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Nonlinear Phase Filter

IP.com Disclosure Number: IPCOM000087109D
Original Publication Date: 1976-Dec-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 39K

Publishing Venue

IBM

Related People

Pilost, D: AUTHOR [+2]

Abstract

In a receiver of a transmission system using discrete phase modulation, a phase filter is provided in a control loop for minimizing the effect of phase errors affecting discrete phase-modulated signals. Thus, the detection of phases is improved.

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Nonlinear Phase Filter

In a receiver of a transmission system using discrete phase modulation, a phase filter is provided in a control loop for minimizing the effect of phase errors affecting discrete phase-modulated signals. Thus, the detection of phases is improved.

The drawing shows the portion of the receiver comprising the phase filter and a nonlinear gain circuit added thereto. The circuit comprises a subtractor 1, the output of which is connected to control loop 2 and to phase detector 3. Phase information extracted from the received signal is applied to the positive input of subtractor 1.

The control loop comprises subtractor 4 which provides the phase error to subtractor 5. This phase error is centered on zero through subtractor 5. The output of subtractor 5 is applied to nonlinear gain circuit 6, having the response curve represented in the figure. The output of circuit 6 is connected to phase filter 7 which is a second-order recursive filter, providing the phase error signal to the negative input of subtractor 1.

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