OPTIMOD-AM DIGITAL TECHNICAL
DATA
6-7
Component-Level Description:
The meter LED matrix consists of ten 10-segment LED bar graph assemblies
(CR1-CR9, CR16) and one discrete LED (CR10). Row selector latches IC4, IC5,
IC6, and IC9 are controlled by the host microprocessor and alternately sink cur-
rent through the LEDs selected by column selector latches IC1 and IC2, which
are also controlled by the SC520. IC1 and IC2 drive the selected row of LEDs
through current limiting resistor packs RP1 and RP2.
Input Circuits
This circuitry interfaces the analog and digital inputs to the DSP. The analog input
stages scale and buffer the input audio level to match it to the analog-to-digital
(A/D) converter. The A/D converts the analog input audio to digital audio. The digi-
tal input receiver accepts AES3-format digital audio signals from the digital input
connector and sample rate-converts them as necessary. The digital audio from the
A/D and SRC is transmitted to the DSP.
Analog Input Stages
Located on input/output/DSP board
The RF-filtered left and right analog input signals are each applied to a floating,
balanced amplifier that has an adjustable (digitally controlled) gain. Analog
switches set the gain. The outputs of a latch set the state of the switches. By writ-
ing data to the latch, the control circuits set the gain to correspond to what the
user specifies via the front panel controls. The gain amplifier’s output feeds a cir-
cuit that scales, balances, and DC-biases the signal. This circuit feeds an RC low-
pass filter that applies the balanced signal to the analog-to-digital (A/D) con-
verter.
The digitally controlled gain circuitry was included on the circuit board
for possible use in future products. In the 9300, its gain is preset so that
the A/D will clip at +27 dBu with respect to the 9300’s analog inputs.
Note that the small RFI “tee” filter assemblies connected to the input and output
connectors are socketed and user-replaceable.
Component-Level Description:
The left channel balanced audio input signal is applied to the filter / load net-
work made up of L100-103 and associated resistors and capacitors. (There are
solder pads available in the PC board to accept an optional 600
termination
load [R106] on the input signal if the user wishes to install one.) A conven-
tional three-opamp instrumentation amplifier (IC100 and associated circuitry)
receives the input signal. R110-114 and quad analog switch IC101 make up the
circuit that sets the gain of IC100. The switches in IC101 set the gain of the in-
strumentation amplifier by switching resistors in parallel with R104. (Smaller
total resistances produce larger gains.)
IC100 feeds IC104 and associated components. This stage balances, DC-biases,
and scales the signal to the proper level for the analog-to-digital (A/D) con-
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...