Audio Media - September 2008 - (Page 57) AUDIO PRECISION | APX525 > At the bottom of the Navigator panel there is a display that continuously monitors the signal at the analyser input. Three displays are available in the form of a Scope, FFT, or meter, and these may all be undocked and moved around the screen. The default Navigator tree shows one signal path. The elements of the tree can be expanded or contracted by clicking on the adjacent + or – box. The main measurement branches are the signal path and reference level setup, and a number of standard audio measurements. To select a measurement, click on the measurement branch. The view for that measurement opens in the main window. Measurements have more than one view, and these are indicated by the sub branches below, which can be viewed in the same manner. Measurements can be added from a comprehensive list or by using copy and paste, or drag and drop. They can also be deleted and the running order can be changed by dragging the elements. A key feature is the Run Sequence button at the top of the Navigator. When this is pressed all measurements in the sequence are processed. To include them in the report, place a tick in the box alongside the appropriate measurement branch. R ight click ing on any of the main measurements brings up a menu of editing and command functions, most interesting of which is the ‘edit prompts and properties’. This allows visual and audio prompts to be presented before the sequence can continue. It can also trigger another program to start. small Signal Monitor screen shows the selected oscilloscope or FFT display. As with all AP analysers, units of measurement, source and load impedances, measurement bandwidths, and labels can all easily be changed. All graphs have zoom and pan facilities, and export options. Right clicking on the mouse brings up a list of scaling, view, editing, and other options. A comprehensive Help facility is available either by pressing the F key or, for in-context help, by right clicking on the button or function or control to query. The Reference Level Navigator branch enables the user to optimise the generator output level and analyser input levels for the tests to be carried out. These settings can be saved and referenced in meter and graph results. The APx carries out measurements in three main ways, depending on the test selected: • Single value measurements using one or two sine waves as stimuli. • Continuous sweeps using a short burst of continuously swept broadband signal. • Stepped sweeps where one parameter is swept across a range of values while another is measured. The signal analysis uses a high resolution FFT technique for both the scope and FFT displays. There is also a measurement recorder for measuring functions against time, and a multitone analyser. Reports are the primary output of the system. They are generated automatically at the end of a sequence of tests or can be created for a single measurement. Reports can be exported in a number of formats, the most convenient of which is PDF. A number of editing facilities are available including customised page layout and addition of a company logo. When a report is generated it is automatically displayed in an undocked window. Additionally graphs and tabulated data can be exported into other applications. tests which had been completed successfully. A warning exclamation mark would have appeared if a test had failed, and the report clearly indicates a failed sequence on its first page. I then used the same Project file as a template and edited it to produce new sequences for other products which included the use of external waveforms. Many of the measurements and facilities provided new insights into the products I tested, and the time saving in setting up the measurements and running them is considerable. All APx m e a s u re m e n t windows share a similar view and similar controls, and after a brief familiarisation, operation becomes intuitive. A nice feature of the main screen for Signal Path Setup is a representation of the front panel of the APx . This changes to reflect the connections made, whether digital, analogue, balanced, unbalanced, or external. The Generator screen is the starting point for most measurements, where stimulus settings such as frequency and level, maximum bandwidth, and input and output connections are made. A loopback facility allows the analyser to directly monitor the generator rather than the device under test. A graph shows the signal measured by the output module and the Carr ying O ut M easurements “Many of the measurements and facilities provided new insights into the products I tested, and the time saving in setting up the measurements and running them is considerable.” There are a few niggles. I found the fan noise too high. Some form of analyser monitor output would have been an asset, as often it is essential to listen to the signal, after all we are talking audio here. I missed the wide bandwidth analogue measurement of some other models, but realise that this would have increased the cost. The presentation of the reports is excellent, however from an R&D point of view, I would have liked to have been able to add notes within a report, without making any changes to the generated information. This is not possible with the convenient PDF output. Evaluating the APx for a week was a pleasure. The system did exactly what I expected, and much more. The user interface soon became second nature to use. The system is equally at home in production test or R&D. Once the tests have been set up, the speed of running them and generating a distributable report was impressive. I would recommend the use of twin screens if practical. This can show the contents of undocked windows such as reports or Scope, without obscuring the main screen. I would also recommend potential purchasers evaluating the demo version of the software by downloading it from AP’s website. Audio Precision has produced an instrument that will be hard to beat for the price. ∫ Conclusion Setting up the system was straightforward under Windows Vista. The software loaded correctly and immediately the USB . connection was made, the drivers were loaded. I spent a few hours defining a lengthy sequence of measurements to produce a full test report on an Amek Series Equaliser. This included setting limits for THD+N, and adding prompts to change settings. A few of my normal tests, such as CMRR against stepped frequency, were not readily available from the menus, however it is straightforward to produce these. The sequence itself took only a few minutes to run and produced a page report. As the test progressed, green ticks appeared alongside Hands- O n I N F O R MAT I O N £ GB£/US$POA A Audio Precision, 5750 SW Arctic Drive, Beaverton, OR 97005 T +1 503 627 0832 W www.ap.com E sales@audioprecision.com AUDIO MEDIA SEPTEMBER 2008 57 http://www.ap.com
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