[time-nuts] strange carrier
paulswedb at gmail.com
Sat Nov 15 21:31:19 EST 2014
I was thinking of a new alternative we may have not considered.
Absolutely near field.
The solar panels popping up on the roofs then hitting an inverter sync'ed
to 60 Hz X 1000 would be a mighty fine transmitter. I know in our area
numbers of homes now have them on the roofs.
On Sat, Nov 15, 2014 at 4:48 PM, Brooke Clarke <brooke at pacific.net> wrote:
> 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."
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