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G8MNY  > ATV      10.12.18 11:00l 51 Lines 1971 Bytes #4 (0) @ WW
BID : 48801_GB7CIP
Read: GUEST
Subj: Hearing the ATV Buzz
Path: ED1ZAC<ED1ZAC<IZ3LSV<IK6ZDE<I0OJJ<GB7CIP
Sent: 181210/0952Z @:GB7CIP.#32.GBR.EURO #:48801 [Caterham Surrey GBR]

>From g8mny%gb7cip.#32.gbr.euro@i0ojj.ampr.org Mon Dec 10 10:53:35 2018
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Message-Id: <48801_GB7CIP@gb7cip.bbs>
>From: g8mny@gb7cip.#32.gbr.euro
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From: G8MNY@GB7CIP.#32.GBR.EURO
To  : ATV@WW

By G8MNY                                (New Jan 09)
(8 Bit ASCII graphics use code page 437 or 850, Terminal Font)

Originally taken from my UK BATC's CQTV 163 "Tuning 70" of 8/93...

Trying to beam up on weak fast scan ATV signals with tight beams on a TV mon is
not that easy. Here is a way that greatly helps when you don't quiet know the
beam heading (e.g. /P). It is of no use for digital TV modes!

Take the recovered video and feed it to the TV audio stages (decent size LS or
HiFi headphones!) after some CR filtering to remove the line timebase & treble
noise.

FM SOUND >컴컴컴컴컴컴컴컴컴컴o  FM
                        SWITCH \o컴컴컴컴>AF AMP 
  VIDEO  >컴6k8컴쩡6k8컴컫컴훟  BUZZ     Volume?
                               BEAM UP
                === u1   === u1
         ________________________

This works by listening to the 50Hz buzz, as your ear/brain is a few dB better 
than the TV sync stages. It also works on 10GHz/1255MHz FM TV just as well as
AM mode.

The extra 6k8 load on the 75ohm video line has no effect.
    _
Tx _picture         Rx 같같같같같같같같     As        /~\ 
___ Info   |_ _        같같굅같같같굅같     AF _     /   '._._./\_
 斌같같같같같 斌같      굅굇굇굇굇굇굇갚         \   /              \   /
                        갚같같같같같같굅          ~-~   50Hz BUZZ    ~-~
 <--- 20mS -->          같같같같같같같같캮oise

This can work on any band including 70cms, although on AM a narrow band SSB/FM
phone Rx may even better if the exact carrier frequency is known!


Why don't U send an interesting bul?

73 De John, G8MNY @ GB7CIP



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