How did early radar determine range/ distance precisely? Wikipedia talks about precise timing of the returned radar pulse, with an animation of a clock.
But they didn't have atomic clocks and such before or during WWII.
So how did they determine distances and (possibly) velocities back rhen?
 A: Early radar uses analog signals and displays.
For example, the WWII Chain Home system would send each pulse at the same instant that an electron beam started across a CRT.  The beam would be deflected by any received signal, and the left-right offset gave the distance from the return time:


Chain Home display showing several target blips between 15 and 30 miles distant from the station. 

Later, the familiar circular display was created. The beam starts at the center and runs outward in a direction corresponding to where the antenna points at that instant, brightening when an echo is received:

Although the radar pulse moves out and back at the speed of light, radar is used over long distances.  A target a kilometer away is a six microsecond echo; 100 miles is six hundred microseconds.  The tracking signals involved are MHz or less, often much less.  
A: There were WWII-era electronic circuits that were designed to readily slice time into fractions of a microsecond, for the purposes of timing pulse returns in the first radars and thus deducing range. 
The imprecision in the time slicing process could be readily dialed out of the system by aiming the radar beam at a target a known distance away for calibration purposes. 
