© 2004 SAGE INSTRUMENTS
9100-0925-01 V1.2
19
special PVIT signal to the far end. At the far end, a 935AT or 925VST configured for
PVIT Receive analyzes the incoming signal for signs of transmission impairments.
To view the current parameters, press the INFO button. For information on how to stop a
test in PVIT mode, see Remote Control of the 925VST on page 38.
E
CHO
G
ENERATOR
Use DTMF digit 2 to specify Echo Generator. The 925VST reboots to a state that
emulates a programmable loop back responder. In this state, the 925VST waits for a
“seizure” stimulus from the far end. When it detects a seizure, the 925VST immediately
loops back the incoming received signal back out toward the far end.
To view the current echo path parameters, press the INFO button after the screen displays
“Echo Generator Waiting for Ring…” The “loop back” can provide up to two echoes.
You can set the echo path loss and echo delay for each echo. The number of echoes and
the level and delay parameters for each echo can be modified by in-band DTMF digit
commands as described in Setting Level and Delay on page 19.
Note: The parameters shown by using the INFO button do not reflect any changes made
during the test from the far end by sending DTMF command digits.
For information on how to stop a test in Echo Generator mode, see Remote Control of the
925VST on page 38.
Setting Level and Delay
When an Echo Generator call is in progress, follow these steps to remotely set the level
and delay for Echo-1 or for both Echo-1 and Echo-2.
•
The pattern for DTMF digits to set
Echo-1 only
is *-L-L-D-D-D-# where L is a level
digit, and D is a delay digit.
•
The pattern for DTMF digits to set
both Echo-1 and Echo-2
is *-L-L-D-D-D-L-L-D-
D-D-# where L is a level digit, and D is a delay digit.
1. Establish a call with the remote unit.
2. Press the * key, and wait for the prompt tone to cease.
3. Press the number keypad to set level and delay.
NOTE: In most cases, the echo level should be set at a decibel value less than
zero. To set the value at zero or greater than zero, precede the number with 9.
4. Press the # key and wait for the prompt tone to cease.
Disabling Echoes
When an Echo Generator call is in progress, follow these steps to remotely disable both
Echo-1 and Echo-2.
1. Establish a call with the remote unit.
2. Press the * key, and wait for the prompt tone to cease.
The * digit indicates that remote programming follows. Echo generation is
temporarily suspended.