Drake SCT4860 8PSK Sat-1024QAM Cable Transcoder - Manual (Page 5)

5 General Description
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)
imbedded 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 reached the null packets in the transport stream are processed 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 1024 qAm 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 information is not modified by the transcoder, all encryption, authorization,
and program guide information is passed on to the CAtV set top box, unchanged.