HFU HF Underground
General Category => General Radio Discussion => Topic started by: Zane on February 09, 2012, 0315 UTC
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I've had a fairly continuous noise that I've been hearing for several months now. It's broadbanded enough to be hear as low as 80m and as high as 20m. The signal strength can vary day by day and also by frequency, generally higher strength with higher frequency. It's continuous. I've not had a situation where I've been listening and its disappeared.
There are some power poles near me that have forever been on the repair schedule due to a noise complaint I provided to the power company a long while back. However, that noise source is very different sounding than this one. It’s much more of a classic 60 Hz buzz whereas this one is much more, err "bassy" sounding.
I've not been able to hear it in my car and I've not yet been out hunting with my R30CC in portable mode. I guess I keep hoping the power company will repair the poles and I kill two birds with one stone. It’s there when the radio is run on batteries, so I’m confident it’s coming in on the external antenna.
I've recorded it and I wonder if any others have heard this and identified it? Joe Farley was nice enough to take a look at it on a scope and he commented that it definitely has 60 Hz content in it.
Any thoughts would be appreciated.
Zane
http://www.yousendit.com/download/T2djNHA4Tkx1YlBvS3NUQw?cid=tx-02002207340200000000&s=19102
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I get that intermittently here as well. All times day or night ???
Peace!
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It's more "ragged" sounding than the types of power-related noise that I get. Good luck getting that noise eliminated!
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At what frequency did you make the recording?
How relatively strong is it?
That "bassy" comment seems to apply.
I think I've that or something very similar to it before.
Fortunately I do not here that at my home location.
That would drive me up a wall
>:(
weaksigs
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At what frequency did you make the recording?
How relatively strong is it?
The recording was made in the 14 mHz ham band.
It never moves my S meter, but I use a low noise antenna. Relatively speaking, a strong pirate (Wolverine or WTCR) would be S8-S9 here when others are reporting S9+20 or greater.
The main problem is weak signal work. Trying to hear Euro's for example. I may just have enough signal for some audio and I'm trying to pull out an ID. It's annoying even up to moderately strong pirates. Of course this varies from day to day.
Z
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Zane;
I took another look at the noise in the time domain with a scope. I found that much to my embarrassment :-[ the variable time base knob on the scope was not in the locked and calibrated position. I have not used the scope since I last looked at the file, so anything I said about a 60Hz component is probably BS. I have no problem falling on that sword, because I earned it.
The noise in general seems to consist of multiple grouped impulses of about 7 or so impulses per group. There seems to be a period of typically 25mSec between groups, suggesting an underlying group frequency of about 40Hz or thereabouts. This would definitely explain the "bassy" feel that has been expressed.
My old scope is getting crusty, and I really wish that I had access to a DSO, but that is not currently an option. Maybe looking at the file with an audio spectrum analyzer could reveal something.
At any rate, I struggle to think of how this noise ties a a common physical process. Most likely not power infrastructure, but what? DFing it with a portable might be the best bet.
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It reminds me of a sound I have [rarely] heard before on HF, sometimes near 6925. If I hear it again, I'll try making a recording, to compare.
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Good you posted a recording. It sounds very much like a noise I hear on am when I plug in my self-charging Norelco rotary shaver. Maybe you have a charger you leave plugged in, or a neighbor does. Hope this helps.
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Good you posted a recording. It sounds very much like a noise I hear on am when I plug in my self-charging Norelco rotary shaver. Maybe you have a charger you leave plugged in, or a neighbor does. Hope this helps.
I ran to the self-charging shaver to give it a try - no go. ;D Thanks for the thought.
Thanks for looking again Joe.
Z