RadioBanter - I want to see SHF FM video signals.

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I want to see SHF FM video signals.

Hi:

Video signals for NTSC, PAL, and SECAM television are transmitted on
AM carriers.

My question is, let's say I have a television set that is capable of
receiving and demodulating FM video carrier waves. What would I see on
the TV? I am aware that no company uses FM video. Would I see sawtooth-
like patterns on the screen due to frequency-modulated electric fields
present in the environment?

I'd really like buy a TV with a FM-video receiver; I want to find out
what FM-video disturbances in the SHF [Super High Frequency ]
frequency-range look like. I am sick n' tired of AM video.

AM should be used for analog audio. FM should be used for digital
video.

Regards,

Radium

I want to see your head on a pike.

Radium wrote:

Hi:

I am annoying troll who loves to **** people off!

Radium

Go away, Idiot!

--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

I want to see SHF FM video signals.

Radium,

Some television is actually transmitted using FM modulation schemes, but not
for commercial broadcasting. Examples of FM TV are ham/amateur ATV/SSTV,
unlicensed 2.4 GHz surveillance links, and a number of point to point and
studio to transmitter systems. FM signaling provides benefits in noise
immunity and also permits better channel re-use, since it exploits one of
the best features of FM called "the FM capture effect", wherein nearly equal
strength signals which would otherwise interfere in AM systems will cause an
FM receiver to "capture" only the stronger signal and ignore the weaker,
even if differences of 1 dB of signal strength exists.

There is no specific answer to what you would see as far as video patterns,
and there is no reason whatsoever to expect to see sawtooth waveforms in
particular. The demodulated signal from FM will conform to the spectral
changes just as the demodulated signal from an AM detector would conform to
amplitude changes, and random noise would be considered "snow" in either
case. Unless a transmitted signal with a frequency ramp (sometimes called "a
chirp") is present, the video would have no sawtooth. A Doppler radar, for
example, could generate such a waveform, since some radars create chirped /
swept signals. The video scan rate(s) would additionally need to be in the
range of the chirp rate to create the appearance of a sawtooth.

FM disturbances in the SHF band are likely to be man-made and not
atmospheric, and thus only "viewable" if the "FM Video Receiver" you
envision had a demodulator / discriminator whose bandwidth was tailored to a
specific transmitted waveform, and even then only if sweep rates were
suitable. Absent a man-made transmitter, the SHF environment is mostly
thermal noise (both circuit and atmospheric) and only a radio telescope or
other enormous aperture / antenna will see beyond the atmosphere.

The choice of using AM versus FM is really way more complicated than "AM for
audio" or "FM for digital video". When designing communication systems of
any type, the engineer is faced with balancing many issues, and the channel,
media, noise environment, interference sources, power budget, multipath,
complexity, and cost are only a few of the considerations involved. A highly
reliable cable modem to transmit fast digital content may indeed by phase
modulated with an amplitude trellis; a secure and interference resistant
link may use spread-spectrum frequency hopping AM for digital signaling; and
FM winds up being used heavily in many voice communication systems mostly
because the capture effect reduces co-channel interference.

The closest I can suggest to what you might enjoy exploring would be a
satellite dish and receiver designed for L band which will see and decode
some broadcasting which is unprotected / unencrypted. It gets you into the
range of SHF, has true TV signaling for public viewing, and is a hobbyist
activity with others involved.

Smarty

"Radium" wrote in message
ups.com...
Hi:

Video signals for NTSC, PAL, and SECAM television are transmitted on
AM carriers.

My question is, let's say I have a television set that is capable of
receiving and demodulating FM video carrier waves. What would I see on
the TV? I am aware that no company uses FM video. Would I see sawtooth-
like patterns on the screen due to frequency-modulated electric fields
present in the environment?

I'd really like buy a TV with a FM-video receiver; I want to find out
what FM-video disturbances in the SHF [Super High Frequency ]
frequency-range look like. I am sick n' tired of AM video.

AM should be used for analog audio. FM should be used for digital
video.

Regards,

Radium

I want to see SHF FM video signals.

In message . com,
Radium writes
Hi:

Video signals for NTSC, PAL, and SECAM television are transmitted on
AM carriers.

My question is, let's say I have a television set that is capable of
receiving and demodulating FM video carrier waves.
I've got one (or at least the demodulator part of it). It's called a
'Grundig Satellite Receiver GSR2'. It receives German TV. I use it to
watch the German version of the Teletubbies. [Talented chaps, those
Teletubbies, speaking German without a trace of an English accent.
However, 'Eh - Oh' in German is still 'Eh - Oh'].

I also sometimes watch that English 'dinner' programme which several
German channels transmit on New Years' Eve.

Radio amateurs also often use FM to transmit TV signals. With a little
ingenuity (and maybe some modifications), you can actually use satellite
TV receivers to watch these transmissions.

What would I see on
the TV? I am aware that no company uses FM video. Would I see sawtooth-
like patterns on the screen due to frequency-modulated electric fields
present in the environment?
No. If the signal is demodulated correctly, you see normal pictures,
usually of very good quality (and in colour too, if you have a colour TV
set), created by waveforms called 'video'. Potentially, on an AM TV set,
you might be able to get some sort of poor quality picture if you could
slope-detect the FM TV signal. However, the deviation of normal
satellite signal is much too great, and I doubt if you would get
anything usable (just a lot of squiggles on the screen, like you
suggest).

I'd really like buy a TV with a FM-video receiver; I want to find out
what FM-video disturbances in the SHF [Super High Frequency ]
frequency-range look like. I am sick n' tired of AM video.
On a spectrum analyser, you see a wide FM signal, where the deviation is
caused by the 'video disturbances'. This is normal.

AM should be used for analog audio. FM should be used for digital
video.
It can be (eg where the instantaneous deviation or frequency corresponds
to the value of a digit). However, for digital signals, the boffins have
devised all sorts of clever systems of modulation. Some of these can be
thought of simplistically as a mixture of AM and FM, but some are really
complicated. These are designed to be much more efficient than 'simple'
AM or FM.

Ian.
--

I want to see your head on a pike.

Walt Davidson wrote:

What did you do to serve your country?

Why? Are you thinking of enlisting? My MOS was Broadcast Engineer.

Bomb Iraq?

No, I was too old, and in the wrong branch. Dropping old TV
transmitters from planes doesn't do much damage, anyway.

--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

I want to see your head on a pike.

Walt Davidson wrote:

In fairness, it wasn't really your fault. If Blair had been our Prime
Minister at the time (perish the thought!), we would probably have
been implicated in it as well!

73 de G3NYY

Well, at least you're getting rid of "Lap-Dog" Blair. We should be so
lucky with Bush/Cheney.

I want to see SHF FM video signals.

On Jun 7, 11:05 am, "Gordon Hudson" wrote:
"Mike Gathergood, G4KFK" wrote in glegroups.com...

On 7 Jun, 08:43, Ian Jackson
wrote:
I've got one (or at least the demodulator part of it). It's called a
'Grundig Satellite Receiver GSR2'. It receives German TV. I use it to
watch the German version of the Teletubbies. [Talented chaps, those
Teletubbies, speaking German without a trace of an English accent.
However, 'Eh - Oh' in German is still 'Eh - Oh'].

So what's German for "Tinky-winky fallen in da tubby-tussard"?

Tinky-winky ist in den fetten Vanillepudding gefallen.

Thanks Gordon, very useful. Now I need to figure out how to bring it
into conversation :-)

I want to see SHF FM video signals.

I generally treat all questions as sincere unless they are conspicuously
juvenile or inflammatory. I am not aware of the trolling reputation /
history of this particular individual, but I fully accept the possibility
that the inquiry was bogus. It is sometimes hard to separate sincere but
poorly stated legitimate questions from those which are deliberately
misguided and troll. Let's see how Radium replies, if at all.

Smarty

"Richard Crowley" wrote in message
...
"Smarty" wrote ...
Radium,

You've been trolled by the latest king of trolls.

I want to see your head on a pike.

"Walt Davidson" wrote in message
...
On Thu, 07 Jun 2007 05:22:13 GMT, "Michael A. Terrell"
wrote:

Service to my country? Been there, Done that, and I've got my DD214 to
prove it.

What did you do to serve your country? Bomb Iraq?

--
Walt Davidson Email: g3nyy @despammed.com
He/she voted for Bush.