公开(公告)号：DE2001496A1

公开(公告)日：1970-07-16

申请号：DE2001496

申请日：1970-01-14

Applicant: IBM

Inventor： PARKER WEST LYNN

IPC: H03D3/04 ,  H03K9/08

公开(公告)号：PH22707A

公开(公告)日：1988-11-14

申请号：PH34197

申请日：1986-08-29

Applicant: IBM

Inventor： PARKER WEST LYNN

IPC: H03H11/04 ,  H03H17/04 ,  H03H21/00 ,  H04Q1/457 ,  H03B1/04

Abstract: A filter suppresses energy at time varying or ensemble varying frequencies. The filter comprises multiplier sections (15, 18, 16, 19) having sets of values which are dynamically varied during the receipt of time varying or ensemble varying energy. The variation of the values of the multiplier sections provides the suppression of energy at the time varying or ensemble varying frequencies. The sets of values for the multiplier sections are chosen such that the poles of such values lie within the unit circle of the z-plane locus. The location of the poles within the unit circle guarantees that the filter remain stable even though the multipliers may be located in a feedback path. In the preferred embodiment, the dynamically varying filter is used in a dual tone multi-frequency (DTMF) receiver.

公开(公告)号：DE1512251A1

公开(公告)日：1969-05-22

申请号：DE1512251

申请日：1967-03-02

Applicant: IBM

Inventor： WARREN CALFEE RICHARD ,  HOPNER EMIL ,  FRED MEYER ORMAN ,  PARKER WEST LYNN

IPC: H03C1/54 ,  H04B14/00 ,  H04L27/10 ,  H04B1/62