Hughes Electronics Corporation

Symbol Technologies, LLC

Hughes Aircraft Company

Mohammad Soleimani

John E Corrigan, Iii

Yezdi F Antia

Moe Rahnema

A Roger Hammons, Jr

Anthony Robert Noerpel

David Alan Roos

Martin J Strzelczyk

Jens Arnold

Ludong Wang

Victor Hugo Molina

Channasandra S Ravishankar

Mark William Duron

Bassel F Beidas

Michael I Parr

Osamu Yamamoto

James D Thompson

Susumu Otani

Yash Vasavada

Jack Lundstedt

Chandra Joshi

Ian D Chamberlin

Son Truong Ngo

Seok Ho Kim

Zhen-Liang Shi

Prabir Datta

Philip Alfonso Lazo

Jeffrey E Outwater

Mohammad N Bukhari

Xiaoping He

Tom Jackson

D Ray Lowe

Barry L Ridings

Xiangdong Liu

Henry Eck

Gerard Stelzer

Eryx Malcolm

Royce Hernandez

Guy Montgomery

Albert Owens

Sasan Rostami

Darrell Pinson

Ron Boschini

Zheng-Liang Shi

Jean-Aicard Fabien

Methods, systems, and apparatuses for testing radio frequency identification (RFID) readers are described. A network communications capability of a first reader may be tested. A second reader may be instructed to perform testing of a radio frequency (RF) communications capability of the first reader. The second reader may include a reader test module. The reader test module includes a first logic module configured to test a forward link of the first reader, and a second logic module configured to test a backward link of the first reader.

Peer-to-peer radio frequency communications for management of RFID readers

A thermal management system and method to control temperature in an RFID reader is described herein. In particular, by inserting variable periods of inactivity (or latency) at the beginning or at the end of each read cycle, proportional to an instantaneous temperature value of the RFID reader, over-heating and damage of RFID reader electronics is prevented. The RFID reader includes a thermal sensor and determines when the high power RF electronics is enabled. If the RFID reader is in an over-heated condition, it can be turned OFF and during this period any requests received on an interface to the RFID reader to perform a read of tag(s) are not processed.

Thermal management within mobile RFID readers through the application of temperature governed variable non-emissive intervals

Methods, systems and apparatuses for RFID readers forming a reader network are described. In an aspect of the present invention, a plurality of RFID readers are configured to interrogate tags. Furthermore, the readers are configured to communicate with one another by transferring a token, represented by a signal. Possession of the token enables the reader to access a RF communications medium. Readers can be arranged in a ring configuration, and interconnected via wired links. A secondary token may circulate in the ring in addition to the primary token, to ensure redundancy in the system. A reader waits for a predetermined time interval before accessing the RF communications medium.

Token passing protocol for RFID systems

Methods, systems, and apparatuses for verifying singulated tags are described. A radio frequency (RF) signal is transmitted to provide power to at least one tag. A powered tag is singulated. A delay time period is waited. A read verify command is transmitted to the singulated tag. A response is received to the read verify command. The response to the read verify command is verified to determine whether it was received from the singulated tag.

Verification of singulated RFID tags by RFID readers

An approach for immediate channel assignment in a wireless communications system involves receiving a channel request message from a wireless transceiver, the channel request message including a dialed party number; forming an immediate assignment message including a channel assignment; transmitting the immediate assignment message to the wireless transceiver; and establishing a communications channel between the wireless transceiver and a called party by establishing a channel between the wireless transceiver and the called party.

Immediate channel assignment in a wireless system

A system and method employing an access terminal for maintaining discontinuous communications including a gateway receiver for receiving the discontinuous information, a radio frequency (RF) communication link via geosynchronous earth orbit satellite for conveying multiple communication channels using time division multiple access (TDMA), the access terminal initiating information communication with the receiver via at least one of the multiple communication channels. The access terminal further includes a memory for storing protocol processing information and a transmitter for establishing the radio frequency communication link to the receiver of the terrestrial gateway system. The access terminal memory provides for destroying of a signal pattern or protocol assigned to the access terminal by the gateway receiver or transmission of keep-alive bursts by the transmitter during periods of inactivity to maintain information communication with the receiver.

Signaling maintenance for discontinuous information communications

A message format and associated method for estimating the frequency and timing offset of a reference burst of a random access channel in a time-division multiple access communications system. A signal structure in which the continuous wave segment is split into two parts separated by some portion of the content of the random access channel burst is used to provide more precise frequency estimation. Iteration of separate frequency and timing estimation procedures is used to refine both estimates, as the individual estimation processes are more accurate when there is less error in the other parameter. Multiple hypothesis testing is used, in which more than one initial frequency estimate is carried through the iteration process, with thresholding to identify the best frequency offset. Reliable rejection of false ambiguities is achieved because the degradation in timing estimation, due to large frequency offsets, can be detected with thresholding.

Burst format and associated signal processing to improve frequency and timing estimation for random access channels

A method and apparatus for performing fractional minimum shift key modulation for a very small aperture terminal. A signal with a fractional modulation which appears to be frequency shift key is generated in the indoor unit. The outdoor unit employs a novel multiplication method to translate this signal to a minimum shift key modulated signal for satellite transmission.

Method and apparatus for performing digital fractional minimum shift key modulation for a very small aperture terminal

A burst analyzer is useful in a digital communication system in which a signal burst has a plurality of reference segments distributed within the signal burst for transmission of a plurality of reference signals. The burst analyzer includes a filter that compares the received signal, for each reference segment thereof, with each reference signal offset by one of a plurality of time offsets to generate correlation data. The burst analyzer then determines, for each reference segment of the signal burst, a maximum correlation value from the correlation data for each time offset. Then the burst analyzer determines the time offset at which a sum of the maximum correlation values, over the plurality of reference segments, is a maximum. The burst analyzer jointly generates a frequency domain representation of the correlation data associated with the time offset at which the maximum correlation sum is a maximum, and then determines a frequency at which the frequency domain representation is a maximum.

Method and apparatus for joint timing synchronization and frequency offset estimation

A system and method of soft decision decoding is disclosed. An average signal magnitude is generated from a plurality of message bits. A scale factor is generated in accordance with the average signal magnitude, and soft decision bits are generated by processing the message bits using the scale factor. The scale factor and soft decision bits are transmitted and received across a communication link. The soft decision bits are rescaled using the scale factor and then rounded to the nearest integer value. The rounded values are then decoded. The soft decision bits are generated using a quantization having at least two bits, and soft decision bits are preferably rescaled using at least five bits.

System and method of soft decision decoding

In a satellite communication system (,), a method (,) and system of locating terrestrial-based user terminals (UTs). A UT (,) is located by a two-tier estimation procedure. Under this procedure, an initial estimate of the UT location is performed based on absolute signal propagation delay and Doppler shift measured from a communication link between a satellite and the UT. A second, refined estimate of the UT location is then performed based on the results of the initial estimate. The second estimate can be a function of the absolute propagation delay and absolute Doppler, as well as differential delay and differential Doppler measured from transmissions from two or more satellites (,) to the UT (,).

Method and system of determining user terminal position using multiple satellites

The present invention is embodied in a method an apparatus for reducing the number of leased E1 lines needed to backhaul communication traffic in a satellite communication situation. The present invention receives and decompressed a satellite signal. A copy of the compressed signal is then encoded into the least significant bits (LSBs) of the decompressed signal. The decompressed signal having the embedded information may be routed to an international PSTN network over leased communications lines. However, the compressed information is extracted from the decompressed signal and sent across the E1 lines, thereby conserving communication bandwidth and reducing the number of leased lines required. After passing through the E1 lines the information is decompressed and connected to the international PSTN network. Alternatively, the decompressed signal having the embedded information may be distributed to local PSTN networks, which interpret decompressed signals. The degradation in voice quality of the decompressed signal due to the embedding of the compressed information in negligible.

Leased line optimization and voice quality improvement in bandwidth constrained communication systems

A method of channel estimation in a wireless communication system has steps of receiving a data burst comprising a plurality of portions of known data, and remaining data that is unknown; comparing reference data to each of the plurality of portions of known data and determining error for each of the portions of known data; averaging the determined error for predetermined ones of the portions of known data; and estimating error for at least a portion of the remaining data as a function of the determined error having been averaged.

Channel estimation in a fading channel

Method and apparatus for performing digital fractional minimum shift key

A frequency generation device for a satellite communication system composed of a central hub station and a number of remote units. The remote units contain a single synthesizer located in an indoor unit. In this invention, the indoor-located synthesizer is a direct digital synthesizer which modulates the baseband signal and conveys the modulated signal to an outdoor unit for communication between the remote unit and the central hub. In the outdoor unit, the signal is converted directly by a fixed number to a Ku band frequency and transmitted to the central hub.

VSAT frequency source using direct digital synthesizer

Growing community of inventors

Rockville, MD, United States of America

Mohammad Soleimani