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Honeywell
COMPONENT MAINTENANCE MANUAL
PART NUMBER 964-0452
I.B.1516A
Mar 30/01
23-12-01
built-in tests can be initiated, manually via a front panel test button, or from the aircraft main-
tenance system, via an ARINC 429 interface.
The results of the continuous monitoring are permanently supplied to the CFDS/CMC in the
normal mode, according to ARINC 604. In the interactive mode, the faults of previous flight
legs, test initiation, and more detailed fault information (troubleshooting data) are displayed.
The BITE system, and modes of operation, are controlled by the Controller Module, A8.
The Transceiver is configured for connection to a 115V, 400Hz, 3-phase, approximately
1000W supply. The internal voltages are generated in the Power Supply, A4.
B. Simplified Theory of Operation
The primary functions of the individual modules in the Transceiver are described here:
(1) Receiver/Exciter, A1
(a)
General
The key signal processing functions for transmitting and receiving are executed in
Receiver/Exciter, A1. The signal progression for receive and transmit operation is
outlined in functional diagram of Fig. 7 .
In the transmit mode, these functions are involved:
• Modulation (AM(E)), SSB)
• Automatic level control
• Voice compressor
• Signal synthesis for conversion oscillators
• Conversion of modulated signal to 2nd IF (25kHz), 1st IF (40.025MHz),
and RF frequency.
In the receive mode, these functions are involved:
• Demodulation (SSB, AM(E))
• Automatic gain control
• IF filteringSignal synthesis for conversion oscillators
• Conversion of RF signal to 1st IF (40.025MHz) and 2nd IF (25kHz)
All the signal processing functions performed on the 25kHz frequency are executed
in a signal processor as described here:
The 2nd IF signal (25kHz) is digitized by an A/D converter (100kHz sampling rate)
and further conditioned in the signal processor. After processing, the signal again
undergoes conversion in the D/A converter (12.5kHz sampling rate), and is supplied
to the audio outputs (audio, SELCAL, data) as an audio signal.
In transmission mode, a signal (audio, data) present at the audio inputs is digitized
by means of an A/D converter (100kHz sampling rate), and converted to the 25kHz
2nd IF signal in the signal processor.
The RF signal is supplied to the 1st mixer via a 30MHz, low-pass filter, and convert-
ed to the 1st IF at 40.025MHz with the aid of the conversion oscillator (42.025MHz)
to 7 0.02499MHz). The conversion oscillator is derived from voltage-controlled os-
cillator (VCO3). VCO3 forms part of a phase-locked loop (PLL), whose reference
frequency is derived from a signal generated by direct digital synthesis (DSS).
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