SCT4860 Digital Headend Transcoder

The R.L. Drake SCT4860 transcoder module is a professional quality, modular, digital headend component providing QPSK or 8PSK to QAM transmodulation and RF upconversion functions in a single module. It receives a wide bandwidth QPSK/8PSK input signal from a satellite transponder, demodulates the digital signal, and resends the recovered MPEG2 digital transport stream through the cable system via a much narrower bandwidth QAM modulated signal. The end user normally utilizes a set top decoder authorizing the programming to be received.

The SCT4860 transcoder module populates the RMT150 rack tray which holds up to ten transcoders. This modular approach allows the system to be expanded one transcoder at a time instead of requiring the purchase of more capacity than desired. Up to ten SCTx860 transcoders may be powered by the PS151 power supply which also mounts in the RMT150 rack tray. The PS151 power supply also serves as an RS232 communications link for the remote control of up to 70 SCT series transcoders.

The SCT4860 accepts RF inputs between 950 and 2150 MHz from an LNB at the satellite dish. The transcoder then demodulates one QPSK or 8PSK satellite transponder signal and utilizes forward error correction (FEC) to retrieve an error free digital transport stream containing the desired digital multiplex programming. If a fixed output clock rate has been selected, the null packets in the transport stream are processed to provide the selected rate. When required, PCRs are recalculated. The SCT4860 transcoder then applies a cable environment FEC to this stream and remodulates it in the QAM format occupying a standard 6 MHz cable channel. QAM modes up to 1024 QAM are supported. Any standard CATV output channel (EIA, IRC, or HRC CATV) or broadcast off-air channel may be selected from 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. Because the MPEG2 transport stream information is not modified by the SCT4860 transcoder, all encryption, authorization, and program guide information is passed to the subscriber unchanged.

Although all programming for the SCT4860 transcoder module can be performed at the front panel of the PS151 power supply, the SCT4860 transcoder and PS151 Power supply operate together to provide an RS232 remote control interface which can be accessed by a personal computer. This can be locally or via a modem. Two DB9 connectors on each PS151 power supply provide remote access to up to ten transcoders in that rack tray and permit “daisy chaining” the RS232 cables between multiple power supplies. Up to 70 SCTx860 transcoders in a headend can be monitored or controlled by a single connection. Configuration changes via remote control access can be password protected. RS232 remote control software is provided with each PS151 power supply. A personal computer with the remote control software installed has the ability to control multiple headends. Up to 64 SCT860 transcoders and PS100 power supplies can be controlled in the same headend as the SCTx860 units with the same RS232 control link and software. Additionally, the SCT4860 may be controlled over a local area network or the Internet with the addition of the optional SCTeci ethernet controller interface (click for details).

Key features of the SCT4860 include:

• Each SCT4860 module may be easily mounted or removed from the RMT150 rack tray to provide for easy expansion or maintenance.
• Rapid programming for HITS and DISH Network transponders using factory stored preset programming configurations with auto configuration for DISH Network transponders.
• High output power of +40 dBmV which may be locally or remotely monitored and adjusted.
• Easy to read, backlit LCD for monitoring and setup from the PS151 power supply. Displays QPSK or 8PSK S/N , data rate, output level in dBmV, and other operational data.
• Remote control functions with monitoring allows changes and activation of “hot” standby units. Controlled over a local area network or the Internet with the addition of the optional SCTeci ethernet controller interface
• Operates in DVB or DigiCipher® II modes.
• Null packet processing and PCR correction built in.
• Fixed or auto output clock modes are selectable.
• QAM output may be programmed in 16, 32, 64, 128, 256, 512 or 1024 QAM modes.
• Bandpass flatness and phase noise are very closely controlled to insure the high MER and S/N ratio required for 1024QAM operation.
• Can be used with standard or stacked LNB installations.
• Forced air cooling in the RMT150 rack mount tray allows for cool operation even when mounted adjacent to other components. Fans are easily maintained from the front panel.
• CW output test mode.
• Recommended Accessory: LBA2030 L band amplifier.
• Recommended Accessory: LBS2250 L Band Splitter with LNB switching and output combiner.