Manual Signal Generator
The signal generator is used to manually generate any signal. In addition to standard audio stimuli (sine, white noise, pink noise, multitone) with user-selected sampling rates and resolution, it can play any wav file, any memory list file, and any complex waveform created by the stimulus editor. This enables testing with speech or music, and also enables measured responses to be listened to – an important step in correlating measured results to audible defects. The signal level can be referenced to Peak, dB or RMS. The signal can be equalized in real time, and custom EQ curves applied, which is useful when using a non-flat source such as a mouth simulator. A specific portion of a waveform can be selected to play, either by selecting a start and stop time in seconds, or by examining the waveform. Signals may be played for a fixed duration, a fixed number of times, or in a continuous loop. Any available calibrated signal path can be selected, and equalization can be applied from calibration measurements or user defined curves. Multiple signal generators can be opened at the same time and their outputs synchronized, or a delay added for non-coherent playback, for example when generating background noise. Outputs from 2 or more signal generators can also be mixed on the same channel.
Like a conventional multimeter, this virtual instrument indicates the overall level of the input in either linear (V, Pa) or logarithmic units (dB, dBSPL). It can be applied to any available signal path, displaying either RMS or peak voltage or sound levels, accelerometer inputs, and even DC measurements with an appropriate DC coupled interface. In compact view, the meter displays just the output, which is useful if you are measuring many inputs simultaneously. In expanded view, a range of options enables customization of the display. This includes averaging options, time weighting, autoscale controls, standard and user-defined filtering, application of correction curves, and limits. With compatible Listen hardware, gain can be automatically read from the device, and also assigned through the instrument. Average, maximum and minimum values can be saved to the memory list and used in sequences.
Oscilloscope / Spectrum Analyzer
This versatile virtual instrument operates as either an oscilloscope (time mode) or spectrum analyzer (frequency mode); a simple tab option toggles between the two. Oscilloscope mode enables a clear visual view of the waveform over time, and a zoom function makes it easy to closely inspect portions of the signal. Triggering enables the oscilloscope to be used to start a measurement when the input exceeds a certain level, and to save the measurements for later recall or use in a test sequence. The spectrum analyzer offers many constant bandwidth FFT analysis options including standard and custom windows and various weighting options. Averaging times and resolution are continuously variable and can be user-specified. Average, maximum and minimum levels can be identified, and overload and real time indicators highlight any problematic signals. The cursor can be automatically snapped to the maximum value which highlights the fundamental, identifies the harmonics, and gives a rapid single-tone THD measurement.
Real Time Analyzer
The Multichannel Real Time Analyzer enables signals to be analyzed using constant percentage bandwidth (1/N octave) filters, which correlates well to human hearing. This provides the gapless filtering required for continuously analyzing complex signals such as speech, music and pink noise, and is widely used for telephony applications and measuring ANC headphones. SoundCheck’s RTA offers true recursive digital filtering conforming to ANSI A1.11 – 2004 class 0 standard. Analysis options include various octave bands up to 1/14, standard and custom weightings, linear and exponential averaging, and time weighting options. It displays multiple channels simultaneously, and offers real time calculation and display of channel addition, subtraction, maximum, minimum and power average. RTA curves are seamlessly integrated with SoundCheck’s standard graphs; live curves from the RTA can be dragged and dropped from the memory list into any graph for easy comparison to limits and reference curves. This is useful for quick comparisons to reference standards or golden units, tuning automotive infotainment systems, and more.
A high resolution frequency counter offers an accurate and clear visual indication of frequency, determining the dominant signal in a selected signal path and returning a precise frequency measurement. This measurement can be saved to the memory list and can be used in a sequence, for example for triggering a measurement at a certain frequency. This is useful for calibration (e.g. calibrating audiometers), for testing playback systems to ensure that they are playing back audio at a constant rate, and for any other application requiring a high-precision frequency measurement.
The real time distortion analyzer offers a quick reading of distortion at a single frequency in real time without having to configure a sequence. Distortion options include THD and THD+N, THD and THD+N residual level, and SINAD. The meter can analyze specific user-selected harmonic, or all harmonics together, and results can be displayed in dB or % relative to the fundamental. Correction curves, and A, B, and C weighting filters along with user-defined arbitrary weighting functions can be applied. Both IEEE and IEC calculation options are available.
Strip Chart Recorder
The strip chart recorder module expands the capabilities of the multimeter, distortion analyzer and frequency counter with the ability to plot measurements over time – the electronic equivalent of connecting a paper chart recorder to a hardware instrument. It plots continuously, or for a predefined amount of time, and can record instantaneous results or repeating averages. This feature is valuable for environmental and reliability testing and in any situation where the behavior of a device over time must be characterized. Results from the strip chart recorder can be saved to the memory list and used inside a sequence just like any other virtual instrument.