Echelon Systems Corporation

Echelon Corporation

Fairchild Camera and Instrument Corp.

Brooks E Cowart

A transceiver for transmitting and receiving digital data is disclosed. The transceiver employs direct sequence spread spectrum communications techniques for reducing interference among multiple users in a communications network environment. Each transceiver has a transmitter for locking a digital bit stream to a predetermined spread spectrum chip sequence and carrier signal. Frequency of the carrier signal and the chip sequence. Both the carrier signal, the chip sequence and the bit stream rate are derived from an integrally related to an accurate reference frequency to facilitate rapid acquisition and decoding of the signal by another transceiver. To provide for multiple communications channels on a single transmission medium, means for producing selectable carrier frequencies and/or selectable spreading sequences are included. The transceiver also has a receiver portion for acquiring and decoding a transmitted and direct sequence spread spectrum signal to recover the digital bit stream using the spread spectrum chip sequence and carrier signal.

Transceiver providing selectable frequencies and spreading sequences

A transceiver the transmitting and receiving digital data is disclosed. The transceiver employs direct sequence spread spectrum communications techniques for reducing interference among multiple users in a communications network environment. Each transceiver has a transmitter for locking a digital bit stream to a predetermined spread spectrum chip sequence and carrier signal. Frequency of the carrier signal and the chip sequence. Both the carrier signal, the chip sequence and the bit stream rate are derived from an integrally related to an accurate reference frequency to facilitate rapid acquisition and decoding of the signal by another transceiver. To provide for multiple communications channels on a single transmission medium, means for producing selectable carrier frequencies and/or selectable spreading sequences are included. The transceiver also has a receiver portion for acquiring and decoding a transmitted and direct sequence spread spectrum signal to recover the digital bit stream using the spread spectrum chip sequence and carrier signal.

An improved correlator for use in a spread spectrum communications system which operates with a predetermined chip sequence includes an N-stage correlation register, wherein each stage corresponds to a signal chip in the sequence, an a means for autocorrelating each of the N stages with the corresponding chips in the sequence. The correlator further includes a means for modifying the sequence to accomodate multiple communication channels.

Correlator for spread spectrum communications systems

A transceiver for transmitting and receiving digital data is disclosed. The transceiver employs direct sequence spread spectrum communications techniques for reducing interference among multiple users in a communications network environment. Each transceiver has a transmitter for locking a digital bit stream to a predetermined spread spectrum chip sequence and carrier signal. Frequency of the carrier signal and the chip sequence. Both the carrier signal, the chip sequence and the bit stream rate are derived from an integrally related to an accurate reference frequency to facilitate rapid acquisition and decoding of the signal by another transceiver. The transceiver also has a receiver portion for acquiring and decoding a transmitted and direct sequence spread spectrum signal to recover the digital bit stream using the spread spectrum chip sequence and carrier signal.

Transceiver employing direct sequence spread spectrum techniques

A tester for conducting parametric tests on semiconductor devices comprises a current source means to be electrically coupled to a particular lead of the device under test to supply the maximum current specified to be drawn by said lead at a fixed voltage, a voltage maintenance means electrically coupled to the lead to maintain the lead at the specified voltage and a current direction-sensing means electrically coupled between the lead and the voltage maintenance means to detect the direction of current flow to determine whether the lead draws more or less current than the constant current.

Growing community of inventors

Mountain View, CA, United States of America

Brooks E Cowart