TTC T-BERD 107A, Справочное руководство

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SECTION 3
3-25
INSTRUMENT
DESCRIPTION
STATUS LEDs
17
The green Status LEDs function as at-a-glance indi-
cations of the T1 circuit’s condition. These LEDs
provide quick identification of pattern and framing
synchronization of the received signal. The Status
LEDs function as follows:
T1 Pulses — Illuminates when a valid T1
signal is detected at the RX jack. If the received
signal is lost, the LED goes out and the Signal
Loss LED illuminates.
Frame Sync — Illuminates when the T-BERD
107A achieves synchronization to the selected
framing pattern within the T1 data stream. The
selected framing pattern is based on the cur-
rently selected mode (i.e., T1 D4, T1 ESF, T1
SLC, T1 D1D, T1 TLB, or T1 LLB). In T1 TLB
and T1 LLB modes, the T-BERD 107A auto-
matically determines the framing type and con-
figures itself to accept either unframed data,
D4-framed data, ESF-framed data, or
SLC-framed data. If frame synchronization is
lost, the LED goes out and the Frame Loss LED
illuminates.
Pattern Sync — Illuminates when pattern syn-
chronization is achieved. Synchronization to a
fixed pattern is declared when 30 consecutive
error-free bits are received. Synchronization to
the pseudo random pattern (QRSS) is declared
upon the reception of 30 + n consecutive error-
free bits for a pattern of length 2
n
- 1. If pattern
synchronization is lost, the LED goes out and
the Pattern Loss LED illuminates.