Abstract: A navigation system includes a first navigation module having a first operational state wherein the first navigation module does not estimate a current location and a second operational state wherein the first navigation module estimates the current location. A second navigation module performs dead reckoning in response to the first operational state of the first navigation module.

Abstract: A navigation system includes a first navigation module having a first operational state wherein the first navigation module does not estimate a current location and a second operational state wherein the first navigation module estimates the current location. A second navigation module performs dead reckoning in response to the first operational state of the first navigation module.

Abstract: Disclosed is a method which synchronizes a slave time with a master time. The master time is derived from a received signal. The master time is compared to the slave time to detect any offset of the slave time relative to the master time. If an offset is detected, the slave time is adjusted to correct the offset. Also disclosed is a method of synchronizing a pseudolite transmitter time with GNSS time. The transmitter time is compared to GNSS time to detect any offset of the transmitter time. The transmitter time is adjusted to correct the offset if an offset is detected. Also disclosed is an improved pseudolite. The pseudolite has a pseudolite transmitter and GNSS receiver. The pseudolite transmitter time is synchronized with GNSS time.

Abstract: Wireless integrated miniature sensing stations which can be organized into a communicating network allow sensitive detection and analysis of vibration, infrared radiation, sound, or other physical signals indicative of an intruder or condition to be monitored over a wide area. The sensing stations operate on low power and include a sensor or sensors, a digital signal processor, a microprocessor, and a wireless transceiver for communication. Network communication is facilitated by multiple relayed transmissions from station to station.

Abstract: A navigation system for spinning projectiles using a magnetic spin sensor to measure the projectile roll angle by sensing changes in magnetic flux as the projectile rotates through the earth's magnetic field is disclosed. The magnetic spin sensor measurements are used to despin a body reference frame such that position, velocity, and attitude of the projectile can be determined by using a strapdown inertial navigation system (INS) algorithm. More particularly, a multisensor concept is used to measure pitch and yaw angular rates, by measuring Coriolis acceleration along the roll axis and demodulating the pitch and yaw rates therefrom.

Abstract: Disclosed is a GPS pseudolite transmitter, receiver and navigation system. The GPS pseudolite transmitter is adapted to transmit a first phase modulated L-band signal at a first signal pulse repetition rate having an associated first period time duration. The first phase modulated L-band signal is modulated with a short period code having a code epoch of at least about one millisecond. For each consecutive transmission pulse having the first period time duration, the pseudolite transmitter transmits the first phase modulated L-band signal during less than one half of the first period time duration, and for at least about 1 millisecond so that the first pseudolite transmitter transmits an epoch of the short period code during each transmission pulse.

Abstract: An attitude determination system uses multiple antenna inputs which are time-multiplexed into a multi-channel receiver. Each channel tracks one incoming signal from a known or ascertainable source. For each of the incoming signals being tracked, digital processing can be used to determine range differences between the different antenna elements for that incoming signal, and to compute attitude based on the range differences and the known configuration of the attenna elements relative to each other.

Abstract: An apparatus and technique is disclosed for demodulating an FM signal provided as an output from a sensor assembly. The FM signal may represent acceleration as measured by a sensor included on a rotating wheel in an attitude and heading reference system. The FM signal is demodulated and directly converted to a digital value to provide digital signal processing with improved performance characteristics. The demodulation is accomplished by detecting each FM cycle to provide a signal output at the occurrence of each cycle. A reference mark on the rotating wheel is detected for providing synchronization such that a demodulation angle of the rotating wheel can be determined. The demodulation angle is represented as a sine value which is read for each FM cycle during one sensor revolution and summed with all previous sine values detected during that one revolution. A digital output of that sum is then provided as a measurement of acceleration or other parameter along an axis of the system.