DRAKE SCT4860 Instruction Manual Download

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to provide the selected rate. When required, PCRs are
recalculated.

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 SCT4860 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.

GENERAL DESCRIPTION
The R.L. Drake model SCT4860 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
SCT4860 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
SCT4860 can transcode DigiCipher II or DVB digital
satellite signals, included those with advanced turbo
satellite FEC modes, outputting QAM modulation.

The SCT4860 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.

If a fixed output clock rate has been selected, the null
packets in the transport stream are processed

General Description / Installation and Mounting 5

INSTALLATION AND MOUNTING
Install the SCT4860 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 SCT4860 to
the PS151 with the cable included with the SCT4860.
Each SCT4860 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.

Connect the LNB signal from the LNB splitter to each
SCT4860 module at the front panel connector. Connect
each SCT4860 RF output "F" connector on the rear of the
unit to the output combiner. 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. SCT4860s can be
mixed with SCT1860s, SCT2860s, or SCT3860s in the
same RMT150, using a common PS151 power supply.

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 SCT4860
transcoders and PS151 power supplies installed. Of
course, air spaces may be left in between RMT150s if
desired.

RF OUTPUT

POWER

RF OUTPUT

POWER

RF OUTPUT

POWER

RF OUTPUT

POWER

RF OUTPUT

POWER

RF OUTPUT

POWER