This mode is used to calibrate MultiMode to the particular timing of your computer. Each computer runs at a slightly different speed, which means that the audio sampling may not be exactly the correct value. Any error in sampling will cause FAX and SSTV images to be skewed and distorted. You only need to calibrate MultiMode once for your machine, the calibration is saved in your MultiMode preferences file.
The easiest way to calibrate is to tune into WWV or WWVH, the standard time stations, which transmit on 2.5, 5, 10, 15, and 20 MHz. (Users outside of North America can use whatever time stations are audible in their region)
This mode draws a new horizontal line on the screen every second. The second pips from the time station should be displayed as a black dot on each line. There may also be some extraneous small dots due to noise or other audio. These black dots should start to form a vertical line. If the computer’s timing is correct, this line should be perfectly vertical. (There are a series of gray vertical lines spaced across the page to help you determine if the black line is indeed vertical)
If the line is slanted one way or the other, you should use the + and - keys on your keyboard to adjust the timing offset, which is displayed as the Delta in the calibration window. Each press of the + or - key will increment or decrement Delta by 0.1. Holding down the option key while you press + or - will increment or decrement by 1.0, to speed things up.
After finding the correct Delta for your machine, select Preferences from the Edit menu. In the box for Timing Delta, under General settings, there should be a number equal to the Delta from the Signal Window. Click the OK button, and the Delta will be saved in your preferences file, so that it is automatically loaded the next time you use MultiMode.
You may want to record the Delta for your machine, so that in case you should lose your Preferences file, you can simply re-enter it, rather than going through the calibration procedure again.
