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Random interleaved sampling has become a widespread operating mode for digital storage oscilloscopes. Different repetitions of (notionally) the same waveform are recorded at random time shifts and are interleaved in memory, resulting in an increase of the equivalent sampling frequency. This procedure requires substantial time, particularly if further averaging is required. In this paper, an approach that ensures accurate time shifts is presented for repeated waveform measurements. Operating two independent oscillators with related frequencies forms the accurate shifts. One of these is used to excite a waveform of interest repeatedly, and the other clocks the analog-to-digital converter (ADC). This architecture was implemented using a commercial ‘off-the-shelf’ field programmable gate array. Examples of experimental waveforms, which are sampled at 2160 MHz using an ADC that is clocked at 80 MHz, are presented. They are compared with the simulated and independently measured waveforms where appropriate. [ABSTRACT FROM AUTHOR]

This paper proposes a novel architecture for a data acquisition system intended to support the next generation of ultrasonic imaging instruments operating at or above 100 MHz. Existing systems have relatively poor signal-to-noise ratios and are limited in terms of their maximum data sampling rate, both of which are improved by a combination of embedded averaging and embedded interleaved sampling. "On-the-fly" pipelined operation minimizes control overheads for signal averaging. A two-clock sampling timing system provides for effective sampling rates that are a factor of 20 or more above the basic sampling rate of the analog-to-digital converter (ADC). The system uses commercial field-programmable gate array devices operated at clock frequencies commensurable with the ADC clock. Implementation is via the Xilinx Xtreme digital signal processing development kit, available at low cost. Sample rates of up to 2160 MHz have been achieved in combination with up to 16384 coherent averages using the above-mentioned off-the-shelf hardware. [ABSTRACT FROM AUTHOR]