I'm designing a radar receiver, whose block diagram is below:
When I compute power received from radar range equation, it varies between -90 dBm to -40 dBm depending on the object's location (60 to 6 meter).
After I downconvert frequency to 1-10 kHz range, the signal is still too weak so I'll need to amplify it once more so here's my question:
How much do I need to amplify the signal so that the input at ADC (say, 16-bit, Vref=1V) is 1 Vpp, not clipping and not too low so it's always properly detected?
I've used ADIsimRF and it looks like if I assume that I receive -90 dBm, I need to amplify the signal by 70 dB to get 200 mVpp, which means that if I receive -40 dBm, it will give me 54 Vpp.
Is there a way to anticipate how much power will I really be getting (say, 6 dBi patch antennas, radiated power is 12 dBm) or is there a way to know how much to amplify the signal?