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Arthur Pini

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Consultant

I am a technical support specialist and electrical engineer with over 50 years experience in the electronics test and measurement industry. I have supported oscilloscopes, real-time spectrum analyzers, frequency synthesizers, digitizers and arbitrary waveform generators for leading manufacturers.


Arthur Pini

's contributions
  • 09.22.2014
  • 50 Shades of Timebase
  • An important thing to keep in mind is that equivalent time (ET) sampling only works with repetitive waveforms. The sample spacing in ET sampling depends on the precision of the scope's time to digital converter (TDC). The TDC is a fast counter that usually measures the time between the trigger event and the nearest sampling clock which is called the horizontal offset. In ET sampling it uses this information to classify the horizontal offsets of multiple acquisitions and uses those with desired ET sampling period to create a composite waveform as shown the article. In addition to a 'smoother' waveform rendition the other beneficiary is timing parameter measurements. An improvement in the accuracy of a timing parameter, such as period, indicated by a decreasing standard deviation occurs for oversampling of factors from 4 to 10 times the RT sampling rate. This is very similar to the reported improvement noted for the displayed waveform. Beyond ten times oversampling with ET there is little further improvement. ET was a more important feature at a time when ADC's had limited maximum sampling rates. With maximum RT sampling rates at 160 GS/s it offers less of an advantage
  • 08.16.2014
  • View noisy signals with a stable oscilloscope trigger
  • Hi Dave, Most oscilloscopes offer high and low frequency reject trigger modes. High frequency reject inserts a low pass filter in the trigger path; while low frequency reject inserts a high pass filter. Most set the cutoff frequencies around 50 kHz.
  • 06.24.2014
  • Digitizers: Finer resolution is better
  • Hello Olehwi, Thanks for your comment. The sampling rate for all three data records is 5 GS/s (200 ps sample period). The lower resolution waveform spends multiple sample periods at the same amplitude because it lacks the resolution to render the intermediate points. These are ideal waveforms so there is no vertical noise to 'dither' the amplitude values hence the quantified appearance. Regards Art
  • 06.24.2014
  • Digitizers: Finer resolution is better
  • I have to agree with GreginOz, for your signal with a 60dB SNR, filtering is probably the best approach. SNR improvement will depend of the spectral distribution of the noise relative to that of the desired signal. If filtering is possible then the added resolution of the digitizer would prove helpful. Another thought is that with any measurement you would like the measuring instrument to have a greater resolution than the device being tested. A 60 dB SNR indicates about 10 bits of resolution. If analyzed with a 10 bit digitizer the noise of the digitizer could be a significant fraction of the device's noise level and your measurement would be compromised. A digitizer with greater resolution and better SNR would provide a better measurement by having a lower noise contribution from the digitizer itself. Art
  • 06.26.2013
  • Product How To: Calculate power with a scope
  • Hello Mailer2628, You can view the line current and voltage traces and measure the phase manually. Also, the most current version of this Teledyne LeCroy Power Analysis software includes a readout of line phase in addition to power factor so you can assess if the current is leading or lagging. The manual for this software shows an example on page 25 http://cdn.teledynelecroy.com/files/manuals/pas_im.pdf.
  • 06.26.2013
  • Product How To: Calculate power with a scope
  • If you have the isolated voltage and current components you can calculate the power of in a 3 phase system. The application note at the URL http://cdn.teledynelecroy.com/files/appnotes/three_phase_power_measurements.pdf outlines how to make such a measurement.