Method and apparatus for performing joint channel and time estimation in a GNSS receiver

A receiver for use with a global navigation satellite system (GNSS) comprising multiple satellites, wherein each satellite transmits a respective navigation signal containing a spreading code, and wherein the GNSS maintains a time reference which is encoded into the navigation signals, the receiver comprising:

• a receiver clock;
• at least one antenna for receiving multiple signals over multiple respective channels, each channel being defined by a transmitting satellite and a receiving antenna at opposing ends of the channel;
• and
• at least one correlator for calculating cross-correlation functions between (i) the signals received over the multiple channels and (ii) reference versions of the navigation signals provided by the receiver;
• wherein the receiver is configured to use the calculated cross-correlation functions to perform a joint estimate of (i) a clock bias of the receiver clock relative to the time reference maintained by the GNSS, and (ii) a composite channel comprising the combined contribution of the multiple channels as a function of time-delay;
• and
• wherein the clock bias of the receiver clock is estimated as an offset from an approximate clock bias.