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Method for calculating bit-error ratios using a self-synchronous scrambler/descrambler

IP.com Disclosure Number: IPCOM000010802D
Publication Date: 2003-Jan-22
Document File: 8 page(s) / 141K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for calculating bit-error ratios (BERs) using a self-synchronous scrambler/descrambler. Benefits include improved functionality.

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Method for calculating bit-error ratios using a self-synchronous scrambler/descrambler

Disclosed is a method for calculating bit-error ratios (BERs) using a self-synchronous scrambler/descrambler. Benefits include improved functionality.

Background

        � � � � � A bit error is defined as a data bit that is received which has a different value than the corresponding data bit transmitted. Bit errors can be caused by:

•        � � � � Noise that affects transmission channels

•        � � � � Transmission channel characteristics that are out of specification

•        � � � � Date rate clocks that are jittery or out-of-frequency specification

•        � � � � Many other factors

        � � � � � A BER is a measurement typically used to determine the quality of a data communication path. The BER is defined as the number of bit errors divided by the total number of data bits during the measurement period.

        � � � � � Reliable communications channels require a low BER. Measurements provide a means for data communications suppliers to troubleshoot, maintain, and evaluate their data communication networks.

        � � � � � BER calculations are usually made with test equipment called bit error rate testers (BERTs). These testers are extremely expensive, not portable, and require time and effort to hook up.

General description

        � � � � � The disclosed method calculates bit-error ratios (BERs) using a self-synchronous scrambler/descrambler. A transmit scrambler is coupled with a self-synchronous receive descrambler. The scrambler/descrambler pair is LFSRs with a common polynomial created from sequential elements, such as flip-flops. The LFSRs can be implemented as serial or parallel LFSRs. They must be implemented as one-to-many LFSRs rather than many-to-one LFSRs to be self-synchronous.

        � � � � � Including this small, inexpensive piece of circuitry greatly increases the ease with which data network suppliers can troubleshoot their networks and isolate failures.

Advantages

        � � � � � The disclosed method provides advantages, including:

•        � � � � Improved functionality due to calculating bit-error ratios using a self-synchronous scrambler/descrambler

•        � � � � Improved functionality due to comparing expected and actual data by adding a multiplexer to the front end of the receive descrambler

•        � � � � Improved functionality due to the use of the synchronization state machine

Detailed description

        � � � � � The disclosed method contains several key elements, including:

•        � � � � Self-synchronous scrambler/descrambler pairs

•        � � � � Predictable sequence generation

•        � � � � Bit error detection

•        � � � � Comparison of expected and actual data

•        � � � � Bit error counter

•        � � � � Computation of total bits during test

•        � � � � Bit error ratio calculation

•        � � � � Synchronization state machine

Self-synchronous scrambler/descrambler pairs

        � � � � � The disclosed method calculates BERs using a self-synchronous scrambler/descrambler. For example, a serial many-to-one transmit scrambl...