Abstract: A wireless spread spectrum communication system comprises a spread spectrum transmitter and spread spectrum receiver which communicate according to an over-the-air protocol. The spread spectrum transmitter transmits a burst comprising a preamble followed by a short gap, followed by a data message. The spread spectrum receiver receives and demodulates the transmitted burst. The receiver detects the preamble using a non-coherent parallel correlator, and from the preamble correlation peak generates a series of integration periods for serial non-coherent correlation. The short gap between the preamble and the data message allows the receiver time to process the preamble and set the timing of the electronics for receiving the data message. The receiver has a plurality of non-coherent correlators operating in parallel to recover the spread spectrum encoded information.

Abstract: A technique for modulating and demodulating CPM spread spectrum signals and variations of CPM spread spectrum signals. A transmitter divides a signal data stream into a plurality of data streams (such as I and Q data streams), independently modulates the I and Q data streams using CPM or a related technique, and superposes the plurality of resultants for transmission. A receiver receives the superposed spread spectrum signal and simultaneously attempts to correlate for a plurality of chip sequences (such as I and Q chip sequences), and interleaves the correlated I and Q data streams into a unified signal data stream. In one embodiment, the receiver separates the received spread spectrum signal into real and imaginary parts, attempts to correlate both real and imaginary parts for a plurality of chip sequences, and combines the real I, real Q, imaginary I, and imaginary Q signals into a unified signal data stream.

Abstract: A spread spectrum receiver for demodulating a CPM spread spectrum signal receives burst comprising a preamble and a data message that have been transmitted by M-ary encoding of a data signal into a single chip stream, dividing the chip stream into I and Q signal streams, independently modulating the I and Q signal streams, and superposing the resultants for transmission. The receiver detects the preamble using a non-coherent parallel correlator, and from the preamble correlation peak generates a series of integration periods for serial non-coherent correlation. A bank of non-coherent, serial correlators operate in parallel to recover the spread spectrum encoded information.

Abstract: A technique for modulating and demodulating CPM spread spectrum signals and variations of CPM spread spectrum signals. A transmitter divides a signal data stream into a plurality of data streams (such as I and Q data streams), independently modulates the I and Q data streams using CPM or a related technique, and superposes the plurality of resultants for transmission. A receiver receives the superposed spread spectrum signal and simultaneously attempts to correlate for a plurality of chip sequences (such as I and Q chip sequences), and interleaves the correlated I and Q data streams into a unified signal data stream. In one embodiment, the receiver separates the received spread spectrum signal into real and imaginary parts, attempts to correlate both real and imaginary parts for a plurality of chip sequences, and combines the real I, real Q, imaginary I, and imaginary Q signals into a unified signal data stream.

Abstract: A technique for modulating and demodulating continuous phase modulation (CPM) spread spectrum signals and variations thereof. A transmitter encodes M data bits using a selected spread spectrum code, divides the spread spectrum code into a plurality of chip codes (such as even chips and odd chips), independently modulates the even and odd chips with orthogonal carrier signals using CPM or a related technique, and superposes the plurality of resultants for transmission. A receiver receives the superposed spread spectrum signal, divides the spread spectrum signal into duplicate signals, separately demodulates the duplicate signals into an odd chip signal and an even chip signal, simultaneously attempts to correlate the odd chip signal with a locally generated odd chip sequence and the even chip signal with a locally generated even chip sequence, and interleaves the correlation signals into a unified correlation signal.

Abstract: A technique for modulating and demodulating CPM spread spectrum signals and variations of CPM spread spectrum signals. A transmitter divides a signal data stream into a plurality of data streams (such as I and Q data streams), independently modulates the I and Q data streams using CPM or a related technique, and superposes the plurality of resultants for transmission. A receiver receives the superposed spread spectrum signal and simultaneously attempts to correlate for a plurality of chip sequences (such as I and Q chip sequences), and interleaves the correlated I and Q data streams into a unified signal data stream. In one embodiment, the receiver separates the received spread spectrum signal into real and imaginary parts, attempts to correlate both real and imaginary parts for a plurality of chip sequences, and combines the real I, real Q, imaginary I, and imaginary Q signals into a unified signal data stream.

Abstract: A technique for modulating and demodulating CPM spread spectrum signals and variations of CPM spread spectrum signals. A transmitter divides a signal data stream into a plurality of data streams (such as I and Q data streams), independently modulates the I and Q data streams using CPM or a related technique, and superposes the plurality of resultants for transmission. A receiver receives the superposed spread spectrum signal and simultaneously attempts to correlate for a plurality of chip sequences (such as I and Q chip sequences), and interleaves the correlated I and Q data streams into a unified signal data stream. In one embodiment, the receiver separates the received spread spectrum signal into real and imaginary parts, attempts to correlate both real and imaginary parts for a plurality of chip sequences, and combines the real I, real Q, imaginary I, and imaginary Q signals into a unified signal data stream.

Abstract: An apparatus and method for synchronizing a spread spectrum receiver comprises a preamble matched filter and a plurality of symbol code correlators for receiving and correlating to a received spread spectrum signal. The preamble matched filter is preferably non-coherent in nature and outputs a correlation signal including a correlation pulse of variable width. The pulse is converted to a square wave having a duration of a discrete number of chip periods. The correlation pulse is used as a timing reference for the symbol code correlators, which are also non-coherent in nature. A center seeking circuit provides an offset to the timing reference according to the width of the correlation pulse. In a preferred TDMA system, a timing window is used for a subsequent time frame for defining a period of time in which the correlation signal output from the preamble matched filter can yield a valid correlation pulse.

Abstract: A technique for modulating and demodulating CPM spread spectrum signals and variations of CPM spread spectrum signals. A transmitter divides a signal data stream into a plurality of data streams (such as I and Q data streams), independently modulates the I and Q data streams using CPM or a related technique, and superposes the plurality of resultants for transmission. A receiver receives the superposed spread spectrum signal and simultaneously attempts to correlate for a plurality of chip sequences (such as I and Q chip sequences), and interleaves the correlated I and Q data streams into a unified signal data stream. In one embodiment, a spread spectrum transmitter comprises a plurality of lookup tables for storing spread spectrum code chip sequences, at least one preamble code chip sequence, and at least one fill code chip sequence. An output from each of the tables is provided to a selection circuit (e.g.

Abstract: A technique for modulating and demodulating continuous phase modulation (CPM) spread spectrum signals and variations thereof. A transmitter encodes M data bits using a selected spread spectrum code, divides the spread spectrum code into a plurality of chip codes (such as even chips and odd chips), independently modulates the even and odd chips with orthogonal carrier signals using CPM or a related technique, and superposes the plurality of resultants for transmission. A receiver receives the superposed spread spectrum signal and divides it into a real signal and an imaginary signal. The real signal is connected to a first correlator which divides its input into a real I signal and a real Q signal, serially correlates the real I signal with the odd chips of a chip code and the real Q signal with the even chips of the chip code, and combines the correlation signals into a real correlation signal.

Abstract: Apparatus and method for despreading a received continuous phase modulated spread spectrum signal includes a power divider for dividing a received spread spectrum signal into a real signal and an imaginary signal. A real CPM correlator demodulates the real signal into I and Q components and separately correlates the real I component and the real Q component without generating a correlation sequence, thereby performing self-synchronizing correlation. Likewise, an imaginary CPM correlator demodulates the imaginary signal into I and Q components and separately correlates the imaginary I component and the imaginary Q component without generating a correlation sequence, thereby performing self-synchronizing correlation. The real I and imaginary I correlation signals are combined into a final I correlation signal, and the real Q and imaginary Q correlation signals are combined into a final Q correlation signal.

Abstract: A technique for modulating and demodulating continuous phase modulation (CPM) spread spectrum signals and variations thereof. A transmitter encodes M data bits using a selected spread spectrum code, divides the spread spectrum code into a plurality of chip codes (such as even chips and odd chips), independently modulates the even and odd chips with orthogonal carrier signals using CPM or a related technique, and superposes the plurality of resultants for transmission. A receiver receives the superposed spread spectrum signal and divides it into a real signal and an imaginary signal. The real signal is connected to a real CPM correlator which demodulates its input into a real I signal and a real Q signal, separately correlates the real I signal with the odd chips of a chip code and the real Q signal with the even chips of the chip code, and combines the correlation signals into a real correlation signal.