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自从采用压控调谐器以来,已研制了电视接收机用的很多种电调谐系统。大规模集成(LSI)技术,容许调谐器及模拟接收机的功能采用数字控制,其价格可以和以前采用可变电容及电位器的机电系统相比。闭环数字系统提供精密的、无漂移的调谐,易于采用编程序的台存储器,并能在屏上及用发光二极管(LED)显示频道及台号,还能控制模拟功能。虽然这些系统是有效的,但因其采用一系列专用的LSI电路,去执行固定的一组控制功能,故是不灵活的。由于这些专用的集成电路,必须执行不同顾客和市场所需的全部功能,所以价格昂贵,在某些系统中数量也太大。
Since the introduction of voltage-controlled tuners, many types of electrical tuning systems for television receivers have been developed. Large-scale integration (LSI) technology allows digital control of tuner and analog receiver functions at prices comparable to those of electromechanical systems that previously used variable capacitance and potentiometers. The closed-loop digital system provides precise, drift-free tuning, easy programming of the stage memory, on-screen and LED display of channels and station numbers, and control of analog functions. Although these systems are effective, they are inflexible because they employ a series of dedicated LSI circuits to perform a fixed set of control functions. Because of these specialized integrated circuits, which have to perform the full range of functions required by different customers and markets, they are expensive and in some systems too large in number.