Abstract: In the whole process of textile manufacturing, the weft error detection rate of optoelectronic measuring method is higher. this paper analyzed the general method of weft signal detection processing, it pointed out that the fluctuate of weft signal and the resistance value of the adjustable resistance on the gain amplifying circuit and threshold comparison circuit are normally distributed ,which were the main factors that cause the test is low reliability. A failure analysis of weft detection was presented, and this paper presented four improved methods. Through the experiments, the results showed the major reasons for weft error detection were upper-saturation and under-saturation of the weft signal gain. For the wefts signal processing between digital processing mode and Analog circuits mode, the important way to improve the detection rate was adopted VGA IC in the amplifier circuit.

Key words: weft, photoelectric detection, reliability, reliability, VGA, saturated distortion