Coherent vs. Non-Coherent MTI Radar: Key Differences Explained

This page compares Coherent MTI Radar and Non-Coherent MTI Radar, outlining the key differences between them.

Coherent MTI Radar

Figure 1 illustrates the block diagram of a Coherent MTI radar. In this type, each cycle of magnetron oscillations begins with a phase unrelated to the previous pulse cycle.

Coherent MTI radar necessitates a high pulse repetition frequency to ensure return pulses from each target. An RF oscillator serves as a phase reference for determining the phase of the reflected signal. A pulse amplifier generates the pulses.

The detected phase data is stored in a delay line for the interval between transmitted pulses. This stored data is then subtracted from the data of the previous pulse. The subtractor outputs a signal only when a moving target is detected; the output is zero for stationary targets. Phase fluctuation caused by the moving target is a critical aspect considered within coherent MTI radar systems.

Non-Coherent MTI Radar

Figure 2 depicts the block diagram of a Non-Coherent MTI radar. In this radar configuration, variations are determined by comparing echoes from stationary and radially moving targets. The echoes from moving targets exhibit both amplitude and phase changes.

Non-coherent MTI radar primarily focuses on changes in amplitude. As shown in the diagram, the modulated output from the magnetron is transmitted. The received echo signal and local oscillator difference are fed into the mixer.

The mixer’s output is then fed to an IF amplifier. The IF amplifier’s output is passed to an amplitude detector, and the detector’s output is subsequently sent to a delay line canceller.