Search results
Results from the WOW.Com Content Network
A plane flying past a radar station: the plane's velocity vector (red) is the sum of the radial velocity (green) and the tangential velocity (blue). The radial velocity or line-of-sight velocity of a target with respect to an observer is the rate of change of the vector displacement between the two points.
Radar is a system that uses radio waves to determine the distance , direction (azimuth and elevation angles), and radial velocity of objects relative to the site. It is a radiodetermination method [ 1 ] used to detect and track aircraft , ships , spacecraft , guided missiles , motor vehicles , map weather formations , and terrain .
Frequency ambiguity resolution is required to obtain the true radial velocity when the measurements is made using a system where the following inequality is true. R a d i a l V e l o c i t y > 0.5 ( P R F × C T r a n s m i t F r e q u e n c y ) {\displaystyle Radial\ Velocity>0.5\left({\frac {PRF\times C}{Transmit\ Frequency}}\right)}
This is an issue only with a particular type of system; the pulse-Doppler radar, which uses the Doppler effect to resolve velocity from the apparent change in frequency caused by targets that have net radial velocities compared to the radar device. Examination of the spectrum generated by a pulsed transmitter, shown above, reveals that each of ...
The unambiguous zone is in the lower left corner. All of the other blocks have ambiguous range or ambiguous radial velocity. Pulse Doppler radar relies on medium pulse repetition frequency (PRF) from about 3 kHz to 30 kHz. Each transmit pulse is separated by between 5 km and 50 km of distance.
Radar cross-section (RCS), denoted σ, also called radar signature, is a measure of how detectable an object is by radar. A larger RCS indicates that an object is more easily detected. [1] An object reflects a limited amount of radar energy back to the source. The factors that influence this include: [1] the material with which the target is made;
A Doppler radar is a specialized radar that uses the Doppler effect to produce velocity data about objects at a distance. [1] It does this by bouncing a microwave signal off a desired target and analyzing how the object's motion has altered the frequency of the returned signal.
In fact, the magnitude of this component of the velocity is proportional to the degree of signal-shift. Therefore, CODAR measures the Doppler-induced frequency-shift (along with the distance from the radar to the sector and directional angle) to provide an estimate of the radial-component of wave-speed in the sector of sea surface of interest.