Functional Description
363-704-121-01, Revision 01
4
July 30, 1999
FLC-704 List 2A
FUNCTIONAL DESCRIPTION
The FLC-704 provides eight POTS interfaces to the CO switch. The unit performs the interface function between
the analog POTS circuit and the internal digital PCM bus. In addition, each channel unit:
•
converts analog signals to 64 kbps A-Law PCM digital format
•
detects ringing voltage
•
detects loop current feed
•
detects forward disconnect
•
detects a subscriber test access signal
•
detects metering tones
•
provides loop closure.
A block diagram of the FLC-704 is shown in Figure 3. One 8-Channel COT Channel Unit supports eight POTS
interfaces.
A status LED is associated with each line to indicate whether the line is off-hook, idle, ringing, or being tested. A
common fault LED indicates a general fault has been detected on the card and it should be replaced.
Test access connections to a specific line circuit are made through the maintenance terminal or by the CO switch
applying the appropriate voltages on the subscriber line as described in the
section.
S
UBSCRIBER
D
ROP
T
ESTING
For subscriber drop testing from the CO, PG-Flex is able to select and connect any subscriber drop to a metallic
test pair at the RT. PG-Flex extends this connection back to the COT where technicians can switch it onto a test
access bus, or to the corresponding subscriber line on the COT channel card.
Metallic access is performed by momentarily p116 Vdc (from the CO) on the subscriber’s Tip lead. (The
Ring lead should be between GND and the Tip value.) Depending on the PG-Flex system configuration, the
selected subscriber drop (assuming a working metallic bypass pair) connects to the corresponding COT subscriber
line.
The metallic connection drops when -116 Vdc is momentarily applied to the subscriber’s COT Tip.
Metallic access may also be activated through and ASCII terminal connected to the RS-232 Craft Maintenance
port located on the front of the FLL-716 line unit or through the FAU-728 or FPI-729 units.
