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Aircraft Symbol with Azimuth Vector |
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|  MIL-D-81347C(AS)
Pilot Display Logic
3.5.3.4.2
Functional Description - This subunit provides the interface
3.5.3.4.2.1
between the computer and the Pilot Display. Under computer command, the Pilot Display Logic (PDL)
provides timing,- control, deflection and vldeo signals to control the presentation of functional data on
the CRT of the Pilot Display.
Figure 114 is a functional flow diagram for the PDL.
General Description
3.5.3.4.2.2
Presentation Repertoire -The PDL shall allow the computer to
3.5.3.4.2.2.1
control the presentation of data on the Pilot's Display. Figure 115 shows the Pilot Display and x and y
coordinate system in octal code. The data displayed is given in the paragraphs that follow:
(1) Aircraft Symbol with Azimuth Vector - The aircraft symbol
to be used shall be selected from the available mode 02 symbols of the Character Generator. (See
Figure 116). An azimuth vector is generated under computer control and has the origin at the center
of the aircraft symbol. The Set Position word (Figure 119) specifies the aircraft position. The ax
and a components of the Azimuth Vector word (Figure 121) determine the vector azimuth angle.
(See Figure 117). This vector shall always have a 4 inch programmed length, but only 1/2 inch of the
vector is unblanked.
(2) Fly-to-Points - A fly-to-point Shall consist of a dot with one
or two adjacent alphanumeric characters, e. g., 31.
(3) Vectors - Vector origin, magnitude, and direction are con-
trolled by the computer. All vectors are centered about the X, Y coordinate contained in the Set Posi-
tion word. The magnitude and direction of the vector are defined by the ax and ay components of the
Vector word, (Figure 121).
(4) Circles - Circle origin and radius are controlled by the
computer. The origin of the circle is defined by the X, Y coordinate contained in the Set Position word.
The radius of the circle is defined by the ax and ay components of the Circle word! Figure 122.
(5) Character Repertoire - The Character Generator shall have a
full nonambiguous alphanumeric capability with eight special symbols. The codes for alphanumeric
characters shall correspond to those shown in Figure 116. The characters presented on the display
shall be controlled by the computer.
(6) Flashing Character - A selected symbol or group of charac-
ters may be caused to flash on the CRT under control of a 1 Hz signal from the Master Timing Logic
(MTL) (this signal shall be referred to as the Flash signal).
(7) Tabular Information Display - An unlimited number of char-
acters, contained in Character words (Figure 120), may be displayed starting at the X, Y coordinate de-
fined in the Set Position word. This multi- character message shall be terminated by the receipt at the
Pilot Display Logic of a new Set Position word.
Timing - The following tabulation specifies the maximum gener-
3.5.3.4.2.2.2
ation time for the various display functions. The generation time initiates at the trailing edge of the
second computer Output Acknowledge signal and terminates at the next Output Data Request signal. The
execution times in the following tabulation are based upon a character writing time of 166.6 micro-
seconds and a 15 KHz low pass filter stabilization time of 240 microseconds maximum. The 166.6
microsecond character writing time is specified in order to enable synchronization of Character Gen-
erator control signals and provide a frequency compatible with 12 KHz sine wave for generation of
vectors and circles.
The computer shall refresh the Pilot Display, via the Pilot Dis-
play Logic at a 40 Hz frame rate. The logic shall cease its request for data from the computer upon
195
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