[Harc] 145.8 signal - print this to paper

[Howard, KB6NN]

Jason,

Running behind on my email as you can tell by me saying nothing heard on that frequency here in Cutten today... (your original question was posted more than 24 hours ago).

And after reading, print this to paper if you are using a desktop/laptop, etc., (something other than a cell phone) to read this, because some troubleshooting steps below require you to turn off your computer.

The audio files you submitted makes me guess it's something terrestrial, that it is noise, not a signal.

You said 145.800, so presuming it is only on that frequency, makes advice by email more difficult, but there are things you can do right now, if you still hear the signal.  (By the way, FLDIGI does have a slightly configurable scope, enable it in the View menu.)  The fact that those who responded said they don't hear it at their location, strongly suggests it is terrestrial and close to you.  In that case, and if the signal is still present for you today, suggest you do the following:

1. First step in almost any case is to rule out the noise/interference as something in your house that's powered by AC: if you can hear the noise on a portable/handheld radio, turn that on, and while listening to the signal on the portable radio, go and turn off the main breaker to your house.  If the noise stops, it's powered by AC in your house.  If so, turn AC back on at the breaker and when the noise resumes, walk around your house and find it by either sussing it out by its strength or by selectively turning things off until you locate the culprit.  If not, it might be an AC powered device in a neighbor's house.

1a. If you can't carry around the radio you hear the signal on but can run the radio you are hearing it on off a battery, do so.  At least you can rule out an AC powered device/appliance in your own house.  Years ago, I had PG&E come out to locate a noise, and the technician used a portable radio to walk around the block with me and found the problem coming from a neighbor's garage.  PG&E opened the meter box, shut off the neighbor's power, and the noise stopped.  Simple basic troubleshooting paid off there.

2. I almost forgot: if you have/have a photovoltaic panels/panel on your roof, rule that out by listening for the sound at night.  This also rules out your neighbor's solar system, where charge controllers are the most likely culprit.

3. If you have a battery powered device that you are using to get the FLDIGI display you attached, that might be the culprit (not very likely but not impossible - could be power supply or display), so if you can listen to the noise and turn that laptop or tablet off (full off) (battery out if it's a laptop - probably unnecessary but gotta say it's easy to do).  If the sound disappears, bingo.  If not, keep testing.

4. If you have not eliminated the source as your own house or a neighbor's, turn your gear back on and change frequency, better, listen with a radio with a means to change frequency by small increments (it's own dial, CAT tuning by computer/FLDIGI), and see if the sound is on other frequencies besides 145.800.  Your FLDIGI screen snippet shows a wide signal, so you'll need to change frequency in steps of 1KHz or more.  This is just to see if it is only on 145.800 and does not reappear every so many KHz up and down the dial.  If it does appear on other than 145.800, very strong indication that it is noise from a local device.

5. If it does not appear on other frequencies (repeater outputs, other satellite frequencies), check to see if it appears on frequencies well below the subject frequency by dividing 145.800 by 2, 3, 1.5, etc. then listen on those frequencies for the source "fundamental" and apply the crude direction finding technique of walking around with a portable radio to sniff it out.

5a. If it does not appear to be in your house but is likely in your neighborhood and you don't have a portable radio to listen to it on, but you do have a mobile radio in your car and can hear the signal on that, you can do drive around the block to find where the signal is the strongest.  If you are driving down a street and the noise is constant and strong, but if you move to another street and it's negligible or gone, it may be on either the power lines or telephone or cable lines.

6. If you don't have a portable to listen on, someone in the club does.  Please post back here to say if you found the source, and answers to questions like if the sound is only on 145.800, and what you did to find it.  Would love to hear you used the steps above to find it.  Or if you or anyone else has another troubleshooting step I've overlooked, let me know.

We have not had, to my knowledge, an RFI Committee within HARC, but we have had ad-hoc teams formed to solve specific issues.

Hope any of the above helps you or anyone, and hope it is not too long an email to read.

Howard
--
KB6NN


   



On 3/26/2020 8:59 AM, Jason Durant via Harc wrote:
> Anyone know what the signal on 145.8 is? It seems like it is always there.
> I'm guessing it's a geosynchronous satellite or beacon...
> 
> 73
> Jason
> KA6F
> 
> 

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