Research of Signal Distortion Compensation Algorithm in Audio/Video Device’s Assessment System
|School||Beijing University of Posts and Telecommunications|
|Course||Communication and Information System|
|Keywords||Video Reviews Signal acquisition Quantization error Distortion compensation Filter Design|
With the rapid development of high-tech , applicable to different areas of colored modern digital the endless video equipment ; , high quality requirements for broadcast TV system is becoming more and more due to the increase in demand for media information . Therefore , the research and development of video equipment compatibility and certification testing , quality inspection , automatic production and testing as well as the open-circuit video system test requires a sophisticated , reliable , convenient , quick video test system . Based on the evaluation of the needs of the modern video equipment , in accordance with international standards and national standards , designed to achieve a set of automatic remote control audio and video measuring system , in order to achieve a comprehensive test of the indicators of the video component of the output of the device under test . The evaluation system is composed by a test signal generator and signal evaluation end . In order to achieve compatibility and convenience of the system , this article uses HD acquisition equipment test signal acquisition in the evaluation of end . Meanwhile, in order to improve the accuracy and stability of the system evaluation , research HD acquisition equipment acquisition principle , analysis of the distortion caused by the quantization error of the acquisition process , and sampling format , take the offset method . In order to eliminate the quantization error , there is proposed adding a ramp signal , the dither signal , and taking the mean of the method ; decline in accuracy caused by the test to eliminate sampling consistent approximation to achieve the desired design FIR filter interpolation sampling . Also studied the overshoot and undershoot distortion , the band-limiting distortion inherent performance of the system such as group delay distortion caused distortion , in order to offset the ideal characteristics of the system itself , the corresponding filtering equalization method - using frequency domain equalization The method eliminates overshoot and undershoot of distortion , the phases are combined with a window function Heng reduce bandlimited distortion IIR all-pass filter , phase compensation to eliminate the group delay distortion . After specific steps of the compensation , the accuracy of the system evaluation results has been greatly improved and reliable test results .