Laser scanning code symbol reading system

A symbol reading system, comprising:

• a scanning module for scanning a light beam across a scanning field in a scanning cycle, the scanning module comprising an oscillating mechanism for scanning the light beam across the scanning field;
• a scan line detector for detecting a start of each scanning cycle performed by the scanning module and generating a start of scan (SOS) signal in response to the detection of the start of each scanning cycle;
• a photo-detector for detecting the intensity of light reflected from the scanning field and generating a first signal corresponding to the detected light intensity;
• a signal processor, comprising:
• a first processing channel for generating a first derivative data signal, the first processing channel having:
• a first differentiation stage for processing the first signal and generating a first derivative signal;
• and
• a first amplification stage for amplifying the first derivative signal using a gain;
• and
• a second processing channel for generating a second derivative data signal and having a second amplification stage for amplifying the amplified first derivative signal generated by the first amplification stage using a fixed gain;
• a gain control module for, during each scanning cycle, controlling the gain of the first processing channel's first amplification stage within the signal processor using the SOS signal generated by the scan line detector, the first derivative data signal generated by the first processing channel, and the second derivative data signal generated by the second processing channel;
• a decode processor for processing the first derivative data signal and second derivative data signal and generating data representative of a symbol in the scanning field;
• and
• a hand-supportable housing having the scanning module, the scan line detector, the photo-detector, the signal processor, the gain control module, and the decode processor disposed therein.

A symbol reading system, comprising:

• a scanning module for scanning a light beam across a scanning field in a scanning cycle, the scanning module comprising an oscillating mechanism for scanning the light beam across the scanning field;
• a scan line detector for detecting a start of each scanning cycle performed by the scanning module and generating a start of scan (SOS) signal in response to the detection of the start of each scanning cycle;
• a photo-detector for detecting the intensity of light reflected from the scanning field and generating a first signal corresponding to the detected light intensity;
• a signal processor, comprising:
• a first processing channel for generating a first data signal and having a first amplification stage for amplifying the first signal using a gain;
• and
• a second processing channel for generating a second data signal and having a second amplification stage for amplifying the amplified first signal generated by the first amplification stage using a fixed gain;
• a gain control module for, during each scanning cycle, controlling the gain of the first processing channel's first amplification stage within the signal processor using the SOS signal generated by the scan line detector, the first data signal generated by the first processing channel, and the second data signal generated by the second processing channel;
• a decode processor for processing the first data signal and second data signal and generating data representative of a symbol in the scanning field;
• and
• a hand-supportable housing having the scanning module, the scan line detector, the photo-detector, the signal processor, the gain control module, and the decode processor disposed therein.