Coding in a positioning system

A system comprising at least one processor that is operable to implement a method for using positioning signals modulated with selected pseudorandom sequences to estimate a position of a receiver, the method comprising:

• computing an estimated position of the receiver using positioning signals acquired by the receiver from a plurality of transmitters,
• wherein at least a portion of a first positioning signal acquired by the receiver from a first transmitter is modulated with a first pseudorandom sequence,
• wherein at least a portion of a second positioning signal acquired by the receiver from a second transmitter is modulated with a second pseudorandom sequence,
• wherein at least a portion of a third positioning signal acquired by the receiver from a third transmitter is modulated with a third pseudorandom sequence,
• wherein the first, second and third pseudorandom sequences are different members of a subset of at least three pseudorandom sequences from a set of pseudorandom sequences,
• wherein a magnitude of an autocorrelation function of each member of the set of pseudorandom sequences, within a range adjacent to the peak value of the autocorrelation function, is equal to or less than a prescribed value, and
• wherein each magnitude of a cross-correlation function between each pair of pseudorandom sequences in the subset of pseudorandom sequences is below a specified threshold.

A non-transitory processor readable memory storing program instructions that, when executed by one or more processors, cause the one or more processors to implement a method for using positioning signals modulated with selected pseudorandom sequences to estimate a position of a receiver, the method comprising:

• computing an estimated position of the receiver using positioning signals acquired by the receiver from a plurality of transmitters,
• wherein at least a portion of a first positioning signal acquired by the receiver from a first transmitter is modulated with a first pseudorandom sequence,
• wherein at least a portion of a second positioning signal acquired by the receiver from a second transmitter is modulated with a second pseudorandom sequence,
• wherein at least a portion of a third positioning signal acquired by the receiver from a third transmitter is modulated with a third pseudorandom sequence,
• wherein the first, second and third pseudorandom sequences are different members of a subset of at least three pseudorandom sequences from a set of pseudorandom sequences,
• wherein a magnitude of an autocorrelation function of each member of the set of pseudorandom sequences, within a range adjacent to the peak value of the autocorrelation function, is equal to or less than a prescribed value, and
• wherein each magnitude of a cross-correlation function between each pair of pseudorandom sequences in the subset of pseudorandom sequences is below a specified threshold.