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精度是仪器测量中一个重要的技术指标,该设计采用NE555与被测电容构成多谐振荡器,单片机通过控制多路选择开关选择相应的接入电阻来产生不同的方波信号,实现了档位的自动调节功能,针对大小电容产生信号的差异,分别用测频和测周期的方法有效地减小了误差,然后运用最小二乘算法调节了线性参数,提升了测量电容的精度。
Accuracy is an important technical indicator of the instrument measurement. The design uses the NE555 and the measured capacitance to form a multivibrator. The microcontroller selects the corresponding access resistance by controlling the multiplexer to generate different square wave signals, realizing the gear The automatic adjustment function, according to the difference of the signal generated by the capacitor, effectively reduces the error by frequency measurement and measurement cycle, and then adjusts the linear parameters by the least squares algorithm to improve the accuracy of the measurement capacitance.