Noise filtering of DC voltages in both the time and frequency domain

We describe a method of obtaining a smaller statistical uncertainty on the DC component of a voltage signal by using a combination of time- and frequency-domain methods than by using time-domain averaging only. This measurement technique is compatible with precision DC voltmeters that poll the input signal less than 100% of the time. The frequency-domain strategy captures information during the time that the voltmeter is not reading the input signal. Alternatively, one can map out low frequency noise spectra using this approach.