Low Cost Radar and Sonar using Open Source Hardware and Software

Lance Williams

Radar Remote Sensing Group

University of Cape Town

Slide 2 © CSIR 2006 www.csir.co.za

Project Goal

• To create a Radar/Sonar application using the USRP and GNU Radio, and examine its effectiveness as a monostatic and netted Radar/Sonar node.

Slide 3 © CSIR 2006 www.csir.co.za

Outline

• Project Concept

• The Universal Software Radio Peripheral (USRP)

• The USRP Basic Layout

• Test Application Overview

• Implementation (FPGA)

• Results

• Further Development

• Conclusion

Slide 4 © CSIR 2006 www.csir.co.za

Project Concept: Reducing Cost

• There is increasing demand on telecom networks for more capability and coverage.

• More specialized DSP chips performing mixing, filteringand analog to digital conversion.

• Performance lost can possibly be regained by using

alternative radar types, configurations and processingtechniques.

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Project Concept: Recovering Performance

• Netted radar may recover performance lost by using non-ideal components.

• Synchronized nodes show an improvement in certain performance metrics over a monostatic system.

• Netted radar: counter stealth, more robust tracking, more information for target classification.

• Cheaper nodes make larger, better performing netted radars more viable.

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Project Concept: Open Source Hardware and Software

• Universal Software Radio Peripheral: A software definedradio hardware solution. A single hardware interface tomany different RF channel types. Re-configurabilityenables applications like FM radio, TV, GPS, Radar andSonar.

• GNU Radio: A flexible open source software application building frame-work that serves for developing small scale RF software systems, quick prototyping, and for educational purposes

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The Universal Software Radio Peripheral

• usb 2.0 via Cypress FX2

• Altera Cyclone FPGA

• 4 14 bit DAC's capable of 128 M samples/sec

• 4 12 bit ADC's capable of 64 M samples/sec

• Interchangeable daughterboard front-ends.

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The USRP Basic Layout

FPGA

ReceiveDaughterboard

Transmit Daughterboard

Transmit Daughterboard

ReceiveDaughterboard

ADC

ADC

ADC

ADC

DAC

DAC

DAC

DAC

Cypress FX2usb

controller

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Daughterboard Functionality

● Basic RX, 0.1-300 MHz receive

● Basic TX, 0.1-200 MHz transmit

● LFRX, DC-30 MHz receive

● LFTX, DC-30 MHz transmit

● TVRX, 50-860 MHz receive

● DBSRX, 800-2400 MHz receive

● RFX1800, 1500-2100 MHz

Transceiver

● RFX2400, 2250-2900 MHz

Transceiver

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Test Application Overview

• SONAR system using ultrasonic tranducers

• Emits chirp signals centred at 40 kHz

• 2 kHz bandwidth

• 1 millisecond pulse lengths (Variable)

• 16 ms pulse repetition interval (Variable)

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Implementation (FPGA)

RamControlmodule

PRI counter

TX Chain module

Delay counter Window counter

RX Chain moduleRX

Buffermodule

TXBuffer

module

enable

enable

enable

enable

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Results (1)

Fed back output showing the USRP capturing the transmitted pulse

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Results (2)

Raw received data showing the PRI

triggered marker samples

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Results (3)

Echo recorded from a stationary object

Echo spectrum

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Further Development (1)

• Development of a USRP and GNU Radio based active radar prototype

Target

USRP with transceiver board, front end, and host computer

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Further Development (2)

• Development of a small scale netted radar prototype

using the USRP and GNU radios existing support for

IP interconnectivity and distributed clocks.

Target

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Further Development (3)

• Development of a passive coherent location

prototype using the USRP TV receiver daughterboard

FM / TV transmitter

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Conclusion

• USRP modifications have proved successful.

• The system design within the USRP has been kept flexible in order to create radar application with little firmware modification.

• The GNU Radio software has been used to produce a basic front-end and perform data gathering.

• The standard USRP contains features that will be needed for netted Radar/Sonar prototypes.

Slide 19 © CSIR 2006 www.csir.co.za

References

1) GNU Radio – GNU FSF Project. 15 November 2006 [accessed online at http://www.gnu.org/software/gnuradio/ on 4 December 2006]

2) Ettus Research LLC. 20 November 2006 [accessed online at http://www.ettus.com/ on 4 December 2006]