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DTMF signal debugging and testing instrument

A tester and dual-audio technology, applied in the field of dual-audio signal debugging and tester, can solve the problems affecting the signal generator signal stability and accuracy, bad phase shift of sidebands on both sides of the carrier, etc. The effect of width and volume reduction

Inactive Publication Date: 2004-03-31
上海卓忆科技发展有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Most of the existing signal debugging testers use semiconductor discrete devices (even electronic tubes). From the circuit point of view, they generally use the subcarrier suppression network to directly suppress the frequency of the subcarrier, which often causes sidebands near the carrier ( Modulation signal low-frequency component) amplitude changes will also cause undesirable phase shifts of the sidebands on both sides of the carrier, which directly affects the stability and accuracy of the output signal of the signal generator

Method used

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  • DTMF signal debugging and testing instrument
  • DTMF signal debugging and testing instrument
  • DTMF signal debugging and testing instrument

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Embodiment Construction

[0010] figure 1 It is a schematic circuit diagram of the subcarrier ratio adjustment circuit 10 and the analog multiplier 11 according to an embodiment of the present invention. The subcarrier ratio adjustment circuit 10 is composed of resistors R9, R10, R11 and potentiometer W, and the analog multiplier 11 is composed of integrated circuit N and its peripheral circuits. Some components of the circuit are connected as follows: the subcarrier signal u3 generated by the subcarrier oscillator 3 is input to pin 10 of N through the coupling capacitor C2, and then input to pin 8 of N through the input impedance adjustment resistor R12. The difference (L-R) signal u1 generated by the sum-difference matrix circuit 2 passes through the low-pass filter 5a, and is input to pin 1 of N through R11, and then input to pin 4 of N through R10, W, and R9. R7 and R8 are input impedance adjustment resistors, respectively connect pin 1 and pin 4 of N to the ground. R6 grounds the 5-pin of N, whi...

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Abstract

The invention is a kind of double audio signal debug and testing device which is made up of left and right sound channel signal input, preaccentuation, sum-and-difference matrix, subcarrier oscillator, low-pass filter, bandpass filter, adder, phase shift amplitude adjustment, output buffer, relative amplitude instructing circuit. It uses subcarrier ratio adjustment circuit and analog multiplier to realize the restraint to subcarrier when modulating the L-R signal, the invention enhances the stability and precision of the whole machine.

Description

technical field [0001] The invention relates to a signal debugging and testing instrument, in particular to a dual-audio signal debugging and testing instrument. Background technique [0002] At present, FM stereo broadcasting in most countries and regions in the world adopts the pilot system, and only the Soviet Union and some countries in Eastern Europe adopt the polarization system. Most of the existing signal debugging testers use semiconductor discrete devices (even electronic tubes). From the circuit point of view, they generally use the subcarrier suppression network to directly suppress the frequency of the subcarrier, which often causes sidebands near the carrier ( Modulation signal low-frequency component) amplitude changes will also cause undesirable phase shifts of the sidebands on both sides of the carrier, directly affecting the stability and accuracy of the signal generator output signal. Contents of the invention [0003] The technical problem to be solved...

Claims

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Application Information

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IPC IPC(8): H04M3/22
Inventor 张文仙
Owner 上海卓忆科技发展有限公司