数字采样卡线性误差校准

目前,数字采样技术被广泛应用于电学计量领域。在宽频带交流功率国家基准建立中,不仅需要确定两路采样信号的幅值和相位误差,同时还需要对采样在不同输入电压下的线性误差进行准确校验。提出了采用感应分压器为参考校验采样板卡两路通道的线性误差的方法,该方法通过研制变比误差可自校的2n:1感应分压器,在频率上限达100 k Hz的频率范围内实现了对NI公司生产的高精度数字采样板卡PXI-5922的幅值和相位的线性误差的准确测量。实验结果表明该板卡在0.004 V~1.024 V的幅值线性误差优于60μV/V,相位的线性误差优于120μrad。

The linearity errors calibration of wideband digitizer

Digital sampling technology is widely used in the field of electrical metrology in recent years.Not only the amplitude errors and phase angle errors of two signals need to be determined,but also the linearity errors of sampling at different input voltages need to be calibrated accurately in establishment of the national high frequency AC power standard.In this paper,a method that using inductive voltage divider (IVD) as the reference to calibrate the linearity errors of two channels of digitizer has been proposed.The method achieves accurate measurements of linearity errors of amplitude and phase angle for high-precision digitizer NI 5922 at frequencies up to 100 kHz by developing the 2n:1 IVD which can be self-calibrated.Experimental results show that the digitizer amplitude linearity errors are less than 60 μV/V,and phase angle linearity errors are less than 120 μrad at input voltage from 0.004 V to 1.024 V.