Honeywell
COMPONENT MAINTENANCE MANUAL
PART NUMBER 964-0452
1I.B.1516A Page 30
Mar 30/01
23-12-01
Low-pass filter, L1, L2, L3, L4, suppresses the oscillator spurious output, which
could reach the RF output via the final balanced attenuation of the mixer.
The RF signal is rectified at the output (nominal value –7dBm) in diode detector,
V1, V68, and V9, and compared to a threshoLd corresponding to an RF level of
about –16dBm. The TTL signal RF detector is required for continuous monitor-
ing, which is effected in IF processor, A12. The RF detector must respond when
a modulation signal threshoLd is exceeded at the input of Receiver/Exciter A1.
(d) Test operation
In the receive mode, the 2MHz test signal generated in the synthesizer is applied to
the receiver input via switch, V300. The IF processor, A12, compares the level of
the received test signal with 2 thresholds, which form a window discriminator. The
results can be inquired by means of the external data bus.
In the transmit mode, the 2 modulation inputs are disconnected for test purposes,
and a 1kHz tone is generated by the IF processor, A12, in the sideband. The level
is 6dB lower than with normal operation. The HF signal is rectified by the same di-
ode detector, V1, V68, V9, and is used for continuous monitoring purposes. Contin-
uous wave operation permits generation of a test signal for tuning the Antenna Cou-
pler and for testing the subsequent assemblies. A 1kHz tone in the sideband is used
as described before with a nominal level of –7dBm.
(2) Airborne Data Link Processor (ADP), A2
The ADP is responsible for implementing data link and network layers of the HF Data Link
air/ground protocols as specified in ARINC 635. It establishes and maintains the data link
between the airplane and the ground, and helps to ensure the timely transmission and
integrity of the data messages sent between the airplane and the ground. The ADP is al-
so responsible for communicating the status of the Data Module to the Controller D, A8,
in the Transceiver. Refer to Fig. 17 for a block diagram of the ADP Assembly and to Fig.
18 for the connector pin assignments, showing the signals interfacing to this assembly.
To perform its intended functions, the ADP has a large number of ARINC 429 and dis-
crete interfaces to the rear connector of the Transceiver, which are connected to other
systems in the aircraft. The ADP also has communication interfaces to both the HF Mo-
dem, A10, and the Controller D, A8.
The ADP uses an 80188EB microprocessor. The software controlling this processor is
written primarily in the "C" programming language with minimal assembly code. This soft-
ware is divided into 4 major functional blocks: Boot, core, Database, and Acceptance
Test Procedure (ATP) code.
The Boot software provides initialization, limited power-up self-tests, and a Data Loader
interface. An ARINC 615 airborne or portable Data Loader may be used to update the
ADP software, attaching to the rear connector of the Transceiver. The ATP functions, al-
though resident on the ADP at all times, are only used for test purposes. The ADP pro-
vides a set of commands to test functions within the Data Module, and is used during
manufacturing and return-to-service testing.
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