CN2137841Y

CN2137841Y - Computer testing instrument for dials

Info

Publication number: CN2137841Y
Application number: CN 92225351
Authority: CN
Inventors: 高峰; 蔡明�; 黄国平
Original assignee: 高峰
Priority date: 1992-06-17
Filing date: 1992-06-17
Publication date: 1993-07-07
Anticipated expiration: 2002-06-17

Abstract

Disclosed is a computer testing instrument for dials belonging to a testing instrument for a telephone set. The utility model is characterized in that the amplitude frequency of the high and low frequency signal of a double-audio telephone set can be displayed accurately and simultaneously in a digital form, and the signal beyond the scope can be prompted. The double-audio testing circuit is mainly composed of a high and a low frequency passageway, an analog-digital transformation, a monolithic computer and the peripheral of the monolithic computer. The utility model has the advantages of reasonable circuit construction, high precision, high reliability, low cost, convenient operation, clear measuring parameter, etc., and the utility model is an indispensable testing instrument for the telephone set manufacturer and the repairing department.

Description

Computer testing instrument for dials

The utility model relates to a kind of telephone set tester, exactly is the computer testing instrument for dial.

According to the requirement of the Ministry of Posts and Telecommunications to telephone set, the double-tone low frequency group amplitude of phone frequently is-9dB ± 2dB that the high frequency group amplitude is-7dB ± 3dB; The difference of high and low frequency group amplitude must not be greater than ± 2dB, and frequency deviation is ± 1.8%, otherwise phone can not accurately be connected.But the present double-tone of China detection means of phone frequently also rests on total amplitude gauge outfit indication, on the level that frequency pass passes through, does not obviously reach the requirement of accurate detection, demonstration high and low group signal amplitude and frequency.

The purpose of this utility model aims to provide a kind of computer testing instrument for dial with accurate high and low frequency passage, accurately detects and digital simultaneously high and low frequency group signal amplitude and the frequency of showing to guarantee that this instrument can be distinguished.

Concrete technical scheme of the present utility model is as follows:

The double-tone that constitutes this tester by high and low frequency passage and analog to digital conversion circuit and single-chip microcomputer and ancillary equipment thereof is testing circuit frequently, it is characterized in that: with a typical accurate small-signal difference amplifier that is made of three amplifiers and peripheral resistance thereof the bell signal of phone is fed to high and low frequency passage (see figure 2); Low channel is connected and composed by low pass filter, shaping circuit, coupling capacitance, rectification circuit and filter amplification circuit successively, and its block diagram is seen Fig. 1.Above-mentioned low pass filter adopts sublevel Chebyshev low pass filter to be connected into typical connection, the low frequency signal in the bell signal is leached deliver to the next stage shaping; Shaping circuit is connected into typical circuit by an amplifier and peripheral resistance thereof, and the waveform of low frequency signal is adjusted is square wave; This square-wave signal is coupled to rectification circuit through coupling capacitance, and this rectification circuit is removed the negative half-wave in the prime signal by the typical rectification circuit that an amplifier and two diodes and peripheral resistance thereof constitute; Signal through rectification is delivered to filter amplification circuit, the typical, filtered circuit that this circuit is made of an amplifier and capacitance resistance, rectified signal is become level and smooth direct current signal, this direct current signal is delivered to single-chip microcomputer after analog-to-digital conversion, under the support of software, finish mensuration, output and the Presentation Function of low frequency signal amplitude by single-chip microcomputer, and finish the discriminating that range signal is made mistakes, pointed out by instrument.Output termination one frequency setting circuit at aforementioned shaping circuit, this shaping circuit constitutes typical amplitude limiter circuit by an amplifier and two voltage stabilizing didoes and peripheral resistance thereof, low frequency signal after the shaping is carried out the interchange amplitude limit, make that the signal frequency that enters single-chip microcomputer is stable.Hf channel is connected and composed by high pass filter, shaping circuit, coupling capacitance, rectification circuit and filter amplification circuit successively, and its block diagram is seen Fig. 1.The active high-pass filter of high pass filter for being connected into by two amplifiers and capacitance resistance, shaping, rectification, filter amplification circuit, circuit structure is all identical with the corresponding circuit structure of low channel; Output at shaping circuit connects a frequency setting circuit, and this circuit is to be made of an amplifier and two voltage stabilizing didoes and peripheral resistance thereof, and its output connects single-chip microcomputer.In order to improve input impedance, the front of the high and low frequency filter in aforesaid high and low frequency passage connects a circuit that is connected into the unity feedback shape by an amplifier respectively.

During use, the retaining of the selection on the instrument is allocated to double-tone tests retaining frequently, press the phone key, then can show the amplitude and the frequency of high and low frequency signal simultaneously, give warning prompt the signal that exceeds requirement.

The utility model has the advantages that: owing to adopted sublevel Chebyshev low pass filter in the circuit, i.e. 5G6514 integrated circuit is convenient to software the decay of unlike signal is compensated; Shaping, amplifying circuit have adopted operational amplifier, circuit element is reduced, circuit working is stable, antijamming capability is strong, and precision improves, thereby it is accurate more to have guaranteed that back level shows, compared with prior art, this circuit has adopted rectification, amplifying circuit respectively in the high and low frequency passage, and it is connected to analog to digital conversion circuit, has realized the numeral of high and low frequency group signal is shown.Use the utility model test double-tone phone amplitude frequently, dynamic range is at-1～2dB, and the signal that gone beyond the scope shows makes mistakes, and the amplitude precision is ± 0.4dB.Because advantages such as its precision height, cost are low, and be easy to use will become the indispensable detecting instrument of phone manufacturer and repairing department undoubtedly, especially be fit to repair and the performance of research and development department's grasp phone.

Specifically describe this utility model below in conjunction with accompanying drawing, embodiment.

Fig. 1 is a block diagram of the present utility model;

Fig. 2 is circuit diagram of the present utility model (one);

Fig. 3 is circuit diagram of the present utility model (two).

Embodiment:

Can know from Fig. 2, Fig. 3 and intactly reproduce a concrete technical scheme of the present utility model that the resistance R 54 of sublevel Chebyshev low pass filter IC36 ' be adjustable resistance is wherein selected the adjustable resistance of 56K, capacitor C ₃₁Be 330P ⁰, regulate R54 ', the bandwidth that makes this low pass filter is 600～1200HZ.High pass filter is by IC ₅Reach electric capacity, resistance formation, wherein C ₁₅, C ₁₄Be 0.01 μ, resistance R ₂₉Be the 10K adjustable resistance, suitably regulating and making the bandwidth of this high pass filter is 1200～1880HZ.Voltage stabilizing didoe low level in the frequency setting circuit is 0～0.3V, and high level is 5～8V.Analog to digital conversion circuit adopts the ADC0809 integrated package, and the single-chip microcomputer model is 8039.

What Fig. 2 described is that the utility model high and low frequency passage prime respectively adopts an operational amplifier IC who is connected into the unity feedback shape ₆, in order to improve input impedance, its model is LM358.

Claims

1, a kind of computer testing instrument for dial, the basic circuit that its double-tone is tested frequently is made up of high and low frequency passage, analog to digital conversion circuit, single-chip microcomputer and ancillary equipment thereof, it is characterized in that:

A, a typical accurate small-signal difference amplifier that is made of three operational amplifiers and peripheral resistance thereof is arranged, the bell signal of phone mechanism is fed to high and low logical frequency channel;

The typical, filtered amplifying circuit that the typical rectification circuit that the typical shaping circuit that b, described frequency passage are connected into by sublevel Chebyshev low pass filter, an amplifier and peripheral resistance thereof, coupling capacitance, an amplifier and two diodes and peripheral resistance thereof are connected into and amplifier and electric capacity, resistance are connected into connects to form successively, total output of low channel connects analog to digital conversion circuit, output termination one frequency setting circuit at above-mentioned shaping circuit, this circuit is an amplifier and two typical amplitude limiter circuits that voltage stabilizing didoe is connected into, and its output is connected to single-chip microcomputer;

The typical, filtered amplification path that the typical rectification circuit that typical shaping circuit, coupling capacitance, an amplifier and two diodes that active high-pass filter, an amplifier and the peripheral resistance thereof that c, hf channel are connected into by two amplifiers and electric capacity and peripheral resistance thereof is connected into and peripheral resistance thereof constitute, amplifier and capacitance resistance thereof constitute connects to form successively, total output of this hf channel connects analog to digital conversion circuit, connects one by an amplifier and two frequency setting circuit that voltage stabilizing didoe constitutes in the output of above-mentioned shaping circuit;

2, computer testing instrument for dial as claimed in claim 1 is characterized in that: have one to be connected into the circuit of unity feedback shape by an amplifier respectively in the prime of described high and low frequency passage, in order to improve input impedance.