Test and Measurement News

September 2006

Tech Tip: PicoScope’s Spectrum Windowing Options

PicoScope’s built-in spectrum analyser produces accurate results, especially when used with a high-resolution converter, and can show them in great detail on your PC’s display. However, no spectrum analyser is perfect, and one type of error common to all FFT-based spectrum analysers is the generation of spurious harmonics. These occur because the FFT operates on a time-limited set of data called a window, which spreads out the spectrum of the original signal and causes ‘spectral leakage’. To minimise this, PicoScope can apply a windowing function to the signal, which smooths out the endpoints of the data. To get the best out of your measurements, we suggest that you experiment with the range of windowing functions that PicoScope offers. Your choice will depend on the balance that you require between frequency resolution and amplitude accuracy.

To choose the windowing function, open a spectrum window, then then go to ‘Settings | Options’ and change the value in the ‘Windowing’ drop-down box. Here is a summary of the window types:

  • Rectangle. Simply truncates the data at the start and end of the window. Suitable only for transient signals, but provides maximum amplitude accuracy.
  • Triangle. Also called Bartlett window. Fades the signal in and out linearly. Suitable for continuous, non-periodic signals. Greatly reduces spectral leakage but has poorer frequency resolution.
  • Gaussian. Very low spectral leakage. Produces minimum possible time and frequency uncertainty, but slow to compute.
  • Hamming. A type of Gaussian window with almost zero first and last samples. Suitable for continuous waveforms. Commonly used in speech analysis.
  • Blackman. Gives maximum frequency resolution. Very close to the 'ideal' window, with minimum possible leakage.
  • Parzen. Superior version of triangle window, with less leakage. Guarantees no negative leakage peaks.
  • Hanning. Also called Hann and von Hann. Uses one cycle of a cosine wave. Simple to calculate, but accurate only for continuous waveforms.

New Money-Saving PC Oscilloscope Bundles

We are offering, for a limited time only, a series of special PC Oscilloscope kits that can save you up to 20% of the price of the individual components. Each kit contains:

  • PicoScope PC Oscilloscope (PCO)
  • Software and reference CD, including PicoScope and PicoLog
  • Oscilloscope probes — one per scope channel
  • USB 2.0 cable
  • Installation guide
  • Hard plastic carry case

Find out more about our PC Oscilloscope kits

Automotive News

New PicoScope 6 Automotive released!

PicoScope 6 Automotive, a major new version of Pico Technology’s award-winning automotive diagnostic software, is now available. It offers higher performance, improved usability and appearance and many new features, and works with all versions of the Pico Automotive Oscilloscope Kit.

The improved performance of PicoScope 6 allows a faster capture rate, making it easier to see fast-moving signals. To make the software easier to use, we have added clearer graphics and text, tool tips and help messages to explain all features, easy point-and-click tools for panning and zooming, and user- configurable toolbars so that you can put all the controls where you want them. There are new features such as a custom probe manager to make it easier to use special probes and sensors; and the ability to create multiple views of the same data, with individual zoom and pan settings for each view.

It’s easy for PicoScope Automotive owners to upgrade to PicoScope 6. The new version can read all waveforms and settings saved by the old version, and supports all models of PicoScope Automotive oscilloscope. The user interface will be familiar to users of PicoScope 5, but improvements behind the scenes will allow us to keep your software up to date and deliver improvements and new features to you faster.

PicoScope 6 is available now, free of charge to existing customers.

Download your free copy of PicoScope Automotive 6

Real-Life Diagnostics article: ABS Part 2

In Part 2 of the ‘Diagnosing ABS’ article in our Real-Life Diagnostics series, dedicated troubleshooter Nick Hibberd, of Hibtech, uses a Pico oscilloscope to track down an unusual fault in some ABS wheel speed sensors. On the way, he gives valuable advice on general fault-finding and on interpreting oscilloscope waveforms.

Read all the Real-Life Diagnostics articles, free of charge and with no need to register.


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Software releases

Our latest software releases are available as free downloads. To check which release you are using, start the software and select Help > About.

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Contact details

UK Headquarters:
Pico Technology, James House, Colmworth Business Park, St. Neots,
Cambridgeshire, PE19 8YP, United Kingdom
Tel.: 01480 396395 (+44 1480 396395)
Fax: 01480 396296 (+44 1480 396296)

North America Office:
Pico Technology, 320 N Glenwood Blvd, Tyler TX 75702, United States
Tel:+1 800 591 2796 (Toll Free)
Fax:+1 620 272 0981

Asia-Pacific Office:
Pico Technology, Room 2252, 22/F, Centro, 568 Hengfeng Road, Zhabei District,
Shanghai 200070, PR China
Tel: +86 21 2226-5152

Email: sales@picotech.com