How to convert 1 frequency to a lower frequency?

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Main Question or Discussion Point

could you describe the hardware needed to convert 5.8 gigahertz to 100 megahertz?
 

Answers and Replies

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i mean could you describe the hardware needed to convert a radio signal at 5.8 gigahertz to a radio signal at 100 megahertz? the hardware receives a radio signal at 5.8 gigahertz and retransmits it at 100 megahertz.
 
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Receiver 5.8 Ghz, Digital data recorder, Transmitter 100 Mhz
 
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but, how does it convert the higher frequency radio signal to the lower frequency radio signal?
 
tech99
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The usual method is to mix the 5.8 GHz with a locally generated CW signal at 5.7 or 5.9 Ghz. This produces a beating action and creates outputs at sum and difference frequencies. We filter off the wanted one at 100MHz and amplify it to the desired power.
The process is called heterodyne action, and the mixer must be a non linear device, such as a square law diode. We usually amplify the 5.8GHz a little before the mixer in order to overcome mixer losses and noise. The circuit producing the CW signal for the mixer is called a local oscillator.
 
tech99
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Yes, the alternative is to demodulate the 5.8GHz signal and then re-modulate the information on to a 100MHz carrier.
 
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Depending on the type of signal or data you plan on sending you may have buffering issues. Keep in mind data rate is basically dependent on carrier frequency, well, data rate is dependent on bandwidth, but the bandwidth cannot be higher than the carrier, so carrier freq puts an upper limit on data rate. The 5.8GHz would have a much higher data rate potential than the 100MHz, just something to be aware of.
 
sophiecentaur
Science Advisor
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could you describe the hardware needed to convert 5.8 gigahertz to 100 megahertz?
Here's another wide open question from you. What have you actually read about this? Search Google for frequency mixing and heterodyne circuits and ask a question about something you have actually found out on your own.
 

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