Axcera CHV400BTD, Technical Manual, Page: 75 / 87

Innovator CHV400BTD ATSC Transmitter System Set Up Procedure
Technical Manual, Rev. 0 71
There is also a frequency response correction network on the board consisting of
R24-R26 and C14-C16. This has been factory set. Any adjustment of these controls
will result in having to reload taps into the digital modulator (See the Linearity
Correction Adjustment (Linear Distortions) section below).
Linearity Correction Adjustment (Linear Distortions)
As shipped, the digital linear precorrector is preset in the factory for optimal
performance of the system and output filter. This precorrection should not require
readjustment in the field.
However, in the event that field adjustment of the digital linear precorrection is
required, Axcera does offer an optional Precorrector Tap Converter (PTC) application.
This application allows the frequency response and group delay precorrection to be
adjusted using one of the following pieces of test equipment:
- Rohde & Schwarz EFA-53 Demodulator with the FIR Coefficient Readout option
- Tektronix VSA-5000 Vector Signal Analyzer
The PTC application allows tap settings to be downloaded from the test equipment to
a PC and then loaded into the Innovator CX through the serial interface. The
instructions included with the PTC application software provide the detailed setup
procedure.
If a problem occurred during the set up, help can be found by calling Axcera field
support at (724) 873-8100.