Altinex VGA Line Receiver DA103-217 - Manual (Page 4)

AP-016 Rev 1 Page 4 of 6
The DA103-217 has a powerful equalization circuitry and can recover degraded VGA signal as
far as 250 ft away when standard VGA cable is used. When connected at the end of a cable, the
DA103-217 can significantly improve image contrast and sharpness. When VGA signal travels
through coaxial cable, the signal gets degraded due to the capacitance and resistance of the cable.
With every foot of cable, the quality of the signal decreases slightly.
Figure 6. The DA103-217 can improve image quality 250 ft away
The DA103-217 has adjustable circuitry to improve signal quality and compensate for the losses
in the coaxial cables. This is done using (EQ) equalization control for image sharpness and
(GAIN) gain control for image contrast. With a wide range of adjustment, the DA103-217 can
restore VGA signals that have been degraded by 30% due to cable length or multiple cable
interconnections using gender benders.
In addition to video quality improvement, the DA103-217 has a built in AGC (Automatic Gain
Control) for horizontal and vertical sync signals that automatically adjusts to any sync signal
from 1volt peak to peak to 5 volt peak to peak amplitude. With this feature, it is virtually assured
that DA103-217 will process any type of sync signal coming in and will convert it to a proper
format for a display or a projector.
Sync adjustment control allows selecting the most stable portion of the sync signal for recovery.
When the sync signal travels more than 25ft, it gets distorted due to improper sync termination
and signal reflections. Most of the sync signals have an output impedance of 10-20 ohms, but the
cable used for sync signals is 75 or 300 ohms. This cable impedance mismatch creates reflections
and sync distortions that results in unstable image, jitter, or loss of image completely.
Figure 7. Automatic Gain control assures stable sync for a display
The DA103-217 provides the user with (SYNC ADJ) sync adjustment control that allows setting