Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
  • H04R3/00—Circuits for transducers, loudspeakers or microphones
  • H04R3/04—Circuits for transducers, loudspeakers or microphones for correcting frequency response
• • H—ELECTRICITY
  • H03—ELECTRONIC CIRCUITRY
  • H03G—CONTROL OF AMPLIFICATION
  • H03G5/00—Tone control or bandwidth control in amplifiers
  • H03G5/16—Automatic control
  • H03G5/165—Equalizers; Volume or gain control in limited frequency bands
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04S—STEREOPHONIC SYSTEMS 
  • H04S7/00—Indicating arrangements; Control arrangements, e.g. balance control
  • H04S7/30—Control circuits for electronic adaptation of the sound field

Definitions

• the invention relates to the correction of frequency transmission faults of an electroacoustic channel including all or part of the capture, recording, transmission, processing, reproduction devices and the space where the reproduction of '' sound information, vocal or musical, high fidelity or not.
• electroacoustic installations have an irregular transmission of the frequencies of the audible spectrum, due to defects inherent in one or more electrical or acoustic elements, defects which can combine to lead to a very unfaithful reproduction of the signal to be transmitted, or even to a total loss of 'intelligibility (resonance, Larsen effect).
• Corrective devices known as parametric equalizers are already known which make it possible to correct the most important faults of this transmission exactly, provided that the frequency transmission curve provided by a second device, the analyzer, is available.
• the present invention aims to remedy these drawbacks.
• the invention as characterized in the claims, solves the problem of obtaining a frequency transmission of an electroacoustic installation which is equal over the whole spectrum audible, instantly and automatically.
• the corrector consists of a set of universal active filters, the parameters of which (central frequency, gain overvoltage coefficient and bandpass or hanger cutter nature), are adjustable by digital control.
• This numerical control is done by the intermediary of digital / analog converters multipliers, which, by multiplying by a coefficient, determined by a binary number with eight bits, the signal which is applied to them, modify the transfer function of these filters.
• the number of these filters is fixed according to the number of faults which one estimates to have to correct and the precision of the equalization which one wants to obtain, three being a commonly suitable number.
• Each of these filters also includes a set of analog switches, also controlled digitally, which make it possible to carry out either a configuration of notch filter or a configuration of bandpass filter, by performing the appropriate summations of the signals available on the filters. , according to the current technique of universal active filters.
• the filters are mounted in parallel and included in the electroacoustic channel which must be equalized.
• the present invention also includes an assembly performing a detection of the signal present at the output of the filters to which it is connected, also by means of a digitally controlled analog switch. The detected signal is digitized by an analog / digital converter, and thus gives the level of reproduction at the filter frequency.
• a source of " pink noise is also part of the device as it can be produced according to this description, and is used to apply to the electroacoustic path which must be equalized, a test signal. All these elements are placed under the control of '' a microprocessor-based calculator, comprising a central processing unit, read-only memories containing the software, random access memories serving as “notepads”, and sufficient input / output ports for the interface of all the commands of all the filters, to control the various switches, and to take into account the data coming from the system.
• the software defining the operation of the assembly after having received an execution order, switches everything into position, analysis, or allowing the injection of pink noise to the electroacoustic channel to be equalized before being between the injection point and the measurement point.
• All the frequencies are scanned by one of the filters and the values of measured voltages are put into RAM.
• the software determines the values the most deviated from an average value, the importance, the direction and the width of these faults, and assigns to each of the available filters, the values of central frequency, coefficient of -supervoltage, gain and the band-pass or band-cutter nature capable of eliminating this defect.
• the software then returns the assembly to the normal operating configuration.
• the present invention can be realized in the form of a complete product taking place among the various preexisting elements of the electroacoustic installation, or can be integrated as part of one of these elements, such as power amplifier, preamplifier or tape recorder, to improve performance.

Landscapes

• Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Acoustics & Sound (AREA)
• Signal Processing (AREA)
• Tone Control, Compression And Expansion, Limiting Amplitude (AREA)
• Measurement Of Mechanical Vibrations Or Ultrasonic Waves (AREA)
• Circuit For Audible Band Transducer (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=9239908

Family Applications (1)

Country Status (3)

Cited By (3)

Families Citing this family (3)

Citations (2)

• 1980
  • 1980-03-13 FR FR8006283A patent/FR2478409A1/fr active Granted
• 1981
  • 1981-03-13 WO PCT/FR1981/000036 patent/WO1981002658A1/fr not_active Application Discontinuation
  • 1981-03-13 EP EP19810900641 patent/EP0047281A1/fr not_active Withdrawn

Patent Citations (2)

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events