TELECOM Digest OnLine - Sorted: Re: What happened to Channel 1?

Re: What happened to Channel 1?

Neal McLain (
Tue, 22 Mar 2005 21:09:02 -0600

I wrote:

> A few years later, we moved HBO to channel 2 (so we could sell
> HBO to hotels and motels), installed negative traps to secure
> it, .....

Whereupon Robert Bonomi <> wrote:

> What science can take away, science can put back. Those traps
> did _not_ *completely* eliminate the signal getting into the
> customer premises, they just made it so weak that a
> conventional TV set couldn't amplify it enough to make a decent
> picture. A decent high-gain single-channel pre-amp, on
> the other hand, installed 'in front of' the TV receiver, could
> do a surprisingly good job of resurrecting the 'killed' signal.
> <grin>

Except that the relevant parameter is noise figure, not gain. To the
extent that the preamp has a better (i.e., lower) noise figure than
the TV set's own tuner (and holding all other variables constant),
you'll get a decibel-for-decibel improvement.

But even a relatively low-gain preamp (say, ca 20 dB) will show
similar improvement if it has a similarly lower noise figure.

Neal McLain

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