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From: john@zygot.ati.com (John Higdon)
Newsgroups: sci.electronics
Subject: Re: Cable
Message-ID: <32651@zygot.ati.com>
Date: 7 Jun 91 00:31:53 GMT
References: <1991Jun3.044218.16908@milton.u.washington.edu> <1991Jun3.132526.67@cmkrnl.uucp>
Reply-To: john@zygot.ati.com (John Higdon)
Organization: Green Hills and Cows
Lines: 18

In article <1991Jun3.132526.67@cmkrnl.uucp> jeh@cmkrnl.uucp writes:

>For example, when a tv set is tuned to a particular channel, the local 
>oscillator in its tuner will be set to about 4.5 MHz higher (assuming 
>that tv tuners still work the way they used to, and that the IF is still 
>4.5 MHz).  

Not to pick nits, but let us at least get the numbers in the right
order of magnitude. TV IF frequencies are in the 40 to 50 MHz range,
not 4.5 Mhz. Hell, that is the same ball park of frequency that you are
trying to communicate (video= DC to 5 Mhz). What you probably meant was
that 4.5 Mhz is the offset between the video and audio carriers of a
broadcast television signal. 4.5 Mhz is known as "intercarrier", and 
there is a SOUND IF strip that terminates in an FM detector for the
audio tuned to that offset of 4.5 Mhz.
-- 
        John Higdon         |   P. O. Box 7648   |   +1 408 723 1395
    john@zygot.ati.com      | San Jose, CA 95150 |       M o o !