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.

On training fractionally spaced equalizers using intersymbol interpolation

Abstract: The use of an intersymbol interpolation method in training fractionally spaced equalizers (FSEs) is investigated. It is shown that the optimal interpolation filter depends on the amplitude frequency response of the transmitter filter and the channel. Using a nonoptimal interpolation filter increases the stead-state mean-square error of the FSE. An interpolated complex FSE (CFSE) using a stochastic gradient, or LMS, adaptive algorithm has very little advantage over an LMS CFSE with symbol-rate updating. However, an interpolated LMS phase-splitting FSE (PS-FSE) has a convergence speed that is twice as fast as a conventional PS-FSE. Special precautions for evaluating the performance of interpolated FSEs are discussed, and a novel evaluation scheme is proposed. >

Adaptive coherent signal detection method and apparatus

Abstract: A detector (100) determines whether an input signal (10) comprises a first signal or a second signal. A first local signal (207) is generated based on the first signal and a second local signal (307) is generated based on the second signal. A first error (211) is formed based on the first local signal and a scaled input signal (50), and a second error (311) is formed based on the second local signal and the scaled input signal. A first distance (215) between the scaled input signal and the first local signal is formed based on the first error, while a second distance (315) between the scaled input signal and the second local signal is formed based on the second error. Whether the input signal comprises the first signal or the second signal is determined by comparing (60) the first distance to the second distance.

Encoder/decoder and method for efficient string handling in data compression

Abstract: A method (100) and device (200) increase efficiency of a data compression encoder or decoder by testing whether an input string is a maximum length string upon successful match of the input string in a dictionary. Where the length of the input string is equal to a predetermined maximum string length, the string matching process is terminated without processing an additional input character that would cause an unsuccessful string match. The maximum length string test is accomplished by testing a string length counter for the value zero, where the string length counter is set to the maximum string length value when the input string is NULL or alternatively is set to the maximum string length minus one when the input string is a one character string, and the string length counter is decremented for each input character that extends the matched input string.

Combinational static CMOS logic circuit

Abstract: A combinational static CMOS logic circuit for providing a plurality of basic two-input logic functions with reduced complexity and integrated circuit area. The combinational static CMOS logic circuit provides either a NAND or an XOR output at a first output terminal and a NOR output at a second output terminal. A configuration input terminal is utilized for selecting between the NAND or the XOR output being provided at the first output terminal. In an alternate configuration, the combinational static CMOS logic circuit provides either a NOR or an XNOR output at a first output terminal and a NAND output at a second output terminal.

A new LPC interpolation technique for CELP coders

Abstract: In low rate code-excited linear predictive (CELP) coders, the LPC spectral information is usually quantized and transmitted on a frame-by-frame basis about every 20 to 30 msec. The quality of speech reproduced by a CELP coder can be improved by making spectral transitions as smooth and continuous as possible. One way in which this can be accomplished without increasing the transmission bit rate is to interpolate the LPC spectral parameters between adjacent extraction frames. This, however, usually leads to a dramatic increase in the computations required for the codebook search. The paper presents a new LPC interpolation technique, based on interpolating the impulse response of the LPC synthesis filter. It demonstrates that this method offers a significant complexity reduction for the codebook search over other typical interpolation schemes. Furthermore, the experiments show that the coder using the impulse response for interpolation produces the same speech quality as the coder using the LSP parameters for interpolation, and both these parameter sets are superior to other LPC representations for interpolation. >