OPTIMOD-AM DIGITAL
INTRODUCTION
1-25
cupied bandwidth specifications of the NRSC-2 standard by June 30, 1990. The NRSC-
2 standard is an RF mask that was derived from the NRSC-1 audio standard. The
purpose of the NRSC-2 RF mask is to provide a transmitted RF occupied bandwidth
standard that any station with a properly operating transmitter will meet if NRSC-1
audio processing is used prior to the transmitter and if the station is not overmodu-
lating.
Audio Frequency (kHz)
10
11
12
13
14
15
Relative Amplitude (dB)
-50
-40
-30
-20
-10
0
Stopband Area
Modulation
10.5
1%
3.2%
0.32%
10%
31.6%
100%
Figure 1-3: NRSC Lowpass Filter
OPTIMOD-AM complies fully with the NRSC-1 standard when the 9.5 kHz NRSC low-
pass filter is in use and the
HF
C
URVE
control is set to
NRSC
.
Unfortunately, at this writing, the trend towards wider band receivers has reversed
and most receivers are no wider than they were in the 1970s. For this reason, many
engineers feel that using a third-order equalizer with 10 dB of ultimate boost pro-
vides a more intelligible sound on the average radio than does the NRSC curve. The
9300’s HF shelving equalizer can provide such a boost.
When a station is transmitting with 5 kHz audio bandwidth, the 9300’s 5 kHz low-
pass filter can produce audible ringing that some find objectionable. Using the
9300’s bell-shaped HF parametric EQ tuned to 3 kHz can reduce the effects of this
ringing by reducing the boost at 5 kHz by comparison to the 9300’s HF shelving EQ,
which maintains full boost all the way to 5 kHz. Additionally, you can use the
LPF
S
HAPE
control to trade off brightness against 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...