OPTIMOD-FM OPERATION
4-15
K) Measure the Pilot Modulation on the stereo monitor. It should read 0%.
L) Set the Mod. Level to 0.0%. Measure the de-emphasized noise at the left and right
outputs of the stereo monitor. It should not exceed –80 dB below 100% modula-
tion.
M) Repeat steps (C) through (L) for the 8400’s COMPOSITE OUTPUT 2.
N)
Measure pilot tone injection: Using the stereo monitor, verify that pilot tone injec-
tion is between 8% and 10% modulation. If it is outside these parameters, it can be
adjusted by navigating to
Input/Output and then to screen Input/Output 3. Adjust Pi-
lot Level
as necessary.
If the measured pilot level varies by more than a few tenths of percent from
the pilot level indicated, this indicates there may be a problem elsewhere—
either in your measuring setup, or with the 8400.
O)
Measure pilot tone frequency: With the Mod. Level still set to 0.0%, connect a fre-
quency counter to either of the 8400’s composite outputs. Verify that the pilot tone
frequency is 19,000 Hz ±1 Hz.
9. Optional tests.
A) You can test each GPI input for functionality in the obvious way, by programming
a function for it and then verifying that the function executes when you activate the
input. To program a GPI input, navigate to
System Setup: Network/Remote 1.
B) You can test the RS232 Port 1 for functionality by verifying that you can connect
to a PC through a null modem cable. See Installing 8400 PC Remote Control Soft-
ware on page 2-56.
10. Return OPTIMOD-FM to service.
A) Remove the 600Ω resistors connected across the outputs.
B) Navigate to the Input/Output screen and restore your normal operating parameters
in all four screens, using the notes you made in step (1.B)a) on page 4-9.
C) Navigate to System Setup. Select Test Modes. Then activate Operate mode: Navi-
gate to the
Operate button and press Enter.
D) Recall your normal operating preset.
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