readme.txtAPx500 release notesVersion 4.2October 2015(c) Copyright Audio Precision 2015. All rights reserved.This document provides late-breaking or complementary information tosupplement Audio Precision APx500 user documentation. The informationhere supersedes information you may find in embedded help files, manualsor in other user documentation.Complete user documentation for APx instruments is provided in the APx500 embedded help files and other documents. You may also visit the Audio Precision Web site at ap.com for more information about APx500, the APx555, the APx515, the APx52x and 58x series of analyzers, and other Audio Precision instruments, options and accessories.Table of Contents:----------------------I. System RequirementsII. API and multiple installation informationIII. LabVIEW compatibilityIV. New Features in this releaseV. Bugs FixedVI. Known IssuesI. System Requirements----------------------APx500 requires a PC with the following characteristics: o Windows Vista, Windows 7 or Windows 8 operating system o USB 2.0 o 2 GHz or faster multi-core processor (2 or more cores). Note: The dual-core Intel Atom processor does not have sufficient performance. o 2 GB or more RAMSystem performance is sensitive to processor speed; faster processorswill yield results faster.APx500 is data intensive and it is recommended that otherdata-intensive applications not be run concurrently. This includesAudio Precision's AP2700, APWIN or ATS.We recommend the following specific editions of Windows: o Windows Vista Business and Ultimate, o Windows 7 Professional and Ultimate 32 and 64 bit, and o Windows 8 Professional 64 bit.APx500 version 4.0 requires the .NET 4.5 framework. The APx installer checks for the presence of .NET, and installs .NET 4.5 as necessary.II. API and multiple installation-------------------------APx500 provides a full API accessible through .NET. The API assembly isspecific to the version of APx500. APx500 permits side-by-side installations of multiple versions. The APx500 uninstaller does not remove API assemblies other than the version to which it is tied.APx API Developer Tools are available from the Audio PrecisionWeb site at http://www.ap.com/display/file/138.III. LabVIEW compatibility-----------------LabVIEW, a graphical programming language made by National Instruments, can beused to control APx500 through the .NET-based API. Users interested incontrolling APx via LabVIEW are referred to the APx LabVIEW Driver and theLabVIEW API examples, both available from the Audio Precision Web site athttp://www.ap.com/display/file/257.IV. New features in this release-----------------See the document "What's_New_in_APx500.pdf" distributed with this software, or at the AP Web site at http://www.ap.com/display/file/131.V. Customer-reported bugs fixed----------------- o A RealTime Bluetooth error can crash APx. This has been fixed. 16974 o POLQA version was out of date. POLQA library has been updated to version 1.18. 22679 o Acoustic Response low-frequency results are inconsistent under some circumstances. This has been fixed by providing flexible time windows. 23034 o BS EN 50332 noise waveform scaled improperly. This has been fixed. 23067 o Impedance Thiele-Small and Loudspeaker Production Test do not allow sense resistor value below 100 mOhm. Changed to allow values to 10 mOhm. 23129 o In Release 4.1 when jitter is applied to the Reference/Sync Output it was also inadvertantly applied to the Digital Output as well. This issue is fixed. VI. Known issues----------------- o When an Output EQ curve causes the output to clip, the curve is scaled downward without notice. 22903 o In POLQA Averaged measurement, files are trimmed to length of shortest file, affecting MOS score. 23093 o Bench Mode bandpass filter does not exactly match ANSI shapes, especially as filter frequency approaches Nyquist. 23299 o When importing data from a file with more than 16 channels, only 16 channels are imported. 23495 o When exporting all points of a large acquisition to an Excel (*.xlsx) file, an out of memory error will occur. 23512 o Large continuous-sweep-based (chirp) acquisitions can cause an Intel MKL (math kernel library) failure. 23792/23834 o Windows regional settings that affect decimal point interpretation ("." versus ",") make data entry ambiguous and can result in dangerously high signal amplitudes. 23944 o Importing a limit offset curve that contains negative values will fail in custom X/Y graph. 24068 o Jitter frequency reading incorrect when Digital Input SR is below 27kHz. 24076 o Square wave and noise jitter generator waveforms must have amplitude limited to 40 ns or less. 24116 o For a Bench Mode external sweep, the pilot tone must be lower in frequency than the maximum frequency in the sweep. 24121 o For sine jitter, jitter level can be derated with frequency without warning. 24193 o Leaving the jitter frequency set to values higher than 20kHz in the Clocks panel can cause some secondary sweeps to be skipped in sweep measurements with Jitter Frequency or Jitter Level configured as the secondary sweep. Set the Jitter Frequency in the Clocks panel to less than 20kHz when running these measurements. 24243 o In Sequence Mode when the Jitter Generator Waveform in the Clocks panel is set to Noise, Jitter Frequency will not be available in the Secondary Source setting for measurements contained in the signal path. Set the Jitter Generator waveform to Sine in the Clocks panel to ensure that Jitter Frequency is available in the Secondary Source sweep settings. 24263 o Bench Mode Recorder never stops when using File Analysis and "Make Settled Readings" is enabled. 24205 o Sweep points in jitter sweeps that would exceed the specified frequency/amplitude limits of the jitter generator will be skipped during the sweep with no indication that the point was skipped. o In Sequence Mode, the signal path with Jitter Generator OFF (in the Signal Path Setup Clocks panel) will switch between the non-jittered clock and jittered clock when jitter measurements become active in the measurement sequence, causing momentary loss of bit-clock. This may reset certain DUTs that require uninterrupted APx sync output clocks or digital interface clocks. SOLUTION 1: The Jitter Generator output should be set to ON (in the Signal Path Setup Clocks panel) and the jitter amplitude set to 0 if jitter is not required during non-jitter measurements in the measurement sequence. This avoids clock switching during jitter measurements and within measurements with nested jitter sweeps (Frequency Response, Signal Analyzer, Continuous Sweep and Acoustic Response). SOLUTION 2: For the PDM interface, if the Jitter Generator output is OFF (in the Signal Path Setup Clocks panel) a jittered clock switch will occur within jitter measurements (Jitter Frequency Sweep, Jitter Level Sweep) before sequence steps are executed. PDM control codes should be sent to the PDM DUT using a Send PDM Control Codes sequence step. This does not apply to measurements with nested jitter sweeps. This ensures the PDM DUT gets programmed after the reset caused by the bit-clock switch but before the jitter measurement starts. Concerning PDM devices, see Technote 126 Jitter Testing with PDM for more details: https://www.ap.com/download/file/783. o When jitter measurements are used in Bench Mode the Jitter Generator should be set to "On" in the Clocks panel prior to sending PDM control codes to the DUT as switching to jittered clock will cause a momentary loss of clock to the DUT. If no jitter is desired when jitter measurements are not running the jitter amplitude can be set to 0 in the Clocks panel. o In Sequence Mode when the Jitter Level Sweep or Jitter Frequency Sweep measurements are selected in Navigator pane the jitter level set in the clocks panel will be overridden by the jitter measurements and may not match the level set in the Clocks panel. 24255 o In Bench mode when a digital output is selected and a waveform is loaded into the generator, it is necessary to set the Output Configuration sample rate to match the sample rate of the file to ensure that jitter Unit Interval is defined correctly for the sample rate of the wavefile. 24240 XV1005171200