The radar transmitter generates short RF pulses of high power.
The time measurement for distance determination begins with the rising edge of the transmit pulse.
The two most commonly used types of transmitters are:
self-oscillating power stages that are either
not coherent or
pseudo-coherent (coherent on receive); and
transmitter power amplifier output stages, which are
fully coherent.
Transmitters may be modulated (or rather, “keyed”) by short rectangular pulses.
Then, the range resolution is essentially determined by the pulse length (duration).
Transmitters may be intrapulse modulated also.
These transmitters emit a relatively long pulse, which is coded internally (frequency- or phase-coded).
Then, the pulse duration essentially determines the radars “blind range”, and the
range resolution is limited by the bandwidth of the transmitter.
If the transmit power varies by up to 10%, then this has got less influence on the radar maximum range.
