Measurement apparatus and method for digital data acquisition. A first operation mode is provided for real-time processing of digital data having a reduced sample rate or resolution. Furthermore, a second operation mode is provided for processing the measurement signal off-line with a higher accuracy. In particular, the high accuracy data may be temporarily stored and analyzed upon the operation mode is changed from the real-time mode to the off-line mode.

A method, apparatus, and energy metering system obtains mains samples of a mains power line signal, performs non-white noise (NWN) filtering of the mains power line signal, obtains adjustable clock source samples of an adjustable clock signal of an adjustable clock oscillator, determines a difference based on the mains samples and the adjustable clock source samples, adjusts an adjustable clock source frequency of the adjustable clock oscillator based on the difference, and applies the adjustable clock source frequency to an analog to digital converter (ADC) to determine a conversion rate of the ADC.

A frequency mask trigger capable of triggering based on a logical combination of two or more areas of a frequency mask transforms a frame of digital data representing an input signal into a frequency spectrum having a plurality of frequency bins, with each frequency bin having a power amplitude value. A frequency mask is defined having a plurality of reference power levels, one reference power level being associated with each frequency bin. Two or more areas of the frequency mask are defined, with each mask area corresponding to one or more of the frequency bins. A violation status is determined for each mask area by comparing all of the power amplitude values within each mask area to the associated reference power level. If any of the power amplitude values within the mask area violates the associated reference power level, then the entire mask area is deemed to be violated. A trigger signal is generated when a logical combination of the violation statuses of the mask areas is satisfied.

A method of analyzing a signal is described. The method includes: setting a trigger condition to be applied; applying the trigger condition; acquiring at least two acquisitions associated with the input signal, each acquisition including a trigger event that matches the trigger condition set; determining a trigger time for each trigger event; storing a time stamp with each trigger event; and generating a histogram based on the time stamps stored, the histogram providing number of trigger events versus time. Further, a signal analysis device for analyzing a signal is described.

Aspects of the invention include an equivalent-time sampling oscilloscope that receives a carrier signal, the carrier signal after it has been modulated with a repeating data pattern, and a pattern trigger signal that is synchronous with the data pattern. The carrier signal and the modulation are asynchronous, that is, they are not phase-locked in any way. The oscilloscope simultaneously samples the modulated carrier signal and quadrature phases of the unmodulated carrier signal at a plurality of timebase delays relative to the pattern trigger signal, and a plurality of times at each timebase delay. After collecting this information, the oscilloscope uses the quadrature samples to calculate phases of the unmodulated carrier signal that correspond to the samples of the modulated carrier signal. The oscilloscope then calculates a stationary representation of the modulated carrier signal by selecting samples of the modulated carrier signal that correspond to a carrier signal phase progression that would have been observed if the unmodulated carrier signal had been synchronous with the pattern trigger signal.

A test and measurement instrument including a digital down converter configured to receive a bus signal and output in-phase and quadrature-phase baseband component waveform data, a trace generator configured to receive the in-phase and quadrature-phase baseband component waveform data and generate at least one radio frequency versus time trace, a decoder configured to receive the at least one radio frequency versus time trace and decode the bus signal based on the at least one radio frequency versus time trace and a wireless modulation scheme, and a trigger configured to capture at least a portion of the bus signal based on the decoded bus signal.

A test and measurement instrument for generating an analog waveform, including an interpolator configured to receive a digital signal and output interpolated samples of the digital signal at a sample rate, a filter modulation controller configured to output first filter coefficients at a first time and second filter coefficients at a second time, a convolver configured to generate a convolved signal by convolving the interpolated samples of the digital signal and the first filter coefficients and convolving the interpolated samples of the digital signal and the second filter coefficients; and a digital-to-analog converter configured to convert the convolved signal to an analog signal based on a fixed, constant clock signal.

A device and method of operation for digital compensation of dynamic distortion. The transmitter device includes at least a digital-to-analog converter (DAC) connected to a lookup table (LUT), a first shift register, and a second shift register. The method includes iteratively adjusting the input values via the LUT to induce changes in the DAC output that compensate for dynamic distortion, which depends on precursors, current cursors, and postcursors. More specifically, the method includes producing and capturing average output values for each possible sequence of three symbols using the shift register and LUT configuration. Then, the LUT is updated with estimated values to induce desired output values that are adjusted to eliminate clipping. These steps are performed iteratively until one or more check conditions are satisfied. This method can also be combined with techniques such as equalization, eye modulation, and amplitude scaling to introduce desirable output signal characteristics.

A method of deriving information from sampled data, for example, in a digital data stream, includes processing the sampled data, for example, in the high-speed data acquisition device to detect an event in the sampled data. The sampled data is converted/transformed to its first derivative representation, and zero crossing information from the first derivative representation of the sampled data is used to determine local minima and maxima and their relative offset in time to a common point in time. Information from, or derived from, the local minima and maxima and the relative offset are provided to an upstream device. The upstream device may process the local minima and maxima and the relative offset, for example, to characterize the event.

A device and method of operation for digital compensation of dynamic distortion. The transmitter device includes at least a digital-to-analog converter (DAC) connected to a lookup table (LUT), a first shift register, and a second shift register. The method includes iteratively adjusting the input values via the LUT to induce changes in the DAC output that compensate for dynamic distortion, which depends on precursors, current cursors, and postcursors. More specifically, the method includes producing and capturing average output values for each possible sequence of three symbols using the shift register and LUT configuration. Then, the LUT is updated with estimated values to induce desired output values that are adjusted to eliminate clipping. These steps are performed iteratively until one or more check conditions are satisfied. This method can also be combined with techniques such as equalization, eye modulation, and amplitude scaling to introduce desirable output signal characteristics.