Pulse Doppler Radar: time delay in down conversion My understanding of Pulse Doppler Radar is the system measures Time Of Flight for the pulse.

My confusion is that during the down conversion process prior to ADC the lowpass filter causes some time delay in addition to the time of flight. In principle the delay should be known beforehand but I'm sure it's not exact and in general the delay is not completely constant even among the band of interest. 

How is this delay dealt with?
The delay is dealt with by knowing it. It is calculated and measured and any residual error is minuscule compared with any other uncertainty.

It’s dealt with design and calibration.