SU1564737A2 - Device for checking polarity of electroacoustic converters - Google Patents

Abstract

This invention relates to electroacoustics and can be used to control the polarity of loudspeakers and microphones. The purpose of the invention is to improve the noise immunity of the device. Inverter-inverters 7 and 8 block both measuring channels for time Τ _and close to the period T _and the pulse generator 1. The counters 9 and 10 prevent the polarity indicators 15 and 16 from firing when the amplitude of the received microphone 3 amplitude interferes, radiated by a speaker system 2. 2 Il.

Description

Rig. one

The invention relates to electroacoustics and can be used to control the polarity of switching on loudspeakers and microphones, as well as for phasing electroacoustic devices and electrical paths of sound amplifying equipment. The purpose of the invention is to improve the noise immunity of the device.

FIG. 1 is a block diagram of the device j in FIG. 2 - voltage diagrams showing operation of the static signal processing unit.

The device contains a pulse generator 1 connected to a controlled acoustic system 2 including frequency separator filters 2 and loudspeakers 2 $, the sound pressure receiver 3 is connected to the preamplifier 4. which is connected to the response pulse extractor 5, two outputs of which are connected to the statistical processing unit 6 signal consisting of two extenders-inverters of the first 7 and second 8, two counters of the first 9 and second 10, and two RC-chains, the first of which is made by a capacitor 11 and a resistor Ohm 12, and the second - a capacitor 13 and a resistor 1.

To determine the loudspeaker turn on polarity, an indication of the maximum amplitude of the response of one of the loudspeaker heads of the speaker system 2 to single excitation pulses from the pulse generator 1 is used. An acoustic signal is received by the sound pressure receiver 3 (microphone). The received electrical signal goes through the preamplifier, block 5, pulse response selection and block 6 of statistical signal processing to the inputs of the display units 15 and 16. Depending on the polarity of the loudspeaker head, a positive or negative pulse with a maximum amplitude comes first to the input of the receiver 3. The amplifier amplified Q signal is divided into positive and negative by the pulse extraction unit 5 of the response, while its amplitude positive and negative values are simultaneously highlighted here. Suppose the polarity of the test device is such that the negative impulse comes first. Highlighted by block 5 he

enters the input of the inverter extender. Extended by duration

0

five

0

five

0

five

0

five

on time

close

V .. blocks

AND

to the period of the following pulses Tn, but somewhat less (by an amount exceeding the instability of the period Ti). and inverted, it temporally enters both channels, preventing the passage of a pulse of opposite polarity and interference to the counter input.

If the first positive impulse arrives at the input of the Inverter Expander 8, then it works in the same way. Thus, secondary protection against interference is implemented. But since the channels are blocked for times Јand, somewhat less than the period Ti. then, for the parasitic CHI-nal, a time window remains between the end of the extended previous pulse and the arrival of the next. If an impulse of the opposite polarity arrives at the input of the device with an amplitude of a not less useful signal during this window, it could cause false indicators triggering, but counters 9 and 10, which are the third stage of protection against acoustic interference, prevent this. Counters 9 and 10 are turned on in such a way that they are filled with the same number of pulses, when one of them is filled, the other counter is reset to 0 and the information from the filled counter goes to the corresponding display unit. With the next pulse, the filled counter itself is set to O. The output of each of the counters is connected to the installation input of another counter via an RC-chain, the time constant of which is no more than n-T, where n is the counting factor of each of the counters, in order to prevent the collapse effect device, which occurs on average once from n cases when switching the field of fi nity of input pulses, for example, during an operational check of the device operability.

The device provides polarity control in conditions of intense acoustic interference, for example, in a real production room.

Claims (1)

The invention of the device for controlling the polarity of electroacoustic transducers 5 15 on auth. St. No. 1 32803, characterized in that, in order to improve the noise immunity, a statistical signal processing unit was introduced, consisting of two pulse extenders-inverters, two counters and two RC chains, the first capacitor being connected to the first input of the first extender - pulse inverter, the output of the first expander - pulse inverter is connected to the second input of the second expander pulse inverter and to the counting input of the first counter, the output of which is 0 7376 dinene with the input of the negative polarity indication unit and, via an RC circuit, with the installation input of the second counter, the second capacitor is connected to the first input of the second expander pulse inverter, the output of the second expander pulse inverter is connected to the second input of the first expander pulse inverter and with the counting input of the second counter, the output of which is connected to the display unit of positive polarity and through the second RC-chain to the installation input of the first counter. Editor M.Tovtin Compiled by S. Yudin Tehred M.Morgental Proofreader M.Kucher va Order 1166 Circulation 519 VNIIPI State Committee for Inventions and Discoveries at the State Committee on Science and Technology of the USSR 113035, Moscow, Zh-35, Raushsk nab. 4/5 2 Subscription