Introduction
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The H.110 Basic Rate ISDN Board
would end the “bus wars” between the various legacy busses such as the
SCbus and the MVIP bus.
PCM is a standard method of digitizing phone signals. It involves encoding
each channel at an 8 kHz rate using eight bits. The signals from multiple
channels are then combined into a frame. On the H.110 bus, each frame
consists of 128 channels or timeslots. The bit rate of the H.110 bus is
8.192 MHZ. Thirty-two wires, also called streams, each carrying 128
timeslots, are combined to form the bus, and provide a total of 4096
timeslots. Two timeslots are required for a full conversation, one for each
talker.
In addition to the streams, a number of other signals necessary to maintain
synchronization between all the boards in the system are carried on the bus.
These signals provide the clocking and framing information. Redundant
clocks are provided to aid in recovery if the primary clock should fail.
The H.110 bus consists of backplane connections on a 6U
Compact
PCI
backplane that is used to interconnect the boards in the system. The CT
Bus connections are made through the J4/P4 connector. The electrical and
mechanical requirements of H.110 boards are tightly specified to insure the
reliability and consistent performance of the CT Bus in any valid
configuration of conforming boards.
1.1.5 Clock Modes
The H.110 BRI Board can operate in a variety of clock modes. Modes are
available so that the master clock can either be derived from the H.110 bus,
one of the Basic Rate Interfaces, or be provided by the H.110 BRI Board.
The clock redundancy and clock fallback functions of the H.110 bus are
also supported so that the H.110 BRI Board can be set to provide a clock
to the H.110 bus if the master clock on that bus should fail.
1.1.6 Hot Swap Capability
The H.110 Specification includes “hot swap” capability. This capability