Time and Frequency Transfer in a Coherent Multistatic Radar using a White Rabbit Network

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dc.contributor.advisorInggs, Mike
dc.contributor.authorLewis, Simon A C
dc.date.accessioned2022-03-04T08:39:28Z
dc.date.available2022-03-04T08:39:28Z
dc.date.issued2021
dc.date.updated2022-03-03T12:35:24Z
dc.description.abstractNetworks of coherent multistatic radars require accurate and stable time and frequency transfer (TFT) for range and Doppler estimation. TFT techniques based on global navigation satellite systems (GNSS), have been favoured for several reasons, such as enabling node mobility through wireless operation, geospatial referencing, and atomic clock level time and frequency stability. However, such systems are liable to GNSS-denial, where the GNSS carrier is temporarily or permanently removed. A denial-resilient system should consider alternative TFT techniques, such as the White Rabbit (WR) project. WR is an Ethernet based protocol, that is able to synchronise thousands of nodes on a fibre-optic based network with sub-nanosecond accuracy and picoseconds of jitter. This thesis evaluates WR as the TFT network for a coherent multistatic pulse-Doppler radar – NeXtRAD. To test the hypothesis that WR is suitable for TFT in a coherent multistatic radar, the time and frequency performance of a WR network was evaluated under laboratory conditions, comparing the results against a network of multi-channel GPS-disciplined oscillators (GPSDO). A WR-disciplined oscillator (WRDO) is introduced, which has the short-term stability of an ovenised crystal (OCXO), and long-term stability of the WR network. The radar references were measured using a dual mixer time difference technique (DMTD), which allows the phase to be measured with femtosecond level resolution. All references achieved the stringent time and frequency requirements for short-term coherent bistatic operation, however the GPSDOs and WRDOs had the best short-term frequency stability. The GPSDOs had the highest amount of long-term phase drift, with a peak-peak time error of 9.6 ns, whilst the WRDOs were typically stable to within 0.4 ns, but encountered transient phase excursions to 1.5 ns. The TFT networks were then used on the NeXtRAD radar, where a lighthouse, Roman Rock, was used as a static target to evaluate the time and frequency performance of the references on a real system. The results conform well to the laboratory measurements, and therefore, WR can be used for TFT in coherent radar.
dc.identifier.apacitationLewis, S. A. C. (2021). <i>Time and Frequency Transfer in a Coherent Multistatic Radar using a White Rabbit Network</i>. (). ,Faculty of Engineering and the Built Environment ,Department of Electrical Engineering. Retrieved from http://hdl.handle.net/11427/35907en_ZA
dc.identifier.chicagocitationLewis, Simon A C. <i>"Time and Frequency Transfer in a Coherent Multistatic Radar using a White Rabbit Network."</i> ., ,Faculty of Engineering and the Built Environment ,Department of Electrical Engineering, 2021. http://hdl.handle.net/11427/35907en_ZA
dc.identifier.citationLewis, S.A.C. 2021. Time and Frequency Transfer in a Coherent Multistatic Radar using a White Rabbit Network. . ,Faculty of Engineering and the Built Environment ,Department of Electrical Engineering. http://hdl.handle.net/11427/35907en_ZA
dc.identifier.ris TY - Doctoral Thesis AU - Lewis, Simon A C AB - Networks of coherent multistatic radars require accurate and stable time and frequency transfer (TFT) for range and Doppler estimation. TFT techniques based on global navigation satellite systems (GNSS), have been favoured for several reasons, such as enabling node mobility through wireless operation, geospatial referencing, and atomic clock level time and frequency stability. However, such systems are liable to GNSS-denial, where the GNSS carrier is temporarily or permanently removed. A denial-resilient system should consider alternative TFT techniques, such as the White Rabbit (WR) project. WR is an Ethernet based protocol, that is able to synchronise thousands of nodes on a fibre-optic based network with sub-nanosecond accuracy and picoseconds of jitter. This thesis evaluates WR as the TFT network for a coherent multistatic pulse-Doppler radar – NeXtRAD. To test the hypothesis that WR is suitable for TFT in a coherent multistatic radar, the time and frequency performance of a WR network was evaluated under laboratory conditions, comparing the results against a network of multi-channel GPS-disciplined oscillators (GPSDO). A WR-disciplined oscillator (WRDO) is introduced, which has the short-term stability of an ovenised crystal (OCXO), and long-term stability of the WR network. The radar references were measured using a dual mixer time difference technique (DMTD), which allows the phase to be measured with femtosecond level resolution. All references achieved the stringent time and frequency requirements for short-term coherent bistatic operation, however the GPSDOs and WRDOs had the best short-term frequency stability. The GPSDOs had the highest amount of long-term phase drift, with a peak-peak time error of 9.6 ns, whilst the WRDOs were typically stable to within 0.4 ns, but encountered transient phase excursions to 1.5 ns. The TFT networks were then used on the NeXtRAD radar, where a lighthouse, Roman Rock, was used as a static target to evaluate the time and frequency performance of the references on a real system. The results conform well to the laboratory measurements, and therefore, WR can be used for TFT in coherent radar. DA - 2021_ DB - OpenUCT DP - University of Cape Town KW - Electrical Engineering LK - https://open.uct.ac.za PY - 2021 T1 - Time and Frequency Transfer in a Coherent Multistatic Radar using a White Rabbit Network TI - Time and Frequency Transfer in a Coherent Multistatic Radar using a White Rabbit Network UR - http://hdl.handle.net/11427/35907 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/35907
dc.identifier.vancouvercitationLewis SAC. Time and Frequency Transfer in a Coherent Multistatic Radar using a White Rabbit Network. []. ,Faculty of Engineering and the Built Environment ,Department of Electrical Engineering, 2021 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/35907en_ZA
dc.language.rfc3066eng
dc.publisher.departmentDepartment of Electrical Engineering
dc.publisher.facultyFaculty of Engineering and the Built Environment
dc.subjectElectrical Engineering
dc.titleTime and Frequency Transfer in a Coherent Multistatic Radar using a White Rabbit Network
dc.typeDoctoral Thesis
dc.type.qualificationlevelDoctoral
dc.type.qualificationlevelPhD
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