What is the main advantage of Doppler radar over conventional weather radar?

Answer 1

Edit-Slight Expansions and simplificationsIn General, the Advantages of Doppler RADAR compared to typical "Pulse" RADAR lies in its capability to differentiate between steady objects and moving objects, Doppler RADAR may also provide "velocity search" which later can be used as a basis for target recognition like the second answerer point (man walking and cars) Doppler effect RadarIn a general type of radar, the signal is transmitted/received in short pulses or bursts. The time width (W) for which the signal is sent/received is very short. And the time between two successive transmitted pulses is called pulse repetition time (PRT). Thus, reciprocal of PRT gives its frequency i.e. PRF = 1/PRT. Similarly, the ratio of time width (W) to PRT is called duty cycle (D).

The Radar that works on Doppler effect : it works on the principle of Doppler Effect. This effect is applicable to sound waves and electro-magnetic waves, which travel through some medium or through free space. The Doppler Effect states that when there is relative motion between the source of very high frequency signals and the observer, then frequency shift occurs.

In CW radar, a constant amplitude continuous microwave sine wave is transmitted. The echo is also a constant amplitude microwave sine wave of SAME frequency, but of lower amplitude, due to loss of energy during traveling of the wave.

While detecting the target like aeroplane, ship, missile etc. the echo undergoes change in its frequency. This change of frequency between the transmitted signal and received echo is used to determine the relative speed and direction of motion of the target. For this following formula is used -

V = 1.1 x fd x l

The above is true, but is also worth noting that Doppler radar offer's the forth degree of freedom in radar tracking as Range dot, or Doppler/Range-Rate. With more degrees of freedom then just Azimuth, Elevation & Range, tracking filtering can offer better results in say a Kalman Filter Tracking solution. Doppler profiles can be useful for distinction of distributions the difference between a man walking and a car driving etc (with man-portable radar like BLightER, or MSTAR). Doppler information can be used for SAR and ISAR imagery when the range Doppler matrix is collected at a high fidelity and interpolated correctly for a formation. It also should be noted that Doppler measurement is made via a Fourier transform rather then an statistical process, the statistical process relay own correlation of signal and de-correlation of noise where as the Fourier process is a reordering process and can provide a better signal to noise.

Answer 2

A Doppler radar works from waves going towards the precipitation. This is called Doppler effect

Traditional radar like a maritime Radar works by transmitting energy at a storm and receiving the back scatter from rain, the antenna maybe angled upwards and the coloring of the radar image may become colored, and is probably an add on mode so maybe horizontally polarised. Doppler weather radar is vertically polarised as it is looking for wind sheer effects from move rain drops moving up wards and down wards in storm clouds system. Doppler system can still detect the picture that the traditional weather radar can by peak summing the Doppler bins for each range cell in a range Doppler map. However the Doppler system will have better signal to noise then the Traditional system as the system is coherent and dose not relay of lossy filter based on statistical differences of a target distribution and rains distribution.

Answer 3

Conventional radar works by transmitting short pulses of electromagnetic energy. A small fraction of the waves that are sent out is scattered by a storm and returned to the radar, the strength of the returning signal indicates rainfall intensity and the time difference between the transmission and return of the signal indicates the distance of the storm. Doppler radar not only performs the same tasks as convention radar but also has the ability to detect motion patterns associated with tornadoes and severe thunderstorms, the conventional radar cannot.

Answer 4

In simplicity it can measure Range Rate changes as well as range, this means that it can distinguish two objects that are on the same angle and at the range but moving at different speeds like an overtaking car for example. They tend two have two receive channels such that complex number can be used to further distinguish positive and negative Range Rates from the Doppler effect that occurs with moving objects.