Signal Present/History Leds; Out Of Frame/History Leds; Blue Alarm (Ais)/History Leds - Fluke 635 User Manual

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Users Manual
An out-of –service T1 usually has framed all ones or a keep-alive
signal present. The test set cannot detect B8ZS in this condition. In
order to make a declaration of line coding, eight consecutive zeros or
a B8ZS substitution (for eight zeros) must be received.
The AMI LED illuminates only when AMI line coding is detected without
B8ZS currently being detected. The B8ZS LED illuminates only when B8ZS
(a zero substitution) is currently being detected. The B8ZS HISTORY LED
illuminates to indicate a previously-received B8ZS substitution and will remain
illuminated until the RESTART key is pressed.

2-65. SIGNAL PRESENT/HISTORY LEDs

The SIGNAL PRESENT LED illuminates if a signal is detected by the Rx T1
receiver. The SIGNAL PRESENT LED turns off when 192 consecutive zeros
(bit times without a pulse) are detected by the Rx T1 receiver.The SIGNAL
PRESENT LED illuminates again when the next "1" is detected by the Rx T1
receiver.
The SIGNAL PRESENT HISTORY LED illuminates if a signal was detected
and then lost (192 consecutive zeros were detected by the Rx T1 receiver).
Once the SIGNAL PRESENT HISTORY LED illuminates, it will remain
illuminated until the RESTART key is pressed.

2-66. OUT OF FRAME/HISTORY LEDs

The OUT OF FRAME LED illuminates whenever an out-of-frame condition is
detected. The test set must have previously detected D4, ESF, or SLC96
framing before an out-of-frame condition will be declared. For D4 or SLC96
framing, an out-of-frame condition is defined as 2 out of 4 FT (terminal
framing) bits in error. For ESF framing, an out-of-frame condition is defined as
2 out of 4 FPS (framing pattern sequence) bits in error. The OUT OF FRAME
LED will remain illuminated as long as the out-of-frame condition exists.
The OUT OF FRAME HISTORY LED illuminates when an out-of-frame
condition is detected and then clears. Once the OUT OF FRAME LED
illuminates, it will remain illuminated until the RESTART key is pressed.

2-67. BLUE ALARM (AIS)/HISTORY LEDs

A blue alarm is declared if an out-of-frame condition exists and 14 or less
zeros are counted in 13,895 bit times. The BLUE ALARM LED is unlit if the
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Note