Spectrum Boxcar averaging function for digitisers

Spectrum has announced the Boxcar averaging function for its extensive range of modularly designed digitisers, which smooths out high-frequency noise to give a clear signal.

The function is useful in situations where signals have been oversampled and can be used to increase vertical resolution, lower noise and improve dynamic characteristics such as signal-to-noise ratio (SNR) and spurious free dynamic range (SFDR). It uses a mathematical signal processing function to recalculate the vertical value of each acquired data point by averaging it with adjacent sample points.

The function allows users to select the number of adjacent points to be averaged from two to 256. The averaged data is subsequently stored with higher resolution by an amount that is proportional to the number of points selected. For example, selecting two adjacent points would increase the resolution of a 16-bit digitiser to that equivalent to 17 bits, selecting four adjacent points equates to 18 bits and selecting the maximum 256 points would produce a theoretical 24 bits.

Boxcar averaging works for single-shot acquisitions without the need for multiple trigger events or a repeatable signal. Boxcar averaged waveforms are also decimated (by the averaging factor) so that stored waveforms are reduced in size and can be transferred and processed faster. Even though the resulting waveforms are decimated, the Spectrum implementation makes sure that the trigger detection is still running with full sampling speed so that there is always a precise timing relationship between the averaged signal and the trigger position.