Definition for the 2890 Excess Jitter Alarm.
Category: 2890 T1 to Fiber Bit-Driver
Date Posted: 08/27/03
On the 2890, what exactly does the "Excess Jitter" alarm mean?
This is an error condition. Jitter is the phase shift of digital pulses over a transmission medium.
The Excess Jitter (red) indicator will emit light if jitter from the fiber link is in excess of 120 unit intervals peak-to-peak (UIpp). It will
turn off when the jitter is less than 120 UIpp. When this indicator is on, it reflects that the fiber link is near
failure. If the received optical power is below the rated sensitivity of the fiber optical receiver, excess jitter
will occur and this indicator will turn on. The optical signal loss indicator may or may not be on, depending on
the optical signal level.
The excess jitter indicator could also turn on if the received T-1 signal has excess jitter. The modem has a jitter
attenuator for up to 120 UIpp, but if the jitter is in excess of this, the fiber link will transparently pass this
jitter to the remote end where the excess jitter indicator will turn on.
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