Quantum Data 801GC, 801GF, 801GX manual Vspd = Hrat x Front Porch

•A spec sheet may give you the vertical front porch in milli-seconds. The value for VSPD can be calculated with this formula:

VSPD = HRAT x Front Porch

Where Front Porch is in units of seconds and HRAT is in units of Hz. Remember to round the result to the nearest integer.

The VSPW parameter sets the width of the vertical sync pulse in units of scan lines. Many spec sheets refer to this parameter as “Vertical Sync Pulse Width.” If your spec sheet gives you the pulse width in units of lines, use this value for VSPW. Here is another way to calculate the value for HSPW from other data on your spec sheet:

•A spec sheet may give you the horizontal sync pulse width in micro-seconds. The value for HSPW can be calculated with this formula:

VSPW = HRAT x Pulse Width

Where Pulse Width is in units of seconds and HRAT is in units of Hz. Remember to round the result to the nearest integer.

❖The vertical sync pulse width is the overall width of the vertical sync interval if you are working with serrated composite sync. Do not use the distance between the individual serration pulses for VSPW.

Some displays that use either a digital or analog composite sync signal need to have extra pulses added to the sync. Serration and equalization pulses help stabilize the display’s horizontal sweep circuitry during the vertical sync interval. The previously discussed DSCT and ASCT parameters determine if serrations and equalization pulses are added to ei- ther of the composite sync outputs. The number of equalization pulses, if used, can also be programmed.

6-54 Chapter 6: Programming Model 801GC, 801GF & 801GX¥Rev. A