up/down conversion of FSK or PSK signals

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KevinHowJones

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Please forgive if this is not the appropriate category or forum to post this question on. I looked through the list carefully and this seemed the most fitting as it is a question about radio theory. If this is a problem, please advise me.

My question is, if one were to take a signal that has been modulated using FSK (frequency shift keying) or PSK (phase shift keying) and shift the frequency of that entire modulated wave using an up/down converter, then shifted it back to the original center frequency, would the information remain intact.

Here's an example:

A radio receives a 2.4 GHz wifi signal. It shifts the frequency down by 1.5 GHz by an up/down converter, then transmits the resulting 900 MHz signal to another radio. The second radio receives the 900 MHz signal, then shifts the frequency back up to 2.4 GHz. Would that signal resemble the original 2.4 GHz signal?
 

RFI-EMI-GUY

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Dec 22, 2013
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My gut feeling is that whatever mixer and LO scheme you use, if you follow it with an identical LO scheme, the result will be same as the original.

There is simple math in the attached , you can do a simple "two tone" calculation to check if the side band products are reversed.





 
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