Tensilica for Automotive Radar

At the recent Linley Fall Processor Conference, Cadence's David Bell presented Tailored Automotive Radar Processing with Tensilica ConnX DSPs.

There are four primary types of sensors that can be used in automotive applications: cameras, lidar, radar, and ultrasonic. These have different strengths and weaknesses, as you can see from the above diagram. However, the sensor types are complementary, and by using all of them, you get an "all green" column. The orange spider diagram above shows the strengths and weaknesses of radar, the focus of David's presentation.

The basic principle of radar is shown above. The radar transmits a wave, the wave is reflected off something, and the reflected wave is then analyzed back at the radar.

By using sophisticated digital signal processing, we can get the three things that we require out of the radar:

• Range determination: How far is the target?
• Velocity determination: How fast is the target moving relative to the radar?
• Angle determination: In what direction is the target moving?

By using frequency-modulated continuous waver (FMCW) radar, we can determine all three. An FMCW chirp is a variable frequency, in this case going from 77GHz to 78GHz over a period of time.

The simplest of the three is range determination. The amount by which the reflected signal is delayed from the transmitted signal can be used directly to calculate the round-trip time and, thus, the distance to the object (based on the speed of light).

To measure the velocity of a target, transmit two chirps. The change in phase of the IF signal across the chirps would correspond to the velocity (change in target location in a single chirp duration) of the target.

Angle determination is the most complex parameter to determine. It requires two or more receiver antennas so that the phase difference between the received signal at the two antennas can be calculated.

The Tensilica ConnX DSP Family

Above is the whole Tensilica portfolio, from audio, to vision, to AI. The box outlined in red is the ConnX DSP family, used for radar, lidar, and communications.

The above diagram shows the Tensilica ConnX DSP family. The 120 and 110 are new. The whole family is software compatible. The processors are certified compliant with ISO 26262 ASIL-B or ASIL-D.

Above are the software libraries available for use with the ConnX processors.

An Example

Here's a real example (using an older Tensilica BBE32 core). This is the Renesas RH850/V1R-M. Here's a video about it:

Summary

Learn More

See the ConnX DSP product page.

 

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