A new phase coding is proposed to eliminate the continuous wave interference (CWI) in Loran navigation systems. In fact, CWI is one of the most important noise sources that make errors in signal phase tracking. Consequently, undesirable errors are constructed in time of arrival (TOA) measurement and ultimately navigation precision is reduced dramatically. The performance of Loran navigation systems is improved by applying the proposed phase coding and also using the averaging and phase decoding method. Analyses results show that if the interference is synchronous, then the proposed phase coding, called as Bayat-Madani phase code interval, cancels interference effects on TOA measurement completely. This interference cancelation is independent from the received signal signal-to-interference ratio. For near-synchronous and asynchronous CWI, the TOA error originated from interference is improved considerably, in some frequencies about 100 times, compared to the standard Loran. Furthermore, almost all of the sky multi-hops are eliminated as well.

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Loran phase code revisited for continuous wave interference cancellation

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