ELEC 242 Lab

Experiment 9.2

Testing the System

We now have a working camera and receiver. We don't yet have a way of synchronizing a receiver with another camera, but if we use the same motor to drive the camera and receiver disk, this isn't a problem (well, not a big problem). If we simply connect the camera output to the receiver input the receiver half of the system should display what the camera half picks up, i.e. we should have a viewfinder for the camera.


Step 1:

 Disconnect from the function generator and connect it to .

Step 2:

 Turn on the power and look into the receiver eyepiece. You should see something that moves when you move the camera. Try holding your hand in front of the camera and see if you can identify your fingers.
One flaw with this simple approach is apparent in hindsight: when the outermost hole in the spiral is scanning the camera image, the hole halfway across the disk, in the middle of the spiral, is scanning the recreated image. This means our image is folded over vertically.

This is easy enough to fix: simply delay the signal by the time required for the disk to make 1/2 a rotation. This is something we can do with a Labview program.


Step 3:

 Disconnect from and connect it to D/A channel 0 (pin 10 on the socket strip). Connect to A/D channel 4 (pin 5 on the socket strip).

Step 4:

 Load the "Video Processor" Labview program. This provides both a delay and adjustments for brightness and contrast of the image. It also provides an automatic gain control (AGC) to keep the image level constant between dark and light scenes.

Step 5:

 Start the program, turn on the power, and look into the eyepiece. The program provides a delay of fixed time duration. To change the amount of rotation of the disk that this corresponds to, we can change the speed of the disk.

Step 6:

 Adjust the 0 to 6V control on the power supply until the image is centered vertically and horizontally.

Step 7:

 Experiment with the brightness, contrast, and AGC controls.