Abstract: An automatic gain control (AGC) system that monitors the distortion of the outer constellation points of a complex modulation format such as quadrature amplitude modulation (QAM) and adjusts both the RF and IF AGC gain to minimize such distortion. In particular, the receiver contains at least two stages of AGC gain. Typically, the RF AGC amplifier is contained in the tuner that is followed by an IF AGC amplifier. The IF amplifier is coupled to a mixer and an associated low pass filter which, in combination and when driven by a particular frequency, produces a baseband (or near baseband) signal, The baseband signal is digitized and processed by a gain control circuit. The gain control circuit produces IF and RF AGC signals that control the gain of the respective AGC stages.

Abstract: In a slide fastener slider, a slider body includes a pair of cantilevered arch-shape attachment lugs spaced from each other by a uniform-width hollow having a bottom surface sloping down to a front side of the slider body and standing on an upper wing at its front end and extending toward its rear end so as to define with the upper wing a gap for passage of an axle of a pull tab, a vertical spring-receiving hole formed through inner surfaces of bases of the attachment lugs into a guide post, a catch lever pivotally mounted between the attachment lugs and having at one end a hook, and a spring received in the spring-receiving hole with its upper end resiliently touching with the other end of the catch lever for urging the catch lever to pivotally move so as to normally close the gap by the hook. The pull tab various in kind can be attached to the assembled slider body.