4. B.
(4) Input and Output Control Discretes
The discrete inputs are in a ground condition when connected to an
airframe dc ground, defined by a voltage of less than +3.5 volts dc.
The open condition is defined as greater than 100,000 ohms or a
voltage between +18.5 and +36 volts dc.
The output control discretes are in the ground condition defined by
a voltage of less than +3.5 volts dc.
The open condition is defined as qreater than 100,000 ohms or a
voltage between +18.5 volts and +j6 volts dc.
Volume III, Section 6, Interconnects, Table 501,
a detailed description of the control discretes.
(5) Global Data Management Unit (DMU) and DL-800/900
Interconnect (See Figure 264.)
Appendix C contains
Data Loader
The DMU interface to the NAV computer is ARINC 429 as described in
paragraph 4.B.(3) and the interface to the DL-800/900 Data Loader is
a synchronous RS-422 serial digital data bus as described in
paragraph 4.B. (2). When the data loader is connected to NAV
computer No. 1, a ground is applied to 121J1B-83 from 123J1-E. If
the data loader is connected to NAV
computer No. 2, a ground to
C121J1B-83 is applied from 123J1-D. Pin 123JI-F is connected
if a
third warm spare NAV computer is installed.
(6) Navigation Modes
The navigation computer develops a position based on a blend or mix
of the sensors.
The navigation modes are listed below by priority
based upon developing the most accurate position blend:
(a) DME/DME
(b) DME/VOR
(c) IRS
Only
(d) IRS/Omega Mix
The FMS freezes IRS drift in memory once IRS updating begins.
When system accuracies fall below specified levels, IRS/Omega
mixing begins,
if the Omega is within 12 NM of the
average IRS
position.
When the Omega is within 12 NM of the
average IRS position, it
is mixed with the average IRS position, and will have the same
weight as one
IRS.
If the Omega position is outside the 12 NM
limit, then
it will not be used in calculation of FMS position.
22-14-00
Page 298.161/298.162
Apr 15/93
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