US5223843A — High performance global positioning system receiv…

Claim 1

Independent Claim 365 words

A high performance global positioning system receiver means for receiving transmitted signals from one or more global positioning satellites and deriving information therefrom used in calculating at least user three-dimensional position and velocity, said transmitted signals from said satellites containing a carrier wave at radio frequency, data regarding ranging information modulated on the carrier wave, and at least one code pseudo-randomly modulated to the carrier wave comprising: a first circuit means including a transmitted signal receiving means, adapted for operative association with an antenna means, for receiving, amplifying and converting transmitted signals from analog to digital signals, said first circuit means comprising; first filter means for selecting a predetermined frequency band signal of the transmitted signal; first amplifying means for pre-amplifying the selected frequency band signal from the first filter means; first frequency mixer means for mixing a first injection frequency into the selected frequency band signal to produce a first intermediate frequency signal; second amplifying means for selectively amplifying the first intermediate frequency signal; signal splitting means for directing the first intermediate frequency signal into first and second pathways; a pair of second frequency mixer means, each mixing an identical but differently phased second injection frequency into said first and second parts of the first intermediate frequency signal to produce differently phased second intermediate frequency signals in each of the first and second pathways; a pair of comparator means for comparing the level of the differently phased second intermediate frequency signals; a pair of analog-to-digital converter means for converting the differently phased second intermediate frequency signals passed by the comparator means to digital signals; and a second circuit means including a signal processing means for processing the digital signals from the first circuit means into ranging information usable in calculating at least the user's position and velocity comprising; frequency correction means for correcting velocity Doppler frequency shifts in the transmitted signal as now represented by the digital signals; third frequency mixer means for mixing appropriate frequencies to multiply off the modulated codes in said digital signals; carrier demodulation means for removing the carrier wave frequencies from the data modulated thereto; means for processing and preparing the digital signals for operative utilization by computer means.

Claim 2

Dependent Claim 365 words

A high performance global positioning system receiver means for receiving transmitted signals from one or more global positioning satellites and deriving information therefrom used in calculating at least user three-dimensional position and velocity, said transmitted signals from said satellites containing a carrier wave at radio frequency, data regarding ranging information modulated on the carrier wave, and at least one code pseudo-randomly modulated to the carrier wave comprising: a first circuit means including a transmitted signal receiving means, adapted for operative association with an antenna means, for receiving, amplifying and converting transmitted signals from analog to digital signals, said first circuit means comprising; first filter means for selecting a predetermined frequency band signal of the transmitted signal; first amplifying means for pre-amplifying the selected frequency band signal from the first filter means; first frequency mixer means for mixing a first injection frequency into the selected frequency band signal to produce a first intermediate frequency signal; second amplifying means for selectively amplifying the first intermediate frequency signal; signal splitting means for directing the first intermediate frequency signal into first and second pathways; a pair of second frequency mixer means, each mixing an identical but differently phased second injection frequency into said first and second parts of the first intermediate frequency signal to produce differently phased second intermediate frequency signals in each of the first and second pathways; a pair of comparator means for comparing the level of the differently phased second intermediate frequency signals; a pair of analog-to-digital converter means for converting the differently phased second intermediate frequency signals passed by the comparator means to digital signals; and a second circuit means including a signal processing means for processing the digital signals from the first circuit means into ranging information usable in calculating at least the user's position and velocity comprising; frequency correction means for correcting velocity Doppler frequency shifts in the transmitted signal as now represented by the digital signals; third frequency mixer means for mixing appropriate frequencies to multiply off the modulated codes in said digital signals; carrier demodulation means for removing the carrier wave frequencies from the data modulated thereto; means for processing and preparing the digital signals for operative utilization by computer means.

Claim 3

Dependent Claim 43 words

The receiver means of claim 1 wherein the first circuit means includes a voltage controlled oscillator adapted for operative connectio to a source of stable reference frequency for providing a frequency output to be utilized in producing the first and second injection frequencies.

Claim 4

Dependent Claim 60 words

The receiver means of claim 2 wherein the first circuit means includes a frequency divider means for dividing the output of the voltage control oscillator means, and including identical outputs for directing second injection frequencies to the pair of second frequency mixer means, said frequency divider including means for offsetting the phase of the second injection frequency from each output.

Claim 5

Dependent Claim 39 words

The receiver means of claim 3 wherein the first circuit means includes a phase lock circuit means for locking the phase of any stable reference frequency with that produced by the voltage control oscillator means and frequency divider means.

Claim 6

Dependent Claim 35 words

The receiver means of claim 3 wherein the frequency divider means includes a timing output means for utilizing the output of the frequency divider means for timing purposes for other parts of the receiver means.

Claim 7

Dependent Claim 19 words

The receiver means of claim 1 wherein the first injection frequency is 137 F, where F equals 10.23 megahertz.

Claim 8

Dependent Claim 35 words

The receiver means of claim 3 wherein the output of the frequency divider means is 137 F divided by 8, where F equals 10.23 megahertz, and the two outputs are related by 90° in phase.

Claim 9

Dependent Claim 21 words

The receiver means of claim 7 wherein the second intermediate frequency is F divided by eight, where F equals 10.23 megahertz.

Claim 10

Dependent Claim 29 words

The receiver means of claim 1 wherein the first circuit means includes a switching means associated with the first filter means for selecting a desired transmitted frequency band signal.

Claim 11

Dependent Claim 21 words

The receiver means of claim 1 wherein the first circuit means includes a multiplexing switch means for switching between multiple inputs.

Claim 12

Dependent Claim 29 words

The receiver means of claim 1 wherein the first amplifying means of the first circuit means includes switch filter means to improve the selectivity of the first circuit means.

Claim 13

Dependent Claim 26 words

The receiver means of claim 1 further comprising a plurality of first and second circuit means for processing transmitted signals from two or more satellites simultaneously.

Claim 14

Dependent Claim 28 words

The receiver means of claim 3 wherein the output of the voltage control oscillator means is divided by the frequency divider means by an integer power of 2.

Claim 15

Dependent Claim 61 words

The receiver means of claim 1 wherein the second amplifying means comprises an automatic gain control circuit including an automatic gain control amplifier connected in an automatic gain control servo loop with a fast automatic gain control function means for providing fast automatic gain control, whereas gain is lowered in the presence of interference, and gain is raised as interference decreases.

Claim 16

Dependent Claim 16 words

The receiver means of claim 1 wherein each second frequency mixer means comprises a quadrature mixer.

Claim 17

Dependent Claim 16 words

The receiver means of claim 1 wherein each comparator means comprises an automatic gain control amplifier.

Claim 18

Dependent Claim 59 words

The receiver means of claim 16 wherein the comparator means further comprises a statistical automatic gain control function means connected in an automatic gain control servo loop with the automatic gain control amplifier to provide slow gain control to the automatic gain control amplifier, whereby the output from the second frequency mixer means is compared to a predetermined level.

Claim 19

Dependent Claim 69 words

The receiver means of claim 14 wherein each comparator means comprises an automatic gain control amplifier having a statistical automatic gain control function means connected thereto in an automatic gain control servo loop for providing slow gain control to the automatic gain control amplifier, so that the fast automatic gain control circuit compensates for time varying amplitude interference, and the slow comparator means provides improved accuracy over long intervals.

Claim 20

Dependent Claim 52 words

The receiver means of claim 1 wherein each analog-to-digital converter means is a three level converter, wherein the converter includes means for recognizing three signal levels, greater than a threshold level, less than the negative of the threshold level, and in between the threshold level and the negative of the threshold level.

Claim 21

Dependent Claim 71 words

The receiver means of claim 19 wherein the converter means includes means to output a digital word having a first bit representing the sign of the signal, whether negative or positive, and a second bit representing the magnitude of the signal, the magnitude falling within the three level, and if the magnitude exceeds the threshold level or is less than the negative of the threshold level, a digital one is output.

Claim 22

Dependent Claim 40 words

The receiver means of claim 19 wherein the converter means includes a pair of signal-to-threshold comparator means for comparing the positive and negative values of the threshold level with the signal, and outputting the signal if it exceeds the threshold.

Claim 23

Dependent Claim 81 words

The receiver means of claim 21 wherein the converter means further comprises adaptive threshold adjustment circuitry including logic means which produces a positive voltage signal if the magnitude of the signal exceeds a threshold level; filtering means for passing voltage a signal representing a fraction of outputs from the comparator means which are non-zero; comparator means for comparing the filtered value with an adjustable variable voltage, the output of this comparison being the threshold level determined by the analog-to-digital converter means.

Claim 24

Dependent Claim 89 words

The receiver means of claim 1 wherein the frequency correction means comprises a phase rotator means which receives the digitized signals from the first circuit means, said digitized signals being offset in phase by 90°, and also receives a velocity Doppler frequency control correction signal computed in a processing computer; a frequency control means for receiving the velocity Doppler frequency control correction signal, and which outputs a frequency control signal to the phase rotator means, so that digitized signals are rotated 90° and the velocity Doppler error is corrected.

Claim 25

Dependent Claim 48 words

The receiver means of claim 1 wherein the second circuit means includes a code generator means for duplicating the codes modulated to the transmitted signal, and directing the duplicating codes to the third frequency mixer means so that the codes can be multiplied off from the digitized signals.

Claim 26

Dependent Claim 43 words

The receiver means of claim 24 wherein a variable code clock means for fine adjustment of the code generator means is operatively connected to the code generator means, and operates from timing frequencies obtained from the first circuit means of the receiver means.

Claim 27

Dependent Claim 85 words

The receiver means of claim 1 wherein the second circuit section further comprises fourth frequency mixer means connected in parallel to the pair of third frequency mixer means, and receiving as one input the digitized signal and as a second input, a code generator signal from a code generator means for duplicating the modulated code of the transmitted signal, the output of the fourth frequency mixer means being directed to the means for processing and preparing the digital signals for operative utilization by computer means.

Claim 28

Dependent Claim 70 words

The receiving means of claim 1 wherein the means for processing and preparing the digital signals to the second circuit means comprises integrate and dump counter means for receiving digitized signals mixed in the third frequency mixer means, counting zero and one values of the digitized signal, and creating eight bit digital signals which can be utilized by computer means and which represent the navigational component of the transmitted signals.

Claim 29

Dependent Claim 17 words

The receiver means of claim 23 wherein the phase rotator means converts the signal to direct current.

Claim 30

Dependent Claim 27 words

The receiver means of claim 28 wherein the signal, prior to entering the phase rotator means, is at F divided by eight where F equals 10.23 megahertz.

Claim 31

Dependent Claim 82 words

The receiver means of claim 1 further comprising a carrier tracking loop means for tracking the carrier wave of the selected transmitted signal from the satellite, providing velocity information regarding the receiver means with respect to the satellites, and demodulating navigational information from the carrier portion of the transmitted signal, and includes a phase rotation means for correcting any Doppler shift between the transmitted signals from the satellite to the receiver means, and correlator means for preparing the signals for software processing.

Claim 32

Dependent Claim 52 words

The receiver means of claim 30 wherein the software means includes means for demodulating the navigational information from the carrier wave of the transmitted signal, means for deriving tracking error for the carrier wave of the transmitted signal, means to compute and derive delta range information, and means to derive velocity information.

Claim 33

Dependent Claim 33 words

The receiver means of claim 30 wherein the output of the correlator means is at 50 hertz, which is the data rate for navigation information on the transmitting signal from the transmitting satellites.

Claim 34

Dependent Claim 82 words

The receiver means of claim 1 further comprising a code lock loop means for tracking the modulated code on the transmitter signal from the satellites, including means for generating early, late, and prompt codes, means for subtracting the early code from the late code, means for correlating the value of the subtracted early minus late code, means to correlate the prompt codes, and software means to multiply the correlated prompt and early minus data codes to produce a code tracking error signal.

Claim 35

Dependent Claim 61 words

The receiver means of claim 33 further comprising first and second delay means connected in series, the prompt signal being produced after passing the signal through the first delay means, the late signal means produced after passing the signal through both first and second delay means, whereas the early signal is not passed through either a first, second and delay means.

Claim 36

Dependent Claim 44 words

The receiving means of claim 34 further comprising a logic device means which subtracts the early code signal from the late code signal and outputs two signals, first indicating whether the remainder is positive or negative, the second containing the magnitude of the remainder.

Claim 37

Dependent Claim 103 words

The receiver means of claim 33 wherein the correlator means comprise a correlator logic device means and an up-down counter means, the correlator logic device means receiving two bit binary signals representing the digitized signal and two bit signals representing digitization of the code, and outputting a two bit binary word representing the multiplication of the two bit signal and code, that output being received by the up and down counter means which is incremented when both magnitude bits are one and sign bits are the same, and which is decremented when the sign bits are different and both magnitude bits are one.

Claim 38

Dependent Claim 32 words

The receiver means of claim 1 wherein a majority of the first circuit means is reducible to microcircuit format; and all of the second circuit means is reducible to a microcircuit format.

Claim 39

Dependent Claim 30 words

The receiving means of claim 37 wherein portions of the first circuit means reducible to microcircuit format can be comprised of hardware on the order of 1.25 micron bulk CMOS.

Claim 40

Dependent Claim 23 words

The receiver means of claim 37 wherein the second circuit means is reducible to microcircuitry on the order of a single GaAs MMIC.

Claim 41

Dependent Claim 199 words

A high performance global positioning system receiver means for receiving global positioning system signals carried at frequencies centered generally at 154 F and 120 F, where F=10.23 Mhz, comprising: a first circuit section including; frequency selection means for selecting between the 154 F or 120 F carrier frequency; frequency generation means adapted to receive a stable reference frequency and convert the same into 137F frequency, that frequency being midway between 154 F and 120 F frequency; means for injecting the 137 F frequency into the selected signal carrier frequency, and to mix the same; signal splitting means for splitting the mixed carrier signal and 137 F generated signal into two pathways; frequency divider means for dividing the 137 F frequency by an integer power of 2; means for injecting the divided 137 F frequency into both pathways and to mix the same to produce a fraction of F frequency; means to convert the fraction of F frequency into a digital representation; a second circuit section including; means to convert the fraction of F frequency to DC; means to process the DC signal to a form usable by a computer means, said DC signal containing the global positioning system information.

Claim 42

Dependent Claim 199 words

A high performance global positioning system receiver means for receiving global positioning system signals carried at frequencies centered generally at 154 F and 120 F, where F=10.23 Mhz, comprising: a first circuit section including; frequency selection means for selecting between the 154 F or 120 F carrier frequency; frequency generation means adapted to receive a stable reference frequency and convert the same into 137F frequency, that frequency being midway between 154 F and 120 F frequency; means for injecting the 137 F frequency into the selected signal carrier frequency, and to mix the same; signal splitting means for splitting the mixed carrier signal and 137 F generated signal into two pathways; frequency divider means for dividing the 137 F frequency by an integer power of 2; means for injecting the divided 137 F frequency into both pathways and to mix the same to produce a fraction of F frequency; means to convert the fraction of F frequency into a digital representation; a second circuit section including; means to convert the fraction of F frequency to DC; means to process the DC signal to a form usable by a computer means, said DC signal containing the global positioning system information.

Claim 43

Dependent Claim 24 words

The means of claim 40 wherein the integer power of 2 is taken from the subset comprising 2, 4, 8, 16, 32, and 64.

Claim 44

Dependent Claim 44 words

The means of claim 10 wherein the integer power of 2 is 8, wherein 137 F divided by 8 equals 17.125 F, which is approximately equal to the difference between 154 F and 137 F, and the difference between 120 F and 137 F.

Claim 45

Dependent Claim 95 words

A high performance global positioning system receiver means comprising: carrier tracking loop means for tracking a carrier wave transmitted by the global positioning system satellites to obtain velocity information and to decode globe position system information, including; phase rotation means for removing the Doppler shift from the signal, said signal having been digitized; correlation means for correlating digitized code and digitized signal signs by taking the exclusive-or logic function result of the same and accumulating this result; number generator means converting velocity information to phase rotation; differentiating means for deriving the derivative of the result.

Claim 46

Dependent Claim 95 words

A high performance global positioning system receiver means comprising: carrier tracking loop means for tracking a carrier wave transmitted by the global positioning system satellites to obtain velocity information and to decode globe position system information, including; phase rotation means for removing the Doppler shift from the signal, said signal having been digitized; correlation means for correlating digitized code and digitized signal signs by taking the exclusive-or logic function result of the same and accumulating this result; number generator means converting velocity information to phase rotation; differentiating means for deriving the derivative of the result.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1996-06-28	1996-12-28	1997-06-29	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2000-06-28	2000-12-28	2001-06-29	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2004-06-28	2004-12-28	2005-06-29	$7700.00	Window Closed / Lapsed

High performance global positioning system receiver means and method

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