Title:
【発明の名称】適応周波数変調方式
Document Type and Number:
Japanese Patent JPH02500157
Kind Code:
A
Abstract:
Improved effifiency of frequency-modulated (FM) transmission of signals through analog channels, i.e., achievement of a higher bandwidth and/or signal-to-noise ratio (SNR) in the received signal for a given channel bandwidth and channel carrier-to-noise ratio (CNR), is accomplished by adaptive adjustment of the modulation index in such a manner that the spectrum of the channel signal more nearly occupies the entire channel more of the time than it would otherwise. Data is transmitted, along with the signal, to enable the receiver to calculate the modulation index at each instant so that the signal can be properly demodulated. The invention has application to FM transmission of signals representing visual image or other information, such as sound, for which human perception of noise is greatest in areas of low amplitude and/or frequency and reduced in and immediately adjacent to areas of high amplitude and/or frequency.
Inventors:
Shreber, William Eff
Application Number:
JP50639488A
Publication Date:
January 18, 1990
Filing Date:
June 10, 1988
Export Citation:
Assignee:
Massachusetts Institute of Technology
International Classes:
H04N5/38; H04B1/66; H04N7/045; H04N7/083; H04N7/12; H04N7/26; H04N11/04; (IPC1-7): H04B1/66; H04N5/38; H04N7/12
Attorney, Agent or Firm:
Kyozo Yuasa (4 outside)