Making Measurements
LT51 User Manual
55
NOTE: For a connection to be established, the remote LT51 must not be
transmitting a single tone between 1.8 and 3.0 kHz, and the line
attenuation at these frequencies must be less than 30dB (600
). The
local LT51 can be used to verify these conditions.
NOTE: When connected as a SLAVE, the remote LT51 will not set TXFREQ to
any frequency between 1.8 kHz and 3.0 kHz, since frequencies within
this range interfere with the modem operation.
Once connected, the current configuration of the local LT51 is transferred to the
remote LT51. The following events will also update the remote LT51:
changing the measurement mode.
changing Zrtx, Ztx, Span, sweeping, terminals, or when pressed: TX or
Centre frequency (non-zero centre frequency is not supported).
The following events will close down the connection to the remote LT51:
pressing the Telephone or keys.
timeout waiting for a command acknowledgment from the remote LT51, eg.
after removing the physical pair connection.
To re-establish the connection, press the key again.
The following table describes the termination conditions the remote LT51
presents to the pair being tested for each measurement mode that can be
selected on the local LT51.
Test
Measurement
Remote LT51 (slave) termination
DC/AC Voltage
a-b
RTX: O/C
Loop Current
a-b
RTX: O/C
Impedance
a-b
RTX: O/C
TDR
a-b
RTX: O/C
DE Loss
a-b
RTX: AC terminated
Return Loss
a-b
RTX: DC terminated
NEXT or FEXT
a-b
RTX: DC terminated
TXa-b: AC terminated
OSB
a-b
RTX: AC terminated
Noise
a-b
RTX: DC terminated
Table 5.1 List of available Auto-Tests & termination conditions
Summary of Contents for UMDT51A
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