SystemView First Steps James K Beard, Ph.D. jkbeard@temple.edu February 15, 2005 Week 5

A Simple SystemView Start A signal Frequency sweep Audio band, 1000 Hz to 3500 Hz Period 1 second Amplitude 1 volt Noise Adjust amplitude (standard deviation) for 20 dB SNR Add to signal System clock Make duration over 2 seconds to let frequency sweep cover the audio band Make the system sample rate large enough to provide a spectrum of the signal 11/28/2018 Week 1

Steps Set up the simulation Set the system clock parameters Run the simulation Open the analysis window Look at the spectrum of the output Select an appropriate sample rate Include the signal bandwidth Maximum frequency to the point the signal falls to the noise level 11/28/2018 Week 1

Setting the SNR Signal to Noise of 20 dB Set RMS noise power to… Signal power is 20 dB higher than noise power Signal power is 1 volt amplitude Signal power is ½ volt2 RMS signal is 0.7071 volts Set RMS noise power to… 11/28/2018 Week 1

Default Printout 11/28/2018 Week 1

An Output Spectrum 11/28/2018 Week 1

Interpretation Note signal power about 20 dB higher than noise power Note step in signal spectrum About 25% of the way across the top About 2.5 dB What is it? Determine what the sample rate must be To keep the signal spectrum To keep everything down to the noise level 11/28/2018 Week 1