question about HDSDR

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question about HDSDR

Post by reble » Thu Jun 11, 2020 9:04 pm

In HDSDR there is 2 frequency bars. 1 is marked "LO a" the other is marked "tune". Why is that?
Also when I click on "bandwidth" it opens up the "sampling rate" window?

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Re: question about HDSDR

Post by rtlsdrblog » Fri Jun 12, 2020 2:59 am

LO is the local oscillator frequency. It's what the tuner in the SDR is actually physically tuning to, and that will be the center of your spectrum display. You can then tune digitally within the SDRs bandwidth without needing to change the LO.

Bandwidth and sample rate are intertwined. On the RTL-SDR 2MSPS = 2MHz bandwidth.

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Re: question about HDSDR

Post by radiolistener » Wed Jun 24, 2020 5:08 pm

LO is the actual tuning frequency for IF (intermediate frequency). The second frequency control allows to tune on desired frequency within IF bandwidth around selected LO.

LO frequency lets tuner know which frequency you're want to get within IF bandwidth. The tuner shift this frequency to the 0 Hz, so it appears in the center of IF bandwidth (in the center of your IF spectrum display).

There are two sample rate - for IF and for audio output. IF sample rate specify IF bandwidth.
Audio sample rate specify audio output bandwidth.

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