OPTIMOD-AM DIGITAL
INSTALLATION
2-27
11.
Test the equipment downstream from OPTIMOD-AM.
Test the RF envelope at the transmitter’s output to determine if it exhibits tilt,
overshoot, or ringing. If you observe these problems, you can often adequately
equalize it them with the 9300’s transmitter equalizer, whose settings are de-
termined by the on-air System Preset.
Dealing with tilt and overshoot may seem fussy, but every dB of tilt or overshoot
is a dB of loudness lost!
Use the 9300's built-in square wave generator to make this test:
A)
Navigate to
S
ETUP
>
T
EST
.
B)
Set the
S
QUARE
M
OD
to 0%.
C)
Set the
M
ODE
to
S
QUARE
.
D)
You may now turn the final amplifier on. Observe the RF envelope at the
common point with a DC-coupled oscilloscope and advance the
S
QUARE
M
OD
L
VL
control until you can easily see the shape of the square wave.
Sweep the
T
ONE
F
REQ
control from 125 to 1000 Hz and observe the shape
of the square wave as you do so. If you are driving more than one trans-
mitter and/or your antenna load changes between day and night, test all
combinations that you will be using.
If the square wave is free from tilt and ringing at all frequencies in the
sweep, you do not need to set up the transmitter equalizer in steps 12
through 13.H)a) below. Otherwise, you must do so to achieve the highest
loudness and coverage that your facility can produce.
If you observe problems with some combinations of transmitter and load
but not others, record which combinations cause problems. You will only
need to set up set up the Transmitter Equalizer for these combinations.
You will dedicate one System Preset for each problematic combination so
that each combination can be equalized independently.
on page 2-29 shows what tilt looks like and
on
page 2-31 shows ringing.
E)
Caution: To avoid damaging the transmitter, do not exceed 50% modu-
lation with square waves.
Important
: Do not place additional clipping devices after OPTIMOD-AM! The
additional distortion introduced by these devices will totally nullify the advan-
tages of OPTIMOD-AM's distortion-canceling clipper and will cause the out-of-
band energy induced by clipping to violate FCC or ITU-R standards. In HD-AM
installations, this energy will interfere with the HD digital carriers.
12.
Equalize the transmitter’s low frequency square wave response.
[Skip the Transmitter Equalizer adjustment steps [(steps 12 though 13.H)a)] if the
RF envelope square wave test you preformed in step 11 above showed no sign of
tilt, overshoot, or ringing.]
Summary of Contents for OPTIMOD-AM 9300
Page 1: ...Operating Manual OPTIMOD AM 9300 Digital Audio Processor Version 2 0 Software...
Page 7: ...Operating Manual OPTIMOD AM 9300 Digital Audio Processor Version 2 0 Software...
Page 178: ...3 46 OPERATION ORBAN MODEL 9300...
Page 200: ......
Page 221: ...OPTIMOD AM DIGITAL TECHNICAL DATA 6 21...
Page 222: ...6 22 TECHNICAL DATA ORBAN MODEL 9300 CONTROL BOARD PARTS LOCATOR...
Page 228: ...6 28 TECHNICAL DATA ORBAN MODEL 9300...
Page 229: ...OPTIMOD AM DIGITAL TECHNICAL DATA 6 29 I O DSP BOARD LEFT AND RIGHT ANALOG INPUTS...
Page 230: ...6 30 TECHNICAL DATA ORBAN MODEL 9300 I O DSP BOARD ANALOG OUTPUTS...
Page 231: ...OPTIMOD AM DIGITAL TECHNICAL DATA 6 31...
Page 238: ...6 38 TECHNICAL DATA ORBAN MODEL 9300 FRONT VIEW REAR VIEW FRONT PANEL PARTS LOCATOR DIAGRAM...
