System Simulation Sandbox (PlayLab)

This LabVIEW Player example permits you to generate a wide variety of signals (including noise and modulated signals), pass them through a simulated Unit Under Test (UUT), and measure the UUT characteristics. You can introduce artificial noise and non-linearities into the virtual UUT, which consists of a wide variety of programmable filters. Possible measurements include Time Domain waveforms, Frequency Response, Frequency Spectrum, coherence, and signal to noise ratio (SNR).

The Simulator provides a very flexible tool for learning about digital signal processing and system analysis.

The following hints will help you get started.

1. A PC with minimum 128M memory is preferred, especially if you use larger FFTs (set by the Block Size control)

2. Due to the large flexibility in display types and formatting, you may occasionally need to hit the "Auto" buttons which autoscale the X or Y axes for the respective graphs. You can also manually scale the graphs by keying in the desired min or max values on the graph annotation.

3. Graphs can be expanded along the X axis using the mouse on the actual graph surface. To undo and expansion, hit CTRL Z (Undo).

4. Note that the left graph only shows the excitation signal, while the right window can show either the excitation (A) or the measured result.

5. Spectrum denotes an unaveraged Fourier spectrum with both Real and Imaginary components (or magnitude and phase).

6. Autospectrum denotes an averaged spectrum. For Frequency Response, use H1, which is the most common and is denoted by a *. The other types of frequency response are for advanced users.

7. If you select very high Filter Orders for the UUT, you may get erroneous results if you do not use large block sizes (high order filters have a very long impulse response which will be truncated by too short a block).

8. The flow of the signal in the UUT is as follows: Filter (left side), Noise Generator (Lower left side), Non-linear element (right side). To simulate a straight wire, the Noise must be set to 0 Volts, and both the Filter and Non-linear Elements must be set to Wire/Ideal Wire.

9. The Sandbox assumes that you have a basic understanding of signal processing and weighting windows, or you may end up with some strange results. However, if you are new to signal processing, we recommend that you start with simple signals, and familiarize yourself with the simulator and interactively learn along the way.

11. Note that there are two places you can apply a weighting window: On the generated signal (left side) and on the received signals (right side). The Received signals Window applies to both channels A and B.

12. If are viewing a measurement function which uses averaging, be sure to Reset the averaging if you change any parameters on your UUT or signal generator, or the block size or window on your measurement. Otherwise, the averaging will be corrupted by a mixture of old and new data.

13. The simulator is set to operate with a fixed sampling frequency of 100 kHz corresponding to a sample interval of 10 microseconds. With the default block size of 1000, the frequency resolution is 100 Hz.

14. When viewing time functions, be sure to select the Real display format. Other display formats (such as imaginary, etc.) are also possible and these complex time functions are computed by Hilbert Transforms (advanced users only).

15. A number of controls have on line help (CTRL H).

16. All measurement functions are computed in parallel and are updated in real time throughout the measurement. Although this is a great user convenience, it is fairly memory intensive. Therefore, block sizes in excess of 10K may result in slow performance, especially if virtual memory disk use kicks in.

Requirements

Filename: playlab.llb

Software Requirements

Application Software: LabVIEW Full Development System 6.0
Language(s): LabVIEW

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