California Institute of Technology

The United States of America As Represented by the Administrator of the

United States of America As Represented by the Administrator of Nasa

Robert M Manning

Dara Sabahi

Adam D Steltzner

Alejandro M San Martin

Tommaso P Rivellini

Jeffrey W Umland

Christopher J Voorhees

Howard J Eisen

Benjamin L Thoma

Louise Jandura

Steven W Lee

Jaime M Waydo

Robert D Rasmussen

William Layman

Eric M Slimko

Richard S Ward

Edward C Wong

Allen Chen

Gary S Bolotin

Suzan M Manning

Blair F Lewis

Descent stage for mars rover

Mars rover

Method and apparatus for estimating signal-to-noise ratio (SNR) &#x3b3; of a composite input signal e(t) on a phase-modulated (e.g., BPSK) communications link. A first demodulator receives the composite input signal and a stable carrier signal and outputs an in-phase output signal; a second demodulator receives the composite input signal and a phase-shifted version of the carrier signal and outputs a quadrature-phase output signal; and phase error &#x3b8;(t) contained within the composite input signal e(t) is calculated from the outputs of the first and second demodulators. A time series of statistically independent phase error measurements &#x3b8;(t), &#x3b8;(t), . . . , &#x3b8;(t) is obtained from the composite input signal subtending a time interval &#x394;t=t&#x2212;twhose value is small enough such that &#x3b3;(t) and &#x3c3;(t) can be taken to be constant in &#x394;t. A biased estimate &#x3b3;* for the signal-to-noise ratio (SNR) &#x3b3; of the composite input signal is calculated using maximum likelihood (ML) estimation techniques, and an unbiased estimate {circumflex over (&#x3b3;)} for the signal-to-noise ratio (SNR) &#x3b3; of the composite input signal is determined from the biased estimate &#x3b3;*, such as by use of a look-up table.

Real-time signal-to-noise ratio (SNR) estimation for BPSK and QPSK modulation using the active communications channel

Skycrane landing system

Motorized invalid chair transport vehicle

This is a distributed computing system providing flexible fault tolerance; ease of software design and concurrency specification; and dynamic balance of the loads. The system comprises a plurality of computers each having a first input/output interface and a second input/output interface for interfacing to communications networks each second input/output interface including a bypass for bypassing the associated computer. A global communications network interconnects the first input/output interfaces for providing each computer the ability to broadcast messages simultaneously to the remainder of the computers. A meshwork communications network interconnects the second input/output interfaces providing each computer with the ability to establish a communications link with another of the computers bypassing the remainder of computers. Each computer is controlled by a resident copy of a common operating system. Communications between respective ones of computers is by means of split tokens each having a moving first portion which is sent from computer to computer and a resident second portion which is disposed in the memory of at least one of computer and wherein the location of the second portion is part of the first portion. The split tokens represent both functions to be executed by the computers and data to be employed in the execution of the functions. The first input/output interfaces each include logic for detecting a collision between messages and for terminating the broadcasting of a message whereby collisions between messages are detected and avoided.

Distributed computing system with dual independent communications paths

Growing community of inventors

Pasadena, CA, United States of America

Robert M Manning