How do you design a frequency modulated continuous wave (FMCW) radar system?

1 What is FMCW radar?

FMCW radar is a type of radar that uses a continuous wave of electromagnetic energy that changes its frequency over time. The frequency of the transmitted wave is modulated by a linear or nonlinear function, such as a sawtooth or a triangular wave. The receiver measures the difference between the transmitted and reflected frequencies, which is proportional to the distance and velocity of the target.

2 Why use FMCW radar?

FMCW radar has several advantages over other types of radar, such as pulse radar or continuous wave (CW) radar. FMCW radar can achieve high range resolution and accuracy with low power consumption and low peak power. FMCW radar can also avoid interference from other sources, such as noise or clutter, by using different frequency bands or coding schemes. FMCW radar can also support multiple-input multiple-output (MIMO) configurations, which can enhance the spatial resolution and diversity of the system.

3 How to design FMCW radar?

The design of FMCW radar involves several steps, such as choosing the waveform parameters, selecting the hardware components, and implementing the signal processing algorithms. Some of the key waveform parameters are the bandwidth, the sweep time, the modulation function, and the repetition frequency. These parameters affect the range resolution, the maximum unambiguous range, the Doppler resolution, and the maximum unambiguous velocity of the system.

4 How to choose the hardware components?

The hardware components of FMCW radar include the transmitter, the receiver, the antenna, and the signal processing unit. The transmitter generates the modulated wave and amplifies it to the desired power level. The receiver detects the reflected wave and converts it to a baseband signal. The antenna transmits and receives the electromagnetic waves and determines the radiation pattern and gain of the system. The signal processing unit performs operations such as filtering, mixing, fast Fourier transform (FFT), and detection.

5 How to implement the signal processing algorithms?

The signal processing algorithms of FMCW radar are used to extract information from the baseband signal, such as the range, the velocity, and the angle of the target. The most common algorithm is the beat frequency method, which calculates the frequency difference between the transmitted and received signals. The beat frequency method can be applied to single or multiple targets, depending on the complexity of the signal. Other algorithms include the chirp scaling method, the range-Doppler method, and the range-angle method.

6 How to test and evaluate FMCW radar?

The testing and evaluation of FMCW radar involve measuring the performance and functionality of the system under different scenarios and conditions. Some of the performance metrics are the range accuracy, the range resolution, the velocity accuracy, the velocity resolution, the angle accuracy, and the angle resolution. Some of the functionality tests are the detection probability, the false alarm rate, the clutter rejection, and the interference suppression. The testing and evaluation can be done in simulation, in laboratory, or in field environments.