Synchronising coherent networked radar using low-cost GPS-disciplined oscillators
| dc.contributor.advisor | Inggs, Michael R | |
| dc.contributor.author | Sandenbergh, Jacobus S | |
| dc.date.accessioned | 2020-01-29T08:57:48Z | |
| dc.date.available | 2020-01-29T08:57:48Z | |
| dc.date.issued | 2019 | |
| dc.date.updated | 2020-01-24T08:07:42Z | |
| dc.description.abstract | This text evaluates the feasibility of synchronising coherent, pulsed-Doppler, networked, radars with carrier frequencies of a few gigahertz and moderate bandwidths of tens of megahertz across short baselines of a few kilometres using low-cost quartz GPSDOs based on one-way GPS time transfer. It further assesses the use of line-of-sight (LOS) phase compensation, where the direct sidelobe breakthrough is used as the phase reference, to improve the GPS-disciplined oscillator (GPSDO) synchronised bistatic Doppler performance. Coherent bistatic, multistatic, and networked radars require accurate time, frequency, and phase synchronisation. Global positioning system (GPS) synchronisation is precise, low-cost, passive and covert, and appears well-suited to synchronise networked radar. However, very few published examples exist. An imperfectly synchronised bistatic transmitter-receiver is modelled. Measures and plots are developed enabling the rapid selection of appropriate synchronisation technologies. Three low-cost, open, versatile, and extensible, quartz-based GPSDOs are designed and calibrated at zero-baselines. These GPSDOs are uniquely capable of acquiring phase-lock four times faster than conventional phase-locked loops (PLLs) and a new time synchronisation mechanism enables low-jitter sub-10 ns oneway GPS time synchronisation. In collaboration with University College London, UK, the 2.4 GHz coherent pulsed-Doppler networked radar, called NetRAD, is synchronised using the University of Cape Town developed GPSDOs. This resulted in the first published example of pulsed-Doppler phase synchronisation using GPS. A tri-static experiment is set up in Simon’s Bay, South Africa, with a maximum baseline of 2.3 km. The Roman Rock lighthouse was used as a static target to simultaneously assess the range, frequency, phase, and Doppler performance of the monostatic, bistatic, and LOS phase corrected bistatic returns. The real-world results compare well to that predicted by the earlier developed bistatic model and zero-baseline calibrations. GPS timing limits the radar bandwidth to less than 37.5 MHz when it is required to synchronise to within the range resolution. Low-cost quartz GPSDOs offer adequate frequency synchronisation to ensure a target radial velocity accuracy of better than 1 km/h and frequency drift of less than the Doppler resolution over integration periods of one second or less. LOS phase compensation, when used in combination with low-cost GPSDOs, results in near monostatic pulsed-Doppler performance with a subclutter visibility improvement of about 30 dB. | |
| dc.identifier.apacitation | Sandenbergh, J. S. (2019). <i>Synchronising coherent networked radar using low-cost GPS-disciplined oscillators</i>. (). ,Engineering and the Built Environment ,Department of Electrical Engineering. Retrieved from http://hdl.handle.net/11427/30829 | en_ZA |
| dc.identifier.chicagocitation | Sandenbergh, Jacobus S. <i>"Synchronising coherent networked radar using low-cost GPS-disciplined oscillators."</i> ., ,Engineering and the Built Environment ,Department of Electrical Engineering, 2019. http://hdl.handle.net/11427/30829 | en_ZA |
| dc.identifier.citation | Sandenbergh, J. 2019. Synchronising coherent networked radar using low-cost GPS-disciplined oscillators. | en_ZA |
| dc.identifier.ris | TY - Thesis / Dissertation AU - Sandenbergh, Jacobus S AB - This text evaluates the feasibility of synchronising coherent, pulsed-Doppler, networked, radars with carrier frequencies of a few gigahertz and moderate bandwidths of tens of megahertz across short baselines of a few kilometres using low-cost quartz GPSDOs based on one-way GPS time transfer. It further assesses the use of line-of-sight (LOS) phase compensation, where the direct sidelobe breakthrough is used as the phase reference, to improve the GPS-disciplined oscillator (GPSDO) synchronised bistatic Doppler performance. Coherent bistatic, multistatic, and networked radars require accurate time, frequency, and phase synchronisation. Global positioning system (GPS) synchronisation is precise, low-cost, passive and covert, and appears well-suited to synchronise networked radar. However, very few published examples exist. An imperfectly synchronised bistatic transmitter-receiver is modelled. Measures and plots are developed enabling the rapid selection of appropriate synchronisation technologies. Three low-cost, open, versatile, and extensible, quartz-based GPSDOs are designed and calibrated at zero-baselines. These GPSDOs are uniquely capable of acquiring phase-lock four times faster than conventional phase-locked loops (PLLs) and a new time synchronisation mechanism enables low-jitter sub-10 ns oneway GPS time synchronisation. In collaboration with University College London, UK, the 2.4 GHz coherent pulsed-Doppler networked radar, called NetRAD, is synchronised using the University of Cape Town developed GPSDOs. This resulted in the first published example of pulsed-Doppler phase synchronisation using GPS. A tri-static experiment is set up in Simon’s Bay, South Africa, with a maximum baseline of 2.3 km. The Roman Rock lighthouse was used as a static target to simultaneously assess the range, frequency, phase, and Doppler performance of the monostatic, bistatic, and LOS phase corrected bistatic returns. The real-world results compare well to that predicted by the earlier developed bistatic model and zero-baseline calibrations. GPS timing limits the radar bandwidth to less than 37.5 MHz when it is required to synchronise to within the range resolution. Low-cost quartz GPSDOs offer adequate frequency synchronisation to ensure a target radial velocity accuracy of better than 1 km/h and frequency drift of less than the Doppler resolution over integration periods of one second or less. LOS phase compensation, when used in combination with low-cost GPSDOs, results in near monostatic pulsed-Doppler performance with a subclutter visibility improvement of about 30 dB. DA - 2019 DB - OpenUCT DP - University of Cape Town KW - Electrical Engineering LK - https://open.uct.ac.za PY - 2019 T1 - Synchronising coherent networked radar using low-cost GPS-disciplined oscillators TI - Synchronising coherent networked radar using low-cost GPS-disciplined oscillators UR - http://hdl.handle.net/11427/30829 ER - | en_ZA |
| dc.identifier.uri | http://hdl.handle.net/11427/30829 | |
| dc.identifier.vancouvercitation | Sandenbergh JS. Synchronising coherent networked radar using low-cost GPS-disciplined oscillators. []. ,Engineering and the Built Environment ,Department of Electrical Engineering, 2019 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/30829 | en_ZA |
| dc.language.rfc3066 | eng | |
| dc.publisher.department | Department of Electrical Engineering | |
| dc.publisher.faculty | Faculty of Engineering and the Built Environment | |
| dc.subject | Electrical Engineering | |
| dc.title | Synchronising coherent networked radar using low-cost GPS-disciplined oscillators | |
| dc.type | Doctoral Thesis | |
| dc.type.qualificationlevel | Doctoral | |
| dc.type.qualificationname | PhD |