User's Manual Part 1

Notice the top line is Peak-of-Sync and two centimeters down from the top line is Blanking. Also,

one centimeter up from the bottom line is “White”. These three points will be referred to later in this

procedure.

To obtain this pattern it is necessary to first setup the Pac-Mono equipment per their procedure.

Connect the “five step” video from the signal generator to the input of the Pac-mono card. The

output of the Pac-Mono equipment is then connected to the video input of the ADC transmitter.

Verify the transmitter is in the Auto-Clamp mode by moving the Manual/Auto Clamp switch

found on the Modulator Module to the right. The scrambling equipment should be in the Normal

or Unscrambled mode.

With the transmitter in Operate, adjust the Depth of Modulation slightly using the Video Gain

control on the Modulator Module until the waveform looks similar to Fig. 1.

Note: Verify the Spectrum Analyzer has a Bandwidth setting of 1MHz to minimize the effects of any

adjacent channels.

Verify the Manual Clamp mode is set correctly by moving the Manual/Auto Clamp switch found on

the Modulator Module to the left and adjust the Manual Bias until the pattern is similar to Fig. 1.

Leave the Manual/Auto Clamp switch in the Manual Mode.

This completes the pre-adjustment of the transmitter with scrambling off.

Place the Pac-mono equipment into the Scrambled Video Mode. This will remove the Peak-of-

Sync. line and move Blanking upward towards the top of the screen.

Locate the Gate Level adjustment control on the front of the Power Amplifier Module. Adjust the

control slightly until the Blanking level moves back to its original position, two centimeters down

from the top of the screen.

Change the signal on the video generator to Zero IRE, No Burst. This will reveal a line 3 centime-

ters down from Blanking. This is the Sync line in Scrambled Mode. Verify this line is 3 centimeters

down. If not, adjust the manual clamp slightly to correct the offset.

Disconnect the Signal Generator and connect Live Video. While viewing the Live Video on the Spec-

trum Analyzer, verify the white levels are one centimeter up from the bottom of the screen. If they

are not, adjust the video coming from the IRD or other video source. Do not readjust the trans-

mitter video gain. This will change the scrambled Sync level and cause picture problems.

This completes the transmitter setup.

NOTE :Peak/Avg fault should be dissabled any time you are transmitting analog signals.....Enabled

when transmitting digital (QAM)

Video present fault should be enabled only when there is NEVER going to be video encoding that

envolves the removal of horiz and/or vertical sync at the baseband level. i.e. Any system that

requires the clamp to be in manual mode should have the video present fault dissabled. This in-

cludes Pac mono and Cal Amp. By the way, the video fault sensing circuitry only works reliably in

the clamp on mode.