DIMAT OPU-1 - Qam Digital Modem Characteristics

OPU-1
UNIVERSAL POWER-LINE CARRIER SYSTEM TYPE OPU-1
GENERAL DESCRIPTION - Rev 7 (May 2019)
49/67
➢ Digital channel: in accordance with
IEC 495 cls. 5.3.1.5.
5.3 QAM DIGITAL MODEM CHARACTERISTICS
Crest factor
8 dB
Modulation
128 QAM
➢ 16 kHz: 81 kbit/s (79 kbit/s).
➢ 8 kHz: 40.5 kbit/s (39.5 kbit/s).
➢ 4 kHz: 20.25 kbit/s (19.75 kbit/s).
16 QAM
➢ 16 kHz: 40.5 kbit/s (39.5 kbit/s).
➢ 8 kHz: 20.25 kbit/s (19.75 kbit/s).
➢ 4 kHz: 10.125 kbit/s (9.87 kbit/s).
4 QAM
➢ 16 kHz: 27 kbit/s (26.3 kbit/s).
➢ 8 kHz: 13.5 kbit/s (13.15 kbit/s).
➢ 4 kHz: 6.75 kbit/s (6.55 kbit/s).
Fall back/increase rate(3)
Automatic. Can be disabled from the
programming software.
The change of speed presents hysteresis,
whose thresholds can be programmed from
the programming software. The factory
configuration is the following:
➢ Medium-Upper step: 23 dB
➢ Upper-Medium step: 20.5 dB
➢ Medium-Lower step: 11.6 dB
➢ Lower-Medium step: 14.4 dB
16 kHz QAM bandwidth
➢ Upper: 81 kbit/s.
➢ Medium: 40.5 kbit/s.
➢ Lower: 27 kbit/s.
(
3
)
The terminal permanently measures the S/N ratio in the digital band to decide the speed increase before retraining (1.5 s).