Instruction manual

FUNCTIONAL DESCRIPTION
● Port Circuits
There are eight port circuits.
Six port circuits are connected to Network Processing
Elements (NPEs). Port circuits 0, 1, 4, and 5 are DTMF tone detector ports. Each of
the six port circuits has an associated Digital Signal Processor (DSP), NPE to DSP
interface circuitry, a DSP restart circuit and an interrupt filter. Port circuits 2 and 6
are general purpose tone detector ports.
Port circuits 3 and 7 provide digital loop-
back testing of each NPE on the circuit pack.
The NPE serializes TDM bus signals that are connected to the DSP in serial form
from the NPEs by the DSP interface circuit.
Serial clock and data signals connect
directly from the NPE to the DSP. The system framing signal is synchronized and
connects to the DSP.
The DSP restart circuit controls the DSPs. When the on-board microprocessor is not
functioning properly, the DSP restart circuit takes all of the DSPs out of service. It
restarts each individual DSP under control of the port I/O and sanity check circuit.
The touch-tone DSPs, under control of the on-board microprocessor, write data
synchronously to the NPEs.
The interrupt filter detects valid touch-tone signals and
allows end-to-end transmission while blocking end-to-end touch-tone signaling.
Pooled Modem (TN758)
The Pooled Modem Circuit Pack supports 0-300 and 1200 bits per second (bps) data speeds
and provides the following:
● Circuitry to provide a signal compatible with the modulation formats of the 212-series
modems
● Modem emulation (see below)
Capability Data Module Mode
0-300 Asynchronous Low
300 Asynchronous 300 Asynchronous
1200 Asynchronous
1200 Asynchronous
● Modem control functions corresponding to 212A-series modem operations.
A maximum of two Pooled Modem CPs are allowed in a single cabinet (six in a 3-cabinet
system).
The Pooled Modem CP (Figure 3-20) consists of common circuitry and two conversion
resources.
The conversion resource (port) allows communications between two dissimilar
endpoints. For example, the Pooled Modem CP enables a digital data endpoint linked to an
ADU connected to a port on the Data Line CP (TN726) to communicate with either a local
analog data endpoint, such as a personal computer with a modem, or a remote host via a
CO trunk connection. Each port has two connections to the TDM bus: one to the digital
data endpoint via an ADU data module, and the other to an analog endpoint.
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