Article View: uk.tech.digital-tv
Article #164Re: Using an FM-Carrier for the Y [Luminance] Signal -- how to relieve the bandwidth issue?
From: Brendan Gillatt
Date: Sun, 23 Sep 2007 22:02
Date: Sun, 23 Sep 2007 22:02
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Green Xenon [Radium] wrote:
> Hi:
>
> One major reason the luminance signals of television are broadcasted on
> an AM-carrier instead of FM is because FM requires large amounts of
> bandwidth. Is there a way to use FM video without hogging so much
> bandwidth?
>
> Quotes from
> http://groups.google.com/group/sci.electronics.basics/msg/0c013cf5371da8dc?hl=en&
> :
>
>>Multiple-level quadrature modulation,
>>"constellation modulation",
>>is most common for packing
>>lots of bits per Hz of bandwidth.
>>The more you pack,
>>the better the s/n ratio has to be.
>
>>http://en.wikipedia.org/wiki/Quadrature_amplitude_modulation
>
>>http://en.wikipedia.org/wiki/Constellation_diagram
>
> Does this mean that Quadrature Modulation and Constellation Modulation
> can -- at least in theory -- be applied to FM video so that excessive
> bandwidth is not needed? If so, then what would be the minimum
> radio-frequency required to transmit the video signal?
>
>
> Thanks,
>
> Radium
Okay now you're actualy irritating me quite a LOT.
Please, do yourself a favour: buy an Amazon book voucher and shut up.
- --
Brendan Gillatt
brendan {at} brendangillatt {dot} co {dot} uk
http://www.brendangillatt.co.uk
PGP Key: http://pgp.mit.edu:11371/pks/lookup?op=get&search=0xBACD7433
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