US 5,694,417 AGranted

Short burst direct acquisition direct sequence spread spectrum receiver

AssigneeHarris Corporation

InventorsCarl Andren, John Fakatselis, Perry W. Frogge, Leonard V. Lucas, Al Petrick, Jim Snell

Life of this patent

Estimating the term…

Loading patent…

Abstract

A direct sequence spread spectrum receiver and method for acquiring radio-frequency signals is provided for acquiring data from signals which have been transmitted in a spread spectrum system. The receiver is capable of receiving short data bursts from transmitters without prior knowledge of the time or location of the transmission and rapidly acquiring the signal before continuing with reliable data demodulation. The system includes one or more antennae for receiving RF signals which may be selectively connected to provide the received signals to the system for processing, a quadrature demodulator for providing I and Q baseband signals to a digital baseband processor which includes A/D converters, dual correlators for despreading the digital I and Q signals, a cartesian to polar converter, a demodulator for demodulating the polar coordinate digital I and Q signals, and a data descrambler for obtaining a serial data stream which may be provided to a serial interface.

Claims36

Dependent claims

A system for receiving RF communications, said communications comprising a carrier signal modulated by a pseudorandom noise ("PN") modulated and phase shift keyed modulated data signal representing data to be communicated, comprising:

plural antennae;
antennae selection switch selectively connecting one of said plural antennae to the remainder of the system;
an impedance matching circuit interconnecting said selected one of said plural antennae to the remainder of the system;
an RF/IF converter downconverting RF signals received on said one of said plural antennae to produce an intermediate frequency signal from said RF signal;
a quadrature IF demodulator demodulating said intermediate frequency signal to baseband and providing quadrature I and Q baseband signals from said intermediate frequency signal;
a digital baseband processor receiving said I and Q signals and providing therefrom digital data symbols related to the data being communicated, said baseband processor comprising:
analog-to-digital converters for converting the I and Q signals to digital I and Q signals;
dual correlators, each despreading the digital signals on one of the I and Q channels;
a cartesian to polar converter converting the despread I and Q signals to polar coordinates;
a phase locked loop PSK demodulator for demodulating the data symbols from the polar coordinates;
a data descrambler descrambling the demodulated data;
and
a serial interface providing the demodulated and descrambled data to an external device.

10 more elements

Dependencies are inferred from the claim text.