Volume 1
MIL-HDBK-162A
Section 1
15 December 1965
ITEM NAME: RADAR SET
TYPE: AN/CPN-4, -4A, -4B
Precision System
radio-telephone communications system for the
Frequency: 900 to 9160 mc
necessary two-way, aircraft-to-ground communications.
Range: At least 8 naut mi
Two special features of the search and precision
Antenna Scan: 2 to 22 deg with respect to normal-to-array
systems are: (1) MTI that functions with either or both
Indicator Maps: -5 to plus 15 deg with respect to runway
systems to eliminate or greatly reduce signals de-rived
parallel
from stationary targets and (2) in-stantaneous direction
Elevation Coverage
finding equipment that functions with the search system
Antenna Scan: 2 to 9 deg with respect to normal-to-array
to located aircraft communicating with the GCA station
Indicator Maps: -1 to plus 6 deg with respect to ground
by radio.
line
In addition to the three major systems, all necessary
Accuracy
equipment and power supplies necessary to permit the
Azimuth: 0.6% of rangel plus 10% of deviation from
functioning of the AN/CPN-4, 4A, 4B, as a completely
optimum approach path
indepen-dent unit are provided.
Elevation: 0.3% of range plus 10% de-viation from glide
RELATION TO SIMILAR EQUIPMENT
path Range: 2% of true range provided range of target
Radar Set AN/CPN-4, 4A, 4B are similar to and
is over 2% of sweep range
interchangeable as a whole, with each other, the
Resolution:
difference being only in the type of Communication
Range - 200 ft target separation
Equipment used.
Azimuth - 1.1 deg target separation
TECHNICAL DESCRIPTION
Elevation - 0.6 deg target separation
Search System
Detectable Deviation From Glide Path: 25 ft at 1-mi
Frequency:
2780 to 2820 mc
range
10 cm band (S)
Pulse Repetition Frequency:
Range: 18 naut mi at 2000 ft,
Normal - transmitter, 1833 or 5500 pps; indicator - 1833
28 naut mi at 6000 ft
pps
36 naut mi at 10,000 ft
MTI - transmitter, 5500 pps; indicator - 1833 pps
Azimuth Coverage: 360 deg
Azimuth Coverage: 2 to 22 deg electrical scan toward
Elevation Coverage:
elevation antenna compartment from normal-to-array (-
0.5 to 45 deg from O to 8000 ft
5 to plus 15 deg with respect to runway parallel line)
Azimuth Accuracy: 1 deg if target range is over 10% of
Antenna Elevation: 2 to 9 deg electrical scan upward from
sweep range
normal-to-array (-1 to plus 6 deg with respect to ground
Range Accuracy: 4% of true range provided target
line)
range is over 20% of sweep range
Modulator Pulse Width: 0.18 sec plus or minus 10% at
Resolution Accuracy:
approx 90% of peak voltage pulse amplitude
Range - 500 ft separation of targets or 1% of sweep
IF. Bandwidth (Normal and MTI): 12 plus or minus 1 mc
range, whichever is greater
between half power points
Azimuth - 3.3 deg if target range is over 30% of sweep
Sensitivity (Normal and MTI): 90 dbm
range
Display:
Azimuth and elevation expanded displays
Pulse Repetition Frequency: 1500 pps plus or minus 2%
combined on 12-in. CRT; elevation on upper half,
Antenna Scan: 360 deg cw mechanical scan
azimuth on lower half; sector limiting to prevent over-
Scan Speed: 20 plus or minus 2 rpm
lapping
Peak Power Output: 600 kw (min) Pulse Width: 0.5
Sweeps: Logarithmic time-base sweeps, 8-5/16 in. long
sec plus 20% or -10% (at 50% of peak current
(may be linear by modification). Log sweep at 1 mi has
amplitude)
3 times the sensitivity of a linear sweep at 1 mi
IF. Bandwidth (Normal and MTI):
(operating on a 10-mi range). The same expansion at
4.5 plus or minus 1 mc between half power points
1 mi will occur for the 6- and 8-mi ranges.
Sensitivity (Normal and MTI): 95 dbm Display: 12-
Range Marks:
in. PPI Calibration Marks:
Ranges - Adjustable for any range between 6 and 10
2-mi intervals on 5- and 10-mi range
naut mi
5-mi intervals on 20- and 30-mi range
Calibration - 1-mi intervals adjustable for a variable delay
Angel Marks: -50, O, and plus 15 deg to indicate outline
between O and 55 usec (O to 4.5 naut mi) with respect
of precision azimuth coverage with respect to
to the time-base sweep origin
runway parallel
Communications System
Direction Finding System
AN/CPN-4
Indicates bearings of target in communication with radar
HF: AN/ART-13
set with delay of less than 35 ms.
AN/CPN-4: 2
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