[FAQ] AWR1843: mmWave Sensor: Detection of two Static Objects

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Part Number: AWR1843

Here is a summary of detection for two static objects. There are dependencies on antenna, algorithm, reflectivity of the objects

Depending on an antenna used, the radar data can contain the following information: range, velocity, angle.

If the objects are static, the velocity information does not help to differentiate between objects because both objects have same velocity (they are in the zero doppler bin)

So, if objects are static we are left with range and angle information.

If both objects are at the same range, the range information will not help us differentiate them because it is the same for both objects.

So, we are left with angle information.

Differentiating the objects with the angle information will depend on several factors

1) Antenna Angular Resolution (please see other threads defining this)

If the angle between the two objects is smaller than the antenna angular resolution, then the radar will not be able to detect two objects with traditional fft based processing chain. It may be able possible to detect with higher resolution algorithms such as MUSIC.

If the angle between the two objects is larger than the antenna angular resolution, then we have to consider the following things

2) Does the processing chain support multiple peak detection for the same range bin (same distance)?

Some of the algorithms TI provides detect only one peak (object) for the same range bin. Some other algorithms support multiple peak detection. If the algorithm does not support multiple peak detection it will not be possible to detect the two objects even if the angle between the two objects is larger than the antenna angular resolution.

If the algorithm supports multiple peak detection, then we need to consider the following

3) What are the relative RCS values of the two objects?

The RCS value determines the intensity of the signal reflected by the object. If the two objects we are trying to detect have a very different RCS this means that one of the objects will be much more reflective than the other one. In this case it is possible that in the fft processing the higher RCS side lobes will mask the smaller RCS. In this case it is not possible to detect both objects with this algorithm.

In order to detect two objects with different RCS we many need to use beam forming algorithms.

Thank you

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