Improving video detector output by correcting IF output response...

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himanshul

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Hi,
The following is a part of IF section of a television receiver...

As it is being visible that the output response of the IF section in superheterodyne receiver has a sharp slope which is necessary for correction of output response of video detector. It has been said that this sharp slope is necessary so that it could provide an attenuation to the lower frequencies near the picture carrier so that they should not gets an extra amplification.

So my query is that how by modifying the output response of the IF section ( sharp slope) prevents lower frequency to gets amplified at the output of the video detector...??
 

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You are talking about old fashioned analog video that we have not used since digital high definition video replaced it here a number of years ago.
 

Audioguru said:
You are talking about old fashioned analog video that we have not used since digital high definition video replaced it here a number of years ago.
Click to expand...

Was it even worth spending the time writing that to the person asking? There is no answer provided by your reply. Just something that smells of trolling. Come on Audioguru, I'll bet you may even know the actual reason.

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himanshul said:
So my query is that how by modifying the output response of the IF section ( sharp slope) prevents lower frequency to gets amplified at the output of the video detector...??
Click to expand...

Hi,

I don't know. Maybe it's similar to hysteresis in comparators and Schmitt triggers, probably not. Maybe the wider the frequency range, the more distorted the signal, so that slope has to be kept in a tight frequency band? Maybe it's related to stability like op amps, doubt it.
 

Since Analog AM generates dual sidebands, in order to maximize BW of video, it is broadcast with single sideband suppressed {Vestigial} and received by the same method. so the upper sideband is suppressed which is closest to next channel. The 2nd purpose is to attenuate baseband low frequency video at the picture carrier frequency representing 0Hz after it is mixed with IF LO for difference frequency.
 

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