[GCARC] Signals Interference Question

[Al KB2AYU]

Most likely a close by piece of crap consumer electronic device.

It could be in your own house, but could also be several houses away.

57 Khz is in the range of the typical switching frequency of a power 
supply/wall wart.

As the temperature changes, the frequency of the device changes too, 
thus the slow sweep.

You have to shut off your main breaker and have a battery powered 
receiver to make sure it isn't in your house.

If it's not, good luck finding the device in someone elses house.

Man made electronic noise is the biggest problem hams face today.

Lots of cheap, poorly engineered, chinese junk being sold.

Al


On 8/24/2018 8:18 AM, David Wade wrote:
> I live in Pitman, and have been receiving reception interference on my SDR receiver from a coordinated group of signals of unknown origin.  They do not seem to be emanating from within my residence, but I am not 100% certain of that yet.  I wonder if any GCARC member(s) might be able to explain this interference to me?
>
> 1) The coordinated group of signals occur within the frequency range of 4.7 - 8.4 MHz.
> 2) The strongest signals occur within the 6.3 - 6.7 MHz range, and the weaker signals occur on either side of this frequency range.
> 3) Most of the time, the signals are separated from each other by about 57 kHz.
> 4) The signals have a bandwidth of about 6 - 10 kHz.
> 5) The signals periodically, slowly, "sweep" back-and forth through a range of 20 kHz, and this "sweeping" motion is coordinated among many of the members of the group of signals.
> 6) The signals occur around the clock (i.e., 24 hours a day).
>
> I can send a 2.75 Mb JPEG file with SDR receiver screenshots (frequency spectrum and associated waterfall data) that illustrate this interference to any interested GCARC member.
>
> Due to the close proximity (12 miles) to Philadelphia International Airport, I wonder if these signals might be radar (e.g., A band radar)?  I attempted to contact the airport about these interfering signals, but have not yet received a reply.
>
> Thanks to anyone who might be able to help solve this mystery.
>
> David Wade (KD2NZS)
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