in southeastern U.S. ,sound on 80 meters around 3.804 USB on some nights,what is it ?

[alok]

I hear a sound on 80 meters at night around 3.804 USB ,it is loud ,anybody know what it is. It is not there everynight. It is there ,steady for long periods each time that I have heard it.

 

[K8EAA]

Could be over the horizon radar. The Russians and Chinese are back in business with this stuff. It is about 12khz wide and on 40 and 80.
I'll check it out tonight on that freq.

 

[AK9R]

This article from the ARRL website talks about OTH radar causing interference on 40m.

I wonder if the 80m interference is something else: noisy power line transformer, noisy cable TV amplifier, nearby cellphone charger, invisible dog fence, neighbor with a plasma TV, etc.

 

[K8EAA]

I just checked 3.804mhz and no noise noted. Not sure if the OHR is on every day. W9BU could be onto something. Get hold of a battery receiver
and take a walk around your area.

 

[Token]

Could be over the horizon radar. The Russians and Chinese are back in business with this stuff. It is about 12khz wide and on 40 and 80.
I'll check it out tonight on that freq.

The Russians and Chinese have really never been out of the HF OTHR business, at least not in the past 25+ years. For that matter, the US, France, Iran, Canada, Australia, England, etc, are all active with HF radars, and have been for years. Many of these nations have multiple differnt types of radars, or radar waveforms, that can be found on HF. They are often over 40 kHz wide, especially the BPSK based Chinese stuff. The Russian 29B6 is using a common mode of 14 kHz width, but I have seen it use 28 kHz as well as a few other widths. The Russian Sunflower radars are wider yet, I have seen them with a spectrum over 30 kHz at the 6 dB points.

However, the signal in question is probably not a radar. There is a STANAG 4285 digital modem on 3803.2 kHz USB, this is very likely to be the signal being discussed here. I am receiving it weak in California, but on east coast remotes it is reasonably strong. On European remotes it is quite strong.

T!

 

[alok]

OK to all that commented. It is not interference in my immediate area ,since it has been heard by others miles away from me, plus it fades in / out like a skip signal would. During the day it is not there. I think the previous comments by Token sums it up.
Tonight ( 1-7-20 ) the signal is there @ 8:30PM ET, but not as strong as last night.