Variable transmission rate digital modem with multi-rate filter bank

摘要

A signal demultiplexer includes serially-connected 2-demultiplexing filter banks (102∼108), including band-stop filters (1021, ...) and down-samplers (1023, ...) for culling sampling frequencies of output signals from filters to 1/2. When the 2-demultiplexing filter bank operates on four types of filters, first to fourth filters (1021, 1022, 1043, 1044) in an ascending order of frequencies, a 2-demultiplexing filter bank is arranged in one of two configurations so that a first filter bank (102, ...) contains at least the first filter or the second filter, or a second filter bank (104, ...) contains at least the third filter or the fourth filter. The filter banks are connected in such a way that signals processed through the first filter are processed by the first 2-demultiplexing filter bank in a next-stage; signals processed through the second filter are processed by the second 2-demultiplexing filter bank in a next-stage. Signals processed through the third filter are processed by the first 2-demultiplexing filter bank in a next-stage; and signals processed through the fourth filter are processed by the second 2-demultiplexing filter bank in a next-stage.