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Refer to the MAPs for tests using the test/operate
switch during modem checkout and trouble-
shooting procedures.
Proper Indicator Action for Test/Operate Switch Positions
READY Indicator
SIGNAL Indicator
(On when 'data set
(On when 'carrier
Test/Operate
ready' is active)
detect' internal is
Switch Position
Note 1
active)
OPERATE
On (note 3)
On when receiving
signal above
threshold
Reset (interme-
Off
On when receiving
diate positions)
signal above
threshold
T1
Off
On (wrap signal)
T2 (or interface
Off (note 1)
On if 'request to
'test')
send' is active
(wrap signal)
T3 (2-wire system
Off
Off
with remote
modem on T4)
T3 {4-wire system
Off
On (remote signal)
with remote
modem on T3 or
T4)
T4 (remote
Off
On (remote signal)
modem on T3)
Notes:
1. 'Data set ready' is active in T2 mode, but the
READY indicator is off. (Interface test,
otherwise identical to T2, does not inhibit
the indicator.)
2. The scramble pattern is being transmitted
with input data clamped to mark. Therefore,
the unscrambled data should be a steady mark
and the OPERATE indicator should be on
steady. Test circuits provide a 200 ms off
period if even a single space is received so
that the erroneous space can be observed.
3. The READY indicator blinks on and off.
4. The signal quality meter should read 0 when
the signal indicator is off.
OPE RATE Indicator
(On for 'receive data'
Signal Quality Meter
mark)
(Note 4)
On or flickering
0-50
On
0
On (note 2)
0+
Depends on data; off
for space, on for mark
0+
On
0
On (note 2)
0-50
On (note 2)
0-50
Data Communications
10-11
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