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HARRIS
STM-1
AM
Stereo
Modulation
Monitor
·• Meets FCC AM Stereo modulation monitoring
requirements
• Provides accurate monitoring
of
Harris Linear AM Stereo
. signal
• .
RF
/I
F inputs
for
thorough exciterandtransmittertesting
• Built-in circuitryeliminatesthe need forspectrum
analyzer duringtransmitter interface
_
,,....._,
• :rhree large, legible meters make monitoring easy
• Four convenient front panel BNC audio jacks provide
quicktestequipmentconnection, plus stereo phono jack
• Pilot frequency injection and calibration monitoring for
quick system checks
The Harris
STM-1
AM
Stereo Modulation
Mo
nitor provides ac-
curate monitoring of the Harris Linear
AM
Stereo signal.
The STM
-1
complements the
Har
ri
s STX
-1
AM
Stereo Ex-
citer. When used with your
current mono modulation
monitor, it fulfills a
ll
FCC
AM
Stereo modulation monitoring
requirements.
RF/IF BASED
MONITORI
NG
To ease checkout
of
both ex-
citer and transmitter,
RF
and
IF input jacks are provided.
The IF baseband signal can
be monitored, and provides
additional checks and align-
ment on the exciter. The RF
input accepts transmitter
.,,---..
•generated signals for com-
pl
ete system monitoring. The
clual
RF/IF inputs provide
flexibility
in
system test and
alignment.
TRANSMITTER SETUP
By utilizing a unique sideband detection circuit
in
the monitor,
your transmitter can be aligned without the use
of
an expen-
sive spectrum analyzer. A front panel switch permits conve-
nient meter display
of
upper sideband (USB) and lower
sideba-nd (LSB) alignment signal
s.
PEAK READING METERS
The STM-1 incorporates three 3
½"
meters, two
of
which mon-
itor left and right channel modulation. A quasi-peak reading
circuit drives each modulation meter with accuracy approach-
i
ng
that
of
a peak flasher.
SYNCHRONOUS DETECTORS
One
of
the outstanding characteristics
of
the Harris Linear
AM
Stereo System is the capability to use synchronous detection
for signal demodulation. The synchronous detector/demod-
ulator used
in
the
STM-1
improves monitoring accuracy when
compared with other detection methods.
Front panel selector switches enable the operator to monitor
left channel, right channel, I-channel (in-phase) information,
Q-channel (Quadrature) information, and the p
il
ot signal.
MULT
IMETER AND STATUS LEDs
One
of
the three
STM-1
front panel meters also serves as
a multimeter. A front panel selector switch allows you to con-
veniently check RF input level and pilot injection level, as well
as to calibrate the pil
ot
frequency. Front panel LEDs also
allow quick status checks
of
transmitter
pi
lot presence and
the monitor's internal P
LL
lock.
ADDITIONAL OPERATIONAL BENEFITS
The Harris STM-1 Modulation Monitor provides left channel,
right channel, I and Q audio outputs with sufficient level to
drive most monitor amplifiers. A convenient front panel stereo
headphone jack is included to drive a pair of stereo head-
phones. Panel connections to a monotor amplifier and remote
outputs
of
I,
Q and pilot
in
jection are also provided.
