RADAR Signal important...............

[rajhere]

when the radar signal is transmited from the antenna .... the signal hits the target..
i want to know wat r the changes that can be seen in the signal...
i.e its phase changes or freq changes or weather there there is attenuation in the signal.. or the amplitude gets reduces....
if the target is stationary or moving....?
pls anyone can explain me briefly or give the links....

 

[Antonios]

Speed measurement
Speed is the change in distance to an object with respect to time. Thus the existing system for measuring distance, combined with a memory capacity to see where the target last was, is enough to measure speed. At one time the memory consisted of a user making grease-pencil marks on the radar screen, and then calculating the speed using a slide rule. Modern radar systems perform the equivalent operation faster and more accurately using computers.

However, if the transmitter's output is coherent (phase synchronized), there is another effect that can be used to make almost instant speed measurements (no memory is required), known as the Doppler effect. Most modern radar systems use this principle in the pulse-doppler radar system. Return signals from targets are shifted away from this base frequency via the Doppler effect enabling the calculation of the speed of the object relative to the radar. The Doppler effect is only able to determine the relative speed of the target along the line of sight from the radar to the target. Any component of target velocity perpendicular to this line of sight cannot be determined by Doppler alone tracking the target's azimuth over time must be used. Additional information of the nature of the Doppler returns may be found in the radar signal characteristics article.

It is also possible to make a radar without any pulsing, known as a continuous-wave radar (CW radar), by sending out a very pure signal of a known frequency. CW radar is ideal for determining the radial component of a target's velocity, but it cannot determine the target's range. CW radar is typically used by traffic enforcement to measure vehicle speed quickly and accurately where range is not important
FOR MORE Visit https://en.wikipedia.org/wiki/Radar

 

[rajhere]

thanks Antonios for replying....
my question was not concerned with measuring speed..
i want know which all theparameters of the RADAR signal gets change when gets hit the target .......