Article,

Novel GNSS Receiver Design Based On Satellite Signal Channel Transfer Function/Impulse Response

, and .
Proc. of the 18th ION GNSS Conf., (2005)

Abstract

Conventional GNSS receiver designs are based on the fundamental concept of correlation between the received GNSS satellite signal and a reference code of interest to acquire. The correlation as implemented in today widely used receivers assume different forms such as active parallel correlators and passive matched filters, either in hardware or in software or hybrid. This paper introduces the concepts of satellite signal channel transfer function and signal channel impulse response and present their use to design GNSS receivers for timing and positioning as well as for propagation and environment characterization. One advantage of this design approach is that the satellite specific signal channel transfer function/impulse response does not depend on the underlying code sequence. This is in sharp contrast to correlation function which is code dependent. Such dependence requires a conventional receiver to handle a BOC modulation code differently than a BPSK modulation code. This is because the former has many sidelobes of significant strength as compared to the mainlobe. Without special hardware and software, a conventional receiver runs the risk of being trapped in nulls (missing detection) or of locking onto a sidelobe (biased measurements). Ideally, the satellite signal channel impulse response is a Dirac delta function which has an infinite time resolution capability, thus being immune to multipath. In practice, however, both the satellite signals and receivers are bandlimited. The impulse response estimated from sample data is a sinc function with its first nulls at +/-Ts, where Ts is the sampling interval. Even so, the impulse response peak still has its base much narrower than that of a correlation function. As such, it is less sensitive to multipath than conventional receivers. In this paper, we formulate the concepts, present the novel GNSS receiver architecture, and detail implementation schemes. Simulation results are also presented to illustrate the utilities of this novel design approach.

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