[SOLVED] digital frequency browsing

[dxtr]

hey everyone
i have this question in my mind
in analog receiver to browse frequencys we just play on the L or C value ( f = 1/root(LxC) )
but in digital receiver how do you do that ?

 

[sky_123]

Depends on what you mean by digital receiver.
If you mean digital tuning (i.e. a radio with maybe an LCD display and push-buttons), that uses a PLL, so technically it is
still varying a C value, but by means of a varactor.
If you mean a software radio type architecture (currently not usually the type of radio you can buy at your local store)
again there are different ways. For example, a conventional front end and mixer may be used (i.e. still relying on a PLL or
maybe DDS or some combination), and then the IF may be sampled with a DAC, and then it's down to software to perform
the demodulation. Other types may directly take the RF input (not mixed to an IF) and software (DSP) filters are used to
select the channel.

 

[ajex]

In the case of 1st that sky_123 mentioned above is using a varactor diode for changing the C value by varying the voltage. so no need to use mechanical system for changing the C value. (like tuning capacitor)
But in digital transmission, Its also use a RF receiver to revive signals. in this case also using above method and difference is transmission data type is digital values.

(This answer is according to my knowledge, but I don't know it's 100% correct or not)
and sorry for my bad English..

 

[dxtr]

thank you guys that was very helpful