Technology

The Requirements

Radar sensors are already widely used in automotive applications due to its nature of longer distance and reliability in all weather conditions.

Legacy Radar

Legacy radar sensors provide detections only in Azimuth plane, car makers cannot tell the height of detected objects, which causes problems in the field, for example false alerts when enter a tunnel.

4D Imaging Radar

For more advanced Autonomous Driving (AD) system, adding elevation information with higher resolutions (spatial point clouds) are requested from car makers, which drive the requirements of 4D imaging radar.

The Challenges

In order to design a Radar with 4 dimensions and imaging like point clouds, many traditional tier ones and radar startups are putting their efforts in adding elevation detection and enhancing higher resolution in range, angular and doppler, this results in:
- More transceivers and antennas, which drives larger PCB size
- Higher data rate (up to tens of Gbps for each radar) and more powerful CPUs, which drives more power consumption and generate more heat
- More EE components, complex ME parts, which drives higher cost

However, adding more antennas and enhancing resolution may not help on some fundamental problems that even the leading AD company like Waymo is facing during their field test:
- False Targets
  - Multi-path reflections from ground, guardrail, metal bridge, large truck, traffic signs…
  - Harmonic signals caused by over-saturation of RX LNA
- Miss Detection
  - Small objects blocked out by larger objects which is caused by poor dynamic range of the radar system

Megasense Solution

Megasense’s radar sensor- Minerva enables 4D scanning by applying our patent technology US ID: 18/052,197 (pending approval). The 4D scanning is constructed by using TX beam forming for Azimuth scan and RX beam cutting for Elevation scan.
With the narrower TX and RX antenna beam width, Minerva also reduces the multi-path and harmonic effects in the field, which dramatically improve the false target detection and false alerts.

Another key issue that has been addressed by car maker is the problem of small objects blocked out by larger objects, Minerva resolve this issue by optimizing the Peak to Side Lobe Ratio (PSLR) in all Angular, Range and Velocity Domains, in this way the amplitudes reflected by larger objects can be rejected. Compared with standard MIMO technology which provide only 14dB of PSLR, our design shows much better PSLR of >50dB.