[time-nuts] strange carrier

Brooke Clarke brooke at pacific.net
Sat Nov 15 16:48:12 EST 2014

Hi Ed:

The DISEqC protocol is a low level signal at 22 kHz which would not make the signal being discussed.
If it was me I wouldn't look to the neighbor until I was sure it was not coming from my house, hence the shut down the 
house first approach.

It's very difficult to generate any signal strength near 60 kHz so rather than suspect a powerful transmitter it's more 
likely near field and very close by.
WWVB has a small fortune in their antenna.  I ran a "Lowfer" beacon "LAH" on 175 kHz with a 50 foot tall antenna and the 
signal strength was quite small because the antenna is a very small fraction of a wavelength.

Mail_Attachment --
Have Fun,

Brooke Clarke, N6GCE
ed breya wrote:
> A signal like that coming from a dish makes some sense to me. I vaguely recall from about ten years ago investigating 
> how the satellite receivers work, that a fairly strong control signal of around 20 kHz was used in some to select the 
> various LNBs and their polarizations in more complicated systems. This was passed via the cables superimposed on the 
> DC power along with the returning IF signals between the set-top box and the dish units.
> If the neighbor's setup has a bad connection in a cable end, there could be a pretty strong third harmonic of a 20 
> kHz-ish signal leaking out, with a good-sized antenna possibly formed by maybe 50-100 feet of partly-opened cable 
> shield, depending on the possible ground loop paths. Another possibility is if the LNB power line from the STB has 
> lots of 20 kHz-ish noise on it from a failure in the local SMPS.
> If the possible faults were large, you would think it would be noticed as a reception problem by the neighbor, but 
> maybe a partial problem is enough for you to see interference. If the interference is from the control signal, it 
> would likely be derived from a uP clock, so quite stable, while if it's from SMPS switching, it should not be very 
> stable, and also loaded with line frequency sidebands.
> If that is the case, maybe you could inform the neighbor so that they can fix the problem (or you fix it for them), 
> thus improving their reception and reliability, and eliminating the interference.
> I could be entirely wrong on this, but your last post rang a bell in my head as soon as I saw "satellite dish."
> Ed
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