Electricaldescription; Indicators - Mitel SX-200 Practices

Circuit Card Descrbtions
On-site Tl termination equipment, the Channel Service Unit (CSU) is required.
Shielded twisted pair cables are run from the CSU to the SX-200 DIGITAL backplane.
The Tl Trunk Card includes switches to set appropriate line equalization for cable
lengths up to 200 meters (655 feet) from the CSU
The Tl Trunk Card can be installed in slot 6 (slot 4 in COMBO Bay 2) of a' digital
peripheral bay. The Tl Trunk Card can also be installed in slot 6 of the Peripheral
Cabinet of the SX-200 FD. An adaptor fitted to the backplane connector provides a
15pin DSub connector for the Tl facility and a 25-pair connector to maintain access
to the adjacent odd-numbered card slot. Only I Tl Trunk Card may be installed in each
digital bay (or Peripheral Cabinet of the SX-200 FD).
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Electrical Description
16.4 In the transmit direction, the data from the system PCM link must be converted from
the Mite1 ST-BUS format of 32 channels at 2.048 MBit/set to the Tl format of 24
channels at I .544 MBit/set. To match the number of data channels, the Tl card skips
every fourth channel on the ST-BUS links. The Tl interface circuits retime the
output data to I .544 Mbits/set and add the framing bits.
In the receive direction, the framing bits are removed, the data is retimed to 2.048
MBiVsec and the channels are mapped onto the system PCM link in the same manner
as above, with every fourth channel left empty.
The system runs a loopback test during power-up or reset. A relay is operated to loop
the card's transmit line back to its receive line, removing the transmit data from the
output line. A 6db attenuation is automatically added to the signal during loopback, to
simulate actual transmission. The card remains in loopback until the test is passed,
The relative phase of the Tl and system clocks is determined as follows: An 8 KHz clock
output derived from the incoming frame rate is divided by two. This 4KHz signal gates
a counter, which counts the number of cycles of the system 2.048 MHz clock occurring
during one cycle of the 4 KHz signal. This phase count is sampled every 100 ms. The
oscillator on the Tl Clock Module on the Main Control Card is adjusted to keep the
phase count value constant over a longer term (I 6 seconds). The Tl circuit data buffer
accommodates shoti-term phase variation (jitter).
Indicators
16.5 If any of the data channels on the Tl link are active, the upper front panel LED lights,
giving visual indication of channel activity.
If the SX-200 DIGITAL or the SX-200 FD is receiving a yellow alarm condition, the
yellow (NO SYNC) LED lights. If transmitting a yellow alarm condition, and not
receiving a yellow alarm condition, then the LED is off,
The lower red LED is the Card Alarm. If the PABX generates or receives a yellow alarm
condition on the Tl link, the AlARM LED flashes.
125 16-2 Revision 0 91094X%-125-NA Issue 1