Notes from the Test Bench
By Bruce Hofer, Chairman & Co-Founder, Audio Precision
Last year we introduced a number of firsts for the industry, and as you might expect, we turned a lot of heads. In fact, I’m proud to say that at least three of the heads we turned belonged to people in the press who give out awards.
At AES in October, Pro Audio Review gave the APx BW52 Ultra-high Bandwidth analyzer option their PAR Excellence Award for “innovation in design, performance/value ratio, enhanced features, and performance improvements over previous versions.”
Then later in the month, Test & Measurement World announced the BW52 option was one of the finalists for the 2010 Best in Test award. For that award, the actual winner is still up for grabs … you can show your support for AP by voting at http://www.tmworld.com/survey/77688/lang-en.
Of course, while winning awards is a great honor, it’s not the reason we constantly advance the state-of-the-art in audio test. I think engineers in general have a drive to improve, refine, and innovate. And I count myself as one of the lucky ones that have that opportunity every day.
p.s. On a slightly more humble note, I'd like to let you know that I've been elected chairman of the revived Portland Oregon section of the AES (Audio Engineering Society) at a recent meeting. I'm proud to be given that honor by my colleagues, and look forward to serving. Thanks also to Floyd Toole and Sean Olive for their presentations to the more than fifty participants.
Output: Customized APx Reports
This article describes a new feature in the up-coming version 2.5 of the APx Measurement Software. APx software updates are provided at no charge to all APx users. The software may also be run in demo mode if you do not have an APx analyzer.
APx’s automatic report generation capability has been greatly enhanced for the upcoming version 2.5 release with the addition of customized report layouts using Microsoft Word .docx format.
This report, created by the APx DTS Digital DVD Compliance Project, looks just like the report DTS provides during the certification process.
The customized report layouts let you decide exactly where numeric and graphical measurement results are placed. This is accomplished by inserting XML tags representing measurement data into the desired locations. Because the report layout file is actually a standard Word document, it can also contain logos, graphics, images, and text to create the desired appearance. As the tag order does not have to match the order in which measurements are made, tests can be better optimized for speed and efficiency.
XLM tags like this can be moved and inserted anywhere in the report layout.
Even if you choose the default APx report layout instead of a customized layout, you can still save the results as a Word file. This offers two advantages. First, it makes it easy to incorporate the results into other company documentation and reports. And second, you may alter the results report as desired and save it back into the APx project as a customized layout.
Various report options can be chosen in the Edit Report Properties dialog.
Other additions include the ability to re-run selected measurements in a project and replace previously collected data, and the ability to automatically save reports to a specific location after a sequence finishes.
The new customized layout features utilize the Microsoft Word 2007/2010 .docx file format. It isn’t necessary to have Word installed on the PC running APx, but you’ll need it to open or edit the files. Word 2003 SP3 (standalone or Professional Edition) with the Microsoft Office Compatibility Pack (a free download) is also supported.
Sound Advice: AP Knowledge Base
Saving Signal Acquisitions as .wav Files with AP2700
I am testing a device with a 2700 Series analyzer. Can I save signal acquisitions as .wav files that I can play back later?
You can export a waveform acquired from any of the 2700 Series analog or digital inputs (including the PSIA digital serial I/O) to a .wav file.
AP2700 Digital Analyzer panel, with the FFT transform and acquisition length controls highlighted.
To do so, you first need to acquire a waveform using the FFT analyzer. In the Digital Analyzer panel, set the Analyzer control to FFT spectrum analyzer (fft). Then, set the FFT control to specify the desired FFT transform buffer length and the Acquire control to specify the desired FFT acquisition buffer length. If you want to record a signal that is longer than that needed to produce the FFT, change the Acquire control from Track FFT to the desired value. System Two and System Two Cascade instruments are limited to 256k. System Two Cascade Plus and 2700 Series instruments have a 4M maximum buffer length.
After the signal has been acquired, navigate to File > Export > WAV file to bring up the Export MS (.wav) Waveform dialog. Here you may select either the transform buffer or the acquisition buffer.
Export MS (.wav) Waveform dialog.
If Transform is selected, and the “Use instrument defaults” checkbox is checked, the exported .wav file will contain the number of samples specified by the FFT transform buffer length control on the Digital Analyzer panel. If this checkbox is not checked, and the number of samples entered in the adjacent text box exceeds the length of the transform buffer, copies of the transform buffer will be appended to itself as required to make up the total number of samples specified. As a result, if the waveform is not synchronous with the transform buffer, the exported .wav file could have glitches or discontinuities at the points where the waveform repeats.
If Acquisition is selected, the exported .wav file will contain approximately the number of samples specified by the Acquire control on the Digital Analyzer panel.
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