WITHOUT THESE RADARS DURING WARS, OUR WORLD WOULD HAVE BEEN TURNED INTO ASHES BY DICTATORS BY NOW… jai ho soldiers, jai ho radars…
Any one who knows about RADAR can easily find out that it was built to meet the requirements of military in tracking the enemy missiles, artifacts, ships, satellites… means when ever we want to track down something, we use these RADARS… hence we now also use these in military war fares… these can be termed as military radar systems…
Military radar systems can be divided into three main classes based on platform: land-based, ship borne, and airborne. Within these broad classes, there are several other categories based mainly on the operational use of the radar system. Though radars now a days are used in multi areas, these can be classified based on their primary use… for each of these radar types, they usually employ a characteristic waveform and signal processing that differentiate it from other radars.
Air defense radars: These radars cover all fixed, mobile, and transportable 2-D and 3-D systems used in the air defense mission. The present largest air defense radar in the world is JORN.
Battlefield, Missile Control, and Ground Surveillance Radars. These radars also include battlefield surveillance, tracking, fire-control, and weapons-locating radar systems, whether fixed, mobile, transportable, or man-portable.
Navigational based Radars. These radars consist of ship borne surface search and air search radars (2-D and 3-D) as well as land-based coastal surveillance radars. These are part of a radar-based fire-control and weapons guidance systems.
Navigational based radar
Military Air Traffic Control (ATC), Instrumentation and Ranging Radars. These include both land-based and ship borne ATC radar systems used for assisting aircraft landing, and supporting test and evaluation activities on test ranges.
Air traffic control radar
Simple Pulse Radar: This type is the most typical radar with a waveform consisting of repetitive short-duration pulses. Typical examples are long-range air test range radars, and weather radars. There are two types of pulse radars that use the Doppler frequency shift of the received signal to detect moving targets, such as aircraft, and to reject the large unwanted echoes from stationary clutter that do not have a Doppler shift. One is called moving-target indication (MTI) radar and the other is called pulse Doppler radar.
Concept of pulse radar
Moving-Target Indication (MTI) Radar: By sensing Doppler frequencies, MTI radar can differentiate echoes of a moving target from stationary objects and clutter, and reject the clutter. Its waveform is a train of pulses with a low PRR to avoid range ambiguities. What this means is that range measurement at the low PRR is good while speed measurement is less accurate than at a high PRR’s.
Automatic generation of MTI
Pulse Doppler radar: As with the MTI system, the pulse Doppler radar is a type of pulse radar that utilizes the Doppler frequency shift of the echo signal to reject clutter and detect moving aircraft. However, it operates with a much higher PRR than the MTI radar so as to have no ambiguities in the measurement of radial velocity. A high PRR, however, causes a highly ambiguous range measurement. The true range is resolved by transmitting multiple waveforms with different PRR’s.
Circuit of pulse Doppler radar
Pulse-Compression Radar: This radar is similar to high-range resolution radar but overcomes peak power and long-range limitations by obtaining the resolution of a short pulse but with the energy of a long pulse. It does this by modulating either the frequency or the phase of a long, high-energy pulse. The frequency or phase modulation allows the long pulse to be compressed in the receiver by an amount equal to the reciprocal of the signal bandwidth.
Coded pulses and advantages of pulse compression radar
Tracking Radar: This kind of radar continuously follows a single target in angle (azimuth and elevation) and range to determine its path or trajectory, and to predict its future position. The single-target tracking radar provides target location almost continuously. A typical tracking radar might measure the target location at a rate of 10 times per second. Range instrumentation radars are typical tracking radars. Military tracking radars employ sophisticated signal processing to estimate target size or identify specific characteristics before a weapon system is activated against them. These radars are sometimes referred to as fire-control radars.
World’s smallest tracking radar
Frequency-modulated Continuous-wave (FM-CW) Radar: If the frequency of CW radar is continually changed with time, the frequency of the echo signal will differ from that transmitted and the difference will be proportional to the range of the target. Accordingly, measuring the difference between the transmitted and received frequencies gives the range to the target. In such frequency modulated continuous-wave radar, the frequency is generally changed in a linear fashion, so that there is an up-and-down alternation in frequency. The most common form of FM-CW radar is the radar altimeter used on aircraft or a satellite to determine their height above the surface of the Earth. Phase modulation, rather than frequency modulation, of the CW signal has also been used to obtain range measurement.
FM-CW radar frequency and work
These are some of the common classification of radars in military purposes…
There are some other major classifications like DOPPLER RADAR, BI STATIC RADAR…
Catch up with some other article on radar guys…for now thanks for your support…
Gopi(3rd year ECE) MGIT
Courtesy: global security.org
For video on military used radars