modified 11 years ago

Heterodyning shake it

00:55:33

@thebugger, would this be digital heterodyning?

published 11 years ago

hamilton1300

11 years ago

You have to give it a shake to get both sides going

yeshaoze

11 years ago

有人会说中文吗？

yeshaoze

11 years ago

都是英文看不懂啊

thebugger

11 years ago

I dont really know if this technique is used in the digital domain. I know it's used in radio processing but that's analog. It sorta shifts the frequency into a new frequency that can be more easily demodulated.

hamilton1300

11 years ago

so what would make the new frequency easier to demodulate?

thebugger

11 years ago

Well by shifting the frequency to a lower one has many advantages. First of all rf gain at 40ghz is costy while at 1ghz its cheaper. 2nd more standard components are used in the demodulation process and in the whole circuit also. 3rd filtering the harmonics at IF (intermediate frequency) is way simpler than in RF (radio frequency). Superheterodyne receivers are a huge improvement that lowers the overall cost and simplicity of the receiver.

hamilton1300

11 years ago

I see, so the goal is to lower the frequency but retain the information. So if we wanted to apply this to fm broadcast radio, would we need to modulate both oscillators our could we modulate just one of them and use the resultant Freq. Shift?

thebugger

11 years ago

The modulated signal is 1. Then you split it in a higher frequency one and a lower frequency one. Typically one is filtered out but I guess you could retain it and use it for something.

thebugger

11 years ago

Plus heterodyning is used in a receiver equipment. When the rf frequency signal is received it is split into 2 frequencies F1+F2 and F1-F2. Since we need to lower the original frequency we simply filter out the upper frequency (RF) and leave the lower one (IF). So not much talk about modulation but rather demodulation instead. Typically it doesn't affect the audio quality but carries certain advantages which I've already listed.

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