Fast sequencing demodulation method and apparatus

Claim 2

In a fast sequencing method for sampling N simultaneously received signals in a multiple correlator system wherein each of said signals is modulated with data at a rate of 1/T, each data bit being of duration T, and wherein said signals are received and sequentially sampled by a single channel, the improvement comprising the steps of: (a) selecting an integer M≧1; then (b) determining a sampling interval s=T/(N×M); then (c) sequentially sampling, for each sampling interval s, the data from each one of said N signals M times during each data modulation period T such that each one of said N signals is sampled once during each interval of duration N×s, the samples from each signal being uniformly spaced with interval N×s between samples from the same signal; and (d) sequentially repeating step "c" over multiple periods of data modulation.

Claim 3

A method as defined in claim 1 wherein at least four signals are received.

Claim 4

A method as defined in claim 2 further characterized in that: (a) said data rate is 50 bits per second; (b) four signals are received; (c) each signal is sampled M=5 times during each data period; and (d) each sampling interval is one millisecond in duration.

Claim 5

A method as defined in claim 2 wherein said signals are transmitted from GPS system satellites.

Claim 6

In a fast sequencing method for sampling N simultaneously received, individually coded signals in a single correlator system wherein each of said signals is modulated with data at a rate of 1/T, each data bit being of duration T, and wherein said signals are received and sequentially sampled by a single channel, the improvement comprising the steps of: (a) selecting an integer M? l; then (b) determining a sampling interval s=T/((N+l)×M); then (c) sequentially sampling data from each one of said N signals times for sampling intervals equal to s during each data modulation period T; and (d) sampling the code of one of said N signals M times per each period of data modulation T, said samplings of said code occurring once per each sequential sampling of said N signals; and then (e) sequentially repeating steps "c" and "d" over at least N periods of data modulation whereby the code of each of said N signals is tracked for at least one period T.

Claim 7

In a fast sequencing method for sampling N simultaneously received, individually coded signals in a single correlator system wherein each of said signals is modulated with data at a rate of 1/T, each data bit being of duration T, and wherein said signals are received and sequentially sampled by a single channel, the improvement comprising the steps of: (a) selecting an integer M? l; then (b) determining a sampling interval s=T/((N+l)×M); then (c) sequentially sampling data from each one of said N signals times for sampling intervals equal to s during each data modulation period T; and (d) sampling the code of one of said N signals M times per each period of data modulation T, said samplings of said code occurring once per each sequential sampling of said N signals; and then (e) sequentially repeating steps "c" and "d" over at least N periods of data modulation whereby the code of each of said N signals is tracked for at least one period T.

Claim 8

A method as defined in claim 5 wherein at least four signals are received.

Claim 9

A method as defined in claim 6 further characterized in that: (a) said data rate is 50 bits per second; (b) four signals are received; (c) each signal is sampled M=4 times during each data period T; and (d) each sampling interval is one millisecond in duration.

Claim 10

A method as defined in claim 6 wherein said signals are transmitted from GPS system satellites.

Claim 11

Apparatus for demodulating N coded signals, each of said signals being modulated with data at a rate of 1/T, comprising, in combination: (a) means for sequentially selecting a sample of each of said N signals; (b) means for sequentially gating each of said selected N signals at M×N times the data rate where M is an integer that is greater than or equal to one; (c) N summers, each of said summers being arranged to sum said samples of one of said N signals; (d) a multiplexing switch for sequentially directing said selected gated signal samples to said N summers to generate N signal sums at M times the data rate; and (e) means for storing said N signal sums generated during each data period T.

Claim 12

Apparatus for demodulating N coded signals, each of said signals being modulated with data at a rate of 1/T, comprising, in combination: (a) means for sequentially selecting a sample of each of said N signals; (b) means for sequentially gating each of said selected N signals at M×N times the data rate where M is an integer that is greater than or equal to one; (c) N summers, each of said summers being arranged to sum said samples of one of said N signals; (d) a multiplexing switch for sequentially directing said selected gated signal samples to said N summers to generate N signal sums at M times the data rate; and (e) means for storing said N signal sums generated during each data period T.