EGR 103/DAQ Audio 1

Volume Control

Optiplex 755

In general, do not follow the writeup; instead, turn all the possible volumes on and set them all to 80%.

If you are on an Optiplex 755, do the following:

1. Open the Volume Control Panel
2. Go to Options, Properties, pick Recording, and make sure all of them are on
   1. Select "Rear Input"
   2. Set this volume about 80% on
3. Change "Recording" to "Playback"
   1. Make sure all are on
   2. Set all volumes to 80%

Oscilloscope

Sample Screens

Proper Setup

Here is an example of a sound file being played at the right volume:

Too Loud

Here is an example of a sound file being played at too high a volume:

Note that the top of the signal hits 10 divisions above the Ch1 pointer. Basically, the signal may be going above 0.5 V, but the DAQ card is not set up to handle voltages that high, so it "clips" the value to 0.5. This will lead to poor sound quality.

Won't Stop!

If the "stop" button does not seem to work, just close the whole oscilloscope.

Troubleshooting

Values not centered

First, note that the Ch1-> on the left side of the screen points to 0V; because you have two channels on, Channel 1 will show up "centered" in the lower part of the oscilloscope window (see the above picture in the Proper Setup section). If the issue is that one side of the signal is clipping, or the signal has an average that is not at the Ch1-> spot, the most likely problem is that the black and green wires connected to Lines 66 and 32 are either connected to the wrong place on the DAQ card or on the breadboard.

No sound

Several possible causes. Make sure all the wires are plugged in correctly and completely; make sure the Volume Control Panel has all voltages unmuted and set to about 80% voltage. Make sure the red and black clips are connected to metal (not insulation) and also that they are not touching.

Weird Errors

The following have been happening semi-randomly:

• softscope issues:
  • Opening softscope gives an error about the GUI - restart the computer you are on.
  • The "stop" button will not work - close the softscope window. This may lead to the following problem:
  • Closing softscope closes MATLAB - just restart MATLAB. This may happen a couple times... If it keeps happening, just use softscope to get your volumes correct, restart MATLAB, then skip to the next part of the lab without reopening softscope.