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discussion of data link.
20.1.11 UHF Automatic Direction Finder. The
UHF/ADF provides the relative bearing to a UHP transmitting
station t?om the aircraft. This information is
displayed directly on the BDHI and on the MPD HSD
format.
20.1.12 Bearing Distance Heading Indicator. A
BDHI is on the left side of the pilot and RIO instrument
panels (Figure 20-4). The BDHI is a remote heading
indicator that displays aircraft magnetic heading, tacan
and UHPIADF bearings, and tacan slant range. The rotating
compass card receives its heading reference from
the SAHRS. Aircraft heading is read against a fixed
index mark at the 12-o’clock position, The two servodriven
needlesa rep ositionedb y relativeb earingi nfomration
provided by the UHP/ADF to the single bar (No. 1)
needle and by the tacan to the double bar (No. 2) needle.
Magnetic bearing to the station is read under the head of
the needle. Relative bearing can be determined by comparing
the bearing reading with magnetic heading. The
range window on the right side of the indicator displays
tacan slant range. When the tacan is off or range is
unreliable, an OFF flag covers the window.
20.1.13 ANIURC-107 Joint Tactical Information
Distribution System. JTIDS is a jam-resistant
communication system that provides the F-14D with
two-way secure data and digital voice communication.
In addition to the JTIDS communication functions, it
also provides the F-14D with navigation and tacan
data.
ORIGINAL 20-10
The JTIDS system internally computes relative navigation
and position location information. All patticipants
(JTIDS terminals) in the same net determine their
position relative to each other. This is referred to as the
JTIDS relative navigation function. The basis of this
function is the TDMA architecture and precise synchronization
of all participants to a common time base (net
time reference). This allows each JTIDS system to accurately
determine the time a message was transmitted
and its TOA, and then compute the range from the
source of the message. JTIDS computes an estimate of
its own relative position coupled with the position and
navigation quality contained in each participants PPLI
message. With data from multiple participants with
equal or better position plus the navigation data from the
INS or SAHRS, JTIDS can compute an excellent estimate
of own-ship position and velocities. JTIDS will
automatically update the own-ship position in the PPLI
message with its estimated position. It also provides an
estimated quality (accuracy) ofthe position it computed.
This quality is provided to the MCS and included in the
PPLI message.
JTIDS is a dual grid system utilizing a geodetic and
an independenrte lative grid. JTIDS can operatei n both
grids simultaneously, but the MCS is limited to operating
in one grid at a time. The relative mode requires a
coordinated grid origin (latitude and longitude) and the
selection of NAV controller (a high-quality navigation
source). The geodetic grid is the F-14D default mode
and, unlike the relative grid, requires no special coordination.
Refer toNAVAIROl-F14AAD-IA forthe MFD
displays of JTIDS navigation parameters.
JTIDS receives navigation sensor data from the MCS
and returns navigation corrections. The sensor data is
used by JTIDS in its relative navigation calculations,
own-ship position in the PPLI message, and for calculating
navigation corrections.
The JTIDS navigation correction data sent back to the
MCS is used to perform track conversions and navigation
updates. The JTIDS correction data will only be
used for track conversions and navigation updates when
it is valid and has a quality 53 (5 18,080 feet in error).
The track conversion function uses the JTIDS delta
navigation corrections to pad all received and transmitted
tracks on the JTIDS link into the JTIDS navigation
reference. This function is performed automatically by
the MCS.
The navigation update function has to be manually
selected. These selections are JTIDS one-fix, continuous
position, and INS in-flight alignment. The aircrew
NAVAIR 01.F14AAD-1
has the ability to select either of the JTIDS grids via the
NAV SYSTEM AID page. This selection determines
which data the MCS will use to perform the track conversion
and continuous position updates. Independent
of this selection, JTIDS one-f= and INS in-flight alignments
will always be performed using the geodetic data.
Internal to the JTIDS system is the equivalent of an
AN/ARN- 118 tacan system. Installation of JTIDS in
　
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本文鏈接地址：F-14D 飛行手冊 Flight Manual 3(17)