Overview
Monitor T1/E1 line application displays the T1/E1 line conditions for one or both the T1/E1 Cards. We can monitor line sync loss, BPV,
carrier loss, frame error, blue alarm, yellow alarm, alarm indication signal (AIS) and ES overflow/underflow in case of T1 and line sync loss,
HDB3 violation, carrier loss, frame error, distant MF, alarm indication signal (AIS) and ES overflow/underflow in case of E1. With this
application the T1/E1 line frequency and the power level also can be monitored.
Description
Distant Multiframe (MF) - (E1 Only):
This indication will flash when a distant multiframe alarm is detected. A
distant multiframe alarm is defined as the reception of three consecutive 1s at bit position of timeslot 16 in frame 0.
This indication is only valid when in CAS mode.
Unframed All Ones - (E1 Only):
This will flash whenever an all ones condition is detected in the received bit
stream. An all ones condition is defined as less than 3 zero bits received between the last align and non-align frames.
CAS Multiframe Error - (E1 Only):
This will flash whenever multiframe errors are detected that cause a resync of
the frame and multiframe alignment to occur.
Remote Alarm Detected - (E1 Only):
This will flash when a remote alarm is detected.
A remote alarm is defined as the reception of three consecutive bit 3s equal to "1" of timeslot 0 of non-align frames.
HDB3 Violations (E1 Only): High Density Bipolar 3(HDB3) is a ternary transmission code in which the number of
consecutive zeros which may occur is restricted to three, to ensure adequate clock recovery at the receiver. In any sequence of four
consecutive binary zeros, the last zero is substituted by a mark of same polarity of the previous mark, thus breaking the Alternate
Mark inversion (AMI) code. This mark termed a violation
Bipolar Violation (T1 Only):
Bipolar violations are recorded within the frame chip in an 8 bit Counter.
This light will flash to RED whenever new bipolar violations are detected.
Blue Alarm (T1 Only):
This will flash when a blue alarm is detected. A blue alarm is defined as the reception of
unframed all ones condition. The algorithm used is to simultaneously check for an out-of-frame (OOF) condition, and check for 14 or less
zeros out of 13,895 bits. All bits, including framing bits, are tested. The alarm is cleared if OOF condition clears, or if 15 or more zeros are
counted within 13,895 bits.
Yellow Alarm- (T1 Only):
This will flash when a yellow alarm is detected. The format of the alarm detected is
determined by the framing format and the settings in the Config Menu. When the format for the yellow alarm is specified as bit 2 suppressed
in 193S or 193E mode, a yellow alarm is defined as a "0" in bit (2nd MSB) of every DS0 timeslot for 256 or more consecutive timeslots. The
alarm clears when a "1" is detected in the bit 2 position of any timeslot. If the yellow alarm is specified as FDL yellow alarm in 193E mode,
then a yellow alarm is declared after 16 repetitions of "00FF" on the FDL. The alarm clears with the detection of any bit, which violates the
sequence. If the yellow alarm is specified as the S-bit yellow alarm in 193S mode, then a yellow alarm is declared whenever a "1" is detected
in the F-bit of frame 12. The alarm is cleared when a zero is detected in the F-bit of frame 12.
Line Sync Loss:
This will flash when a receiver resync is in progress. If the receiver is set to auto resync in the
Configuration Menu the receiver will begin resync when an OOF (Out Of Frame) event or Loss of Carrier is detected.
Carrier Loss:
Carrier loss alarm is declared when 128 ± 1 consecutive zero's are detected. Carrier loss clears
when a "1" is received.
Frame Error:
This will flash whenever a framing bit is in error. For T1 systems, in 193S mode, the Ft bits are
monitored (odd F-bits). In 193E mode, FPS bits are monitored (F-bits of frames 4, 8, 12, 16, 20 and 24). For E1 systems, framing bit errors
are detected in timeslot 0.
Alarm Indication Signal (AIS):
The receiver detects an AIS pattern when it receives less than three
zeroes in any
string of 2048 bits. The AIS condition is cleared when three or more zeros are detected in 2048 bits.
ES Overflow/Underflow:
The following
discussion applies to line receiver interface clock recovery circuit. Elastic Stores (ES) are used to adjust bit clock timing and to adjust
clock jitter. When the bit count in the Elastic Store (ES) is within two bits of overflowing or under flowing, the ES adjusts the output
clock by 1/8th of a period. A Jitter Attenuation (JA) Loop with an ES provides jitter attenuation. The device can enable or disable the
JA circuit, which can be placed in transmit or receive sections. The device is also programmable for 32 X 2-bit or 64 X 2-bit registers.
(Portable USB T1/E1, PCI Ultra T1/E1 and Dual Ultra HD card defaults are: Transmit, 32 bit depths). The device clocks data into the ES
using either TCLK or Receiver Recovered Clock depending on whether the JA circuitry is in transmit or receive data path, respectively.
Data is shifted out of the elastic store using the de-jittered clock from the JAL. When the First-In-First-Out (FIFO) for the data is within
two bits of overflowing or under flowing, the ES adjusts the output clock by 1/8 of a bit period. The ES produces an average delay of
16 bits (or 32 bits) in the associated path.
Legends:
Active:
Whenever any alarms are active, the Active indicator glows in RED informing about the alarms status.
Not Active:
The alarms are said to be not active if none of the alarms are detected on E1/yt1 link. This will be
show with a Green LED for the corresponding alarms.
History:
When any of the alarm is detected and then switches to not active state, the alarm is considered as
History and will be shown will Yellow LED.
Signal Inputs
Frequency:
This shows the line frequency T1/E1 in Hertz (Hz)
Level:
This shows the T1/E1 line power in dBm
Error Counters
BPV:
This provides a counter for the BPV alarms. Uses an eight bit counter
OOF:
This provides a counter for the Out of frame alarms. Uses an eight bit counter
Frame:
This provides a counter for the frame errors. Uses an eight bit counter
CRC:
This provides a counter for the CRC errors. Uses an eight bit counter
Missing Interrupt Instances :
Missing Interrupt Instances will
appear on the monitor box, when there is a problem with the Interrupt configuration for the cards.
Beep On:
This feature when checked will beep whenever any alarm present in monitor box is found active.
Log Alarms:
Checking this option will log all the alarms to a log file (.txt). The log file will have all the information
about the alarms: such as date, time, and active/inactive state.
