PRIMUS
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1000 Integrated Avionics System
A28--1146--112--00
C--5
PRIMUS
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II Radio System
SYSTEM DESCRIPTION
General
The PRIMUS
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II Radio System is comprised of the following cockpit
controls and remote radio units.
D
Integrated Navigation Unit
D
Integrated Communications Unit
D
Audio Panel
D
Radio Management Unit (RMU)
D
Tuning Backup Control Head.
Except for the audio panel, all data for these control functions are
transmitted through a radio system bus. Audio switching is controlled
by the controls on the audio panel. The audio signals are transmitted
from the remote units to the audio panel through a dedicated digital
audio bus.
All the navigation data is displayed on the EDS. Data is also displayed
on either RMU display when they are operating as a standby navigation
display.
There are three levels of built--in test. First, at power up, the RMU
checks itself and the buses, and then commands each of the remote
functions to run through a full self--test. Any error is annunciated on the
RMU. Second, the pilot can activate a self--test of any individual
function through the RMU. Third, key parameters in the radios are
monitored at all times. If a discrepancy occurs, it is recorded in
nonvolatile memory located in the remote module. The discrepancy is
recorded in the memory and remains there, even after power down.
Discrepancy information includes: the discrepancy itself, the time into
flight it took place, and the temperature. The memory can be read in the
aircraft on the RMU, or the remote unit can be taken into the shop where
a technician can read out the results on a digital interface unit.
Integrated Navigation Unit
The integrated navigation unit, also known as the NAV unit, is a
complete self--contained navigation system. It contains the VOR,
localizer, glideslope and marker beacon receiver module, automatic
direction finder (ADF) module, and a six--channel scanning distance
measuring equipment (DME) module.
In the NAV unit, each module has its own independent housing and
power supply. The DME and ADF are mounted on the outside edges
of the unit and the VOR and cluster module are in the center. The DME
and ADF modules are both part of the NAV unit structure. They reduce
the RMUs installed volume and they heat sink to the outside surfaces.
