A METHOD OF PROCESSING OFFSET CARRIER MODULATED RANGING SIGNALS

摘要

A method of processing certain offset-carrier modulated ranging signals which are synchronously broadcast with another signal having a nearby centre frequency. The method comprises receiving a first radionavigation signal from at least one of a plurality of transmitters and deriving therefrom a first OCM signal S A , and generating a combined correlation value Y C , the combined correlation value Y C corresponding to the correlation of a combined signal S C with a replica of the first OCM signal, the combined signal S C resulting from the coherent combination of first OCM signal S A with a second signal S B having the same or nearby centre frequency to the first OCM signal S A . The method further comprises deriving ranging information based on the combined correlation value Y C . The second signal S B may comprise one of (i) an OCM signal and (ii) a BOC signal. The combination of the two signal components may be done before or after the correlation operation. When adopted by a ranging receiver, the technique offers improved performance in the area of: signal acquisition and reacquisition, in particular reducing the likelihood of side-peak acquisition; fine-acquisition and tracking: reducing or eliminating the likelihood of false code-lock.