Volume 1
MIL-HDBK-162A
Section 1
15 December 1965
TYPE: AN/GPX-27
state of -..5v, and trigger goes positive to
function is accomplished for two separate modes of
ground.
interrogation for any selected interface ratio of the
Rise Time: 0.4 usec or less
modes. In addition, the Defruiter does the thresholding
Pulse Repetition Frequency (PRF):
of input noise that is required for decoding, and shapes
200 to 400 pps
the input-output characteristic for optimum defruiting
Precision (PAR) Beacon Unit 1833 pps
and decoding action. Basically, the Defruiter is an
Impedance: Any value between 75 ohms and 10 k as
electronic equipment that can eliminate false target
required.
replies and clutter from ground-beacon radar displays.
Timing: Between 37 and 100 usec ahead of radar main
trigger.
RELATION TO SIMILAR EQUIPMENT
Output Video Characteristics
None.
Polarity: Positive
Amplitude: O to 7v (adjustable)
TECHNICAL DESCRIPTION
Duration: 0.4 to 0.6 usec when input pulse
Primary ac Power
width is not greater than 0.5 usec
Type: 117v, 2-wire, single ph, 60 and 400 cps,
Rise Time: Not greater than 0.10 usec when
575 w
input pulse width is 0.05 usec or less.
Regulation: 105 to 125v, 50 to 63 cps and 390
Fall Time: Not greater than 0.15 usec when
to 410 cps
input is o.1 usec or less.
Input Video Characteristics
Ambient Temperature
Polarity: Positive
Operating: -29 deg C to plus 52 deg C
Amplitude: 2 to 7v across 75 ohms Amplitude
Non-operating: -54 deg to plus 71 deg C
Variations: Not to exceed 10 pct within a
Salt Atmosphere: As encountered in coastal regions
reply group.
and during ocean transportation.
Selective Identification Feature (SIF)
Pulse Duration: 0.35 to 0.55 usec
INSTALLATION CONSIDERATIONS
Rise Time: 0.1 usec or less
Siting:
The Defruiter should be installed
Decay Time: 0.2 usec or less
between, or adjacent to, the Beacon
Minimum spacing between pulses in a particular
Interrogator-Receiver
(AN/UPX-6,
reply train: 1.35 usec
AN/UPX-14, or other) and Beacon-Coder
Peak signal-to-noise ratio: 4 to 1
(KY-120/GPX, KY-274/GPX, or other).
Mark X Identification Friend or Foe (IFF)
When the Interrogator-Receiver and
Pulse Duration: 0.8 to 1.2 usec
Decoder are at different locations, the
Rise Time: 0.2 usec or less
Interference Blanker Group should be
Decay Time: 0.1 usec or less
located at the Coder Interrogator site.
Minimum spacing between pulses in a particular
Mounting: The Defruiter cabinet is bolted to the
reply train: 16 usec
floor.
Peak signal-to-noise ratio: 4 to 1
Cabling Requirements:
Cables required to
Input Trigger Characteristics
connect the Defruiter into the beacon
Mode 1, Mode 2, and Mode 3 triggers shall have
system are not supplied. Different site
the following characteristics:
arrangements would make it impossible to
Polarity: Positive*
prefabricate cable lengths suitable for all
Amplitude: 4 to 150v
installations.
Duration: 2 to 10 usec
Related Equipments: The Defruiter is used with,
* AC coupling in the Defruliter trigger input permits u se
but not part of, various IFF and SIF
of KY-27.1/GPX Coder which has a quiescent
equipment.
AN/GPX-27: 2
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