#### Maitry07

##### Advanced Member level 4

I am using high speed data converter , in which there is an inbuilt RF-ADC along with DDC. which can directly digitize RF input and generate I and Q samples accordingly at DC.

Below is the example.

RF frequency=35 MHz, NCO frequency =34 MHz, DDC output = I and Q samples at 1 MHz.

Now I am capturing these I and Q samples in signed decimal format. and stored it in the excel.

My RF input power: -25 dBm

DDC output I and Q sample example when my RF input is -25 dBm

I_sample (signed decimal value) = 1785

Q_sample (Signed decimal value) = 687

Pdbm = 10log(I^2+Q^2) = 65.6 dBm

So, is there any calculation I am missing? PdBm should come -25 dBm. My DDC output is in the FIX16_0 format, from which I have taken the signed decimal values. could you please guide on this?

Is there any requirement to scale down the I and Q samples by fixed scaling factor to get the correct pdBm result?