Rebroadcast from TV IF?

[L. Fiar]

"Jan Panteltje" <pNaonStpealmtje@yahoo.com> wrote in message
news:c7ln6k$jtd$1@news.epidc.co.kr...

Once I lived close to a ch 4 TV transmitter (that is around 67MHz), and
got good video from a xtal diode and one tuned circuit.
No need for any LO.

It's 22 years since we in the UK had VHF TV. The last transmitter, in
Hertfordshire, was switched off in 1982.

I believe that there are still some high power transmitters on UHF. Last I
heard, Crystal Palace and Sandy Heath were pumping out 1000KW each.
I hear that the sale of microwave ovens and sun beds are low in those
areas... nobody needs them. I'm not saying that all that UHF RF is bad, but
children there are being born with square eyes

 

[Paul Burridge]

On Tue, 11 May 2004 07:59:35 +0100, "L. Fiar" <_@_._> wrote:

For UK TV, there are sound, vision and chroma IFs.

The transmitter frequencies are between 471MHz and 853MHz.
From these, the TV uses two IFs:
Vision = 39.5MHz
Sound = 33.5MHz
The two create the final sound IF:
6MHz.

Chroma (colour) information uses a subcarrier:
Chroma = 4.43MHz

Vision is amplitude modulated, sound is frequency modulated, chroma uses
suppressed carrier sideband.

Thanks. Looks like a thoroughly comprehensive answer - a rarity these
days on this group.
--

"What is now proved was once only imagin'd." - William Blake, 1793.

 

[John Gillham]

Don't forget that those figures are EIRP. This refers to the power from an
isotropic radiator that would give the same signal at your location, so, if
the beam is flat-topped, the EIRP will be about double that actual power.
If the beam only covers 45 degrees in azimuth, and is flat topped there will
be about a facto of 16 between EIRP and actual power.

Having said that, our local TV relay blots out my car radio when I drive
past it, so the signal is quite high close up !

"L. Fiar" <_@_._> wrote in message news:40a07b93.1@entanet...

"Jan Panteltje" <pNaonStpealmtje@yahoo.com> wrote in message
news:c7ln6k$jtd$1@news.epidc.co.kr...

Once I lived close to a ch 4 TV transmitter (that is around 67MHz), and
got good video from a xtal diode and one tuned circuit.
No need for any LO.

It's 22 years since we in the UK had VHF TV. The last transmitter, in
Hertfordshire, was switched off in 1982.

I believe that there are still some high power transmitters on UHF. Last I
heard, Crystal Palace and Sandy Heath were pumping out 1000KW each.
I hear that the sale of microwave ovens and sun beds are low in those
areas... nobody needs them. I'm not saying that all that UHF RF is bad,
but
children there are being born with square eyes