Re: Using an FM-Carrier for the Y [Luminance] Signal -- how to relieve the bandwidth issue?

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#126

From: John Evans
Date: Sat, 27 Oct 2007 17:06

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On Sat, 27 Oct 2007 01:45:25 -0700, "Green Xenon [Radium]"
<glucegen1@excite.com> wrote:

>Dave Platt wrote:
>
>> In article <46fc71d2$0$24285$4c368faf@roadrunner.com>,
>> Green Xenon [Radium] <glucegen1@excite.com> wrote:
>
>
>>>So there is no way to decrease how far the sidebands will go?
>
>
>> With FM?  Nope, not in the way you're hoping.  Modulate a carrier Fc
>> with a frequency Fm, and the first sidebands will be at Fc+Fm and
>> Fc-Fm, just as would be true with AM.  That's the narrowest you can
>> get.


Oh dear - what about the deviation?

The rule of thumb bandwidth required for FM (Carson's Rule) says the
bandwidth is given by

2x(peak deviation x  highest modulating frquency).

So a system with a maximum modulating sinusoidal frequency of 15khz
using a deviation of 75khz needs 180khz bandwidth minimum.

Note a pulse would require a far greater bandwidth.

http://www.fmsystems-inc.com/eng_fm.htm

http://en.wikipedia.org/wiki/Frequency_modulation





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From: John Evans <query@noreplyrequired.com>
Newsgroups: uk.tech.digital-tv,rec.video.production,uk.media.tv.misc,sci.electronics.components,uk.tech.broadcast,sci.electronics.misc,aus.radio.broadcast,ba.broadcast,alt.radio.broadcasting
Subject: Re: Using an FM-Carrier for the Y [Luminance] Signal -- how to relieve the bandwidth issue?
Date: Sat, 27 Oct 2007 18:06:46 +0100
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