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General description, Installation and mounting, Configuration – Drake ACT1000 ATSC to QAM Transcoder User Manual

Page 5

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General Description

the R. L. Drake® model aCt1000 is a commercial grade,

modular digital headend component providing 8VSB or

Qam input to Qam transmodulation and Rf upconversion

in a single unit. up to 10 aCt1000 modules, along with the

required PS151 power supply module, can be installed into

a single Rmt150 rack mounting tray, occupying only 2 rack

units (3.5''). the aCt1000 supports atSC 8VSB and itu

j.83 annex B 64Qam and 256Qam inputs, and outputs an

agile itu j.83 annex a or B Qam channel. the aCt1000

supports Rf inputs from 54-1002mHz from an antenna

or cable feed. the modulator supports Rf channels from

54-1002mHZ, and all annex a and annex B Qam modes up

to 256Qam, including all interleaver settings for annex B. the

transcoder demodulates the desired digital channel, adapts

the bitrate from the input to output if necessary, and modulates

the entire multiplex of programs on the output channel.

PCR values are recalculated as required when the input

and output bit rates are not identical, and channel display

numbers (PSiP and mGt/VCt table entries) can be changed.

Installation and Mounting

install the aCt1000 transcoders into the Rmt150 rack

frame. insert each aCt1000 into the frame until the ''f''

connector extends through the front panel hole, the LeD is

aligned with the opening in the front panel, and the hook-

shaped projection near the rear of the aCt1000 engages

the rear of the frame. Secure the module into the frame

with the supplied nylon washer and 1/2'' ''f'' connector nut.

Connect the supplied power supply cable between the

aCt1000 and the frame-mounted PS151, ensuring that

the correct power supply port is used for the frame slot

location (slot 1 is the left-most slot, as viewed from the front).
Connect the aCt1000's input signal source to the front-

panel ''f'' connector. Connect the rearmounted output ''f''

connector to the output combiner as required for the system

configuration. ensure that the PS151 is plugged into an aC

power source. When using the Rmt150 rack frame, it is not

necessary to leave vertical airspace between the frame and

other equipment in the rack, unless other equipment in the rack

specifies minimum gaps. the transcoders and power supply

are designed to provide sufficient cooling and airflow, even

when mounted with adjacent Rmt150 units above and below.

General Description/ Installation and Mounting/ Configuration

Configuration

the aCt1000 is controlled primarily via the Drake

model PS151 front-panel interface. the following menu

options are available for configuring the aCt1000

(menu name listed in bold, valid settings listed in italics:
· IN MODE: VSB-8, QAM-64B, QAM-256B – this configures

the input modulation mode that the aCt1000 will use
· IN PLAN: OTA, CATV, IRC, HRC – this selects the

channel plan for the receiver section (uS off-

air, uS standard cable, iRC, or HRC respectively)
· IN CHAN: 1-158 – this selects the input channel number;

the range varies depending upon the channel plan selected
· ENCODER: ITU-B, ITU-A – this selects the output modulator

Qam mode (itu j.83 annex B or annex a, respectively); for

uS cable applications, this should typically be set to itu-B
· MODULAT: 256-QAM, 128-QAM, 64-QAM, 32-QAM,

16-QAM – this selects the output modulator Qam density;

only 256- and 64-Qam modes are available in annex B
· INTERLV: All ITU interleave modes supported – this

allows the operator to choose a specific output interleave

mode, as necessary (annex a mode only supports one

interleave mode, as only one is specified in the standard)
· CLOCK: PRESET, MANUAL – when set to maNuaL the

output symbol rate is continuously variable via the next

setting; when set to PReSet the symbol rate is fixed at

the appropriate bitrate for the modulation mode chosen
· BD RATE: 1.0000-7.0000 Ms/s – when the previous

setting is configured for maNuaL, this allows the output

symbol rate to be configured to an arbitrary symbol

rate. Note that some higher-bitrate symbol rates may

occupy more than 6mHz channel bandwidth, and that

very-low-bitrate symbol rates will not fill a 6mHz channel
· OUTPUT: NORMAL, STANDBY, CW – changes the

output mode to StaNDBy (no output) or CW (a CW

pilot with the correct output power) from NoRmaL
·

RF OUT: 29.5-45.0dBmV – sets the

output power level of the modulator
· CH PLAN: OTA, CATV, IRC, HRC – sets the

output channel plan in use (uS broadcast, uS

standard cable tV, iRC, or HRC respectively)
· CHANNEL: 1-158 – sets the output channel number; the

range varies depending upon the channel plan selected
· PSIP: ORIGINAL, MODIFY, BASIC – the aCt1000 can

modify or insert PSiP tables as needed. oRiGiNaL passes

the incoming PSiP tables unchanged. moDify will modify

the incoming PSiP tables to user-defined channel numbers,

and BaSiC will insert newly-generated PSiP tables based on

user-defined settings; both of these settings must be used in

conjunction with the R. L. Drake Digital Headend Control

Program

1

, which allows the user to set the new values.

1 version 3.8 or later must be used – the newest version can be downloaded from http://giant.rldrake.com/RLDrake_Digital_Headend_Control.zip