1.1.1 RADAR: Radar is an electromagnetic system for the detection and location of reflecting objects such as aircraft, ships, space craft, vehicles, people, and the natural environment. It operates by radiating energy into space and detecting the echo signal reflected from an object, or target. The reflected energy that is returned to the radar not only indicates the presence of a target, but by comparing the received echo signal that was transmitted, its location can be determined along with the target-related information. In RADAR the transmitter generates an electromagnetic signal that is radiated into space by an antenna. A portion of the transmitted energy is intercepted by the target and…show more content… 1.1.2 ESM Systems:
Sanket is an Electronic Support Measures (ESM) system is used to intercepts, analyses and identifies radar signals operating in the frequency range and displays the radar parameters along with Direction of arrival on the display. The information displayed includes Frequency, Pulse Width, Pulse Repetition Frequency, Direction of Arrival, Antenna Scan Period, Amplitude etc, The system is configured to suit the different Indian Ships. The main function of Sanket system is to measure bearing accuracy with the highest accuracy which is very critical. The system uses amplitude comparison technique to measure bearing accuracy at any frequency in the operating frequency range. DF receiver subsystem is used to measure bearing of the received signal.
The DF measurement is based on amplitude comparison technique. The intercepted pulse amplitude is compared among the adjacent DF channels after the channel mismatch is computed and corrected and the DOA is computed. The technique essentially consists of finding the first and second maximums over the channels and the ratio of these two provides the required DF value. The pattern difference between the two adjacent channels is computed at the bore-sight and the crossover angles from which the DOA values are computed. The antenna pattern and channel matching is key parameters for calculating the final DOA. The DF accuracy depends on the channel mismatch and antenna patterns.
The channel mismatch can be reduced