METHOD AND APPARATUS FOR AUTOMATICALLY ADAPTING THE AMOUNT OF WARPING IN A SYSTEM TRANSMITTING INFORMATION THROUGH A NON-LINEAR CHANNEL

摘要

The present invention discloses an improvement over existing techniques for transmitting data over voice-band telephone channels by automatically adapting the amount of warping or compression that is applied to a sequence of signal points. A sequence of warped signal points, each of which is related to a respective signal point of a predetermined base constellation according to a warp function, is received in a decoder via a transmission channel having a non-linear component. After each of the received signal points is unwarped using substantially an inverse of the warp function, the average dispersions of the received inner and outer signal points about corresponding sequences of expected signal points are calculated. The difference between the average dispersion of the inner and outer points is then computed and used to update the amount of warping or compression in order to further minimize the effects of the channel non-linearity. The desired amount of warping is communicated to the transmitting encoder.