Comtech EF Data SDM-2020 - Manual (Page 186)

SDM-2020 Satellite Demodulator Revision 4
SMPTE-310M Data Interface MN/SDM2020D.IOM
12–4
12.1.3.1 Specification Summary
Table 12-1. SMPTE-310M Specification Summary
Video Interface (Terrestrial)
Signal Type Biphase mark coded synchronous serial data per SMPTE-310M and
TM 449.
Connector Type 75 Ω BNC.
Interface and Connector
Impedance Resistive 75 Ω unbalanced, per SMPTE-310M.
TX and RX Signal Level 800 mV ± 10% per SPMTE-310M.
DC Offset 0.0 V ± 0.5 V.
Rise And Fall Times The rise and fall times, determined between the 20 and 80%
amplitude points shall be within 0.4 ns and 5.0 ns and shall not differ
by more than 1.6 ns, per SMPTE-310M.
Overshoot 10% maximum (on both rising and falling edges) per SPMTE-310M.
Receiver Sensitivity The receiver shall operate with up to 3 dB amplitude loss at 1/2 the
interface clock.
Return Loss 30 dB minimum, 100 kHz to the interface clock frequency per
SMPTE-310M.
ATSC Data Rate 8VSB: 19.392 658 46 Mbps = (4.5 E6) x (684/286) x (564/313)
Clock Accuracy Programmed data rate ± 100 ppm.
Clock Jitter, Drift And Wander The interface clock frequency error (drift limit) shall not exceed
± 2.8 ppm.
The rate of frequency change (drift rate) shall not exceed 0.028
ppm/s.
The jitter in the timing of the interface signal transitions shall not
exceed 2 ns p-p, measured over a bandwidth of 1 Hz to 1/100 of the
interface clock frequency.
Cable Length, Typical RG59 180 meters (591 feet)
Belden 8281 250 meters (820 feet)
Auxiliary Function Port
Signals
DF (Demodulator Fault, open-collector output).
CD (Demodulator Carrier Detect, TTL output).
RTS (Modulator Control, TTL input)
Connector 9 Pin D, female.
Monitor and Control
Monitored Functions
TX – PLL Lock (monitors presence of input data)
TX – State of RTS input on auxiliary function port
TX - FPGA load failure.
RX - FIFO Underflow/overflow.
RX - PLL lock.
RX - FPGA load failure.
Controlled Functions Interface Loopback.
Interface Loop-through
General
Framing Formats
(to be provided by the
demodulator, not this interface)
187 (no framing, pass-through mode).
188 (DVB/MPEG2 frame consisting of a sync. byte and 187 data
bytes).
204 (frame consisting of sync. byte , 187 data bytes and 16 Reed-
Solomon check bytes).