[opendtv] Re: Fox stations disappear ... strange reason

Sounds like tropospheric ducting and good, old-fashioned 'non-working' 8-VSB
coming through from afar.  You should be able to find the station on the
FCC's web site; it was behind the channel 26 Fox signal.

John Willkie

-----Mensaje original-----
De: opendtv-bounce@xxxxxxxxxxxxx [mailto:opendtv-bounce@xxxxxxxxxxxxx] En
nombre de Doug McDonald
Enviado el: Wednesday, November 21, 2007 8:47 AM
Para: opendtv@xxxxxxxxxxxxx
Asunto: [opendtv] Fox stations disappear ... strange reason

Last night I could not get any of our three Fox TV stations.

We were having a cold front come in from the west. One station
is 68 mile west, 1 MW, 1300 foot tower. One is 45 miles NW,
1 MW, 800 foot tower, over a small hill. One is 23 miles east,
300 kW, 800 foot tower, over a small hill. All are usually
receivable with small (3-6 dB) signal margin.

I have a permanently installed spectrum analyzer.

Last night the two westerly stations were too weak, apparently due
to the signal being less-than-usually bent down by atmospheric
refraction.

The easterly one was a bit (3 db) higher than normal. BUT ...
about 1.5 MHz below the top of the channel was an interfering
apparently CW signal. It was about 6 dB higher than the ATSC
carrier. I could not tell if it were modulated; even at 30 kHZ BW it
seemed to be pretty much CW, at 3 kHZ it was too noisy to tell.

WTF????? !@$@#$^#^????????????

What is a CW carrier doing at that frequency? This is Ch. 26. There
is a digital station on 25 which is 120 miles east of us and
sometimes comes in, it was in nicely last night, but unreceiveable
because of a co-channel ordinary NTSC.

But the interference on Fox 26 was NOT NTSC! What was it? I worried
about harmonics in my preamp, but the interference was
there with the antenna directly into the spectrum analyzer.

Doug McDonald
 


 
 
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