Abstract: A real-time integrated navigation system for a vehicle includes a GPS receiver, connected to a first antenna, where the GPS receiver receives GPS data from satellites and outputs GPS position data. The system also includes a communications link, connected to a second antenna and to the GPS receiver, receiving range and carrier phase measurements from at least one base station. The system further includes navigation aids which provide relative position data of said vehicle and a Kalman filter, connected to the output of the GPS receiver and the navigation aids, that integrates the GPS position data and the relative position data and outputs smoothed position data. The smoothed position data is used in transportation applications, especially detection of lane departure. This GPS-based positioning system is suitable for highway speeds during all weather conditions.

Abstract: A real-time integrated navigation system for a vehicle includes a GPS receiver, connected to a first antenna, where the GPS receiver receives GPS data from satellites and outputs GPS position data. The system also includes a communications link, connected to a second antenna and to the GPS receiver, receiving range and carrier phase measurements from at least one base station. The system further includes navigation aids which provide relative position data of said vehicle and a Kalman filter, connected to the output of the GPS receiver and the navigation aids, that integrates the GPS position data and the relative position data and outputs smoothed position data. The smoothed position data is used in transportation applications, especially detection of lane departure. This GPS-based positioning system is suitable for highway speeds during all weather conditions.

Abstract: A variable pulse rate circuit for correlating a locally generated code with code that is being transmitted by a space vehicle. A computer means is used for providing a binary word to a latch. The binary word in the latch is used in turn by a delay line, to control the amount of delay that is presented to pulses. The pulses are emitted by a pulse generator having a fixed rate reference. The pulse rate, of pulses being emitted by of the delay line, is varied from the reference pulse rate. This variation is the result of computer means that rapidly changes the amount of delay of the delay line. The pulse rate and the pulse phase are varied in order to cause a locally generated code to become phase aligned with the code received from the space vehicle. The space vehicle is tracked using the variable pulse rate circuit.

Abstract: An apparatus for generating pseudo-random codes is disclosed. The apparatus uniquely stores a set of codes in a memory and uniquely retrieves a particular code sequence. The apparatus has particular application to Global Position Satellite (GPS) earth receivers.

Abstract: The reception, downconversion and retransmission of the 1575.42 MH.sub.z Global Positioning System (GPS) satellite signal is accomplished by the following. First, an RF stage comprising of an antenna, filter and preamplifier receiver, filters and amplifies the 1575.42 MH.sub.z signals. Following the RF stage, a converter stage, consisting of a bandpass filter, converts the GPS signal to a lower frequency. Then, an Intermediate Frequency (IF), comprising an IF amplifier, multiplier, bandpass filter and limiter further amplifies and filters the signals to remove the effects of the signals. A final downconverter converts the signal to a base band frequency and in a zero crossing detector the signal is amplified and 1 bit quantized. Finally, a local oscillator controls a frequency synthesizer to latch the signal from the zero crossing detector in a flip flop, which in turn is used to control a quadraphase monitor, whose signals are amplified and transmitted out the transmit antenna.