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Posted by Green Xenon [Radium] on 10/30/07 01:13
Green Xenon [Radium] wrote:
> Paul Martin wrote:
>
>> In article <ujr6i3dolk1qjon2ij5tta8aip26tff9qa@4ax.com>,
>> John Evans wrote:
>>
>>
>>> 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).
>
>
> What is peak deviation measured in? Hz?
>
>>
>>> 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.
>
>
> Require a far greater bandwidth compared to what? A sine wave of the
> same frequency and amplitude?
>
>>
>> Depends on the type of pulse. A wavelet might be about the same.
>>
>
> Are you talking about the pulses [bauds] of QAM signals?
>
> Quotes from
> http://www.howstuffworks.com/framed.htm?parent=modem.htm&url=http://www.physics.udel.edu/wwwusers/watson/student_projects/scen167/thosguys/index.html
> :
>
> "The carrier signal is characterized by the number of signal intervals,
> or pulses, that are transmitted per second. Each pulse is called a baud."
In the original post of the "Using an FM-Carrier for the Y [Luminance]
Signal -- how to relieve the bandwidth issue?" I was describing
converting the luminance signal to QAM and then broadcasting the QAM
video on a ULF [300 Hz] FM carrier in which the QAM uses
1-symbol-per-second and a sufficient amounts of bits-per-symbol to
represent the video.
Unfortunately for me, it is not possible to do this.
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