Inversion prevention device
AssigneeMitsubishi Denki Kabushiki Kaisha
InventorsKeiji Hatanaka, Yoshiyuki Shirasaki
Life of this patent
Estimating the term…
Abstract
An inversion prevention device to prevent inversion and provide the best S/N ratio detects a point where the zero crossing is missing from a quantized FM signal. An output is provided by switching between the digital FM signal and the output signal of at least one sideband suppression filter based on a result of the inversion detection. Alternatively, an output is provided by switching between the digital FM signal and a specified value based on a result of the inversion detection. As a further alternative, an output is provided by switching between the digital FM signal, the output signal of a low-sideband emphasis filter and the output signal of a sideband suppression filter based on a result of the inversion detection.
Claims54
An inversion prevention device to prevent an inversion in an FM signal, comprising:
- a sideband suppression filter which receives a quantized digital FM signal as an input and suppresses either both upper and lower sidebands or said lower sideband of said digital FM signal;
- inversion detecting means for detecting an inversion of said digital FM signal;
- and
- selecting means for selecting either said digital FM signal or an output signal of said sideband suppression filter, on the basis of output from said inversion detecting means.
An inversion prevention device to prevent an inversion in an FM signal comprising:
- a sideband suppression filter which receives a quantized digital FM signal as an input and suppresses either both upper and lower sidebands or said lower sideband of said digital FM signal;
- inversion detecting means for detecting an inversion of said digital FM signal;
- and
- selecting means for selecting either said digital FM signal or a specified preset value on the basis of output from said inversion detecting means.
An inversion prevention device to prevent an inversion in an FM signal, comprising:
- inversion detecting means for receiving a quantized digital FM signal as an input and for detecting an inversion of said digital FM signal, said inversion detecting means including a judging unit to judge a sign of a subtraction between said digital FM signal and an earlier digital FM signal, and a sign of a result of subtraction between said digital FM signal and a later digital FM signal;
- and
- selecting means for selecting either said digital FM signal or a specified preset value on the basis of output from said inversion detecting means.
An inversion prevention device to prevent an inversion in an FM signal, comprising:
- inversion detecting means for receiving a quantized digital FM signal as an input and for detecting inversion of said digital FM signal said inversion detecting means including a detecting unit to detect that said digital FM signal is within a predetermined range, and a judging unit for judging a sign of said digital FM signal, a sign of a result of subtraction between said digital FM signal and an earlier digital FM signal, and a sign of a result of subtraction between said digital FM signal and a later digital FM signal;
- and
- selecting means for selecting either said digital FM signal or a specified preset value on the basis of output from said inversion detecting means.
An inversion prevention device to prevent an inversion in an FM signal, comprising:
- at least two sideband suppression filters having different suppression ratios which receive a quantized digital FM signal as an input and suppress either both upper and the lower sidebands or said lower sideband of said digital FM signal;
- inversion detecting means for detecting inversion of said digital FM signal;
- and
- selecting means for selecting either said digital FM signal or an output signal of one of said sideband suppression filters on the basis of output from the inversion detecting means.
An inversion prevention device to prevent an inversion in an FM signal comprising:
- at least one low-sideband emphasis filter receiving a quantized digital FM signal as an input, and suppressing an upper sideband or emphasizing a lower sideband of said digital FM signal;
- at least one sideband suppression filter suppressing either both said upper and lower sidebands or said lower sideband of said digital FM signal;
- inversion detecting means for detecting an inversion of said digital FM signal;
- and
- selecting means for selecting either said digital FM signal an output signal of said low-sideband emphasis filter or an output signal of said sideband suppression filter, on the basis of output from said inversion detecting means.
An inversion prevention device to prevent an inversion in an FM signal, comprising:
- a sideband suppression filter which receives a quantized digital FM signal as an input and suppresses either both upper and lower sidebands or said lower sideband of said digital FM signal;
- inversion detecting means for detecting an inversion of said digital FM signal based on said digital FM signal and an output signal of said sideband suppression filter;
- and
- selecting means for selecting either said digital FM signal or said output signal of said sideband suppression filter based on output from said inversion detecting means.
Dependencies are inferred from the claim text.