0
\$\begingroup\$

How to read IF data in GNU SDR?

As i had tried a lot to read IF data in SDR but it can be readable in MATLAB but not in SDR..

\$\endgroup\$
  • 1
    \$\begingroup\$ You mean GNU Radio when you say "GNU SDR", right? \$\endgroup\$ – Marcus Müller Apr 16 '18 at 12:56
  • 1
    \$\begingroup\$ And is IF intermediate frequency? \$\endgroup\$ – nidhin Apr 16 '18 at 13:40
  • \$\begingroup\$ GNU SDR means SDR kit is used with GNU radio and IF means intermediate frequency ... \$\endgroup\$ – user185950 Apr 19 '18 at 5:06
1
\$\begingroup\$

IF data refers to real-valued data sampled from an intermediate frequency, while IQ data is complex-valued and has been downmixed to a zero IF.

You need to know the IF center frequency, then you can convert one to the other by mixing with a complex sine.

It is rare to work with ADC data from the IF unless you are building a superheterodyne receiver yourself, because you need to know the quantization error of the LO that was used to downmix this data -- normally, this is a VCO controlled by a DAC, so it can be controlled only in discrete steps depending on the DAC resolution. The error introduced here needs to be corrected subsequently by shifting the frequency, and typical implementations then shift it all the way down to zero IF and give you IQ data.

\$\endgroup\$
  • \$\begingroup\$ Can i read the IF data by GNU radio for SDR based implementation \$\endgroup\$ – user185950 Apr 19 '18 at 5:08
  • \$\begingroup\$ That depends on what kind of SDR you have. If it's direct conversion (likely), then the intermediate frequency is zero, and the IQ data is the IF data. \$\endgroup\$ – Simon Richter Apr 19 '18 at 13:21

Not the answer you're looking for? Browse other questions tagged or ask your own question.