Sure sounds like TV set radiation to me. Color subcarrier is 3,579.545
kcs. Hor rate is 15,734.26 kcs.with lower sidebands at +/- 60 hz from each
15 kc burst.
Larry W3LW
At 07:00 PM 4/12/03 +0000, you wrote:
A few days ago, a new interference appeared on 80m. It consists of rough,
60kHz modulated carriers, spaced at 15.7325 kHz intervals. At first I
thought it might be a touch lamp, but the carrier frequencies are
extremely stable, despite the rough sounding modulation. The strongest
carrier appears to be at 3579.55 kHz. Carriers are clearly audible from
3406.48 kHz to 3736.9 kHz, with vestiges detected above 4 mHz. The sound
of the modulation changes every few seconds, and the signal strength
varies as the modulation changes. At its strongest point it is about 10
dB above S9. I get the strongest signal on the 160m. beverage, but it is
audible on the 10m. ground plane and indoor loop. The signal is weakest
on the transmitting dipole.
I measured the frequencies using a DDS vfo with 1 Hz
resolution. Individual frequencies may be inaccurate due to the
difficulty in finding zero-beat in the presence of the rough 60Hz
modulation, but the spacing of the signals was determined by averaging the
difference in measured frequency between adjacent carriers throughout the
band. At the time, the DDS vfo was zero-beat with WWV at 10 mHz.
Readings were taken at the following frequencies:
3500.88
3516.662
3532.25
3548.15
3563.69
3579.55
3595.29
3611.02
3626.74
3642 (approx)
3698 (approx)
3674 (approx)
3690 (approx)
3706 (approx)
3721 (approx)
3736.9
I am hoping someone might save me from having to re-invent the wheel in
chasing down this interference, by identifying a probable source based on
the above data.
73 de K4KYV
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