Communication solutions for power utilities
UNIVERSAL POWER-LINE CARRIER SYSTEM TYPE OPU-1
WHOLE BAND QAM MODEM MBPU - Rev. 0 (July 2011)
7/28
2 OPERATING
PRINCIPLE
2.1
MODULATION STANDARD AND SPEED
The MBPU modem has 7 modulation standards: V.34, V.32bis, V.32, V.22bis, V.22, V.23
and V.21, at different line speeds.
It can be programmed by means of commands AT, in order to operate at a predetermined
speed and modulation standard.
Table 1 shows the possible standards, their transmission speeds associated, and the AT
Hayes commands that configure the modem in order for it to operate according to the said
standards and speeds.
The automatic modulation scheme detection mode, that is programmed by means of
command ATF0 or ATN1, must always operate with modulations that comply with the ITU-T
standards (except V.22 at 600 bit/s QAM).
2.2
DATA TRANSMISSION IN ASYNCHRONOUS MODE
There are two asynchronous operating modes: direct or with intermediate storage
(buffering). The modem has a memory storage area (buffer), both in transmission and
reception, so that it can transmit at its own speed without having to depend on that of the
data terminal equipment.
It is possible to disable the intermediate storage mode (buffering), functioning therefore in
direct mode, by means of command AT\N1 or AT&Q0. In direct mode, the speed selected in
the communications program must be the same as that of the line speed.
The character format used by the series interface is selected according to the result of the
automatic speed negotiation or autobauding or, in the opposite case, to the S23 register.
The asynchronous formats permitted are those that include 1 start bit, 7 or 8 data bits, even
parity, odd parity or none, and 1 or 2 stop bits.