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.

Timing Recovery for Equalized Partial-Response Systems

Abstract: It is shown that the sensitivity of the performance of least mean-square error (LMS) equalizers to the sampler phase is a function of equalizer length for partial-response systems. An LMS algorithm for the adjustment of sampler phase is derived for partial-response systems. This algorithm does not require the transmission of any pilot tones and is relatively easily implementable by digital circuits. A method of selecting a "good" initial sampler phase is also proposed.

System and method for call-by-call source routing with rule-based fallbacks

Abstract: A fallback strategy for a system (700) and method (200) is provided for rerouting a call that fails to be established utilizing a first set of constraints in a communication network system. This strategy enables the communication network system to utilize a look-around-first type of preemption that avoids unnecessary preemption and provides alternate routing for a call according to predetermined constraints selected by a user.

Polyphase filter matrix for rational sampling rate conversions

Abstract: The polyphase filter array has been used for efficient implementations of filters with integer sampling rate conversions. [1] The filter in the high sampling rate side is decomposed into its polyphase filters which can be moved to the lower sampling rate side without changing their functions. For FIR filters the computational complexity is reduced by a factor equal to the sampling rate ratio. A rational (L/M) sampling rate conversion system realized with a 1-to-L interpolator followed by an M-to-1 decimator has three sampling rates F, LF and (L/M)F involved. By using the polyphase filter array a filter operating at the sampling rate of LF can be implemented in either the input side or the output side with lower sampling rates. The polyphase filter matrix structure will operate at the sampling rate of F/M, which does not show in the above model and is lower than any one of those three rates. For FIR filters the computational complexity is reduced by a factor of LM compared to the direct realization of the integral filter or by a factor of M (or L) compared to the polyphase filter array realization while the system input-output relation is maintained.

Simplified decoding of lattices and codes

Abstract: A decoder including first and second decoding stages for selecting a codeword near to a given N-tuple r which is a sequence of N real values ri representing signals. The first stage includes substages associated respectively with sections rj of N-tuple r, each substage for evaluating distances between multiple sets of possible partial codewords and the section rj and for selecting a survivor from each of the multiple sets based on the distances. The second stage includes n-1 substages, each of which operates with respect to a supersection made up of a combination of two parts, each part being a section or a supersection combined in an earlier substage of the second stage and it includes a final substage which operates with respect to a final supersection whose parts make up the complete N-tuple r. Eachof the n-1 substages is for evaluating distances between multiple sets of possible partial codewords and the received values in the corresponding supersection based on the survivor distances for the survivors corresponding to each of the two parts and for selecting a survivor from each of the multiple sets based on the distances. The final substage is for evaluating distances between the codewords and the N-tuple r based on the survivor distances for the survivors corresponding to each of two parts, for selecting a finally decoded codeword based on the distances between the codewords and N-tuple r, and for providing information about the finally decoded codeword as decoder output.

Transmitting encoded data on unreliable networks

Abstract: Information encoded by data compression (or another data encoding technique, e.g., encryption, requiring synchronization between the encoder (12a) and decoder (22b) is transmitted over an unreliable network (16) by checking for transmission errors after decoding. if an error is detected, the encoder (12a) is reset, using a reset protocol, which may operate over an unreliable re-verse channel (16) by using a timer (46) to generate further reset requests when the receiver does not acknowledge them in a timely fashion.