Codex Corporation

About: Codex Corporation is a based out in . It is known for research contribution in the topics: Signal & Network packet. The organization has 189 authors who have published 241 publications receiving 32205 citations.

A bounded-distance decoding algorithm for the Leech lattice, with generalizations

Abstract: An algorithm is given that decodes the Leech lattice with not much more than twice the complexity of soft-decision decoding of the Golay code. The algorithm has the same effective minimum distance as maximum-likelihood decoding and increases the effective error coefficient by less than a factor or two. The algorithm can be recognized as a member of the class of multistage algorithms that are applicable to hierarchical constructions. It is readily generalized to lattices that can be expressed in terms of binary code formulas, and in particular to construction B lattices. >

Gain-Adaptive Vector Quantization with Application to Speech Coding

Abstract: The generalization of gain adaptation to vector quantization (VQ) is explored in this paper and a comprehensive examination of alternative techniques is presented. We introduce a class of adaptive vector quantizers that can dynamically adjust the "gain" or amplitude scale of code vectors according to the input signal level. The encoder uses a gain estimator to determine a suitable normalization of each input vector prior to VQ encoding. The normalized vectors have reduced dynamic range and can then be more efficiently coded. At the receiver, the VQ decoder output is multiplied by the estimated gain. Both forward and backward adaptation are considered and several different gain estimators are compared and evaluated. Gain-adaptive VQ can be used alone for "vector PCM" coding (i.e., direct waveform VQ) or as a building block in other vector coding schemes. The design algorithm for generating the appropriate gain-normalized VQ codebook is introduced. When applied to speech coding, gain-adaptive VQ achieves significant performance improvement over fixed VQ with a negligible increase in complexity.

Two-pass multiplier/accumulator circuit

Abstract: A two-pass Multiplier/Accumulator Circuit is provided which performs various arithmetic operations on operands contained within an X Register 10 (FIG. 1) and a Y Register 20 and places the result in an Accumulator Register 40. The arithmetic operations are carried out by passing the product of the operands successively through an array of adders in the Adder unit 34. Each adder adds an appropriate multiple of the contents of the X Register to the Accumulator 40 or to the output of the previous adder. The multiples are selected according to the contents of the Y Register. The X and Y Registers are fully buffered so that additional data transfers and functions may be performed while an arithmetic operation is in progress in a "pipeline" manner. The circuit is also capable of indicating the maximum or minimum value in a sequence of numbers in response to a single computer instruction to the circuit.

Adaptive rate control for echo cancelling modem

Abstract: Channel distortion and echo signals detrimentally affect data communication over a channel. The invention provides an echo cancellation modem for full-duplex communication which selects a modulation scheme prior to data communication, and requests changes to the level of modulation during data communication when channel quality has changed significantly. The modem includes an echo canceller (12, 14), a monitor (24) for determining the quality of the channel based on analysis of a residual echo component, and a controller (46) for selecting an acceptable modulation scheme based on the analysis by the monitor. The modem requests the remote device to operate at a selected rate, and operates at the selected rate only if the the remote device concurs. The modem uses a fall forward flag (68) to prevent contention between the modem and the remote device when the remote device cannot support a requested higher level modulation scheme. The modem includes re-initialization logic which selects appropriate monitor thresholds for coded and uncoded modulation options.

Automating offender documentation with RFID

Abstract: The disclosure relates to systems and methods for automating offender documentation with RFID. Such a system can include a transponder associated with an offender and a radio frequency identification reader configured to transmit an interrogating signal to the transponder and receive an identifying signal in response to the transponder receiving the interrogating signal. The system can further include a server configured to receive data from the radio frequency identification reader through a network, transmit the received data to a web service through the network, and receive an alert from the web service that a monitoring rule relating to the offender was violated. The system can allow a user to pre-program one or more programmable events and associate an individual RFID reader with one or more of the programmable events to allow the RFID reader to help perform multiple functions simultaneously.