Test and Measurement News

Prism Sound launches new dScope Series III software at Electronica 2006

Cambridge, UK - October 2006: Prism Sound is using the Electronica 2006 platform for the European launch of version 1.20 of its successful dScope Series III audio analyzer software.

The new dScope Series III version 1.20 software represents a major upgrade in the functionality of the unit. Many new features have been added at the request of the audio test community, including new tools for acoustic measurements, PC audio and 192kHz sampling on digital audio interfaces. As usual, the new software will be available free of charge to all registered dScope users.

Highlights include:

• Generation and analysis using Windows sound devices, including multi-channel device support.
• 192kHz sample rate support on AES3 and S/PDIF digital audio interfaces
• Support for acoustic measurements of transducers and rooms
• Very fast measurements (including frequency response) using swept-sine (Farina) method or bin-centred noise with impulse response and FFT
• Quasi-anechoic measurement using an adjustable time-window to eliminate acoustic reflections
• Support for measurement microphone & driver transducer sensitivity and frequency response compensation
• Time domain averaging to reduce the effects of random noise on measurements
• Analogue I/O can now sample at 48kHz as well as 96 and 192kHz to increase LF resolution of FFT analysis
• Script debugger allows breakpoints, single stepping, examination/setting of variables etc.

A number of smaller enhancements and improvements have also been implemented, including:

• Importing and exporting of sample buffers (WAV files can also be imported); these can also be saved/loaded as part of dScope configurations.
• User interface enhancements including revised trace window and additional toolbar icons
• Ability to run a script on every Sweep step
• New Trace Transformation: "relative to another Trace"
• Clip flags on Monitor Outputs
• New dBSPL unit
• Run multiple scripts simultaneously
• New non-intrusive warning system gives the user warning of potential set-up problems

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Use of Windows sound devices for generator output or analyzer input
The PC Audio package is aimed at users who need to test the complex devices that appear as part of the PC's audio system (sound cards, Bluetooth headsets etc). Full dScope signal generation and FFT-based analysis via Windows sound devices is supported in V1.20. The Windows sound devices appear as additional outputs or inputs along side those provided by the dScope Series III system hardware.

192kHz sample rate support on AES3 and S/PDIF digital audio interfaces
The 192kHz and 176.4kHz sampling rate capability on the digital I/O now allows engineers to thoroughly test digital interfaces including electrical characterisation and jitter performance. This is even more critical at higher sampling rates. This upgrade does not require any hardware update and is provided along with the other features of V1.20 free-of-charge to existing users.

Time domain averaging
Averaging the time domain sample buffer reduces the effects of un-correlated random noise by 3dB per doubling of number of averages, allowing you to see low level measurement detail with even greater precision.

Support for acoustic measurements of transducers and rooms
The acoustic tools package marks the start of a new phase of development for Prism Sound and the dScope product. This first release (V1.20) allows measurement of microphones and speakers as well as measurements of acoustic spaces. Introduction of these capabilities coincides with other enhancements that are also useful in electronic measurements, such as the Farina (log-chirp) method. An integral part of this capability is the addition of calibration factors for measurement microphones or driver transducers, support for suitable measurement units (dBSPL), as well as frequency response compensation for acoustic measurements.

Fast measurements using swept-sine (Farina) method
The Farina method employs a log-chirp signal which sweeps rapidly from low to high frequency. Most of the common audio measurements can be made from this stimulus including frequency response and total harmonic distortion plus noise, although in release V1.20 only the frequency response measurement will be available using this method.

Bin-centre test signals
These are a special case of multi-tone where there is a tone at the bin-centre frequency of every FFT bin. When viewed on a synchronous system, the FFT of this signal will give a line equivalent to the frequency response. This can update several times a second, depending on the number of FFT points selected, effectively giving a very smooth real time reading of the frequency response of a system.

Quasi-anechoic measurement
By inspecting the impulse response when making acoustic measurements in a reflective space, it is possible to identify the first acoustic reflections of the impulse. By applying a time window to the impulse response to eliminate the first and subsequent reflections, it is possible to compute the anechoic frequency response by calculating the FFT of the windowed impulse data. The measurement time window is adjusted graphically in the dScope's trace window.

Microphone & driver transducer sensitivity and frequency response compensation
Transducer calibration factors (mic or speaker) can be independently set up that relate acoustic sound pressure to voltage, hence allowing the provision of measurement results or driver settings as a specific sound pressure level. In addition, pre-weighting is now allowed on the FFT parameters dialogue for importing of microphone calibration data, so enabling a frequency response measurement pre-corrected for the microphone's own response.

Analogue I/O running optionally at 48kHz as well as 96 and 192kHz
This has significant ramifications for multi-tone and acoustic measurements: Because the frequency resolution of an FFT is given by the sample rate divided by the number of FFT points, it follows that with a new, lower sample rate (half the rate of the previous minimum) the frequency resolution for the same number of FFT points will be twice as good. Likewise, for the same frequency resolution, you can use half the size of FFT points leading to faster measurements. When measuring asynchronous multi-tones, particularly with low frequency tones, the greater frequency resolution this affords can make a real and practical difference. With 48kHz now being supported, you can choose between twice the frequency precision or faster test times. Also, with acoustic measurements, the longer FFT buffer time allows greater low frequency performance and facilitates more accurate room response measurements where time aliasing may be a problem in rooms with long reverberation times.

Script debugger
As the power and capability of dScope Series III continues to increase, so the task of script development becomes more complex too. To help test engineers develop more powerful automation scripts more quickly, script debugging is now provided within the dScope Series III script editor. This allows much quicker problem solving with the ability to set execution break points and to set or inspect the contents of variables.


Version 1.20 will be available for download shortly from the downloads page.