Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Posting-Version: version B 2.10.1 6/24/83; site ttidcb.UUCP
Path: utzoo!watmath!clyde!burl!ulysses!gamma!epsilon!zeta!sabre!petrus!bellcore!decvax!mcnc!philabs!ttidca!ttidcb!speaker
From: speaker@ttidcb.UUCP (Kenneth Speaker)
Newsgroups: net.video
Subject: Re: HQ VHS
Message-ID: <607@ttidcb.UUCP>
Date: Fri, 3-Jan-86 12:16:57 EST
Article-I.D.: ttidcb.607
Posted: Fri Jan  3 12:16:57 1986
Date-Received: Sun, 5-Jan-86 01:35:35 EST
References: <14200002@hplsla.UUCP> <485@nicmad.UUCP> <596@ttidcb.UUCP> <486@nicmad.UUCP> <600@ttidcb.UUCP> <491@nicmad.UUCP>
Reply-To: speaker@ttidcb.UUCP (Kenneth Speaker)
Organization: Transaction Technology, Inc. (CitiCorp), Santa Monica
Lines: 34
Summary: 

In article <491@nicmad.UUCP> brown@nicmad.UUCP (Mr. Video) writes:
>In article <600@ttidcb.UUCP> speaker@ttidcb.UUCP (Kenneth Speaker) writes:
>>In article <486@nicmad.UUCP> brown@nicmad.UUCP (Mr. Video) writes:
>>>In article <596@ttidcb.UUCP> speaker@ttidcb.UUCP (Kenneth Speaker) writes:
>>>>In article <485@nicmad.UUCP> brown@nicmad.UUCP (Mr. Video) writes:
>
>[all kinds of talk about scanning at SP speed (VHS) on JVC decks.]
>
>Sorry to hear that your machine rolls the TV picture when fast scanning.
>After reading your point about your TV rolling, a thought came to mind,
>ie, does your TV have a vertical hold control?  If not, that may be where
>some of the problem lies.  I have noticed on tvs that do not have the 
>vertical hold, they tend to lose vertical sync when a video deck is
>scanned.  A deck that I had worked fine on my TV (w/ hold) and rolled
>on a Zenith tv, which doesn't have vertical hold.  Since fast scanning
>does cause some change in the vertical rate, some tvs lose vertical sync.
>

It isn't this.  At EP speed everything works as expected.  I have noticed
that on most non-top-of-the-line decks (beta and VHS) you get rocksteady
shuttle-scan/beta-scan at only one speed, like it is too difficult to 
synchronize the tape speed/head switching to switch properly.  Rather, just
run the tape at some speed and switch the heads when they loose contact
with the tape.  If the tape is not running at some integral multiple of 
frames (or fields maybe), the heads switch at some random location in a
field and the picture rolls up/down/left/right/pincushion distortion/
barrel distortion, and all sorts of mean nasty stuff.  It would "only"
require, I think, controlling the tape speed to be a stable multiple of
normal.  (Decks with knowledge:  Sony 900, NEC 739E (stable at both speeds)
Sony 400, Sanyo 7250, JVC 566 (stable only at low speed).

Oh well, I think this topic is now talked to death...

--Kne