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- Path: sparky!uunet!caen!rphroy!link.ph.gmr.com!vbreault
- From: vbreault@rinhp750.gmr.com (Val Breault)
- Newsgroups: sci.electronics
- Subject: Re: Cable TV Tech Question
- Message-ID: <VBREAULT.92Nov9164900@rinhp750.gmr.com>
- Date: 9 Nov 92 21:49:00 GMT
- References: <3NOV199209442919@utrcv1> <720883631snx@nlbbs.UUCP>
- <1992Nov5.122636.5499@hemlock.cray.com>
- <1992Nov5.181038.17264@doug.cae.wisc.edu>
- <lfti4mINNlfu@jethro.Corp.Sun.COM>
- Sender: news@rphroy.ph.gmr.com
- Organization: General Motors Research Labs
- Lines: 50
- Nntp-Posting-Host: rinhp750.gmr.com
- In-reply-to: acm@Sun.COM's message of 9 Nov 92 20:22:46 GMT
-
- In article <lfti4mINNlfu@jethro.Corp.Sun.COM> acm@Sun.COM (Andrew MacRae) writes:
- I split the cable after the in-line filter that unscrambles the Disney
- channel and ran a length ~25 ft upstairs. There I feed it into a
- distribution amplifier and from that to two TVs (one about 20 ft, the
- other about 30 ft).
-
- Everything is fine *except* that I don't get any thing on channels above
- 13. I checked the amp and it is supposed to amplify VHF, UHF, and FM.
- The splitters are supposed to split those as well. I tried adding yet
- another amplifier (again, one that amplifies VHF, UHF, and FM) downstairs
- right after the split, but it didn't make a difference.
-
- Anyone have a suggestion or two?
-
- Andrew MacRae
-
- Although the channels on your television are numbered in smooth
- increments the frequencies that they select are not. The television
- channel allocations are in at least three (four?) bands of frequencies
- with other services occupying the space between them. There is a large
- gap between channel 6 and 7 and another, larger, gap between 13 and 14.
-
- Channels 14 and up are in the Ultra High Frequency (UHF) band. Those
- frequencies do not lend themselves to wide distribution via cable.
- Your cable provider cannot and therefore does not send programming
- via UHF frequencies.
-
- "But" you say "my cable converter box tunes channel 14 just fine."
-
- Aha! Here's the confusion... Broadcast channel 14 is NOT the same
- as cable channel 14. They are at different frequencies. The
- broadcast channel 14 is a UHF frequency but cable channel 14 is
- a VHF frequency.
-
- Actually, since the cable system is a closed system, your cable provider
- is free to use any frequencies they want to use. Even frequencies
- that are allocated to other services. I can't find my list of
- cable television frequencies, but I wouldn't be surprised to find
- that cable channel 14 and the next half dozen or so were cable-cast
- on the frequencies that lie between television channels 6 and 7.
-
- -val-
- --
-
- Val Breault - GM Research - vbreault@gmr.com - N8OEF
- Instrumentation dept., 30500 Mound Rd., Warren, MI 48090-9055
- The opinions expressed by the author do not necessarily reflect
- those of GMR or those of the General Motors Corporation.
-
-
-