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Time and Frequency Transfer in a Coherent Multistatic Radar using a White Rabbit Network
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 operatio...
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| Format: | Thesis |
| Language: | English |
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Department of Electrical Engineering
2022
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| _version_ | 1867613187801612288 |
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| access_status_str | Open Access |
| author | Lewis, Simon A C |
| author2 | Inggs, Mike |
| author_browse | Inggs, Mike Lewis, Simon A C |
| author_facet | Inggs, Mike Lewis, Simon A C |
| author_sort | Lewis, Simon A C |
| collection | Thesis |
| description | 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. |
| format | Thesis |
| id | oai:open.uct.ac.za:11427/35907 |
| institution | University of Cape Town (South Africa) |
| language | eng |
| last_indexed | 2026-06-10T12:32:09.918Z |
| license_str | Not specified — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UCTD — University of Cape Town Open Access Repository |
| publishDate | 2022 |
| publishDateRange | 2022 |
| publishDateSort | 2022 |
| publisher | Department of Electrical Engineering |
| publisherStr | Department of Electrical Engineering |
| record_format | dspace |
| source_str | UCTD — University of Cape Town Open Access Repository |
| spelling | oai:open.uct.ac.za:11427/35907 Time and Frequency Transfer in a Coherent Multistatic Radar using a White Rabbit Network Lewis, Simon A C Inggs, Mike Electrical Engineering 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. 2022-03-04T08:39:28Z 2022-03-04T08:39:28Z 2021 2022-03-03T12:35:24Z Doctoral Thesis Doctoral PhD http://hdl.handle.net/11427/35907 eng application/pdf Department of Electrical Engineering Faculty of Engineering and the Built Environment |
| spellingShingle | Electrical Engineering Lewis, Simon A C Time and Frequency Transfer in a Coherent Multistatic Radar using a White Rabbit Network |
| thesis_degree_str | Doctoral |
| title | Time and Frequency Transfer in a Coherent Multistatic Radar using a White Rabbit Network |
| title_full | Time and Frequency Transfer in a Coherent Multistatic Radar using a White Rabbit Network |
| title_fullStr | Time and Frequency Transfer in a Coherent Multistatic Radar using a White Rabbit Network |
| title_full_unstemmed | Time and Frequency Transfer in a Coherent Multistatic Radar using a White Rabbit Network |
| title_short | Time and Frequency Transfer in a Coherent Multistatic Radar using a White Rabbit Network |
| title_sort | time and frequency transfer in a coherent multistatic radar using a white rabbit network |
| topic | Electrical Engineering |
| url | http://hdl.handle.net/11427/35907 |
| work_keys_str_mv | AT lewissimonac timeandfrequencytransferinacoherentmultistaticradarusingawhiterabbitnetwork |