[opendtv] Re: Fcc Question
- From: "John Limpert" <john.a.limpert@xxxxxxxxx>
- To: opendtv@xxxxxxxxxxxxx
- Date: Thu, 21 Jun 2007 16:58:48 -0400
The first thing I'd do is compute the necessary dot clock.
70 * 25 * 80 * 60 = 8.4E6 Hz
You then need to multiply it by a fudge factor to allow time for sync
and retrace. As far as the total video bandwidth is concerned, that's
going to also depend on how much smearing of the video signal is
considered to be acceptable.
On 6/21/07, Larry Bloomfield <Larry@xxxxxxxxxxxxx> wrote:
Hi all:
I have a question for you. I have been studying the FCC element 8 for
radar and several of the questions have been making me crazy. One goes
like this
A shipboard raster scan radar has a CRT with the following
characteristics: 70 pixels per character, 80 characters per line, 25
lines per screen and it scans 60 screens per second.
What is the minimum required bandwidth for the electron beam control signal.
The answer is 12.6MHz, and I'll be dammed if I can figure out how they
came up wit this figure. I have searched the web and all they talk
about is pixels and refresh rates.
I know that there are 140,000 pixels on this screen or 2000 characters i
think.
Any ideas as to how it is calculated or where might I go to find out???
--
Larry Bloomfield - KA6UTC
1980 25th St. - Florence, OR 97439
(541) 902-2424 (My Everything Phone #)
WWW.Tech-Notes.TV
See you on the Tech-Notes Taste of NAB 2007 Road Show
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