Casio Computer Co., Ltd.

Kikuji Tanaka

Kohtaro Hanzawa

Goro Sakata

Ryutaro Hayashi

In a signal processing apparatus which stores a program inside, and performs a series of processes on a received signal according to the program, such as an arithmetic operation or a delay process, and outputs the processed signal, for rewriting the program in order to change the contents of the processing. Program data is prevented from being output in synchronism with a sampling clock generated at the timing of an input signal. This design can minimize noise occurring due to a change in the algorithm of the signal processing during signal processing. Further, in the case where a program for a separate signal processing circuit is rewritten in response to an instruction that is given from outside at an arbitrary timing, noise can also be minimized by proceeding with the rewriting in synchronism with a sampling clock.

Signal processing apparatus

A signal processing apparatus according to the present invention is used as a sound source, an effecting machine and/or a communication equipment, which simultaneously generates or processes a plurality of musical tones and sounds on the basis of a plurality of input data such as performance data, musical tone data and/or communication data. This signal processing apparatus stores a program prepared for controlling operation to generate or process musical tones and sounds only for one channel. The program is read out in accordance with a lower bit of a readout counter. A upper bit of the readout counter is used to designate a channel to which the generated or processed musical tones and sounds are assigned in accordance with the read out program. As a result, only a small area is required for storing the program and a simple construction may be employed in the apparatus.

Signal processing apparatus for repeatedly performing a same processing

A single signal processor performs a pitch process which produces musical sound waveform data having a frequency corresponding to received pitch data, a filtering process for filtering the generated musical sound waveform data, and an amplitude process which controls the amplitude of a musical sound generated on the basis of the filtered musical sound waveform data in order to produce a musical sound. It simultaneously performs outputting the produced musical sound waveform data to a plurality of output terminals and an effect process which imparts an effect to the musical sound data. The signal processor outputs at least one of musical sound waveform data to which the effect is imparted and musical sound waveform data to which no effects are imparted, using at least one of an external and an internal effect circuit to thereby impart a variety of effects to the resulting musical sound.

Musical sound generator with single signal processing means

Using stored discrete samples of filter coefficients at each of a plurality of discrete operating points, a filter control (e.g., CPU) provides dynamic control of a digital filter through an interpolator in accordance with a variable input indicative of a desired operating point (e.g., cutoff frequency) of the digital filter. In response to a large change in the desired operating point, the control produces a succession of operating point subgoals progressively approaching the changed desired operating point and a corresponding succession of filter coefficient subgoals. Each filter coefficient subgoal is calculated as a function of stored discrete filter coefficient samples near each operating point subgoal. In response to a new parameter set from the filter control, containing a new subgoal of the coefficients, the interpolator starts coefficient interpolating to smoothly move the operating point of the digital filter toward the new subgoal. By starting the interpolating operations after the updating of the parameter set has been completed, synchronization may be established among the interpolating operations on the coefficients.

Digital filter system with changeable cutoff frequency

Using stored discrete samplers of filter coefficients at each of a plurality of discrete operating points, a filter control (e.g., CPU) provides dynamic control of a digital filter through an interpolator in accordance with a variable input indicative of a desired operating point (e.g., cutoff frequency) of the digital filter. In response to a large change in the desired operating point, the control produces a succession of operating point subgoals progressively approaching the changed desired operating point and a corresponding succession of filter coefficient subgoals. Each filter coefficient subgoal is calculated as a function of stored discrete filter coefficient samples near each operating point subgoal. In response to a new parameter set from the filter control, containing a new subgoal of the coefficients, the interpolator starts coefficient interpolating to smoothly move the operating point of the digital filter toward the new subgoal. By starting the interpolating operations after the updating of the parameter set has been completed, synchronization may be established among the interpolating operations on the coefficients.

An electronic keyboard instrument has a plurality of key displacement sensors disposed in relation to respective keys of a keyboard. Each sensor detects a continuously variable key displacement induced by the key operation to provide an analog signal indicative of the displacement. An analog-to-digital converter digitizes the analog signal at a predetermined sampling rate to derive a stream of digital samples of key displacement. A control, which operates based on a predetermined tone control algorithm receives and analyzes the stream of digital samples. According to the analysis, tone parameters such as envelope and vibrato are produced for controlling the characteristics of a tone, so that a tone having a very dynamic key touch response is developed. In a preferred embodiment, there are provided a plurality of tone control algorithms adapted to process the stream of key displacement samples in manners different from one another. A manually operative selector selects the desired one of the algorithms to be used by the control during the play of the instrument. '

Growing community of inventors

Fussa, Japan

Kikuji Tanaka