Victor Company of Japan, Limited

Thomson-brandt

Mamoru Inami

Yoshiaki Tanaka

Zenju Otsuki

Zenju Ohtsuki

Masatsugu Kitamura

Tsuyoshi Ono

Tomohiro Mori

Akio Hasegawa

An input audio signal is AD converted into digital signals which are processed by a central processing unit (CPU) in which Fast Fourier Transform (FFT) operation and power spectrum calculation are effected. As a result power spectrum data is obtained, and then position determination is effected to determine the position of each bar of a bar graph to be displayed on a display unit screen, according to the power level at different frequencies within the spectrum of the audio signal. Pattern data is then produced in correspondence with the determined position, and output data from the CPU is fed via a video display processor to a video RAM, thereby displaying the spectrum by way of a predetermined pattern of a bar graph on the screen. In order to reduce the number of digital data used in FFT operation the input audio signal may be divided into a plurality of different frequency bands so that different sampling frequencies are used for AD conversion of signals of respective bands. As a result, operating time is reduced. To further reduce the operating time the CPU may be arranged to execute parallel operations in various manners. Furthermore, two or more CPUs may be employed to further increase the operating speed.

Spectrum display device for audio signals

A graphic equalizer comprises an equalizer for separately level adjusting the input signal for each of a number of divided frequency bands which are different from each other, control knobs provided one for each of the divided frequency bands, which are operated for carrying out level adjusting of the equalizer, a spectrum analyzer supplied with the output signal of the equalizer and having a display for displaying the level of each of the divided frequency bands, and a casing provided with a panel face having the control knobs and the display section of the spectrum analyzer disposed in a corresponding relationship to each other and accommodating the equalizer and the spectrum analyzer therein.

Graphic equalizer with spectrum analyzer and system thereof

A level display device for audio signal comprises a plurality of bandpass filters having filtering bands of respectively different center frequencies, for band-dividing and filtering an input signal supplied thereto through an input terminal, a pulse width converter provided in correspondence with respective bandpass filters, for converting the input signal into a signal in synchronism with a vertical synchronizing signal of a video signal and having a pulse width in accordance with the level of the vertical synchronizing signal, a level indication signal producing circuit connected with outputs of the pulse width converter in parallel, for serially producing the converted pulse signal in synchronism with a horizontal synchronizing signal by successively time-dividing the converted pulse signal during a horizontal scanning period, a character indication signal producing circuit stored with information signals for displaying characters and the like, for serially obtaining a character indication signal in synchronism with a synchronizing signal of the video signal, and a video signal composing circuit driven by the video signal, for obtaining a video signal by composing an output of the level indication signal producing circuit and an output of the character indication signal producing circuit. Bars corresponding to the audio signal level in a vertical direction, characters, and the like, are composed and displayed on a screen of a picture tube, by the outputs of the level indication signal producing circuit and the character indication signal producing circuit.

Level display device for audio signal

In a circuit arrangement for automatically correcting frequency response so as to set a desired frequency response in view of a frequency response of a sound field, a frequency response control circuit is improved such that precise level control at a number of bands is effected with a simple structure. A microcomputer is used to determine the difference between a desired frequency response curve and a frequency response curve obtained by measuring the sound pressure level in a sound field, to which pink noise or the like is emitted through the frequency response control circuit, so as to produce a control signal used in the frequency response control circuit to give a desired frequency response to an audio signal. The frequency response control circuit comprises an amplifier, a plurality of resonance circuits corresponding to the bands, a plurality of variable resistor circuits each including a parallel circuit of a plurality of series circuits of a resistor and an analog switch; and an interface circuit responsive to serial data of the control signal from the microcomputer for controlling the analog switches.

Circuit arrangement for correcting frequency response in accordance with

An automatic recording bias current setting apparatus comprises a bias current generating circuit for generating a bias current with varied level of the bias current, a testing signal generating circuit for generating two kinds of testing signals having different mid and high frequencies of an audio signal, by independently varying the levels of the testing signals, a recording and reproducing circuit for recording the two kinds of testing signals with the bias current onto a magnetic recording medium and reproducing the same, and a bias current detecting circuit for detecting the level of a bias current. The recording and reproducing circuit repeats an operation in which the two kinds of testing signals are recorded onto the magnetic recording medium and then reproduced with independently varied levels of the two kinds of testing signals under the same bias current obtained from the bias current generating circuit, for each of the different varied bias currents. The bias current detecting circuit detects respective reproduced output levels of the two kinds of testing signals with respect to the different bias currents, to detect a bias current level at a point where a difference between respective maximum reproduced output levels becomes equal to a preset predetermined value.

Automatic recording bias current setting apparatus

An input audio signal is analog-to-digital (AD) converted into digital data which is processed by a central processing unit (CPU) for determining pitch of each sound by effecting Fast Fourier Transform (FET) operation and power spectrum calculation. The determination of the sound pitch is effected twice in sequence, and by using frequency and level data resulted from two consecutive determinations, the time length of the sound is detected. After the pitch and the time length are determined, data indicative of a given musical note pattern is produced so that a musical note indicative of time value is indicated at an appropriate position on a staff displayed on a screen of a display unit. Such data from the CPU is fed via a video display processor to a video RAM to be stored therein where the video display processor produces a video signal fed to the display unit in turn. In one embodiment, a note indicative of only sound pitch is displayed immediately after the pitch is determined, and the pattern of the note is changed to indicate time value if the sound is detected as a continuous sound. In another embodiment, the relationship between the time value of a note and actual time length can be manually set so that desired tempo can be selected. Furthermore, rhythm sounds corresponding to a selected tempo may be emitted, while data indicative of the selected tempo may be displayed.

Apparatus for displaying musical notes indicative of pitch and time value

An input audio signal is AD converted into digital data which is processed by a central processing unit (CPU) in which Fast Fourier Transform (FFT) operation and power spectrum calculation are effected. Furthermore, spectrum data obtained in this way is processed to obtain a fundamental tone to determine the pitch of each sound of the input audio signal. After the pitch is determined, data indicative of a given pattern is produced so that a musical note is indicated at an appropriate position on a staff displayed on a screen of a display unit. Such data from the CPU is fed via a video display processor to a video RAM to be stored therein where the video display processor produces a video signal fed to the display unit in turn. Since the fundamental tone does not necessarily have the highest level within the spectrum of the input audio signal, various ways for accurate determination of the pitch are used. Furthermore, a reference pitch preset in the musical note display device may be changed so as to be equal to a reference pitch emitted from a musical instrument or the like by changing sampling frequency of sampling pulses fed to an AD converter.

Musical note display device

A test signal is recorded on a magnetic tape prior to the recording of audio signals and reproduced to allow detection of an average value of the magnitude of the reproduced test signal. A drop-out in the reproduced signal is detected if it occurs during the process of deriving the average value. If the drop-out is not detected, a difference between the average value and a reference value is detected to adjust the signal level of the recorded test signal so that the difference reduces substantially to zero. If a drop-out is detected the average value is renewed by repeating the process of recording and reproducing the test signal.

Automatic level adjustment with means for minimizing drop-out effects

A level display device for audio signal comprises a plurality of bandpass filters having filtering bands of respectively different center frequencies, for band-dividing and filtering an input signal supplied thereto through an input terminal, a level indication signal producing circuit for converting the input signal into a signal in synchronism with a horizontal synchronizing signal of a video signal and having a pulse width in accordance with the level of the horizontal synchronizing signal, and serially obtaining the converted signal in sychronism with a vertical synchronizing signal of the video signal by successive time-division carried out during a vertical scanning period, a character indication signal producing circuit stored with information signals for displaying characters and the like, for serially obtaining a character indication signal in synchronism with a synchronizing signal of the video signal, and a video signal composing circuit driven by the video signal, for obtaining a video signal by composing an output of the level indication signal producing circuit and an output of the character indication signal producing circuit. The level display device composes and displays bars in a horizontal direction corresponding to the audio signal level, characters, and the like, on a screen of a picture tube, by the outputs of the level indication signal producing circuit and the character indication signal producing circuit.

Display device for displaying audio signal levels and characters

A maximum output level automatic measuring apparatus comprises a testing signal generating circuit for generating a plurality of testing signals having different frequencies, by independently varying respective levels of the testing signals, a recording and reproducing circuit for recording the plurality of testing signals from the testing signal generating circuit onto a magnetic recording medium, and reproducing the recorded testing signals, a level detector for detecting reproduced levels of the plurality of testing signals from the recording and reproducing circuit, and a display device for displaying a maximum output level curve according to reproduced levels detected at the level detecting circuit. The level detector detects that reproduced levels of the plurality of testing signals have reached predetermined values preset with respect to the respective testing signals. The display device comprises a display screen having a frequency axis and a level axis, and independently displays the reproduced levels which reached the predetermined values detected by the level detector for each of the frequencies.

Maximum output level automatic measuring apparatus

A signal spectrum display apparatus comprises a plurality of band-pass filters respectively having filtering bands of different center frequencies and operating to filter an input signal thereby to band-divide the input signal fed through an input terminal a plurality of rectification and charging circuits connected respectively to said band-pass filters, a display section having displaying systems of the same number as the band-pass filters respectively corresponding to the band-pass filters and for displaying the outputs of the rectification and charging circuits, and a switch connected between a point between the rectification and charging circuit and the display section, and the ground. A capacitor of the rectification and charging circuit charges and discharges during said switch is closed, whereby the input signal level is displayed in real-time in the display section, and stops charging and discharging during the switch is opened, whereby the maximum input signal level is successively displayed in the display section in response to the output voltage held in response to successive higher input signal voltage.

Signal spectrum display apparatus

An apparatus for displaying the spectrum of multichannel signals includes band-pass filtering circuits of a plurality of channels provided to respectively correspond to the channels of a plurality of channels. Each of the band-pass filters of respective channels comprises a group of band-pass filters having filtering bands having a respectively different center frequencies and filtering by band dividing input signals. The apparatus comprises level comparing circuits for at least rectifying respectively the outputs of band-pass filters mutually having the same filtering band of the band-pass filtering circuits of the plurality of channels, thereafter level comparing the same, and obtaining the band signal of the higher level, an indication device having indicating parts of systems of the same number as the number of the band signals thus obtained, and circuits for supplying said band signals thus obtained to the indicating device and causing the levels thereof to be displayed by the indicating parts of the respectively corresponding systems.

Spectrum displaying apparatus for multichannel signals

A spectrum display apparatus comprises a plurality of band-pass filters respectively having filtering bands of different center frequencies and operating to filter an input signal thereby to band-divide the input signal, a holding circuit normally passing the output signals of the band-pass filters and, upon the application thereto of a control signal, operating in response to the control signal to hold output signal voltages of the band-pass filters at the time of the control signal application, a display section having displaying elements of systems of the same number as the band-pass filters respectively corresponding to the band-pass filters, a circuit for supplying output signals of the holding circuit to the displaying elements and causing level displaying by the displaying elements of those systems corresponding respectively to the output signal levels of the band-pass filters, a control manipulation switch, and a circuit for producing the control signal and applying the same to the holding circuit during a specific time period after manipulation of the switch.

Spectrum display apparatus

A fluorescent signal level indicator includes two parallel rows of anode electrodes coated with a layer of fluorescent material to emit light when energized in response to an input analog signal exceeding a corresponding one of graduated reference potentials. A cathode electrode is provided for emitting electrons toward the anodes and a grid electrode is mounted between the cathode and anode electrodes for controlling the amount of electrons passing therethrough.

Fluorescent indicator tube and related circuit

A pulse amplifier has a first grounded emitter transistor arranged to receive input pulses to change its on-off states in accordance with the presence and absence of the applied pulses and a pair of second and third transistors having their collectors connected in common to a power supply. The second transistor has its base connected to the collector of the first transistor and its emitter connected to the base of the third transistor. The third transistor has its emitter connected to an output terminal from which a high voltage heavy current pulse is obtained so that the pair of transistors change their on-off states alternately with the first transistor. A semiconductor circuit is connected across the emitter and base of the second transistor to instantly put the base potential of the third transistor to a level equal to the base potential of the second transistor when the second transistor changes its state from conducting to nonconducting to thereby assure short decay time at the trailing edge of the output pulse.

Growing community of inventors

Yokohama, Japan

Mamoru Inami