower frequency AM stations and it was there on every radio - sometimes it jumped a few hundred cycles and it wan't there after 10-ish at night. Sometimes first thing in the morning you could hear it come on with a very high pitch which slowly and down to about 1kHz and stayed there. I got a portable and followed it around and it was strongest out by our phone line connection box. More investigation showed that there was a carrier on sub-harmonics too. My two neighbours were hearing it too. I called a radio inspector friend and he put me through to the 'radio interference' people in the Post Office Telecoms who were there pretty sharpish with a detector van before I went to work. When I came home there was a detailed description on all the work they had done. I found it hard to believe but they tracked it down to a cracked ferrite transformer (I guess it was the local oscillator) in a stereo receiver in someones' house about 30metres away AND later they left another note to say they took the receiver away, repaired it and brought it back to the owner free of charge! My radio inspector friend said it was free of charge because they used the whole exercise as training for a couple of apprentices! Restores your faith in a Gummint department, doesn't it.

 

[Boombox]

Sounds like a bad CFL, bad LED, or a dimmer switch. CFL and LED lights can operate perfectly, light-wise, but still throw out hash on the AM band.