Orban Optimod-TV 8382, Руководство по эксплуатации

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6-10
TECHNICAL DATA ORBAN MODEL 8382
3. Digital Sample Rate Converter (SRC) and Output Transmitter
Located on input/output board
An integrated output sample rate converter (SRC) and AES3 line driver chip,
IC502, converts the 32 kHz 8382 system sample rate to any of the standard 32
kHz, 44.1 kHz, 48 kHz, 88.2 kHz, and 96 kHz rates, and also contains a digital au-
dio interface transmitter to encode digital audio signals using the AES3 interface
format (AES3-1992). This chip is surface-mounted and is not field-replaceable.
DSP Circuit
The DSP circuit consists of eight Motorola DSP56362 24-bit fixed-point DSP chips that
execute DSP software code to implement digital signal processing algorithms.
The algorithms filter, compress, and limit the audio signal. The eight DSP chips, each
operating at approximately 100 million instructions per second (MIPS), for a total of
800MIPS, provide the necessary signal processing. A sampling rate of 32 kHz and
power-of-two multiples thereof, up to 256 kHz, is used.
System initialization normally occurs when power is first applied to the 8382 and can
occur abnormally if the 8382’s watchdog timer forces the SC520 to reboot. Upon ini-
tialization, the SC520 CPU downloads the DSP executable code stored in the flash
memory. This typically takes about 7 seconds. Once a DSP chip begins executing its
program, execution is continuous. The SC520 provides the DSP program with pa-
rameter data (representing information like the settings of various processing con-
trols), and extracts the front panel metering data from the DSP chips.
During system initialization, the SC520 queries the DSP hardware about its opera-
tional status and will display an error message on-screen if the DSP fails to initialize
normally. Please note any such messages and be ready to report them to Orban Cus-
tomer Service.
The DSP chips are located on the DSP board—see the drawings starting on page 6-
46. U701 and U702 are local voltage regulators on the DSP board that derive the
+3.3V supply for the DSP chips from the system digital 5V bus.
Power Supply
Warning! Hazardous voltages are present in the power supply when it is connected
to the AC line.
The power supply converts an AC line voltage input to various power sources used
by the 8382. To ensure lowest possible noise, four linear regulators provide

15VDC
and

5VDC for the analog circuits. A switching regulator provides high current
+5VDC for the digital circuits. An unregulated voltage powers the fan and feeds lo-
cal regulators.
The power supply circuits are straightforward and no explanation is required be-
yond the schematic itself. Be aware that C1, C4, C5, and C12 in the switching regula-