OPTIMOD-AM DIGITAL TECHNICAL
DATA
6-9
Stereo Digital-to-Analog (D/A) Converter
Located on input/output/DSP board
The D/A, IC211, is a stereo, 24-bit delta-sigma converter. It receives the serial left
and right audio data samples from the DSP at 64 kHz sample rate, and converts
them into audio signals requiring further, relatively undemanding analog filter-
ing. IC211 is surface-mounted and is not field-replaceable.
Analog Output Stages
Located on input/output/DSP board
The 9300 uses the two channels of the stereo D/A converter to drive the 9300’s
Analog 1 and Analog 2 outputs. This allows the 9300 to use DSP to obtain sepa-
rate independent control of the two outputs in DSP.
The left (Analog Output 1) and right (Analog Output 2) signals emerging from
are each filtered, amplified, and applied to a floating-balanced integrated line
driver, which has a 50
output impedance. The line driver outputs are applied to
the RF-filtered left and right analog output connectors.
Component-Level Description:
IC201 and associated components filter the left channel signal emerging from
IC211. The purpose of these stages is to reduce the out-of-band noise energy
resulting from the delta-sigma D/A’s noise shaping filter and to translate the
differential output of the D/A converter into single-ended form. These com-
ponents apply a 3
rd
order low-pass filter to the differential signal from the D/A.
This filter does not induce significant overshoot of the processed audio, which
would otherwise waste modulation.
IC212 and associated components form a low-frequency servo amplifier to re-
move residual DC from the signal. The 0.15Hz
3 dB frequency prevents tilt-
induced overshoot in the processed audio.
The buffered output of IC201 is applied to IC213, a balanced output line driv-
er. This driver emulates a floating transformer; its differential output level is
independent of whether one side of its output is floating or grounded. IC213
and its right channel counterpart IC214 are socketed for easy field replace-
ment. All other circuitry is surface-mounted.
The corresponding right channel circuitry is functionally identical to that just
described.
Digital Sample Rate Converter (SRC) and Output Transmitter
Located on input/output/DSP board
Output sample rate converter (SRC) chips IC400 and IC402 convert the 64 kHz
9300 DSP output sample rate to any of the standard 32 kHz, 44.1 kHz, 48 kHz,
88.2 kHz, and 96 kHz rates for the 9300’s Digital Out 1 and Digital Out 2 respec-
tively. The sample rate converters drive digital audio interface transmitters IC403,
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...
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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...