Table of Contents
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What is a System Configuration?-
2.1.1 CO Card
2.1.2 DSP Card
2.1.3 Hard Disk Drive
2.1.4 CPU Card
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Manager's Guide
Configuration
& Installation
M-2-5
The telephone line interface (CO card) transmits and
receives analogue signals to and from the telephone line.
The analog input signal is digitized at a sampling rate of 8
kHz to create an 8-bit digital signal.
The CODEC facility is on the DSP card and consists of
two digital signal processors (DSP) and voice buffer. When
a user calls the VPS, one of the DSPs compresses the digi-
tal signal sent from the CO card. The compressed signal is
stored in a voice buffer, then written to the hard disk.
When a message stored on the hard disk is played back,
the DSP first decompresses the stored data and the result-
ing signal is then sent to the CO card.
The hard disk drive is connected to the central micropro-
cessor via a SCSI interface. The hard disk stores the pro-
prietary system program, the system administration table
and the voice prompts (about 40 minutes' worth). In addi-
tion, it has the capacity to record approximately 4.6 hours
of recorded messages from callers.
The CPU Card comprises the central microprocessor,
ROM, dynamic RAM, the clock generator for the time-
sharing switch, a Rotary switch, an RS-232C interface and
a SCSI host adaptor.
The central microprocessor communicates with and con-
trols the sub-microprocessors on the CO card and DSP
cards via FIFO memory.
The system ROM stores ROM-based system programs,
self-diagnostic software, test programs and backup pro-
grams.
Application programs and the system administration table
from the hard disk are read into dynamic RAMS for use by
the system.
The rotary switch on the CPU card is used, for example,
when performing initial parameter settings. There are
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