| 摘要 |
PCT No. PCT/SE82/00362 Sec. 371 Date Jun. 16, 1983 Sec. 102(e) Date Jun. 16, 1983 PCT Filed Nov. 2, 1982 PCT Pub. No. WO83/01715 PCT Pub. Date May 11, 1983.An FIR-type balance filter for preventing, in adaptive echo cancellation in a telecommunication system in which digital information transferred in duplex over a single conductor pair, that the local data transmitter disturbs the local data reception. The filter is thereby arranged so that the total number of links (N) in the filter is divided into at least a first group (I) and a second group (II). The apparatus contains a memory (MI) addressable from the filter links and said first group, there being written into and read from said memory the correction values from and to a correction unit (KB1), sending signals for correcting the filter parameters. The memory (M1) also sends signals to a summing circuit (A2), to which are also supplied the output signals from said second group of filter links, said output signals possibly being originated by table look-up in a further memory, or by vector multiplication. A second correction unit (KB2) corrects the filter parameters in said second group. The output signal from the summing circuit is digital-analogue converted and with its sign added to the signal coming from the remote end and transmitted to the local transmitter, thus compensating for the nonlinearity in the echo signal.
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