What is the difference between IF data and IQ data? How we can read IF data in SDR?
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.