RF receiver design - estimate received power

Question

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?

Answer 1

The dynamic range of the signal is what it is and you cannot know beforehand if that signal is going to suddenly rise. You amplifiers and ADC have to cope with that dynamic range but often I've seen non-linear gain amplifiers used to reduce the dynamic range. ADI make a log amp that may be useful: -