User’s manual FlexGain Plex, V2
Version 1.3 37 from 99
1.16 Use of the cyclic redundancy check in the E1 stream.
The error performance monitoring in digital E1 channels (each separately) is
performed according to ITU-T Rec. G.826. The evaluation of the G.826 error performance
parameters is based on CRC (Cyclic Redundancy Check) error detection. A multiframe
structure is used consisting of 16 frames, which are subdivided into two sub-multiframes
(SMF). Four CRC4 check bits are generated per sub-multiframe (SMF) and compared with
the corresponding bits of the next SMF. If they do not match, the CRC4 error counter is
incremented.
To activate the CRC4 error monitoring, the user should configure the device in the
PCM30C or PCM31C mode by the <PCMMODE> command.
1.17 Mechanic design.
The FlexGain Plex, V2 device is manufactured in three mechanic designs:
• SubRack – a unit to be inserted into a 19’’ FlexGain shelf (for example, FG-R-W-E, FG-
LIT, FG-Compact and other FlexGain shelves).
• MiniRack – a 1U (44.5 mm) unit to be inserted into a 19’’ cabinet.
• Stand Alone – a unit to be mounted on a horizontal surface.
1.17.1 Sub-Rack
From the mechanic point of view, the Sub-Rack devices represent a printed circuit
board with a front panel, on which port interfaces and LEDs are located. Up to two
daughter boards can be installed on the basic boards, which are mounted parallel to it. The
board of an additional E1 port (FG-Plex-E1) can be installed on the basic board as well.
The devices are attached with the help of racks and screws. Each daughter board has up
to four similar user interfaces. The RINGER board can be installed on the basic board.
Apart from pin connectors, daughter boards are fixed with screws to the racks of the basic
board.
1.17.2 Mini-Rack
From the mechanic point of view, the MiniRack Orion 2 device represents a housing
made of stainless steel, which embeds the main elements of the device (for example,
~220/-48V power supply source). Daughter boards are installed on the basic board
similarly to the case of Sub-Rack devices.
The board of an additional E1 port (FG-Plex-E1) can be installed on the basic board
as well.
The daughter boards represent printed circuit boards on which replaceable
multiplexer interfaces are fixed: FXO, FXS, E&M. The modules are connected to the basic
board with the help of two groups of pin connectors. One group is used by the internal
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