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Distortion measurement method of building intercom system

A technology of intercom system and test method, which is applied in the direction of monitoring/monitoring/test arrangement, selection device, electrical components, etc., to achieve the effect of improving accuracy

Active Publication Date: 2010-06-23
THE THIRD RES INST OF MIN OF PUBLIC SECURITY +1
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  • Abstract
  • Description
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  • Application Information

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Problems solved by technology

In order to make up for this defect, people add a window function to reduce the influence of spectrum leakage, such as the common Hanning window, but after adding a window function, the maximum jump will be reduced from 6dB to 1.5dB, which is required in practical applications. 0.1dB still has a long way to go

Method used

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  • Distortion measurement method of building intercom system
  • Distortion measurement method of building intercom system
  • Distortion measurement method of building intercom system

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Embodiment Construction

[0018] The present invention will be further described below.

[0019] A distortion test method for a building intercom system, characterized in that it comprises the following steps:

[0020] (1) Send the audio time domain signal to the Louyu intercom system;

[0021] (2) Collect the audio time domain signal output by the building intercom system;

[0022] (3) Transform the collected audio time-domain signal into a high-precision frequency-domain signal;

[0023] (4) Measure the fundamental voltage U1 and the second and third harmonics U2 and U3 of the high-precision frequency domain signal, according to

[0024] γ = U 2 2 + U 3 2 / U 1 × 100 %

[0025] Calculate the distortion rate γ.

[0026] Described step (3) further comprises the following steps:

[0027] (31) add ...

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Abstract

The invention relates to a distortion measurement method of a building intercom system. In the method, FFT (fast discrete Fourier series transformation) is adopted to test, and window functions are added to reduce the influence of frequency spectrum leakage, and finally, the transferred frequency domain signal is further analyzed and compensated, wherein, the amplitude of the frequency domain signal is 0.1dB, and the frequency is 1Hz. Compared with the prior art, the accuracy of distortion measurement is improved in the invention.

Description

technical field [0001] The invention relates to a distortion test, in particular to a distortion test method of an apartment intercom system. Background technique [0002] The main purpose of testing the intercom is to test the distortion of the sound, so it has very high requirements for the external environment, and filters are usually used for testing. For example: To measure a 1KHz distortion, make a 2KHz, 3KHz filter to receive the harmonic quality of the 1KHz signal. Usually the boundary number of the filter is made higher (to prevent the influence of environmental noise on it), and contains more resistance capacitor devices. In this way, there will be problems in its stability, especially after a period of use, there will be deviations. In addition, the bandwidth of a high-bound filter is also a problem that cannot be ignored. [0003] People use FFT (fast discrete Fourier series transform) to realize the distortion test of the signal. Using the FFT method for test...

Claims

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Application Information

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IPC IPC(8): H04Q3/54H04M3/22
Inventor 牟晓生戎玲胡融徐家霖
Owner THE THIRD RES INST OF MIN OF PUBLIC SECURITY