Method and apparatus for prefiltering a global positioning system receiver

Claim 1

A method for prefiltering a global positioning system receiver, comprising the steps of: a) receiving a plurality of L-band radio frequency signals having unique modulation and originating in a plurality of global positioning system satellites; b) splitting said plurality of radio frequency signals into at least a first L1 radio frequency signal and a second L2 radio frequency signal; c) passing said first L1 radio frequency signal to a first radio frequency receiving section through a L1 signal passage defining a path from a common junction point to said L1 radio frequency receiving section, while simultaneously passing said L2 radio frequency signal to a second radio frequency receiving section through a L2 signal passage defining a path from said common junction point to said L2 radio frequency receiving section; d) filtering said L1 radio frequency signal from the L2 signal passage and filtering said L2 radio frequency signal from the L1 signal passage, while substantially preserving the L1 radio frequency and the L2 radio frequency signals and matching the lengths of said L1 passage and said L2 passage such that the impedance at the end of said L2 passage is substantially infinite with respect to a center frequency of the L1 radio frequency signal and the impedance at the end of said L1 passage is substantially infinite with respect to a center frequency of the L2 radio frequency signal; and e) feeding said L1 and said L2 radio frequency signals in step d to said first L1 radio frequency receiving section and said second L2 radio frequency receiving section, for determining position information.

Claim 2

A method for prefiltering a global positioning system receiver, comprising the steps of: a) receiving a plurality of L-band radio frequency signals having unique modulation and originating in a plurality of global positioning system satellites; b) splitting said plurality of radio frequency signals into at least a first L1 radio frequency signal and a second L2 radio frequency signal; c) passing said first L1 radio frequency signal to a first radio frequency receiving section through a L1 signal passage defining a path from a common junction point to said L1 radio frequency receiving section, while simultaneously passing said L2 radio frequency signal to a second radio frequency receiving section through a L2 signal passage defining a path from said common junction point to said L2 radio frequency receiving section; d) filtering said L1 radio frequency signal from the L2 signal passage and filtering said L2 radio frequency signal from the L1 signal passage, while substantially preserving the L1 radio frequency and the L2 radio frequency signals and matching the lengths of said L1 passage and said L2 passage such that the impedance at the end of said L2 passage is substantially infinite with respect to a center frequency of the L1 radio frequency signal and the impedance at the end of said L1 passage is substantially infinite with respect to a center frequency of the L2 radio frequency signal; and e) feeding said L1 and said L2 radio frequency signals in step d to said first L1 radio frequency receiving section and said second L2 radio frequency receiving section, for determining position information.

Claim 14

A method for pre-filtering a global positioning system receiver, comprising the steps of: (a) receiving a plurality of L-band radio frequency signals having unique modulation and originating in a plurality of global positioning system satellites; (b) splitting said plurality of radio frequency signals into at least a first L1 radio frequency signal and a second L2 radio frequency signal; (c) passing said first L1 radio frequency signal to a first radio frequency receiving section through a L1 signal passage defining a path from a common junction point to said L1 radio frequency receiving station, while simultaneously passing said L2 radio frequency signal to a second radio frequency receiving section through a L2 signal passage defining a path from said common junction point to said L2 radio frequency receiving section; (d) isolating said L1 radio frequency signal from the L2 signal passage and isolating said L2 radio frequency signal from the L1 signal passage, while substantially preserving the L1 radio frequency and L2 radio frequency signals; (1) fixing the lengths of said L2 passage such that the impedance at the end of said L2 passage is substantially infinite with respect to said L1 radio frequency signal; (2) fixing the length of said L1 passage such that the impedance at the end of said L2 passage is substantially infinite with respect to said L2 radio frequency signal; (3) matching the lengths of said L1 passage and said L2 passage such that the impedance at the end of said L2 passage is substantially infinite with respect to the L1 radio frequency signal and the impedance at the end of said L1 passage is substantially infinite with respect to the L2 radio frequency signal; and (4) simultaneously, substantially minimizing unwanted reflection of L1 and L2 radio frequency signals along the L2 and L1 paths, respectively; (e) feeding said L1 and said L2 radio frequency signals to said first L1 radio frequency receiving section and said second L2 radio frequency receiving section; (f) developing intermediate frequency signals in the first L1 radio frequency receiving section and the second L2 radio frequency receiving station; and (g) processing said intermediate frequency signals for determining a relative phase for each signal and end quantities of position, distance, velocity, time or the like.

Claim 15

A method for pre-filtering a global positioning system receiver, comprising the steps of: (a) receiving a plurality of L-band radio frequency signals having unique modulation and originating in a plurality of global positioning system satellites; (b) splitting said plurality of radio frequency signals into at least a first L1 radio frequency signal and a second L2 radio frequency signal; (c) passing said first L1 radio frequency signal to a first radio frequency receiving section through a L1 signal passage defining a path from a common junction point to said L1 radio frequency receiving station, while simultaneously passing said L2 radio frequency signal to a second radio frequency receiving section through a L2 signal passage defining a path from said common junction point to said L2 radio frequency receiving section; (d) isolating said L1 radio frequency signal from the L2 signal passage and isolating said L2 radio frequency signal from the L1 signal passage, while substantially preserving the L1 radio frequency and L2 radio frequency signals; (1) fixing the lengths of said L2 passage such that the impedance at the end of said L2 passage is substantially infinite with respect to said L1 radio frequency signal; (2) fixing the length of said L1 passage such that the impedance at the end of said L2 passage is substantially infinite with respect to said L2 radio frequency signal; (3) matching the lengths of said L1 passage and said L2 passage such that the impedance at the end of said L2 passage is substantially infinite with respect to the L1 radio frequency signal and the impedance at the end of said L1 passage is substantially infinite with respect to the L2 radio frequency signal; and (4) simultaneously, substantially minimizing unwanted reflection of L1 and L2 radio frequency signals along the L2 and L1 paths, respectively; (e) feeding said L1 and said L2 radio frequency signals to said first L1 radio frequency receiving section and said second L2 radio frequency receiving section; (f) developing intermediate frequency signals in the first L1 radio frequency receiving section and the second L2 radio frequency receiving station; and (g) processing said intermediate frequency signals for determining a relative phase for each signal and end quantities of position, distance, velocity, time or the like.

Claim 19

An apparatus for prefiltering a global positioning system receiver, comprising: means for receiving a plurality of L-band radio frequency signals having unique modulation and originating in a plurality of global positioning system satellites; means for splitting said plurality of radio frequency signals into at least a first L1 radio frequency signal and a second L2 radio frequency signal; passing means for passing said first L1 radio frequency signal to a first radio frequency receiving section through a L1 signal passage defining a path from a common junction point to said L1 radio frequency receiving station, and passing said L2 radio frequency signal to a second radio frequency receiving section through a L2 signal passage defining a path from said common junction point to said L2 radio frequency receiving section; means for filtering said L1 radio frequency signal from the L2 signal passage and filtering said L2 radio frequency signal from the L1 signal passage, while substantially preserving the L1 radio frequency and the L2 radio frequency signals, said filtering means includes a first length defined as the length of said L2 passage such that the impedance at the end of said L2 passage is substantially infinite with respect to said L1 radio frequency signal, and a second length defined as the length of said L1 passage such that the impedance at the end of said L1 passage is substantially infinite with respect to said L2 radio frequency signal.

Claim 20

An apparatus for prefiltering a global positioning system receiver, comprising: means for receiving a plurality of L-band radio frequency signals having unique modulation and originating in a plurality of global positioning system satellites; means for splitting said plurality of radio frequency signals into at least a first L1 radio frequency signal and a second L2 radio frequency signal; passing means for passing said first L1 radio frequency signal to a first radio frequency receiving section through a L1 signal passage defining a path from a common junction point to said L1 radio frequency receiving station, and passing said L2 radio frequency signal to a second radio frequency receiving section through a L2 signal passage defining a path from said common junction point to said L2 radio frequency receiving section; means for filtering said L1 radio frequency signal from the L2 signal passage and filtering said L2 radio frequency signal from the L1 signal passage, while substantially preserving the L1 radio frequency and the L2 radio frequency signals, said filtering means includes a first length defined as the length of said L2 passage such that the impedance at the end of said L2 passage is substantially infinite with respect to said L1 radio frequency signal, and a second length defined as the length of said L1 passage such that the impedance at the end of said L1 passage is substantially infinite with respect to said L2 radio frequency signal.