Differential doppler velocity GPS receiver

Claim 2

method for computing the velocity of a GPS satellite receiver from information obtained from the apparent doppler frequency shift of (four) carrier signals, each transmitted by a respective one of at least two (four) satellites, wherein the receiver comprises: means for receiving each of the carrier signals and means for computing, the method including the steps of computing a first number which represents the difference between the apparent doppler frequency shift of the received carrier signal which is transmitted by a first one of the satellites and which is measured over a first predetermined time period, and the apparent doppler frequency shift of the received carrier signal which is transmitted by one of said satellites other than said first satellite and which is measured over a predetermined time period at least a portion of which includes at least a portion of said first predetermined time period, and using said first number for computing said receiver velocity.

Claim 3

The method set forth in claim 1 further including the steps of computing a second number which represents the difference between the apparent doppler frequency shift of the received carrier signal which is transmitted by a second one of said satellite and which is measured over a second predetermined time period, and the apparent doppler frequency shift of the received carrier signal which is transmitted by one of said satellites other than said second satellite and which is measured over a predetermined time period at least a portion of which includes at least a portion of said second predetermined time period, computing a third number which represents the difference between the apparent doppler frequency shift of the received carrier signal which is transmitted by a third one of said satellites and which is measured over a third predetermined time period, and the apparent doppler frequency shift of the received carrier signal which is transmitted by one of said satellites other than said third satellite and which is measured over a predetermined time period at least a portion of which includes at least a portion of said third predetermined time period, and computing the velocity of the receiver (8) from said first, said second and said third numbers.

Claim 4

The method set forth in claim 1 or 2 for computing means alloted to a j th , a k th , a l th , a m th , a n th and an o th satellite, wherein said first number represents the difference between the apparent doppler frequency shift of the received carrier signal which is transmitted by the j th satellite and which is measured over a first predetermined time period and the apparent doppler frequency shift of the received carrier signal which is transmitted by the k th satellite and which is measured over a predetermined time period at least a portion of which includes at least a portion of said first predetermined time period, said first number being equal to: (( v j · r j + v u · r j ) - ( v k · r k + v u · r k ))­(2f c /c) where: v j is the (three dimensional) velocity of said jth satellite, r j is a unit vector pointing from said jth satellite to the receiver, v k is the velocity of said kth satellite, r k is a unit vector pointing from said kth satellite to said receiver, v u is said receiver velocity, f c is the carrier frequency of said satellites, and c is the speed of light, said second number represents the difference between the apparent doppler frequency shift of the received carrier signal which is transmitted by the l th satellite and which is measured over a second predetermined time period and the apparent doppler frequency shift of the received carrier signal which is transmitted by the m th satellite and which is measured over a predetermined time period at least a portion of which includes at least a portion of said second predetermined time period, said second number being equal to: (( v l · r l + v u · r l ) - ( v m · r m + v u · r m ))­(2f c /c) where: v l is the (three dimensional) velocity of said lth satellite, r l is a unit vector pointing from said lth satellite to said receiver, v m is the velocity of said mth satellite, r m is a unit vector pointing from said mth satellite to said receiver, and said third number represents the difference between the apparent doppler frequency shift of the received carrier signal which is transmitted by the n th satellite and which is measured over a third predetermined time period and the apparent doppler frequency shift of the received carrier signal which is transmitted by the o th satellite and which is measured over a predetermined time period at least a portion of which includes at least a portion of said third predetermined time period, said third number being equal to: (( v n · r n + v u · r n ) - ( v o · r o + v u · r o ))­(2f c /c) where: v n is the (three dimensional) velocity of said nth satellite, r n is a unit vector pointing from said nth satellite to said receiver, v o is the velocity of said oth satellite, r o is a unit vector pointing from said oth satellite to said receiver.

Claim 5

A GPS satellite receiver for computing the velocity of the receiver from information obtained from the apparent doppler frequency shift of (four) carrier signals each transmitted by a respective one of at least two (four) satellites, the receiver (8) comprising the combination: a receiver channel (10) for receiving each of the carrier signals; a first tracking channel (98) connected to said receiver channel (10), said first tracking channel for determining the apparent doppler frequency shift of the one of said received carrier signals which is transmitted by a first one of the satellites; a second tracking channel (110) connected to said receiver channel (10), said second tracking channel for determining the apparent doppler frequency shift of the one of said received carrier signals which is transmitted by a second one of said satellites; and computing means (70) connected to said first and said second tracking channels (98, 110), said computing means for computing a first number which represents the difference between the apparent doppler frequency shift of said first satellite-received-carrier signal measured over a first predetermined time period and the apparent doppler frequency shift of said second satellite-received-carrier signal measured over a predetermined time period at least a portion of which includes at least a portion of said first predetermined time period and for computing the velocity of the receiver with said first number.

Claim 6

A GPS satellite receiver for computing the velocity of the receiver from information obtained from the apparent doppler frequency shift of (four) carrier signals each transmitted by a respective one of at least two (four) satellites, the receiver (8) comprising the combination: a receiver channel (10) for receiving each of the carrier signals; a first tracking channel (98) connected to said receiver channel (10), said first tracking channel for determining the apparent doppler frequency shift of the one of said received carrier signals which is transmitted by a first one of the satellites; a second tracking channel (110) connected to said receiver channel (10), said second tracking channel for determining the apparent doppler frequency shift of the one of said received carrier signals which is transmitted by a second one of said satellites; and computing means (70) connected to said first and said second tracking channels (98, 110), said computing means for computing a first number which represents the difference between the apparent doppler frequency shift of said first satellite-received-carrier signal measured over a first predetermined time period and the apparent doppler frequency shift of said second satellite-received-carrier signal measured over a predetermined time period at least a portion of which includes at least a portion of said first predetermined time period and for computing the velocity of the receiver with said first number.

Claim 7

The GPS satellite receiver as recited in claim 3 further comprising a third tracking channel (112) connected to said receiver channel (10), said third tracking channel for determining the apparent doppler frequency shift of the one of said received-­carrier signals which is transmitted by a third one of said satellites, wherein said computing means (70) further computes a second number which represents the difference between the apparent doppler frequency shift of said first satellite-received-­carrier signal measured over said first predetermined time period and the apparent doppler frequency shift of said third satellite-received-carrier signal measured over a predetermined time period at least a portion of which includes at least a portion of said first predetermined time period, and wherein said computing means further computes the velocity of said receiver with said first and said second numbers.

Claim 8

The GPS satellite receiver as recited in claim 4 further comprising a fourth tracking channel (114) connected to said receiver channel (10), said fourth tracking channel for determining the apparent doppler frequency shift of the one of said received-­carrier signals which is transmitted by a fourth one of said satellites and a fifth tracking channel (116) connected to said receiver channel (10), wherein said computing means further computes a third number which represents the difference between the apparent doppler frequency shift of said first satellite-received-carrier signal measured over said first predetermined time period and the apparent doppler frequency shift of said fourth satellite-­received-carrier signal measured over a predetermined time period at least a portion of which includes at least a portion of said first predetermined time period, and wherein said computing means (70) further computes the velocity of said receiver from said first, said second and said third numbers.

Claim 9

The GPS satellite receiver as recited in any of claims 4 to 6 wherein said first tracking channel (98, 112, 114, 116) includes carrier-synthesizer means (54) for generating a signal (on 84) having a frequency established by a first set of number signals and counter means (60) connected to said receiver channel (20-50) and connected to said first tracking-­channel-carrier-sythesizer means (54), said first tracking-­channel-counter means (60) for developing signals representing a count which is incremented at each of a series of times marked by said first tracking-channel-carrier-synthesizer-­means-generated signal (on 84) when a signal developed from said first satellite-received-carrier signal has a predetermined one of two states and decremented at each of said first tracking-channel-carrier-synthesizer-means-­generated-signal marked times (on 86) otherwise, wherein said second tracking channel (110) includes carrier-­synthesizer means (54′) for generating a signal having a frequency established by a second set of number signals and counter means (60′) connected to said receiver channel (20-50) and connected to said second tracking-channel-carrier-­synthesizer means (54′), said second tracking-channel-counter means (60′) for developing signals representing a count which is incremented at each of a series of times marked by said second tracking-channel-carrier-synthesizer-means-generated signal (on 84′) when a signal developed from said second satellite-received-carrier signal has a predetermined one of two states and decrmented at each of said second tracking-­channel-carrier-synthesizer-means-generated-signal marked times (on 86′) otherwise, wherein said computing means (70) is responsive to said first tracking-channel-counter-means-developed signals and operative to develop said first tracking-channel-carrier-synthesizer-­means-first-number signals (on 84) so as to lock the frequency of said first tracking-channel-carrier-synthesizer-means-­ generated signal to the frequency of said first-satellite-­received-carrier signal, and wherein said computing means (70) is responsive to said second tracking-channel-counter-means-developed signals (on 84′) and operative to develop said second tracking-channel-carrier-­synthesizer-means-second-number signals so as to lock the frequency of said second tracking-channel-carrier-synthesizer-­means-generated signal to the frequency of said second-­satellite-received-carrier signal.

Claim 10

The GPS satellite receiver as recited in any of claims 4 to 7 for carrier signals which are transmitted by a respective one of four satellites and each biphase modulated by a respective PRN code, wherein the receiver channel (10) is adapted for down-converting the frequency of each of the carrier signals; said first tracking channel (98) connected to said receiver channel and adapted for determining the apparent doppler frequency shift of the one of said down-converted-carrier signals which is transmitted by said first satellite, said first tracking channel (98) including, carrier-synthesizer means (54) for generating a first signal (on 84) having a frequency established by a first set of number signals; PRN-code-synthesizer means (52) for generating an early (76), a punctual (74) and a late (78) signal each representing said first satellite-PRN code and each having a phase established by first tracking-channel-PRN-code-synthesizer-means-driving signals; exclusive-OR-gate means (56) connected to said first tracking-­channel-PRN-code-synthesizer means (52) and connected to said receiver channel (20-50), said first tracking-channel-­exclusive-OR-gate means (56) for comparing the state of a signal (on 50) developed from said first satellite-down-­converted signal with the state of said first tracking-­channel-PRN-code-synthesizer-means-generated punctual signal tracking-channel-Q-counter means for developing signals representing a count which is incremented at each of a series of times marked by said second tracking-channel-carrier-­synthesizer-means-generated first signal when said second tracking-channel-exclusive-OR-gate-developed signal has a predetermined one of two states and decremented at each of said second tracking-channel-carrier-synthesizer-means-­generated-first-signal marked times otherwise; and computer means (70) connected to said first tracking-channel-­carrier-synthesizer means (54), connected to said first tracking-channel-Q-counter means (60), connected to said second tracking-channel-carrier-synthesizer means (54′), and connected to said second tracking-channel-Q-counter means (60′), said computer means (70) being responsive to said first tracking-channel-Q-counter-means-developed signals and operative to develop said first tracking-channel-carrier-­synthesizer-means-driving first number signals so as to lock the frequency of said first tracking-channel-carrier-­synthesizer-means-generated first signal to the frequency of said first satellite-down-converted signal and responsive to said second tracking-channel-Q-counter-means-developed signals and operative to develop said second tracking-channel-carrier-­synthesizer-means-driving second number signals so as to lock the frequency of said second tracking-channel-carrier-­synthesizer-means-generated first signal to the frequency of said second satellite-down-converted-signal.

Claim 11

The GPS satellite receiver as recited in claim 8 wherein said first tracking channel (98) further includes early/late means (62, 64, 66, 68) connected to said first tracking-channel-PRN-code-synthesizer means (52), connected to said first tracking-channel-carrier-synthesizer means (54), connected to said receiver channel (60) and connected to said computer means (70), said first tracking-channel-early/late means (62, 64, 66, 68) for comparing the state of said signal developed from said first satellite-down-converted-signal (on 50) with the state of said early and said late first tracking-­channel-PRN-code-synthesizer-means-developed signals (on 76, 78) to develop controller-means-driving signals representing the difference between an early and a late count, wherein said a second tracking channel (110) further includes early/late means (62′, 64′, 66′, 68′) connected to said second tracking-channel-PRN-code-synthesizer means (52′), connected to said second tracking-channel-carrier-synthesizer means (54′), connected to said receiver channel (10), and connected to said computer means (70), said second tracking-channel-­early/late means (62′-68′) for comparing the state of said signal develop from said second satellite-down-converted-­signal with the state of said early and said late second tracking-channel-PRN-code-synthesizer-means-developed signals to develop controller-means-driving signals representing the difference between an early and a late count, wherein said controller means (70) is further responsive to said first tracking-channel-early/late-means-developed signals and operative to develop said first tracking-channel-PRN-code-­synthesizer-means-driving signals so as to lock the phase of said first tracking-channel-PRN-code-synthesizer-developed signals to said first satellite-signal PRN-code phase, and wherein said controller means (70) is further responsive to said second tracking-channel-early/late-means-developed signals and operative to develop said second tracking-channel-­PRN-code-synthesizer-means-driving signals so as to lock the phase of said second tracking-channel-PRN-code-synthesizer-­developed signals to said second satellite-signal PRN-code phase.

Claim 12

The GPS satellite receiver as recited in claim 8 or 9 wherein said first tracking-channel-carrier-synthesizer means (54) further generates a second signal (on 82) which is in phase quadrature with said first tracking-channel-carrier-­synthesizer-means-generated first signal (on 84), wherein said first tracking channel (98) further includes I-­counter means (58) connected to said first tracking-channel-­exclusive-OR-means (56), connected to said first tracking-­channel-carrier-synthesizer means (56) and connected to said computer means (70), said first tracking-channel-I-counter means (58) for developing computer-means-driving signals representing a count which is incremented at each of a series of times marked by said first tracking-channel-carrier-­synthesizer-means-generated-second signal (on 82) when said first tracking-channel-exclusive-OR-gate-developed signal (on 86) has a predetermined one of two states and decremented at each of said first tracking-channel-carrier-synthesizer-means-­generated-second signal marked times otherwise, wherein said second tracking-channel-carrier-synthesizer means (54′) further generates a second signal which is in phase quadrature with said second tracking-channel-carrier-­synthesizer-means-generated first signal, and wherein said second tracking channel (110) further includes I-­counter means (58′) connected to said second tracking-channel-­exclusive-OR-gate means (56′), connected to said second tracking-channel-carrier-synthesizer means (54′) and connected to said computer means (70), said second tracking-channel-I-­counter means (58′) for developing computer-means-driving signals representing a count which is incremented at each of a series of times marked by said second tracking-channel-­carrier-synthesizer-means-generated-second signal when said second tracking-channel-exclusive-OR-gate-developed signal has a predetermined one of two states and decremented at each of said second tracking-channel-carrier-synthesizer-means-­generated-second signal marked times otherwise.