Orban OPTIMOD-FM 8600, Operating Manual

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TECHNICAL DATA ORBAN MODEL 8600
Stereo Analog-to-Digital (A / D) Converter
Located on Input/output board
The A/D converter, IC107, is a stereo 24-bit sigma-delta converter. (This is a sur-
face-mount part and is not field-replaceable,)
The A/D oversamples the audio, applies noise shaping, and filters and decimates
to 64 kHz sample rate, which is the fundamental sample rate in the 8600.
Digital Input Receiver and Sample Rate Converter (SRC)
Located on Input/output board
The integrated receiver and input sample rate converter, IC500, accepts digital
audio signals using the AES3 interface format (AES3-1992). The built-in sample
rate converter (SRC) accepts and sample-rate converts any of the “standard” 32
kHz, 44.1 kHz, 48 kHz, 88.2 kHz, and 96 kHz rates in addition to any digital audio
sample rate within the range of 32 kHz and 96 kHz. The SRC converts the input
sample rate to 64 kHz, which is the 8600’s fundamental sample rate.
This chip is surface-mounted and not field-replaceable.
Output Circuits
This circuitry interfaces the DSP to the analog and digital audio outputs. The digital
audio from the DSP is transmitted to the digital-to-analog converter (D / A) and out-
put sample rate converter (SRC). The digital-to-analog (D / A) converter converts the
digital audio words generated by the DSP to analog audio. High-speed D/A convert-
ers do the same for the composite outputs, each of whose outputs is smoothed by a
passive LC reconstruction filter. The analog output stages scale and buffer the D/A
output signal to drive the analog output XLR connectors with a low impedance bal-
anced output. The digital output transmitter accepts the digital audio words from
the output sample rate converter (SRC) and transmits them in AES3-format digital
audio signals on the digital output connector.
Stereo Digital-to-Analog (D / A) Converter
Located on Input/output 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 board
The left and right analog signals emerging from IC211 are each filtered, ampli-
fied, and applied to a floating-balanced integrated line driver, which has a 50
Ω
output impedance. The line driver outputs are applied to the RF-filtered left and
right analog output connectors. These analog signals can represent either the
transmitter or monitor output of audio processing.