IBM 3745 Series, Hardware Maintenance Reference

Page: 251 / 712

During the test execution, TI is raised, RFS and CD dropped at the local and
remote DTE interfaces, and the data traffic through the DCE is interrupted.
DSR drops at the remote DCE, if DTR is OFF.
This test loops on local and remote error counters, until the 'STOP' key is pressed.
Digital Test (Transmit/Receive) for LIC Type 6
This test, which is not protocol-transparent, can be selected only if LPDA-2 is
enabled. During this test, local and remote DSU/CSUs exchange predefined bit
patterns.
Analog Line Analysis Test
Causes the DCE, after about 10 s, to display some parameters of a telecommuni-
cation line between two DCEs (defined as local 'L' and remote 'R').
At test initialization some parameters are already available, because they are
derived from data signal and continuously carried out during normal transmission,
these values are inserted into line analysis report.
The other parameters are measured during the test itself:
Ÿ Data driven parameters:
– Received level
'RL'
– Minimum received level (last 15 mn) 'MRL'
– Number of impulse hits ( " " ) 'HIT'
– Number of line breaks ( " " ) 'LBK'
Larger than 10 dB below average value, for a duration longer than 10 ms
(typical values).
Ÿ Impairments measured during test:
– Line round trip delay, 'RTD'
Measured at local side, is the difference between command sending and
acknowledgment receiving times. The measure does not include the DCEs
passthrough delay.
– Non linear distortion 'H2' and 'H3'
– Signal-to-noise ratio 'S/N'
Measured from a 1004 Hz tone, into voiceband.
– Phase jitter 'PJ'
Phase modulation imposed by the channel to a 1004 Hz tone. Peak-to-
peak phase jitter is measured in a 300 Hz bandwidth.
– Frequency shift 'FS'.
LIC Line Analysis Procedures (LLAP)
The LLAP is a set of tests initiated manually from the PKD and which are automat-
ically chained. They are intended to test a communication facility: the line itself
and the two DCEs.
Chapter 4. Transmission Subsystem (TSS)
4-99