User's Manual

Digital ATSC Exciter-Modulator System Chapter 4, Axciter Modulator Detailed
Alignment Transmitter Set Up Procedures
Axcera Axciter, Rev. 0 47
Chapter 4: Axciter Modulator and Transmitter Set Up
Procedures
Axciter Alignment Overview
It is one of the features of the Axciter that it has no internal adjustments that are made
on it's circuitry. There is not even an adjustable pot, capacitor, or coil anywhere on the
boards. This is made possible through the use of almost entirely digital electronics that
are under software control. Even component aging should not put the unit out of normal
operation.
Several system parameters are adjusted through the user interface screens, such as
power output, AGC levels, etc. Mostly this is through commands sent from the Axciter
to the upconverter. Proper setting of these parameters is system dependent, and other
systems manuals should be referenced for information on their setting.
Transmitter Set Up Procedures
System Preparation
This Exciter Digital transmitter was aligned at the factory and should not require
additional adjustments to achieve normal operation.
The Sled-Based System is made up of an Axciter Modulator Tray and a LX or HX
Driver/Amplifier Assembly that contains an Axciter Downconverter Sled and an Axciter
Upconverter Sled.
Each Module, in the Driver/Amplifier Chassis Assembly, has an assigned slot and will not
fit properly or operate in the incorrect slot. Do not try to place a Module in the wrong
slot as this may damage the slot or the connectors on the backplane board. Each
module has the name of the module on the front, bottom for identification and correct
placement. The Modules are placed in the HX or LX Amplifier/Driver Chassis Assembly
from left to right; (1) Axciter Downconverter, (2) Blank panel, (3) Blank Panel, (4)
Axciter Upconverter, (5) Controller/Power Supply and (6) Driver Power Amplifier.
Initial Test Set Up
This section describes the set up of the Axciter Modulator Sled-Based system. The Axciter
Modulator takes the SMPTE 310 digital stream input and converts it to the desired On
Channel RF Output that is amplified to produce the systems output power level.
Check that the RF output at the DTV Mask Filter is terminated into a dummy load of at
least the rated output of the system or connected to the antenna for your system. While
performing the alignment, refer to the Test Data Sheet for the transmitter and compare
the final readings from the factory with the readings on each of the modules. The
readings should be very similar. If a reading is way off, the problem is likely to be in that
module.
Switch On the main AC for the system and the individual circuit breakers on the cabinets
and assemblies. Check that AC is present to all systems.