Non coherent MTI radar | Block Diagram | Radar Systems | Lec-41
Non-Coherent MTA Radar
In this section, the concept of non-coherent MTA radar is explained. The difference between coherent and non-coherent radar is discussed, along with the purpose of using a reference signal in the receiving section.
Coherent vs. Non-Coherent Radar
- Coherent radar uses a transmitted signal frequency that is coherent with the received signal frequency.
- The purpose of coherence is to eliminate the amount of transmitted signal frequency from the receiving section.
- Non-coherent radar, on the other hand, focuses on amplitude variations rather than frequency variations.
Purpose of Reference Signal
- In non-coherent MTA radar, a reference signal is used in the receiving section to eliminate the transmitted signal frequency.
- The amplitude fluctuations of a moving target are used to extract information, as stationary targets have constant amplitudes.
Amplitude Fluctuations in Non-Coherent MTI Radar
This section explains why amplitude fluctuations are used instead of frequency variations in non-coherent MTI radar. The block diagram of a non-coherent MDR header is also discussed.
Amplitude Fluctuations vs. Frequency Variations
- Amplitude fluctuations are preferred over frequency variations because stationary targets have constant amplitudes while moving targets exhibit changing amplitudes.
- By analyzing differences in successive samples' amplitude variations, we can extract transmitted information related to moving targets.
Block Diagram of Non-Coherent MDR Header
- The transmitting section consists of a pulse modulated signal generated by a modulator and amplified by a power amplifier or oscillator.
- A duplexer (transmit-receive or TR) separates transmitting and receiving signals when using a single antenna for both purposes.
- During reception, the received signal frequency is mixed with a local oscillator frequency and converted into an intermediate frequency (IF).
- The IF signal is then amplified by an IF amplifier to extract the desired intermediate frequency component.
- Finally, the amplitude detector detects and analyzes the amplitude variations in the received signal.
Summary of Non-Coherent Empty Radar
This section provides a summary of the steps involved in non-coherent empty radar.
Steps in Non-Coherent Empty Radar
- Pulse modulation and amplification of the transmitted signal.
- Separation of transmitting and receiving signals using a duplexer.
- Conversion of received RF signal into an IF signal through mixing with a local oscillator frequency.
- Amplification of the desired intermediate frequency component using an IF amplifier.
- Detection and analysis of amplitude variations in the received signal using an amplitude detector.
The transcript does not provide further information beyond this point.
Coherent Empty Radar and Phase Detector
In coherent empty radar, a phase detector is used to detect the difference between phases. The phase of a moving target changes due to its motion, resulting in a frequency shift (ft +/- fd). The purpose of the phase detector is to measure this Doppler frequency component (fd).
Purpose of Phase Detector
- Phase detector detects the difference between phases.
- It measures the change in phase caused by a moving target.
- The received signal's phase can be expressed as ft +/- fd, where ft is the transmitted signal's phase and fd is the Doppler frequency component.
Non-Coherent Empty Radar and Amplitude Detector
In non-coherent empty radar, amplitude fluctuations are focused on instead of phase or frequency fluctuations. An amplitude detector is used to calculate the difference between successive pulse outputs for stationary and moving targets.
Purpose of Amplitude Detector
- In non-coherent empty radar, amplitude fluctuations are considered.
- Amplitude detector calculates the difference between transmitted signal amplitude, receiver signal amplitude, and previous IQ values.
- It focuses on measuring changes in amplitude for both stationary and moving targets.
Calculation of Differences Between Successive Outputs
The amplitude detector calculates differences between successive outputs for each pulse. This calculation helps determine changes in amplitudes for multiple moving targets.
Calculation Process
- For each pulse, the amplitude detector calculates differences between successive outputs.
- This calculation allows for tracking changes in amplitudes over time.
Changes in Target Amplitudes
When targets move away from the radar system, their echo signals exhibit changes in amplitude. Stationary targets maintain constant amplitudes, while moving targets experience varying amplitudes.
Changes in Amplitude
- Echo signals from stationary targets maintain constant amplitudes.
- Moving targets exhibit changing amplitudes from pulse to pulse.
- In subsequent cycles, moving targets that are moving away from the radar system will have reduced amplitudes.
The transcript is already in English, so no language conversion is required for this summary.