UBS Axcera DT835A-6, LU1000ATD Users Manual

Instruction Manual

DM8-R

Digital Modulator Tray

AXCERA, LLC

103 FREEDOM DRIVE, P.O. Box 525 LAWRENCE, PA 15055-0525 USA

[phone] • FAX [phone]

www.axcera.com • [e-mail]

DM8-R Digital Modulator Tray Table of Contents

DM8-R DIGITAL MODULATOR TABLE OF CONTENTS

SECTION...................................................................................................PAGE

Overview ......................................................................................................2

Inputs and Outputs ........................................................................................2

Front Panel Interface......................................................................................2

DM8-R Modulator Board Configuration..............................................................3

Detailed Circuit Descriptions............................................................................3

DM8-R Modulator Board Description..............................................................3

SMPTE-310 Input.....................................................................................3

Channel Coder.........................................................................................3

Analog Output Section .............................................................................4

Pilot Frequency Generation.......................................................................4

DM8-R Front Panel Board Description............................................................4

Initial Setup ..................................................................................................5

Drawing List ..................................................................................................6

DM8-R Digital Modulator, Rev. 0 1

DM8-R Digital Modulator Tray Tray Description

DM8-R Modulator Tray

Overview

The DM8-R modulator Tray is an ATSC compliant 8 VSB modulator that mounts in a
standard 19” rack. The DM8-R modulator accepts a SMPTE-310 MPEG data stream and
outputs a 6 MHz wide IF output centered at 44 MHz with a pilot carrier at 46.69 MHz.
The DM8-R modulator provides linear and nonlinear correction capability for the
transmission path as well as internal test sources that are used during initial transmitter
installation. All of the functions of the DM8-R modulator are controlled from the LX
Controller LCD display and pushbuttons.

Inputs and Outputs

The inputs and outputs of the DM8-R modulator are described in the table below.

Description

IF Output J4

10 MHz Input J3

SMPTE-310M Input J2

110/220 VAC J1 Input Power to the Modulator

Front Panel Interface

Reference

Designator

Function

Provides a 44 MHz IF Output with a 50
ohm output impedance
10 MHz input to the DM8-R modulator.
Provides the reference frequency to the
pilot VCXO.
SMPTE-310 input that provides the MPEG
stream to the modulator.

The following table describes the connectors and indicators on the front panel.

LED Indicator or
Connector

PWR Indicates that the DC power supply is operating

MPEG

LED

PLL A

LED

PLL B

LED

IF Sample Jack

BNC

RS-232 SERIAL Serial Port used for initial modulator alignment

DM8-R Digital Modulator, Rev. 0 2

Function

Indicates the presence of a valid MPEG stream at the
J1-2B input
Indicates that the DM8 symbol clock is locked to the
frequency of the 10 MHz reference.
Indicates that the pilot frequency is locked to the
incoming 10 MHz reference.
Provides a sample of the IF output from the modulator
at approximately a –20 dBm level.