[GCARC] Signals Interference Question

[David Wade]

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)