Evaluation of coherent netted radar carrier stability while synchronised with GPS-disciplined oscillators

In this paper the dual-mixer time delay (DMTD) technique is used to characterize netted radar carrier stability. Moreover, the performance of synchronization via twisted-pair (TP) cable was compared to that of GPS-disciplined oscillators (GPSDO). This was done using an experimental coherent netted radar (NetRAD), developed at University College London (UCL), UK, and quartz-based GPSDOs, developed at the University of Cape Town (UCT), South Africa. NetRAD was configured as a DMTD test bench, using the existing radar hardware. Parameters such as time and frequency offset, time deviation and Allan deviation were extracted through post-processing of the sampled IF signal. Zero-range measurements conducted under laboratory conditions are presented alongside field measurements conducted over a base-line of 100 metres. Performance of the UCT GPSDOs and the reference TP cable systems were comparable in terms of frequency stability and phase jitter. However, as was expected, the GPSDO time sync was much less precise.