Sarah Middleton Supervised by: Anton van Wyk, Jacques Cilliers, Pascale Jardin and Florence Nadal 3 December 2010

1. Introduction to Phased Array Radar versus MIMO Radar. 2. Project Objectives. 3. The Acoustic Array Hardware System. 4. Testing Procedures. 5. Beampattern Measurements. 6. Target Parameter Estimation Results. 7. Conclusion.

 Phased array  The i th element transmits a base signal multiplied by a complex weight w i.  The signals sum constructively and destructively to form a high powered beam in a desired direction.  MIMO  Each element transmits a signal which is orthogonal to all of the other signals.  This allows an omnidirectional pattern to be transmitted, and increases the degrees of freedom L-2 L-1 wavefront Δτ L-1 Δτ L-2 Δτ 2 Δτ 1

 If a set of orthogonal signals is transmitted, a matched filter bank can be used to extract the signals from the received signal.  Transmitter beamforming can then be applied to the signals, after they have been received.  This also has the effect of increasing the effective array aperture.  Also, the radar field of view can be scanned for targets after the transmission of a single burst.

Design and build a transmitter array which can be used to demonstrate radar array techniques. Transmitter Array Compare the patterns that can be formed with phased array and MIMO techniques. Beampattern Design Compare the accuracy and resolution of phased array and MIMO target range and angle estimation techniques. Parameter Estimation Literature Review -> Simulation -> Hardware Design -> Testing -> Results Analysis Approach

Receiver Array Transmitter Array Master Control Unit (MCU) Implemented on an FPGA. Master Control Unit (MCU) Implemented on an FPGA. PC C application receives Ethernet packets from MCU. Matlab applications perform signal processing. PC C application receives Ethernet packets from MCU. Matlab applications perform signal processing.

 16 small speakers make up the transmitter array.  The transmitter analogue board consists of:  A digital to analogue converter.  A low-pass reconstruction filter.  A Class AB audio amplifier.

 16 small microphones are configured as a ULA.  The receiver analogue electronics consists of:  An amplifier board.  An second amplifier stage.  A low-pass anti-aliasing filter.  An analogue to digital converter.

Finish Transmit 400 samples on 16 channels. Receive 800 samples on 16 channels. Send received signal over Ethernet. Start Xilinx Virtex 5 on an ML505 development board.

 The PC is responsible for  Designing the set of 16 signals which combine to give a desired pattern.  Receiving Ethernet packets from the MCU.  Converting the data in the Ethernet Packet into the voltages that it represents.  Calibrate the received signal.  Band-pass filtering, demodulating and low-pass filtering the signals.  Applying parameter estimation algorithms to determine the target locations.

 Testing was performed in an anechoic chamber.  The sampling frequency was 40 kHz.  The chirp bandwidth or MIMO signal symbol frequency was 4 kHz.  The carrier frequency was 10 kHz.  Transmitted signal duration was 10 ms.

The phased array and MIMO patterns are very similar, but the power of the phased array pattern is approximately 7 dB higher.

The side lobe levels of the measured signals are higher than the simulated signals.

Between -60° and 60°, the measured pattern has about 3.5 dB variation making it significantly more omnidirectional than the other patterns.

Phased Array MIMO

Phased ArrayRankMIMORank Conventional Beamformer+Capon Beamformer+ +Amplitude and phase estimation (APES) - Music Algorithm+Generalised Likelihood Ratio Test (GLRT) + Deterministic Maximum Likelihood (DML) -Approximate Maximum Likelihood (AML) ? Transmitter Beamforming on Reception ++ MIMO Transmitter Beampattern DesignRank Omnidirectional Pattern- Maximum Power Design-- Pascales Design+ Beampattern Matching Design+

Phased Array MIMO

 An acoustic array hardware system has been successfully built and tested.  Beampatterns which transmit power omnidirectionally, in one direction and in three directions have been generated.  Target parameter estimation shows:  A corner reflector target can be detected.  MIMO techniques can provide higher angular resolution estimates.