ASE Flashcards
Methodology For Achieving Survivability
- Tactics
- Signature Reduction
- Aircrew Warning
- Jamming/Decoying
- Aircraft Hardening
PG 5-1
Radar Signal Detecting Set (RSDS)
AN/APR-39(V)1
What does APR-39 Provide
Bearing and Mode of operation of radars that operate in E-J and portions of C- and D- bands for radar associated signals
What does APR-39 Display and Accompanied By
Displays strobes
Accompanied by audio proportional to the pulse repetition frequency.
What Are the Components of APR-39
- 4x Radial Antennas
- 1x Fwd Blade Antenna
- 2x Receiver
- 1x Comparator
- 1x Radar Signal Indicator
- 1x Control Set
APR-39 Radial Antennas Locations, Spiral, Cover Area, and Why?
Mounted on each side of the nose and aft end of the tailboom.
Left Spiral - R front and L rear.
Right Spiral - L front and R rear.
Covers the four 90-degree quadrants
Placement of the Antennas is critical for maximum performance of the RSDS.
How are APR-39 Radial Antennas Be Mounted
Mounted at each of the four intercardinal heading and should be mounted with a depression angle of 0-20 degrees with all antennas being mounted at the same angle.
What do APR-39 Radial Antennas Detect and Where do they Relay
Detect high-band signals and relay them to the respective radar receivers.
Where is APR-39 Blade Antena Mounted and Its Purpose?
Mounted on the underside of the helicopter. As an omnidirectional antenna picks up low band signals (C- and D-bands) and passes them to the comparator.
How many APR-39 Radar Receivers do we have and Why?
Fwd - inside the nose of the A/C for the nose spiral antennas.
Aft - inside the tailboom for the aft spiral antenna.
Radar Receivers receive, filter, and amplify signals detected by the spiral antennas
What does APR-39 Comparator do?
Electronically decides if received signals meet necessary conditions to indicate a threat.
High-band from Radar Receivers
Low-band from Blade Antenna.
Provides high-band video signals to the Radar Signal Indicator.
When Will APR-39 Comparator Activate Missle Alert
When the high-band signals correlate with low-band signals, comparator activates the missle alert lamp on the radar signal indicator and
audio alarm system, indicating the presensce of C- or D- band signals associated with missle guidance.
APR-39 Radar Signal Indicator
Cathode ray tube that provides a visual display warning of a possible threat.
Has four quadrants - 1 for each Spral Antenna.
Video Signals from the Comparator which displayed as strobe in the direction of the radar Emitter.
With DSCRM ON when will Missle Alert Lamp Flash
When Low band signals associated with missle guidance systems are correlated with high band signals associated with radar tracking systems (SAM radar complex)
With DSCRM Off when will Missle Alert Lamp Flash
When processed low-band signals are intercepted.
When Missle Alert function May Activate and What you should not Assume About Strobe Lenghts
MA may active in close proximity to active microwave transitters
Strobe Lengths indicate received signal amplitude only.
Many variable can affect the atmospheric attenuation of the singals, therefore storbe lenghts should not be interpreted as being directly indicative of distance to an emitter.
When Happens when APR-39 Operated With DSCRM OFF Mode
All received high-band signals with an amplitude greather than the predetermined threshold level are displayed on Radar Signal Indicator and an audio signal is present.
The Display indicate the total radar environment in which A/C is operating.
Each radial strobe on the Radar Signal Indicator is a line of bearing to active emitter.
What Does Augio Signal for APR-39 Represent?
Combined Amplitudes and Pulse Repetition Frequencies (PRF).
How does APR-39 display when SAM Radar Complex becomes a threat to the A/C?
(low band signals correlated with high band signals)
the unique alarm audion is superimposed on the PRF audio signa, and the MA lamp and associated strobe being flashing.
Lengths of strobes and audio levels depend on the relative strength of the intercepted signals.
What does APR-39 dispay when Low-Band Signals are not correlated with Wideband?
MA will flash and an alarm audio will be present.
Strobe will not flash.
How are signals processed with DSCRM ON?
Warning:
DSCRM On will significantly reduce sensitivity and reception/display capability of the APR-39. For this reason DSCRM ON/OFF swith must remain in the OFF position in TACTICAL SITUATIONS.
- The signal level must be greater then the min threshold level.
- Pulse with must be less then the maximum pulse with.
- PRF must be greater than the min pulses per second.
- The pulse train must exist with not less than min pulse train persistence.
How are Strobes displayed in the particular quadrants?
Strobes are displayed only in those quadrants in which signals meeting all treat criteria are present.
Thsi reduces display clutter by eliminating low-level and wider pulse with signals and by selective sector display.
Note:
In DSCRM ON mode, uncorrelated low-band signals will not give any indication.
APR-39 Start Up Procedures
- Check to seet that the 28-VDC CB is in
- Set PWR to ON and allow a min of 30 Sec for Eq’t to be fully operational. Control unit panel light will illuminate.
- Press and Hold SELF-TEST switch while adjusting BRIL and FILTER. Adjust the AUDIO.
- Release the SELF-TEST Swithc.
Missle Warning Set
AN/AAR-47 MWS
Purpsoe and Theory of AAR-47
Designed to PASSIVELY detect attacking IR missles and battlefield lasers while minimizing false alarms.
What are battlefield Lasers
Range Finders
Target Designator
Beam Rider Missiles
What and How Four Sensors of AAR-47 Operate
Sensors are Wide Field of View (FOV) detectors that sense in-band ultraviolet (UV) radiation from rocket motor plume of missiles as well as other man-made sources, and converts UV radiation into electronic signals.
Which Sepctrum Does AAR-47 Operate
MWS sensors operate in the ultraviolet spectrum, where the earth’s ozone layer absorbs all in-band photons (radiation) from the sun.
Laser Warning of AAR-47
- Detect laser pules in the 0.5-1.6micron region.
- Detection is based on extremely fast rise time of pulsed laser.
- HARLID provides azimuth angle of arival (AOA).
- Sensitive photodiode is limited to quadrant detection, but has the ability to detect very weak laser signals.
- Software in the sensor determines the Pulse Repeition Interval (PRI)
- Software classifies battelfield lasers based on PRI.
Hostile Fire Indication (HFI) of AAR-47
- HFI eveluates the same UV photon counts stream that MWS detection algorithsm use.
- Detect small arms and unguided munitiosn that are directed at the A/C adn attempts to ingore those directed away.
- It is done by attempting to match a specific temporal pattern or by measuring the angular rate of change of the projectile’s phone count as it passes by two or more sensors.
IOSC
-Integrated Optical Sensor
-Contains UV and LW Functions
-MW optics - top of IOSC collects UV radiationa and filters out photons of the wrong wavelenght.
-Photodiote LW - lower right, detect low-power laser Beam Riders, Range Finders and Designators.
-HARLID LW- lower left, provides precise angle of arrival for high power Range Finders and Designators.
- Dynamic Blanking Adjucnt Detector - Left of HARLID, protects IOSC from saturation during periods of intense in-band radiation.
Why IOSC needs to be mounted in the “UP” etched oriented at the top and what does IOSC contain
To provide the correct angle of arrival informaiton to the aircrew.
Contains nickel Sulfate, a hazardous material in powdered form. If Sensor is broken DO NOT PUCK UP THE REMNANTS WITHOUT PROTECTIVE GEAR.
