Performance comparison of waveforms for high-precision RF ranging

摘要

This thesis investigates the performance of modulating waveforms for use in a land-based, high precision, continuous-wave RF ranging system operating in the VHF frequency range. Carrier phase measurement is the basis for many high precision RF ranging systems. However, with continuous-wave RF systems the integer ambiguity of the carrier cycles must also be resolved when integrating carrier phase measurement into the range calculation. By using a suitable modulating waveform in these ranging systems, the receiver will have the ability to obtain both accurate carrier phase as well as resolution of carrier cycle ambiguity. Seven waveforms are proposed in this thesis. The selection was based on either their outstanding autocorrelation characteristics or their distinctive power spectrum. The performance of each proposed waveform, with respect to ranging accuracy and resolution of carrier cycle ambiguity, was analyzed and simulated in the presence of white Gaussian noise and multipath interference. The performance comparison was carried out under the same criteria including equal signal power, bandwidth and integration time. The best performance was obtained with a binary offset carrier (BOC) PN code whose subcarrier is a square wave with a fundamental frequency twice its PN code chip rate. From all the proposed candidate waveforms, the BOC PN code would be the optimum signal for a ranging system using high precision carrier phase measurement.