Volume 1
MIL-HDBK-162A
Section 2
15 December 1965
AN/APN-22
TECHNICAL DESCRIPTION
FUNCTIONAL DESCRIPTION
The AN/APN-22 is a microwave altimeter that is
Frequency: 4200 to 4400 mc
designed to measure the terrain clearance of an aircraft
Reliability Range: 0 to 10, 000 ft over land; 0 to
without the necessity of adding antennas or other
20,000 ft over water
equipment external to the surface of the aircraft.
Accuracy: 2 ft from 0 to 40 ft; + 5% of the correct
The drop-out altitude (the altitude at which the signal
terrain clearance from 40 to 20,000 ft.
becomes too weak to operate the system) is above
Transmitter Power Output: 1w nom
10,000 feet when flying over land and higher when flying
Modulation Capability: 60 mc
over water. The drop-out altitude is reduced in banks of
Type of Modulation: FM
60 degrees or more and in climbs or dives of 70 degrees
Modulation Method: Vibrating reed
or more. A reliability circuit disables the indicator and
Operating Voltages and Power Requirements:
shields the needle behind a mask to prevent the pilot
28 vdc, 1.35 amp normal, 4 amp max; 115
using the indication when the signal is too weak to
vac, 320 to 1, 000 cps, 0.85 pf, 0.87 amp
provide reliable operation. Provisions have been made
normal, 1 amp max; 115 vac, 380 to 420 cps,
for completing a tie-in to automatic pilots or other
0.95 pf, 0. 13 amp normal, 0.15 amp max
devices requiring selected altitude data.
INSTALLATION CONSIDERATIONS
RELATION TO SIMILAR EQUIPMENT
None.
Not available.
PRINCIPAL COMPONENTS AND PHYSICAL DATA
COMPONENT
QTY
HEIGHT
WIDTH
DEPTH
UNIT WT.
(Inches)
(Inches)
(Inches)
(Pounds)
Electronic Control Amplifier
1
19.5
AM-291/APN-22
Mounting MT-803/APN-22
1
4.0
Height Indicator ID-257/APN-22
1
2.0
Radar Receiver-Transmitter
RT-160/APN-22
1
4.75
Housing, Receiver-Transmitter
1
2.75
CY-1409/APN-22 or
CY-1409A/APN-22
Connector AN31088-18-15
1
REFERENCE DATA AND LITERATURE
Technical Manuals:
AN16-30APN22-1
AN16-30APN22-2
AN16-30APN22-4
Technical Order:
12P5-2APN22-2
AN 'AP' 22: -2
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