Pseudorandom noise ranging receiver which compensates for multipath distortion by dynamically adjusting the time delay spacing between early and late correlators

A receiver for demodulating and decoding a composite radio-frequency ranging signal, consisting of a plurality of transmitted signals, one of which is modulated with a predetermined pseudo-random code, the receiver including:

• A. a code generator for generating the pseudo-random code;
• B. a correlation means for synchronizing with the received version of the code the output of the code generator, the correlation means operating in an acquisition mode to synchronize the code generator to within one code chip and operating in a subsequent tracking mode to track the received version of the code, the correlation means
• i. when operating in the tracking mode making correlation measurements that correspond to a correlator spacing that is substantially narrower than one code chip, to reduce the adverse affects of multipath distortion on the code tracking operations;
• and
• ii. when operating in the acquisition mode making correlation measurements that correspond to stepping through the code in steps that are substantially wider than the narrow correlator spacing used in the tracking mode.

A receiver for demodulating and decoding a composite radio-frequency ranging signal, consisting of a plurality of transmitted signals, one of which is modulated with a predetermined pseudo-random code, the receiver including:

• A. a code generator for generating the pseudo-random code;
• B. correlation means for synchronizing the output of the code generator with a version of the code received at the receiver, the correlation means operating in an acquisition mode to synchronize the code generator to the received version of the code and operating in a subsequent tracking mode to track the received version of the code, the correlation means
• i. when operating in the tracking mode simultaneously making early and late correlation measurements at a spacing of less than one code chip in which noise in the measured signals correlates;
• and
• ii. when operating in the acquisition mode making correlation measurements in which the noise in the measured signals does not correlate.

A receiver for demodulating and decoding a composite radio-frequency ranging signal, consisting of a plurality of transmitted signals, one of which is modulated with a predetermined pseudo-random code, the receiver including:

• A. a code generator for generating the pseudo-random code;
• B. a correlation means for synchronizing the output of the code generator with a version of the code received at the receiver, the correlation means operating in an acquisition mode to synchronize the code generator to the received version of the code and operating in a subsequent tracking mode to track the received version of the code, the correlation means
• i. when operating in the tracking mode making early minus late correlation measurements at a spacing of less than one code chip in which noise in the measured signals correlates;
• and
• ii. when operating in the acquisition mode making early and late correlation measurements in which noise in the measured signals does not correlate.

A receiver for demodulating and decoding a composite radio-frequency ranging signal, consisting of a plurality of transmitted signals, one of which is modulated with a predetermined pseudo-random code, the receiver including:

• A. a code generator for generating the pseudo-random code;
• B. correlation means for synchronizing the output of the code generator with a version of the code received at the receiver, the correlation means operating in an acquisition mode to synchronize the code generator to the received version of the code and operating in a subsequent tracking mode to track the received version of the code, the correlation means
• i. when operating in the tracking mode making early and late correlation measurements at a spacing of less than one code chip in which noise in the measured signals correlates and adverse effects of multipath distortion are minimized;
• and
• ii. when operating in the acquisition mode making correlation measurements in which the noise in the measured signals does not correlate.

A receiver for demodulating and decoding a composite radio-frequency ranging signal, consisting of a plurality of transmitted signals, one of which is modulated with a predetermined pseudo-random code, the receiver including:

• A. a code generator for generating the pseudo-random code;
• B. a correlation means for synchronizing the output of the code generator with a version of the code received at the receiver, the correlation means operating in an acquisition mode to synchronize the code generator to the received signal and operating in a subsequent tracking mode to track the received version of the code, the correlation means
• i. when operating in the tracking mode making early minus late correlation measurements at a spacing of less than one code chip in which noise in the measured signals correlates and adverse effects of multipath distortion are minimized;
• and
• ii. when operating in the acquisition mode making early and late correlation measurements in which noise in the measured signals does not correlate.