Texas Instruments Corporation

Jerry D Holmes

Phillip W Ward

Charles R Johnson

Benjamin L Lowe

Charles Robert Hewes

Joe H Lindley

Robert A Maher

Leonard J LaPadula, Iii

Hatcher E Chalkley

Troy D Fuchser

Samuel D Moore

H Logan Scott

Allen S Jones

A GPS single-receiver pointing/attitude system derives pointing/attitude measurements by correlating a selected GPS code (either P or C/A), recovered from GPS navigation signals using a single GPS receiver with multiple GPS antennas (a reference antenna and at least two slave antennas for pointing or three for attitude). For a two antenna pointing application, the GPS receiver (FIG. 4) includes, for each receiver channel, the incoming GPS signals are applied to three code correlators (72-75) assigned to the reference antenna, and three code correlators (76-77) assigned to the slave antenna, which provide corresponding reference and slave I and Q correlation outputs. The single-receiver pointing technique involves: (a) using the reference I and Q correlation outputs to establish a conventional reference antenna tracking loop; and (b) processing the reference and slave I and Q correlation outputs (using differential carrier doppler phase or code phase measurements) to determine phase differences from which pointing can be computed.

GPS system and method for deriving pointing or attitude from a single

A Global Position System (GPS) receiver is disclosed which includes an RF converter and quadrature digitizer implemented in hardware and a signal processor including a computer, code generator and preprocessor. The preprocessor has a divide by 1,2,3 divider for controlling the code generator so as to provide I,Q early, prompt and late digital signals of 0.5 chip separations to the computer for tracking code phase, carrier phase/frequency and signal amplitude. This structure eliminates the need for numerically controlled oscillators implemented in hardware while maintaining accurate performance.

Global position system receiver

A global positioning system comprises an RF receiver for receiving L.sub.1, L.sub.2 p-code or ca code modulated frequency outputs from one or more space vehicles, a multiplexer operably connected to the receiver multiplexes the L.sub.1 and L.sub.2 signals to the receiver, and code and carrier tracking loops operably connected to the receiver, each loop including a plurality of filters, one for tracking line-of-sight dynamics and another for determining ionosphere effects on the L.sub.1 and/or L.sub.2 signals.

Global position system (GPS) multiplexed receiver

An improved spread spectrum communication system having a transmitter subsystem and a receiver subsystem is disclosed. The transmitter subsystem comprises a data source of 50 bps rate which is modulo-2 added to a C/A (clear/acquisition) code of 1,023K chips/sec in an EXCLUSIVE OR gate, phase modulated on a carrier signal at about 154 f.sub.o where f.sub.o = 10.23 MHz in a phase shift keying modulator and transmitted. The receiver subsystem comprises an antenna for receiving the phase modulated signal, a plurality of filter/amplifier mixer stages for reducing the phase modulated signal to baseband, an in-phase CCD matched filter channel and a quadrature phase CCD matched filter channel for determining the presence of the C/A code and the phase of the incoming C/A code for synchronizing a replica of the C/A code with the incoming C/A code, a mixer for beating the replica C/A code signal with the C/A code signal, a Costas loop for automatic phase control, a sampler for sampling the baseband signal, an integrator for integrating the sampled signals, and a clocked comparator for comparing the integrated signals with a zero voltage at a 50Hz rate to demodulate the data code. Two embodiments of the CCD matched filter are disclosed. The first comprises a CCD having a length equal to five times the number of stages for each period of the C/A code. The second comprises a CCD transversal filter having a feedback loop for use in its transversal filter mode and in a recursive filter mode to enhance C/A code signals relative to noise.

Spread spectrum communication system

A system for generating angular modulation comprising a balanced modulator and an adding circuit to which a surface wave device quadrature oscillator applies two signals at the carrier frequency differing 90.degree. in phase, such phase difference being accurately maintained independent of aging and variations in operating temperatures. More particularly, an information signal is applied to one input of the balanced modulator, the output of which is applied to the adding circuit. The surface wave device oscillator completes the system by applying an in-phase carrier frequency to a second input of the balanced modulator and a carrier frequency shifted 90.degree. in phase to a second input of the adding circuit. Angular modulation is thus produced at the output of the adding circuit.

Surface wave device angle modulator

An SWD structure is employed in an FM receiver for signal demodulation and band limiting. An FM signal is applied to the input of an SWD patterned for bandwidth limitation. Two SWD output channels characterized by predetermined differential delays of the modulated input signal are amplitude limited and mixed to produce an audio modulation component.

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Dallas, TX, United States of America

Jerry D Holmes