Electrical Description - Mitel SX-200 Practices

Circuit Card Descriptions
Electrical Description
12.4 Control information from the backplane is converted to a 32 kHz amplitude
shift-keyed (ASK) data stream. The audio information is taken from the 2 Mb/s data
link, converted to analog audio and combined with the control information for
transmission to the telephone. Conversely, the audio and ASK data signals from the
telephone are separated and converted. The ASK data is demodulated and sent to
the bay processor. The audio is digitized and transmitted on the data link.
There is only one UART and one modem on the card. The six lines are
time-division-multiplexed to the communication circuit. Transmission and reception
are simultaneous, but the card receives data from the telephone to which tit last
transmitted. For example, if the card is transmitting to telephone 2, it is receiving from
telephone 1. In the next time slot, it will transmit to telephone 3 and receive from
telephone 2.
The COV Card has seven indicators on the front panel. There is an activity LED for each
subscriber line. The LED at the bottom of the panel is an alarm indicator for the entire
card.
The maximum loop lengths for COV circuits are:
Wire Gauge (AWG) Max. Loop length
26 1000 m (3300 ft)
24 1500 m (5000 ft)
22 2000 m (6600 ft)
125 12-2
Revision 0 9109-096-125-NA Issue1