DRAKE SCT3860 Manuale di istruzioni - Pagina 5

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General Description / Installation and Mounting

GENERAL DESCRIPTION
The R.L. Drake model SCT3860 is a
professional quality, modular, digital headend component
providing QPSK or 8PSK input to QAM transmodulation
and RF upconversion functions in a single module. Up to
ten SCT3860 modules and a power supply module can
be accommodated in the RMT150 rack mounting tray,
occupying only a 2 unit (3.5") high rack space. The
SCT3860 can transcode DigiCipher II or DVB digital
satellite signals, included those with advanced turbo
satellite FEC modes, outputting QAM modulation.
The SCT3860 accepts L band RF inputs between 950
and 2150 MHz from the LNB at the satellite dish. The
transcoder demodulates the selected satellite QPSK or
8PSK signal. The forward error correction (FEC) imbed-
ded in the data stream is used to help retrieve an error
free digital transport stream containing the desired digital
programming multiplex.
INSTALLATION AND MOUNTING
Install the SCT3860 transcoders in the RMT150 rack
mounting frame. Slide each module into the tray so that
the "F" connector extends though the front panel hole, the
LED is properly aligned behind its front panel hole, and
the hook shaped projection on the bottom of the module
engages the rear of the mounting tray. Secure the
module with the supplied standard 1/2 inch "F" connector
mounting nut and nylon washer.
Similarly, mount the PS151 power supply in the RMT150
tray, making sure that the LCD display and control buttons
line up with their corresponding holes in the front panel,
and that the hook shaped projections on the rear of the
unit engage the rear of the mounting tray. Secure the
unit in place, with the supplied Philips head black
screws, from the front panel. Connect each SCT3860 to
the PS151 with the cable included with the SCT3860.
Each SCT3860 can connect to any one of the ten sockets
on the power supply. However, to minimize confusion, it
is suggested that the left most unit (as viewed from the
front panel) be connected to power supply socket
number 1, the second from the left to number 2, etc.
1
2
3
4
RS232 OUT
5
6
RS232 IN
+3
+12
GND
+5
RX
TX
7
8
FAN POWER
100 - 240 VAC
47 - 63 HZ, 125 W
9
10
L BAND INPUTS
RF OUTPUT
RF OUTPUT
RF OUTPUT
RF OUTPUT
POWER
POWER
POWER
POWER
The transcoder then applies cable environment FEC to
this stream and remodulates using QAM modulation that
occupies a nominal 6 MHz wide cable channel slot. QAM
modes up through 1024QAM are supported.
The RF upconverter then upconverts the IF QAM signal to
the selected output channel - any standard EIA, IRC, or
HRC CATV channel or a broadcast off-air channel
frequency in the range of 54 to 860 MHz.
Bandpass flatness and phase noise are very closely
controlled in the SCT3860 to insure a high MER and S/N
ratio of the output signal. This insures that the transcoder
will not introduce a source of errors into the distribution
process. Because the MPEG2 transport stream informa-
tion is not modified by the transcoder, all encryption,
authorization, and program guide information is passed
on to the CATV set top box, unchanged.
Connect the LNB signal to each SCT3860 module at the
front panel connector. Connect each SCT3860 RF output
"F" connector on the rear of the unit to the output com-
biner. The Drake model LBS2250 is a combination LNB
L band multiswitch/amplified splitter in addition to a CATV
output combiner. It provides these functions in only 1 RU
of rack space. Also, plug the cable from the front panel
fan module into the FAN POWER receptacle on the rear
of the power supply. Plug the line cord from the PS151
into the AC power source. SCT3860s can be mixed with
SCT1860s, SCT2860s, or SCT4860s and one PS151.
When installing the RMT150 tray of transcoders, it is not
necessary to leave a vertical airspace between the
transcoder tray and other equipment unless that other
equipment specifies that a space should be left open.
The air flow through the transcoders and power supply
has been designed to allow immediate adjacent
mounting of multiple RMT150 trays with SCT3860
transcoders and PS151 power supplies installed. Of
course, air spaces may be left in between RMT150s if
desired.
RF OUTPUT
RF OUTPUT
RF OUTPUT
RF OUTPUT
POWER
POWER
POWER
5
DRAKE TRANSCODER SYSTEM
ID
1.1
12.45 dB
UNIT
SELECT
ENTER
RF OUTPUT
RF OUTPUT
POWER
POWER
POWER