## 2020年11月1日星期日

### Measurement methods of radar distance, target angle, target azimuth and target speed

Radar, derived from the abbreviation of radio detection and ranging, means "radio detection and ranging". Its basic function includes measuring the distance, angle, azimuth and speed information of the target. This article briefly summarizes its methods of measuring the above four information.

## 1. Distance measurement

Pulse method: the difference between arrival and return time;

Frequency modulation method;

Phase method: the difference between phases, 2Π corresponds to a wavelength;

## 2. Measurement of target angle

The effectiveness of the radar antenna beam is used for measurement.

Maximum beam method: Launch a beam, then the received signal is strongest when the center point is facing the target, and the angle of the center point is the target angle;

Dual beam method: Two beams are emitted. When the energy of the two received beams is equal, the angle at which the center is located is the target angle.

## 3. Measurement of azimuth

Generally, a 360-degree scan is used to determine the target azimuth by using energy changes;

## 4. Target speed measurement

Utilizing the Doppler effect, the fixed point transmits a sine wave to the target, and the transmitting frequency and the receiving frequency are different. The speed v can be calculated by the frequency difference Δf