System Description
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TIDUEN5A–June 2019–Revised March 2020
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Imaging Radar Using Cascaded mmWave Sensor Reference Design
An IMPORTANT NOTICE at the end of this TI reference design addresses authorized use, intellectual property matters and other
important disclaimers and information.
1 System Description
ADAS control of a vehicle provides quality-of-life and safety benefits in addition to making the relatively
mundane act of driving safer and less difficult. The quality-of-life features include the ability of a vehicle to
park itself, or to determine whether a lane change is possible, and provide features like automatic cruise
control—where a vehicle maintains a constant distance with respect to the car ahead of it, essentially,
tracking the velocity of the car in front of it. Autonomous braking and collision avoidance are safety
features that prevent accidents caused by driver inattention. These features work by observing the area in
front of a car and alerting the ADAS subsystems if obstacles are observed that are likely to hit the car.
Implementing these technologies requires a variety of sensors to detect obstacles in the environment and
track their velocities and positions over time.
1.1 Why Cascade Radar?
Frequency-modulated continuous-wave (FMCW) radars allow the accurate measurement of range and
relative velocity of obstacles and other vehicles; therefore, radars are useful for autonomous vehicular
applications (such as parking assist and lane change assist) and car safety applications (autonomous
breaking and collision avoidance). An important advantage of radars over camera and light-detection-and-
ranging (LIDAR)-based systems is that radars are relatively immune to environmental conditions (such as
the effects of rain, dust, and smoke). FMCW radars can work in complete darkness and also bright
daylight (radars are not affected by glare) because they transmit and receive electromagnetic waves.
When compared with ultrasound, radars typically have a much longer range and much faster time of
transit for their signals.
Despite the many advantages of radar technology, in many cases, automotive manufacturers today still
use camera sensors as the primary sensor technology used to make final safety decisions in the system.
The radar sensor is being used as the secondary sensor; meaning, the vehicle system receives the Radar
warning, but decides to take an action only upon the camera sensor verification. The main reason is
limitation in radar angular resolution. The radar sensors deployed today in most vehicles lack the ability to
distinguish between static objects with the same range and same relative velocity.
Today, a typical front radar sensor has about a 5-degree angular resolution that corresponds to the ability
of the sensor to distinguish between objects that are 8.5 m apart at 100 m. Objects that are closer than
8.5 m appear as one object. For example, a vehicle stopped in the right lane, might look like a shoulder
road street lamp for example, and therefore would be ignored by the safety system.
This is about to change with the introduction of the Imaging Radar solution from Texas Instruments (TI).
The TI Imaging Radar is a four-chip cascade solution, that acts like a single-chip sensor but achieves
20Log10(N
TX
) SNR gain in TX beamforming mode and 360/(N*pi) angular resolution (N is the number of
virtual antennas in a MIMO configuration).
Using the TI Imaging Radar solution, we can distinguish between static objects 0.6 degrees apart with all
antennae placed in single dimension linearly, and reach a 350-m object detecting range(angular resolution
is dependent on the antenna configuration and the number of TX/RX antennae).
This performance enables TI Imaging Radar to become the primary sensor in the vehicle and enhance
safety across weather and visibility conditions by providing a high-resolution image for both static and
moving objects.
1.2 TI Cascade Radar Design
TIDEP-01012 is an introductory application that demonstrates both a long-range beam-forming
configuration, and a shorter range, high-angular resolution MIMO configuration. This reference design can
be used as a starting point to design a standalone sensor for a variety of long range and imaging radar
applications. The TI Cascade RF reference design has demonstrated automobile target detection in
excess of 350 m along with 1.4 degree angular resolution.
