Path: utzoo!mnetor!uunet!seismo!sundc!pitstop!sun!decwrl!decvax!ucbvax!pasteur!ames!ptsfa!ihnp4!alberta!calgary!amc-vlsi!dale
From: dale@amc-vlsi.UUCP (Dale Wlasitz)
Newsgroups: sci.electronics
Subject: What causes this?
Message-ID: <438@amc-vlsi.UUCP>
Date: 26 Feb 88 23:24:26 GMT
Organization: Alberta Microelectronic Centre, Calgary, AB.
Lines: 27


>......the microwave link looses line of site and the picture breaks up.
>This has happened during the ice skating which I presume uses cameras
>with cables. What happens is that a few frames seem to be lost.
>Someone will be skating along and all of a sudden mysteriously is
>a few feet from where they were last.......


	I have not seen this problem myself, however your
description leads me to believe that the source is begin fed
through a digital scan converter or frame storage unit. These
devices are capable of storing entire frames. When the source
has been identified as unacceptable by the micro controller
they fill that particular frame from the image in memory. If this
continues longer than one or two frames the human eye begins to
pick up on this.

	These frame store units evolved from the line storage
units used to "fill" in lines which had drop-outs from the play
back of video tape. The particular line being scanned would be
passed through a delay line to enable the system to detect any
drop-outs. If any drop-outs existed the previous good line would
be used as a filler. The image appears to be quite good actually
.....until you find a tape with a crease in it.


Dale K. Wlasitz