Re: LF: Strange signal 500khz

[markusvester@aol.com]

Gary,

 

interesting - one of your family members seems to be switching channels rapidly ;-)

 

During my LORAN monitoring, I often saw a grid pattern which didn't average out in 5 minutes or longer integration times. It appeared only on certain chains, having group repetition intervals which were multiples of 40 (i.e. 0.8 ms).

 

The explanation turned out to be a weak carrier at 93.750 kHz (6x line scan) from my neighbour's TV. This became visible only when she was watching either "ZDF" which used to have their line rate sysnchronized to UTC, or "3sat" which showed a small variable slant due to geostationary satellite residual Doppler.

 

73 de Markus, DF6NM

-----Ursprüngliche Mitteilung-----
Von: g4wgt@tiscali.co.uk
An: rsgb_lf_group@blacksheep.org
Verschickt: Mi., 4.Okt.2006, 20:30
Thema: RE: LF: Strange signal 500khz

Hi Alan & LF,

I checked out the strange stepped signal on 500KHz & sure enough it is my
own TV set downstairs.

73

Gary - G4WGT.

-----Original Message-----
From: owner-rsgb_lf_group@blacksheep.org
[mailto:owner-rsgb_lf_group@blacksheep.org]On Behalf Of Alan Melia
Sent: 02 October 2006 14:51
To: rsgb_lf_group@blacksheep.org
Subject: Re: LF: Strange signal 500khz


Hi Tom 500kHz is 32 times the 15.625kHz line frequency for 50Hz framing TV
sets. That is why I suggested to the RSGB representative that we do not ask
for an allocation at 500 exactly !! I remember this as in the early days of
personal computers we used to generate TV line sync by dividing a 1MHz
oscillator by 64.

Cheers de Alan G3NYK

----- Original Message -----
From: <dl8aam@9a0tcp.ampr.org>
To: <rsgb_lf_group@blacksheep.org>
Sent: 02 October 2006 14:24
Subject: Re: LF: Strange signal 500khz


> Hi,
>
> I don't know if it's the same. I have on 500 kHz an unid signal from TV
sets.
> It's not only mine but also from the neighbourhood. I always know when
they
> went to bed ;-) First I thought if came via the AC net, but even when I
use
> batteries that 500 kHz TV signal is there. Even when I were on a
campground
> I was able to identify 2-3 TV sets from other campers. I don't know what
> exactly is responsible (inside the TV set system), but it came 100% from
them.
> Maybe that is also your "problem" ?
>
> 73, Tom - DL8AAM
>
>
>