| 摘要 |
<p>METHOD AND APPARATUS FOR IMPROVING TELEPHONE HYBRID NETWORK A circuit and method for controlling the connection of a cancellation network between the four-wire input and output of a hybrid transformer at the two-wire to four-wire interface of a telephone line. The relative phase of a signal applied to the four-wire input appearing on the four-wire output, is used to determine whether the two-wire telephone line appears loaded or non-loaded. This in turn controls the selection of the appropriate cancellation network which will give the greatest singing return loss.</p> |
