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Barcode scanner with linear automatic gain control (AGC), modulation transfer function detector, and selectable noise filter
Barcode scanner with linear automatic gain control (AGC), modulation transfer function detector, and selectable noise filter
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机译：带有线性自动增益控制（AGC），调制传递函数检测器和可选噪声滤波器的条形码扫描仪
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摘要
According to embodiments of the present invention, a barcode scanner platform is provided in which the gain of an analog signal representative of a barcode is controlled using a control loop. In embodiments, an MTF detector generates a value (e.g., DC) representative of a low frequency portion (wide or out of optical focus elements) of the analog signal and a second value (e.g., DC) representative of a high frequency portion (narrow elements or in optical focus elements) of the analog signal. The processor uses the first and the second values and a reference amplitude to determine a gain signal. The processor provides the gain signal to an AGC circuit that provides a linear response to the gain signal using matched JFETs. A noise filter can be enabled or disabled based on the first value, the second value, and/or the barcode scanner platform read rate.
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