User's Manual Part 1

50
Besides, the final amplifier is switched off.
l No Sync
In case the synchronism is missing the sync icon in the top bar blinks.
In this case the value of the output power is decreased by 3dB only
if analog signal type is selected and AGC control is selected. In case of 3dB otput power decrease, the output
power value in the bottom bar will be written between round brackets.
l Squelch
After a selectable time the video input signal is missing the VEGA mute the output power. When the video
signal come back the output power is switched on. During the squelch period the output power (0W) will be
written between square brackets.
2.4 EXTERNAL AGC: IMPLEMENTATION AND DETAILS
Scope
This paper explain the External AGC implementation inside VEGA TV Transmitter.
The use of External AGC help the VEGA Transmitter to maintain stable the Output Power. With a menu
setting you can choose between stabilizing the output power of VEGA transmitter (External AGC disabled)
or stabilizing the output power of a bigger transmitter with the VEGA acting as driver/modulator (External
AGC enabled). In this case a cabling is necessary between VEGA and Power Section.
Cabling
In case of AGC stabilizing output power of a transmitter where VEGA acts as Driver, the VEGA needs to be
connected to the Amplifier section with a cable connected to VEGA Telemeasuring port. The corresponding
pin on the Amplifier side depends on the specific amplifier used.
VEGA
DB9 TELEMEASURE
AMPLIFIER
5GND
4
¬ FWD Power (0 - 5V)
8
¬ Alarm (0V= Alarm - 5V= Ok)