The M5i series digitizers offer real-time sampling at up to 6.4 GS/s with 12-bit resolution and can transmit all acquired data directly over the PCIe bus at a record speed of 12.8 GB/s. This capability is further enhanced by a new firmware option that allows averaging of acquired signals at an astonishing rate of 15 million events per second.
“This new option for the M5i series is one of the most powerful averaging systems available today,” says Oliver Rovini, Chief Technology Officer at Spectrum. “FPGA-based processing enables ultra-fast averaging, even on complex and long waveforms. In fact, there is enough processing power available to average waveforms containing up to 1 MS sample per acquisition. The result is an averaging package that will be of interest to anyone working with high-frequency signals or very narrow, low-level pulses, or where signal detail is lost due to large amounts of noise. This includes applications such as mass spectrometry, lidar, radio astronomy, automation, radar, biomedicine, nuclear physics, communications, sonar, and many more.”.
About Summation Averaging:
Summation averaging is a common, time-domain processing technique used to reduce the random (uncorrelated) noise component of a signal, improving its signal-to-noise ratio (SNR), while simultaneously increasing the measurement resolution and dynamic range of a digitizer. Figure 2 shows an example of how averaging can be used to reveal signal details that would otherwise be hidden by excessive noise.
In this example, a low-level signal (approximately 3 mV) is completely buried by random noise (top trace). Although the source signal is not even visible in the original single-shot acquisition, averaging 10 times reveals that there is actually a signal with 5 peaks (middle trace). Averaging 1,000 times further improves the signal quality, revealing the true shape of the signal, with secondary peaks and lows (bottom trace).
In the ideal case, if the signal and noise are uncorrelated—that is, if the noise is random and the signal is repetitive—the sum-average function can improve the SNR in proportion to the square root of the number of measurements (or averages). For example, averaging a signal 256 times can improve the SNR by up to 24 dB or increase the measurement resolution by about 4 bits. Thus, this technique can be used to enhance and extend the 12-bit resolution of the M5i Series digitizers.
Built-in Threshold-Defined Averaging (TDA):
To further improve averaging capabilities and enable the M5i Series digitizers to detect and average rare events that might otherwise be lost in excessive background noise, the new firmware option includes a data suppression technique called Threshold-Defined Averaging (TDA). TDA allows the user to set a threshold level so that only waveform samples exceeding that level contribute to the accumulated waveform. Baseline noise samples, those falling below a set level, are suppressed by setting them to zero or, alternatively, to a user-defined value. Figure 3 shows a block diagram of the FPGA functionality, and Figure 4 presents a schematic of the TDA process.
Because any waveform data below the threshold is removed from the averaged waveform, TDA can be a very useful tool for rejecting low-level, correlated (synchronous) noise and other waveform artifacts, such as baseline drift. These are signal anomalies that cannot be eliminated by a conventional summation averaging process.
The averaging option (M5i.33xx-spavg) is already available for the M5i.33xx series of high-speed PCIe digitizers.
