US 4,912,722 A · Self-synchronous spread spectrum transmitter/receiver

Abstract

The present invention relates to a self-synchronous spread spectrum transmitter and an associated remote spread spectrum receiver which communicate with each other by the transmission of both (1) a spread spectrum Pseudo Noise Code (PNC) sequence signal, and (2) a combined PNC sequence plus the data information (PNC+data) signal. The two signals can be transmitted concurrently using either different frequency bands or on a quadrature carrier; or the two signals can be transmitted with a time offset between signals. At the receiver the PNC and the PN+data signals are separately recovered for the case of the concurrent transmission techniques, and directly mixed to despread the received signal and recover the data signal at baseband. For the time offset technique, the delay provided in one of the time offset signals is again introduced to the previously delayed signal, and the delayed and undelayed signal portions of the received combined signal are directly mixed and then low pass filtered to recover the data signal. Such techniques eliminate the necessity for providing PNC acquisition and tracking circuits in associated spread spectrum transmitter and receiver combinations.

Claims11

Dependent claims

A spread spectrum transmitter comprising:

a generator for generating a pseudo-noise code sequence;
combining means for combining the pseudo-noise code sequence from the generator and a data information signal provided as an input to the transmitter to generate a spread spectrum data information output signal;
a modulator/combiner for separately modulating each of (1) the spread spectrum data information output signal from the combining means and (2) the pseudo-noise code sequence from the generator to place both modulated signals into a predetermined synchronous multiplexing relationship to each other so that each signal is capable of being simultaneously received, separated and multiplied together to provide self-synchronous instantaneous despreading at a remote receiver, and combining the two modulated signals into a multiplexed modulator/combiner output signal;
and
means for transmitting the multiplexed output signal from the modulator/combiner in an appropriate frequency band to a remote receiver.

2 more elements

A method of transmitting signals from a transmitter in a spread spectrum communication system, the method comprising the steps of:

(a) generating a predetermined pseudo-noise code sequence signal;
(b) combining the pseudo-noise code sequence signal with a data information input signal received by the transmitter to generate a spread spectrum data information output signal;
(c) separately modulating each of (1) the spread spectrum data information output signal generated in step (b), and (2) the pseudo-noise code sequence signal generated in step (a) to generate a modulated spread spectrum data information output signal and a modulated pseudo-noise code sequence output signal, respectively, which signals are disposed in a predetermined synchronous multiplexing relationship with each other;
(d) combining the modulated spread spectrum data information signal and the modulated pseudo-noise code sequence signal from step (c) to generate a multiplexed output transmission signal wherein each modulated signal is capable of being simultaneous received at a remote receiver to provide self-synchronous instantaneous despreading at the remote receiver;
and
(e) transmitting the multiplexed output transmission signal from step (d) to the remote receiver in an appropriate frequency band.

3 more elements

Dependencies are inferred from the claim text.

Self-synchronous spread spectrum transmitter/receiver

Life of this patent

Self-synchronous spread spectrum transmitter/receiver

Life of this patent

Abstract

Claims11