System and method for improving conversion between A-law and U-law coding
AssigneeSiemens Information and Communication Networks, Inc.
InventorsWilliam J. Beyda, Shmuel Shaffer
Life of this patent
Estimating the term…
Abstract
A modem or other telephone device (102, 502) is configured to identify (or receive notification of) the companding law used by a destination modem or telephone device. The telephone device (102, 502) can then, using stored conversion tables, predict the inverse mapping from the converted encoding law. Having done so, the telephone device (102, 502) can identify distorted portions of the decoded signal and modify the original signal before it is sent to the encoding or encoding-converter unit.
Claims20
A telecommunications device, comprising:
- means for determining a conversion of a data signal from a first encoding law to a second encoding law;
- and
- means for changing a level of said data signal prior to conversion to ensure that a conversion of said data signal to said second encoding law more closely approximates said data signal than if said data signal had been converted without said changing.
A telecommunications device, comprising:
- a first encoding unit for encoding an input signal according to a first encoding law;
- a converting unit for determining a conversion of said input signal encoded according to said first encoding law to a second encoding law;
- and
- means for adjusting said input signal so that an output of one or more remote decoding units operating according to said second encoding law is optimized to said input signal.
A method of converting a data signal intended to be sent from a first site following a first coding law to a second site following a second coding law different from said first encoding law, said method comprising steps of:
- determining the first coding law at said first site;
- adjusting and encoding said data signal using said first coding law to produce an encoded changed data signal, said adjusting and encoding step ensuring that conversion from said first coding law to said second coding law results in a decoded data signal at said second site being more closely approximated to a normally decoded data signal if said data signal were to be sent from said first site to a third site following said first coding law;
- and
- transmitting said encoded changed data signal to said second site where said first coding law encoded changed data signal will be converted to said second coding law format and then decoded using said second coding law to a closer reproduction of said data signal at said second site.
Dependencies are inferred from the claim text.