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Meter Display
6.8.2 FERR: counts frame errors in increments of 4. The result is a change every fourth
Frame error. A Frame error occurs when an incorrect bit occurs as the frame bit.
6.8.3 CRC: is used only in an ESF framing mode. The resolution of the counter is 1. A CRC
is counted when the calculated CRC on the receiver (AM8a) does not match the CRC
sent as part of the next ESF.
6.8.4 SLIPS: counts the number of times there is an insertion or deletion of data bits in the
data stream. A slip is commonly due to buffer overflow or underflow of the network
equipment.
6.8.5 YELLOW: counts the number of yellow alarms received from the transmitting
equipment indicating the loss of synchronization to its received signal. The AM8a will
count a yellow alarm when this condition exists for more than 600ms. Once the yellow
alarm condition is removed, the condition must be absent for a 200ms blanking
interval. The conditions for YELLOW are:
•
For D3/D4 framing, bit 2 set to a "zero" for all 24 time slots.
•
For ESF, the yellow alarm is generated by a 16 bit stream, 8 "1" bits followed by 8
"0" bits. The same timing conditions as D3/D4 are used.
6.8.6 BLUE: counts the number of blue alarm conditions detected. The blue alarm is present
when two (2) frames of "1" bits and an out-of-frame condition exists.
6.8.7 STATUS BLUE: is YES when the receiver has detected two (2) frames of "1"s and an
out-of-frame condition (refer to 6.8.6, above).
6.8.8 STATUS YELLOW: is YES when the receiver has detected a "0" in the bit 2 positions of
every DS1 channel (for further definition refer to 6.8.5).
6.9 PCM 1 OR PCM 2 FRAME SYNC MEASURE
This display allows the user to monitor the phase relationship between the spans connected to
the PCM1 RX and TX jacks or the PCM2 RX and TX jacks. The indication should remain stable
without any change or jitter occurring.
PCM TX FRAME SYNC:
PCM RX FRAME SYNC:
February 10, 2000
(18-0037)
6-14
AM8a Instruction Manual
0037-S06.L_
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