Switched Switched MonopulseMonopulse Radar Radar for Automotive Applicationsfor Automotive Applications

SLRSLR

Tyco Electronics M/A-COMEuropean Technology & Application Center

Schweinfurt, Germany

TypicalTypical ApplicationsApplications

Reverse Back-up Aid

Blind Spot Detection

Parking Lot Size Estimation

Parking Aid

Stop & Go Applications

Pre-Crash Sensing

Improved ACC

Functionality

Closing Velocity

Pedestrian Safety

Sensor Sensor ObjectivesObjectivesRadar Parameters

• Radar Principle: Pulse Radar

• Frequency: 24.125 GHz

• Tx Power: <17dBm EIRP

• Bandwidth: 4 GHz @ 20 dB points

• Pulse width: 1.0..1.5 ns

• Pulse Repetition Frequency: ~3 MHz

• Detection Cycle Time: 40 ms

• Antenna Detection Characteristic: ± 8° Elevation 3dB limit

± 65° Azimuth 3dB limit

Object Parameters• Number of Objects: 10

• Parameters Types: Range, Bearing, Velocity, Yaw Rate, Quality, Track ID

Range Parameters• Detection Range: 30m

• Range Performance: 20m (10sqrm target)

• Range (Object) Resolution: 15 cm

• Range Accuracy: 3 cm

Sensor Sensor ObjectivesObjectives ((continuedcontinued))Bearing Parameters

• Bearing Detection Principle: Switched Monopulse

• Bearing Detection Range: ± 40°

• Bearing Accuracy: ± 2° for Bearing Range ±5°

± 5° for Bearing Range ±5°..25°

± 10° for Bearing Range ±25°..40°

Velocity Parameters• Velocity Detection Principle: Range Rate Velocity Measurement

• Velocity Range: ± 100 km/h

• Velocity Accuracy: ± 1 km/h

• Velocity Resolution: 0.05 m/s

Tracking Parameters• Tracking Principle: Extended Kalman Filter Approximation

• Track Initiation: Retrospective Detector (4 in a row)

• Track Kill: 4 consecutive cycles with no detection

PrinciplePrinciple of Operationof Operation

TXAntenna

24 GHzDRO

Time DelayComparision

TimeNormal

Output Signal

High Resolution Radar

RXAntenna

Correlation

Correlation occurs when the pulse traveling time is equal to the internal delay. The resulting IF signal is related to the range of the detected object.

Pulse Radar Correlation

Minimum range: 15cm

Maximum range: 20m (10sqm)

Object Resolution: 15cm

Time Delay Comparison

Pulse traveling time is compared with internal time delay

Block DiagramBlock Diagram

VCO

Power Splitter

RX Switch

TX Switch

IF Out

TX Antenna

PRF ?

DualChannel LNA

Switchable RX Antenna

Signal Processing

Control Circuitry

Sensor Bearing Sensor Bearing CapabilityCapabilitySwitchable antenna characteristics provide bearing information through signal processing based on the monopulse theory

Sum Pattern Delta Pattern

-30

-20

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60o

30o

0o

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-60o

Serr: Magnitude of delta pattern

Sref: Magnitude of sum pattern

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-10

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10 0

105

Pattern log

phi/ deg

S/log

ErrorReference

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0.5

1

1.5

2Pattern lin

phi/ deg

S/ lin

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0

0.5

1ASR

phi/ deg

ASR

-1 -0.5 0 0.5 10

20

40

60

80

100ASR -1

ASR

phi/deg

Typical Angle AccuracyTypical Angle Accuracy Angle accuracy

-40-30-20-10

010203040

-40 -30 -20 -10 0 10 20 30 40

Real Angle

Mea

s A

ng

le

Absolute Angle Error

0

5

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-40 -30 -20 -10 0 10 20 30 40

Angle

Ab

s(A

ng

le E

rro

r)

System Impact of Sensor Bearing System Impact of Sensor Bearing Capability Capability

Illustrated is a typical parking situation.

In this case our test car is equipped with 4 sensors that are NOT capable of reporting bearing information on sensor level.

The central processing unit of the radar network has difficulties to resolve the scenario and reports false targets due to ambiguities.

System Impact of Sensor Bearing System Impact of Sensor Bearing Capability Capability

The screenshot beside shows the output of a SINGLE sensor in a similar scenario as illustrated on the slide before.

In conjunction with other sensors of the network redundancy can be achieved leading to a more stable system.

WhyWhy OperatingOperating at 24GHzat 24GHz5.8GHz:•Integration of large antenna sizes into vehicle bumpers is not feasible•Fractional BW for high resolution not realistic

24GHz:•Integration of moderate antenna sizes into vehicle bumpers is feasible•Acceptable attenuation of µWave propagation through bumper material•Fractional BW for high resolution possible•Availability of off-the-shelf components, mature production processes•Economical hybrid design on softboard possible without MMIC‘s

64GHz / 79GHz:•High attenuation of µWave propagation through bumper material•no discrete packaged components available•currently no affordable MMIC‘s available•significant commercial and manufacturing technology deficiency issues

Conclusion:24GHz SRR is the key enabling technology on a short and medium term basis