Digital communication device
AssigneeCanon Kabushiki Kaisha
InventorTatsuya Yaguchi
Life of this patent
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Abstract
A digital communication device of the present invention is provided with a modulation circuit for modulating a digital transmit signal, a first interpolater for converting the modulated signal in frequency, a coding circuit for coding the signal converted in frequency into an audio PCM transmission code with reference to a voice companding code table, a decoding circuit for decoding a coded audio PCM receive code into a digital signal with reference to the voice companding code table, a second interpolater for converting the decoded digital signal in frequency, and a demodulation circuit for demodulating the converted signal, and digitally performs modem modulation/demodulation and voice codec processing.
Claims38
A modulation device for outputting digital data representing a modulated signal to a digital transmission path, said modulation device comprising:
- first conversion means for performing a modulation process by converting input signals into first digital signals representing the modulated signal and outputting said first digital signals at first intervals, said first intervals being predetermined for performing the modulation process;
- and
- second conversion means for converting said first digital signals, input at said first intervals, into second digital signals representing the modulated signal at second intervals which are different from said first intervals and which correspond to a sampling frequency of the digital transmission path, and outputting said second digital signals at said second intervals to the digital transmission path.
A demodulation device for demodulating data representing a modulated signal received from a digital transmission path and decoded by a decoding circuit, said demodulation device comprising:
- conversion means for converting the data representing the modulated signal input at first intervals from the digital transmission path into converted data representing the modulated signal at second intervals different from said first intervals, said first intervals corresponding to a sampling frequency of the digital transmission path;
- and
- processing means for performing demodulation based on said converted data at said second intervals.
A digital communication device connected to a digital network for performing modem and voice code processing, comprising:
- a transmitting section comprising:
- modulation means for outputting first signals representing a first modulated signal using a modulation process;
- first conversion means for converting the first digital signals inputted at a first frequency, which is predetermined for the modulation process used by the modulation means, to second digital signals representing the modulated signal sampled at a sampling frequency of the digital network;
- coding means for coding the second digital signals converted by said first conversion means;
- and
- means for outputting the coded second digital signals to the digital network;
- and
- a receiving section comprising:
- means for receiving, from the digital network, coded third digital signals representing a second modulated signal;
- decoding means for decoding the coded third digital signals;
- second conversion means for converting the third digital signals representing the second modulated signal decoded by said decoding means at the sampling frequency of the digital network into fourth digital signals representing the second modulated signal at the first frequency;
- and
- demodulation means for demodulating the fourth digital signals converted by said second conversion means.
A communication apparatus for communicating digital data representing a modulated signal via a digital transmission path, said apparatus comprising:
- procedure means for performing a communication control procedure;
- first conversion means for converting a communication control procedure signal into first digital signals and outputting said first digital signals at first intervals, said first digital signals representing a modulated signal modulated by a modulation process in accordance with the communication control procedure signal, and said first intervals being predetermined for the modulation process;
- and
- second conversion means for converting said first digital signals, input at said first intervals, into second digital signals representing the modulated signal at second intervals which are different from said first intervals and which correspond to a sampling frequency of the digital transmission path, and outputting said second digital signals at said second intervals to the digital transmission path.
A method for generating digital signals representing a modulated signal to be transmitted via a digital transmission path, said method comprising the steps of:
- inputting digital transmission signals;
- producing first digital signals, using a modulation process, representing the modulated signal corresponding to the digital transmission signals at first intervals, the first intervals being predetermined for the modulation process;
- converting the first digital signals into second digital signals representing the modulated signal at second intervals which are different from the first intervals and which correspond to a sampling frequency of the digital transmission path;
- and
- outputting the second digital signals at said second intervals to the digital transmission path.
A demodulating method for demodulating reception signals from a digital transmission path, said method comprising the steps of:
- inputting digital reception signals from the digital transmission path at first intervals which correspond to a sampling frequency of the digital transmission path;
- converting the digital reception signals into converted digital signals which have values of an envelope represented by the digital reception signals sampled at second intervals different from the first intervals;
- and
- demodulating the converted digital signals.
A demodulating method for demodulating reception signals from a digital transmission path, said method comprising the steps of:
- inputting, from the digital transmission path, digital reception signals representing a modulated signal at first intervals which correspond to a sampling frequency of the digital transmission path;
- interpolating the digital reception signals at second intervals different from the first intervals such that the interpolated digital reception signals represent the modulated signal;
- and
- demodulating the interpolated digital reception signals.
Dependencies are inferred from the claim text.