Errors introduced into ac waveform measurements based on discrete amplitude samples because the waveform period is not an integral number of sampling intervals are substantially averaged out by computing the aggregate average of the set averages of sets of samples. Each set is taken over approximately an integral number of waveform cycles, and the set terminations are spread uniformly over approximately an integral number of cycles. Each set may overlap the previous set by all but one sample. As a short cut to the computation, each sample of the first set may be weighted with a weighting factor that is a respective member of an arithmetic series, starting at one and increasing in steps of one. Each remaining sample may be weighted by a factor that is a member of symmetrical series decreasing in steps of one and ending in one. The sum of all the weighted samples is accumulated and divided by the sum of all the weighting factors to produce the average of averages, or dc value of the waveform. The rms value can be produced by squaring the samples before weighting and taking the square root of the average of averages.
A method and apparatus for block averaging measurement data from dynamic, repeating input signals, for example, frequency modulated signals, take into account the time variability of the measurement sampling. Each block of measurement data is referenced to a synchronizing stimulus, and measurements are averaged both on the time axis and on the modulation axis. On the time axis, the time alignment for each individual measurement is placed at the center of the time interval during which the measurement was made. For each block of data acquired, the measurement blocks are averaged together in both dimensions, time (x-axis) and modulation (y-axis result being computed), using a stimulus synchronizing signal provided by the user as a time reference (time=0). The stimulus synchronizing signal should be a stable reference with respect to the modulation function being measured. For example, if frequency versus time is being measured, the reference should identify a repeating frequency reference. The times from the stimulus synchronizing reference to the input signal events are measured and accounted for in the block averaging method of the invention.
Received signal strength calculations in a radio are carried out by hardware which scales the absolute value of components of the received signal in a linear fashion by using two scaling factors.
A voltage measurement system is provided which concurrently measures peak voltage and root mean square voltage. The voltage measurement system employs a digital peak detection circuit for peak voltage measurement. The voltage measurement system employs a memory device for storing samples of a voltage signal at predetermined intervals corresponding to a line frequency multiplication factor. The samples in the memory device are then used to calculate root mean square voltage.
An improved metering unit is described which samples a power-related waveform and simultaneously captures its analog signal parameters for temperature and all phases of voltage and current, providing a more accurate and clearer waveform sample that effectively detects harmonics problems and does not require signal interpolation methods. The improved metering unit comprises signal conditioning circuitry interfacing with the power line for sensing temperature and all desired phases of voltage and current parameters of the waveform. The metering unit further comprises a processor having a timer output. The timer output controls track and hold circuitry and an A/D converter. The timer output places the track and hold circuitry in the hold mode to simultaneously capture temperature and all the desired phases of voltage and current of the waveform, and, at the same time, the timer output triggers the A/D converter to convert the captured analog signal parameters into digital sample values.
A compensator for use in connection with the metering of electricity calculates multi-level losses due to loss devices such as transformers and transmission lines. The compensator calculates losses to delivered electricity due to the presence of such loss devices and can sum losses from multiple loss devices to determine the electricity being delivered at various points, or levels, in the transmission system.
