Abstract: In a communications system including a transmitter and a receiver with a multiple antenna array having null steering apparatus attached thereto, a desired signal and an identifier signal are summed and utilized to frequency-shift key (FSK) modulate a carrier prior to transmission, the desired signal including bits of data delayed a predetermined period relative to the identifier signal and the identifier signal including the bits of data summed with a pseudo random signal and substantially reduced in amplitude relative to the desired signal, which transmitted signal is received in the null steering apparatus where the pseudo random signal is removed from the identifier signal and the data is utilized to FSK modulate a carrier to produce a reference signal, which reference signal is utilized to cause the null steering apparatus to have high response to the desired signal.

Abstract: Delay devices including CCD delay lines clocked and sampled to simulate a multitap delay line with a weighter, correlator and integrater connected to the delay line by switches which are operated to time share the weighter and correlator with each output of the delay line.

Abstract: In a multiple antenna array including null steering apparatus of the type utilizing a reference signal generator for preventing a null on a desired signal, weight oscillation eliminating apparatus for shifting the phase of the reference signal to make it generally equal and opposite to the desired signal so that weight oscillation of the system is eliminated.

Abstract: A transmitter for transmitting a desired signal composed of a carrier modulated by a pseudorandom noise code and periodic bursts of data and a receiver including null steering apparatus wherein the desired signal is applied to a demodulator for removing the PN code, or collapsing the spectrum of the signal, and the collapsed signal is demodulated to provide the data and the carrier, after which the carrier is remodulated with the PN code to provide a reference signal between bursts of data for the null steering apparatus to form a lobe in the antenna pattern in the direction of reception of the desired signal.

Abstract: In a communications system including a multiple antenna array with null steering apparatus, a desired signal and an identifier signal are transmitted, the desired signal including a first carrier modulated with bits of data delayed a predetermined period and with a random code and the identifier signal being substantially reduced in amplitude relative to the desired signal and including a second carrier in phase quadrature with the first carrier and modulated with the bits of data and with the random code, which transmitted signal is received in the null steering apparatus where the data from the identifier signal, which leads the data of the desired signal, is utilized to modulate the recovered first carrier and is adjusted in amplitude to cause the null steering apparatus to lobe on the desired signal, the remodulated carrier being utilized as a reference signal in the feedback circuits of the null steering apparatus.

Abstract: A communications system including a first channel adapted to receive data on a first carrier and a second channel adapted to receive data on a second carrier having a frequency substantially equal to the frequency of the first carrier and polarized approximately orthogonal thereto and wherein degradation in the orthogonality occurs during transmission so that portions of the first carrier appear in the second channel and portions of the second carrier appear in the first channel, a summing device in each channel and apparatus for coupling a portion of the output signal from the summing device in one channel to the input of the summing device in the other channel, in the correct phase relationship and amplitude, so as to cancel the portion of the second carrier appearing in the first channel and the portion of the first carrier appearing in the second channel.

Abstract: Null steering apparatus in a multiple antenna array including means associated with each antenna for separating signals therefrom into in-phase and quadrature components which can be adjusted so that unwanted signals from the array are cancelled and further including circuitry for separating an identifier signal, which is a low level signal substantially in-phase quadrature with the AM signal on the carrier, to produce a reference signal which is subtracted from signals in the feedback loop of the null steering apparatus to form a lobe in the antenna pattern in the direction of the carrier modulated with the AM signal. In this circuit the identifier signal is a PN code signal and the circuitry decodes the PN code signal and shifts the phase of the remaining carrier 90.degree. so that it is a replica of the carrier signal received by the antenna.

Abstract: Null steering apparatus in a multiple antenna array including means associated with each antenna for separating signals therefrom into in-phase and quadrature components which can be adjusted so that unwanted signals from the array are cancelled and further including circuitry for separating an identifier signal from the desired signal and utilizing the identifier signal to produce a replica of the desired signal which is subtracted from the feedback loop of the null steering apparatus to form a lobe in the antenna pattern in the direction of the desired signal. In this circuit the desired signal is a PSK digital data signal and the identifier is a similar signal transmitted at a lower level and leading by one bit. The circuitry in the null steering apparatus delays the identifier by one bit so that it is a replica signal of the desired signal.

Abstract: Null steering apparatus in a multiple antenna array including means associated with each antenna for separating signals therefrom into in-phase and quadrature components which can be adjusted so that unwanted signals from the array are cancelled and further including circuitry for separating an identifier signal, which is a low level signal substantially in-phase with the carrier, to produce a reference signal which is substracted from signals in the feedback loop of the null steering apparatus to form a lobe in the antenna pattern in the direction of the carrier modulated with the FM signal. In the transmitter, the FM modulation is periodically blanked for a short period of time so that only the carrier modulated with the identifier signal is transmitted and the feedback loop of the null steering apparatus is only activated during the blanking periods with the null steering apparatus maintaining the status quo between blanking periods.