Abstract: A receiver receives signals and noise over a frequency spectrum of a desired received signal. The desired received signal is spread using code division multiple access. The received signals and noise are demodulated to produce a demodulated signal. The demodulated signal is despread using a code uncorrelated with a code associated with the desired received signal. A power level of the despread demodulated signal is measured as an estimate of the noise level of the frequency spectrum.

Abstract: A system and method for optimally combining multi-path signals is presented. A first signal is received that traveled a first path from a transmitter to a receiving location and a second signal is received that traveled a different second path from the transmitter to the same receiving location. The paths are different so that the first and second signals contain the same signal data but the first signal has a first distortion that is different than a second distortion in the second signal. According to an objective function, the method adaptively generates a first weight value and a second weight value. The first and second weight values are applied to the respective first and second signals to produce respective first and second weighted signals. The first and second weighted signals are linearly combined producing a combined signal with a combined signal degradation.

Abstract: A system and method for generating a low probability of detection (LPD) waveform is presented. The method modulates pre-modulated symbols using pulse-position modulation (PPM) to produce PPM modulated signals with a modulated in-phase (I) component and a modulated quadrature (Q) component. Next, frequency hopping is used to transmit the modulated I component at a randomized start time within a time slot and to transmit the modulated Q component at the randomized start time within the same slot. The modulated Q component does not overlap with the modulated I component. The method can also overlay transmission security (TRANSEC) pseudorandom (PN) overlay on the modulated Q component and the modulated I component before the modulated Q component and the modulated I component are transmitted.

Abstract: A subscriber unit for use in a communication system includes a spread spectrum radio interface, responsive to a rate function signal from a base station, and first and second despreaders. The base station assigns the rate function spread-spectrum message channels and the first despreader recovers and modifies an information signal one of the spread spectrum message channels. The information channel mode is then modified for processing by the second despreader, with the second despreader supporting a different information signal rate. The subscriber unit has a capability of communicating with a dynamically changing a transmission rate of an information signal which includes multiple spread spectrum message channels. The system includes a closed loop power control system for maintaining a minimum system transmit power level for a radio carrier station and the subscriber units, and system capacity management for maintaining a maximum number of active subscriber units for improved system performance.

Abstract: A spread signal is produced having an adjustable spread spectrum. A data signal is provided for transmission. The data signal is processed to have a first spread spectrum. The processed first spread spectrum data signal is filtered to have one out of a plurality of spread spectrums. The filtering capable of producing a signal having a spread spectrum of any of the plurality of spread spectrums. The filtered one spread spectrum data signal is transmitted.

Abstract: A subscriber unit for use in a multiple access spread-spectrum communication system includes a spread spectrum radio interface, responsive to a rate function signal from a base station, and first and second despreaders. The base station assigns the rate function spread-spectrum message channels and the first despreader recovers and modifies an information signal one of the spread spectrum message channels. The information channel mode is then modified for processing by the second despreader, with the second despreader supporting a different information signal rate. The subscriber unit has a capability of communicating with a dynamically changing a transmission rate of an information signal which includes multiple spread spectrum message channels.

Abstract: A system and method for calculating a time of arrival (TOA) of an electromagnetic signal is presented. A method receives a fast Fourier transform (FFT) signal that is a FFT of an original electromagnetic signal containing symbol data. The FFT signal is either multiplied or divided with a value to remove the symbol data. Removing the symbol data generates a perturbed data values representing perturbed signal with a perturbed covariance. The method calculates a perturbed covariance of the perturbed data values. After the perturbed covariance is calculated, the method at least partially corrects the perturbed covariance to produce a corrected covariance. The TOA of the original electromagnetic signal is calculated based, at least in part, on the perturbed covariance.

Abstract: A spread signal is produced having an adjustable spread spectrum. A data signal is provided for transmission. The data signal is processed to have a first spread spectrum. The processed first spread spectrum data signal is filtered to have one out of a plurality of spread spectrums. The filtering capable of producing a signal having a spread spectrum of any of the plurality of spread spectrums. The filtered one spread spectrum data signal is transmitted.

Abstract: A system and method for optimally combining multi-path signals is presented. A first signal is received that traveled a first path from a transmitter to a receiving location and a second signal is received that traveled a different second path from the transmitter to the same receiving location. The paths are different so that the first and second signals contain the same signal data but the first signal has a first distortion that is different than a second distortion in the second signal. According to an objective function, the method adaptively generates a first weight value and a second weight value. The first and second weight values are applied to the respective first and second signals to produce respective first and second weighted signals. The first and second weighted signals are linearly combined producing a combined signal with a combined signal degradation.

Abstract: A spread signal is produced having an adjustable spread spectrum. A data signal is provided for transmission. The data signal is processed to have a first spread spectrum. The processed first spread spectrum data signal is filtered to have one out of a plurality of spread spectrums. The filtering capable of producing a signal having a spread spectrum of any of the plurality of spread spectrums. The filtered one spread spectrum data signal is transmitted.

Abstract: A desired signal modulated with N symbols is detected in the presence of a constant modulus (CM) interferer that produces M symbols. Observation samples corresponding to the desired signal and the interferer are obtained from a signal recovery stage. N observation constellations are defined, each having M constellation points corresponding to the symbols produced by the interferer, and the points form a circular perimeter of the constellation with a radius corresponding to the strength of the interferer. The perimeter of each constellation is centered on one of N defined symbol points representing the different possible symbols of the desired signal. Distances between the observation samples and the circular perimeter of each observation constellation are determined. For each observation sample, the symbol point on which the constellation perimeter closest to the sample is centered, is selected as a symbol of the desired signal.

Abstract: A spread signal is produced having an adjustable spread spectrum. A data signal is provided for transmission. The data signal is processed to have a first spread spectrum. The processed first spread spectrum data signal is filtered to have one out of a plurality of speed spectrums. The filtering capable of producing a signal having a spread spectrum of any of the plurality of spread spectrums. The filter one spread spectrum data signal is transmitted.

Abstract: A spread signal is produced having an adjustable spread spectrum. A data signal is provided for transmission. The data signal is processed to have a first spread spectrum. The processed first spread spectrum data signal is filtered to have one out of a plurality of spread spectrums. The filtering capable of producing a signal having a spread spectrum of any of the plurality of spread spectrums. The filtered one spread spectrum data signal is transmitted.

Abstract: A base station for controlling transmission power during the establishment of a communication channel utilizes the reception of a short code during initial power ramp-up. The short code is a sequence for detection by the base station which has a much shorter period than a conventional access code. The ramp-up starts from a power level that is lower than the required power level for detection by the base station. The power of the short code is quickly increased until the signal is detected by the base station. Once the base station detects the short code, it transmits an indication that the short code has been detected.

Abstract: A spread signal is produced having an adjustable spread spectrum. A data signal is provided for transmission. The data signal is processed to have a first spread spectrum. The processed first spread spectrum data signal is filtered to have one out of a plurality of spread spectrums. The filtering capable of producing a signal having a spread spectrum of any of the plurality of spread spectrums. The filtered one spread spectrum data signal is transmitted.

Abstract: A base station for controlling transmission power during the establishment of a communication channel utilizes the reception of a short code during initial power ramp-up. The short code is a sequence for detection by the base station which has a much shorter period than a conventional access code. The ramp-up starts from a power level that is lower than the required power level for detection by the base station. The power of the short code is quickly increased until the signal is detected by the base station. Once the base station detects the short code, it transmits an indication that the short code has been detected.

Abstract: A system and method for calculating a time of arrival (TOA) of an electromagnetic signal is presented. A method receives a fast Fourier transform (FFT) signal that is a FFT of an original electromagnetic signal containing symbol data. The FFT signal is either multiplied or divided with a value to remove the symbol data. Removing the symbol data generates a perturbed data values representing perturbed signal with a perturbed covariance. The method calculates a perturbed covariance of the perturbed data values. After the perturbed covariance is calculated, the method at least partially corrects the perturbed covariance to produce a corrected covariance. The TOA of the original electromagnetic signal is calculated based, at least in part, on the perturbed covariance.

Abstract: A code-division-multiple-access (CDMA) system employing spread-spectrum modulation. The CDMA system has a base station (BS), and a plurality of subscriber units. The signals transmitted between the base station and subscriber unit use spread-spectrum modulation. The improvement apparatus for adaptive forward power control (APC) from a base station (BS) to a subscriber unit (SU), includes sending from the base station, using spread-spectrum modulation, a BS-spreading code on a forward channel. The subscriber unit despreads the BS-spreading code on the forward channel as a despread signal, determines a first power level P.sub.d which includes power of the despread signal plus noise and a second power level P.sub.N, which includes despread-noise power. The subscriber unit determines a first error signal e.sub.1, from the first power level P.sub.d, the second power level P.sub.N, and a required signal-to-noise ratio SNR.sub.REQ for service type, and a second error signal e.sub.

Abstract: A spread signal is produced having an adjustable spread spectrum. A data signal is provided for transmission. The data signal is processed to have a first spread spectrum. The processed first spread spectrum data signal is filtered to have one out of a plurality of spread spectrums. The filtering capable of producing a signal having a spread spectrum of any of the plurality of spread spectrums. The filtered one spread spectrum data signal is transmitted.

Abstract: A desired signal modulated with N symbols is detected in the presence of a constant modulus (CM) interferer that produces M symbols. Observation samples corresponding to the desired signal and the interferer are obtained from a signal recovery stage. N observation constellations are defined, each having M constellation points corresponding to the symbols produced by the interferer, and the points form a circular perimeter of the constellation with a radius corresponding to the strength of the interferer. The perimeter of each constellation is centered on one of N defined symbol points representing the different possible symbols of the desired signal. Distances between the observation samples and the circular perimeter of each observation constellation are determined. For each observation sample, the symbol point on which the constellation perimeter closest to the sample is centered, is selected as a symbol of the desired signal.