Rev. 1.0
FMX30/FMX100/FMX250 User’s Manual
2—12
Processed, de-emphasized samples of the left and right audio inputs to the stereo
generator are available at the Monitor jacks on the rear panel. The signals are
suitable for feeding a studio monitor and for doing audio testing. De-emphasis is
normally set for 75 µsec.; set to 50 µsec. by moving jumpers, JP203 and JP204, on
the Stereo Generator board.
Select the pre-emphasis curve (75 µsec., 50 µsec., 25 µsec., or Flat) by jumpering
the appropriate pins of header JP1 on the audio processor board. If you change the
pre-emphasis, change the de-emphasis jumpers JP203 and JP204 on the Stereo
Generator board to match. (See Section 2.8, Composite Input Connection for
additional information.)
You may bypass the audio processor in order to feed the left and right (pre-
emphasized) audio directly to the stereo generator. The Normal-Bypass slide switch
is near the left-rear corner of the motherboard. If the audio source is already
processed and you do not desire further processing, use the Normal mode, but turn
the Processing control (on the front panel) to “0.” (See also Section 3.4, Processing
Control.)
Illustration 2–10 Composite In and Audio Monitor Connections
CAUTION
In the BYPASS position, the pre-emphasis circuits and the filters that protect the
pilot and stereo subcarrier are bypassed. As a result, the occupied bandwidth
specifications of the transmitter could be compromised. The 15–Hz high-pass
filters are also bypassed which may mean that modulation with frequencies below
10 Hz could cause the frequency synthesizer to unlock.
OFF
SC A IN
COMPOSITE IN
MO NITO R
R
L
2
3
REMO TE I/ O
RI GHT
LEFT/MONO
B
A
T
T
E
R
Y
36 VDC
+
–
CIRCUI T
BREAKER
1
Composite In
BNC Connector
Audio Monitor
Jacks
