DRAKE DTD1000 사용 설명서 - 페이지 6

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General Description

GENERAL DESCRIPTION

The R.L. Drake model MEQ1000 is a commercial grade hybrid

QAM modulator. The MEQ1000 features plug in input modules

that include an ATSC/QAM tuner, an ASI input, an IP input, and

analog NTSC inputs; thus the description 'hybrid' is used to

describe it. A multiplexer is built in to combine the transport

streams and input the filtered and groomed transport stream to

the QAM modulator. This manual includes the SDE24 Dual

Program Encoder Module, the DTD1000 input module and ASII.

Other input modules will have instructions provided with them.

Each commercial quality SDE24 module contains two encoders

and if MPEG2 encoding is desired for two programs, two MPEG2

transport streams can be generated. If MPEG4, H.264 encoding

is desired, each SDE24 module can encode one program to an

H.264 output stream. Another option is to encode one program in

MPEG2 and another program in H.264

Each SDE24 module provides two sets of input connectors for

NTSC composite or S-video with stereo audio. Audio is encoded

using Dolby AC-3 encoding.The SDE24 encoder modules provide

standard definition encoding. The SDE24 encoders accept

analog NTSC video input from either composite or S video

sources and provide commercial quality MPEG2 or H.264, 480i

video outputs in both DVB-ASI and RF QAM.

The MEQ1000 has two input module slots and the outputs

interface to the MEQ1000 multiplexer, internally, where they are

MPEG program filtered, multiplexed, and groomed. Programs,

among the total group from input module A and input module B,

may be selected or not selected by the operator to be sent to the

QAM modulator. Each input must contain no more than 20

programs and a maximum of 20 programs per input may be

selected. Also, the total bitrate of the selected programs must not

exceed that of the output QAM channel capacity.

Some common applications include: drop/add, cherry picking

programs from ASI or IP MPTS inputs, digital channel processing,

or local origination additions.

The MEQ1000 contains a high performance QAM modulator that

can operate in most ITU-A or ITU-B modes up through 1024

QAM. The very low noise, high output, upconverter provides

coverage from 54 MHz to 1002 MHz while maintaining exception-

ally low phase noise and broadband noise. Output level can be

selected at a value between + 45 and + 61 dBmV.

The MEQ1000 operates in a fixed output clock mode and

processes null packets when required to maintain the set fixed

clock rate. PCR correction is included.

DIGITAL CHANNEL PROCESSING (One input module)

The DTD1000 input module tunes any 8VSB or QAM channel

between 54 and 1002 MHz. It is ideal for digital 'channel process-

ing' applications where a single digital video signal is received,

error corrected, clocked at a user determined fixed rate and

remodulated on the same or another RF channel. Applications

include cleaning up a low MER QAM signal received from a

CATV source or fiber link receiver, or shifting the RF frequency of

a QAM modulated signal. It may be used to convert one off-air

ENTER

QAM OUTPUT

0.000 Mbits/S

MEQ1000 Multiplexing Edge QAM Modulator

SELECT

ATSC 8VSB signal to a QAM output with rate adjustment. Used in

the processor mode with only one input, the DQT1000 can

process ATSC or CATV QAM inputs. No multiplexing or altering

of any MPEG tables is performed in this mode.

Used in the non multiplexing mode, the data rate of the incoming

signal can be any rate that falls within the specification range.

The output rate can be set to any fixed output rate (equal to or

faster than the input rate).

MULTIPLEXING TWO ATSC TRANSPORT STREAMS

Utilizing two DTD1000 input modules, two off-air 19.4 Mbps ATSC

signals (QAM modulated CATV delivered signals could also be

used) can be received and multiplexed to obtain a 38.8 Mbps

256QAM output. Thus two ATSC inputs can be output on a single

6 MHz bandwidth 256 QAM channel.

Another way of combining two ATSC 19.4 Mbps streams is to

receive the first stream using the 8VSB input (DTD1000) and

input the second stream, if available in ASI format, through the

ASII module in the second input slot. Again the two combined

ATSC signals will be modulated at 256QAM in a 6 MHz wide

channel.

If it is desired to provide both ATSC signals from two ASI sources,

two ASII modules can be used.

When the MEQ1000 is used as described above, no loss of

picture or sound packets occurs. There is no added compression

of the video or audio streams. Only the necessary control

packets are rewritten to prevent duplication of MPEG2 program

numbers and major and minor channel number assignments in

the tables.

Using a PC interface, the operator can select the major and minor

program numbers that he desires for each program in the output

multiplex.

PROGRAM FILTERING

A 'Select Program' function is provided to allow the operator to

select which of the MPEG programs present on the A and B input

streams are to be included in the output multiplex.

PSIP OPTIONS

When operating in the multiplex mode, the MEQ1000 can be set

to process PSIP information from both sources and rewrite tables

containing combined PSIP information, or in cases where the off-

air broadcast channels may not be transmitting some or all of the

tables, it can be set to ignore and discard the PSIP tables

completely, or it can be set to generate MGT and VCT tables

without EIT tables. Null packet processing is applied as neces-

sary to keep the output data rate at the desired setting. PCR

correction is provided. The operator can program desired major

and minor channel numbers for each program in the output

stream.

OUTPUTS - RF and ASI

The 54 to 1000 MHz RF output is always QAM regardless of

whether the input is VSB or QAM. This same filtered stream is

also output via the rear panel ASI output jack.