The document discusses automotive radar systems, including how they use radio signals to detect objects at a distance and help features like adaptive cruise control. It covers the components of a radar system like the antenna and processing unit, how radar detects objects through timing signals, and applications in driver assistance systems. Radar systems are becoming more important for advanced features in self-driving cars.

1. Automotive RadarSystem
From : Prasad Malai

2.  Automotive driving is
mentally demanding
activity, since driver has
to maintain high level of
concentration for long
time and take action
within split of seconds.

 In todays scenario this
task is now handled by
ACC(adaptive cruise
control system)
Introduction to adaptive cruise control system(ACC)
Involves in automatically adjusting vehicle speed and to maintain safe
distance from vehicle ahead
Control is based on sensor information from on-board sensor, allowing
vehicle to apply break when detect obstacle and accelerate when traffic
allows
ACC is widely regarded as key component for future generation of
intelligent cars
Link

3. Basic component
ofACC unit

4. System
network
ACC sensor
and control
Transmission
control
Drive train
control
ESP control
Display and
control

5. Introduction to
radar sensor
Radar(Radio detecting and ranging) emits an electromagnetic beam from
an antenna. Object(obstacle) in the path of beam reflect it back to radar
antenna
It ideally suitable for distance(range) measurement and superior to
optical system due to their insensitiveness to poor weather condition
Features supported by radar include
 Blind spot detection
 Lane change assist
 Forward collision warning
 Automotive emergency braking
 Adaptive cruise control

6. Principle and
method of
operation
 Measurement of distance by all radar system is based on direct or indirect
timing interval between transmission and reception of radar signal
 IfT is time interval between transmission and reception of signal then
distance(D) is determined by
Here C is speed of light that is 300000km/sec
 If the object detected is moving with respect to transmitter/receiver at
relative speed ofVrel, then echo signal undergoes frequency shift Fd that
is given by
Here fc is carrier frequency

7. 
Principle and
method of
operation

8. Component of
radar
A basic radar has following component
Gun oscillator: A electronics semiconductor component
that generates microwave oscillations when subjected
to strong electrical field. By applying suitable voltage
frequency can be varied between 77-78Ghz band hence
they are called as voltage controlled oscillator
 Driver circuit and antenna feed: Is a printed circuit
board meant for dividing or distributing electrical
power between different trans receivers antenna
 Mixer: Is a non-linear electrical circuit that creates new
frequency signal from two or more signal applied to it
Radom: Is outermost cover radar apparatus with
thickness of around 1 micrometer, it should be properly
sealed along with other radar component
Gunn oscillator
Mixer

9. Component of
radar
Radar antenna
 Planar antennas are common component in sensing application due to
their low cost and their ease of integration with system and normally
opted for frequency range of 77 GHz
 One special advantage of planar antenna is they can easily form array
structure combining simple element like micro strip patches
 .These antenna array element is embedded in radar PCB of radar module
Planar antenna

10. Component of
radar
Preamplifiers: As echo's from distant object produces
higher frequencies and lower voltage amplitudes
hence weaker is received signal hence preamplifier
are used to amplify such signal
Lens: For a given frequency best results are obtained
by positioning beam source at optimum distance
from lens. Also includes heater element embedded
inside lens to melt ice or snow over lens element
Electronics component: The basic electronic circuitry
of ACC SCU(sensor control unit) implanted on
printed circuit board, and mainly consist of three
parts radar trans-receiver unit, signal processing unit,
regulation processing unit
PCB for signal
processing and
power supply
Lens

11. Exploded view
of automotive
radar system
Second generation long range
radar
Third generation long range
radar

12. Radar
functionality
Digitize received signal using analog to digital converter
Performing FFT on digitized signal to get range, velocity and angular resolution
about object
Maintain the safe distance from vehicle in front
Exchange data with transmission control, electronic stability control and
display unit using CAN(controlled area network)
Monitoring voltage levels and signal

13. Object
detection,
selection &
tracking
Radar based object detection has following steps
Reception of scattered signal from obstacle
Received signal is first digitized using analog to digital converter, and subjected
for spectral analysis
Spectral analysis is performed using FFT(Fast FourierTransform)

14. Object identification:
During performing FFT on received signal, time domain sequence is
converted to frequency domain signal, both transmitted and received
signal analyzed to determine range and velocity of target
vehicle(obstacle)
Angular position of object is determined by comparing amplitudes of
reflecting signal from same object from three different antenna lobes
Object
detection,
selection &
tracking

15. Tracking:
For these function previously detected target object position is
continuously compared with present target position based on this
comparison future target position is estimated as
p(future)=p + v(relative) * ∆t
Here v(relative) is relative velocity of vehicle and it can be positive and
negative
Additional object tracking procedure are necessary if received signal
has multiple echo signal from different object
Note: frequency and range estimation accuracy depends on the
number of FFT points. Typical values: 128-4096 points, angular
resolution depends on number of antenna lobe
Object
detection,
selection &
tracking

16. Classification
of
automotive
radar
LRR: Long range radar; MRR: Mid range radar; SRR: Short range radar

17.  Radar sensor has huge scope in future driverless cars and in advanced
driver assistance system(ADAS), to achieve that stage development in
following field is necessary
Reduction in external dimension of radar sensor and control unit
Ease of production of high frequency circuit
Expansion in sensor detection range and angular resolution
Adaption and development of radar fusion technology with camera,
LIDAR etc.
Future
development

18. Automotive
radar
applications

19. Suppliers of automotive on-board radar system include
Bosch
Delphi automotive
Denso corporation
Hitachi automotive system
Renesas
Continental
Major
compotators
of automotive
radar system

20.  https://www.intechopen.com/books/radar-technology/planar-antenna-
technology-for-mm-wave-automotive-radar-sensing-and-
communications
www.radartutorial.eu/index.en.html
https://www.caranddriver.com/features/path-to-autonomy-self-driving-
car-levels-0-to-5-explained-feature?
www.digitaltrends.com/cars/best-radar-detectors
www.cvel.clemson.edu/auto/sensors/distance-radar.html
References:

21. •By: Prasad Malai
•Email id: malai.prasad@gmail.com
Thanks for reading it. For further reference and issues related to above topic please
contact at given mail address.