TO-BMS-ANAPG68-1-1

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AN/APG 66 and AN/APG 68 Fire Control Radar Manual

TO-BMS-ANAPG 68-1

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List of Effective Changes

Change 0 (V0.1 draft)

Acknowledgements

Firstly thank-you to Stephen ‘HotDogOne’ French who compiled the first radar manual, and was the inspiration of this update.

Thanks to Red Dog and Darkman for the excellent dash one and dash 34 manuals. Unsung heroes, my respect only got greater after attempting to write this manual.

Thank-you to the BMS developers for their continued dedication to this simulator.

Finally someone who never seems to get the acknowledgement he deserves. Louis Gilman who gave those of us who would never get to experience flying a jet fighter some idea of what it might be like.

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The FCR is a coherent, multimode, digital fire control sensor designed to provide all-weather air-to-air and air-to-air-to-surface modes with advanced dogfight and weapon delivery capabilities. The air-to-air-to-air-to-air modes provide the capability to detect and track targets at all aspect angles and at all altitudes both in the clear and in the presence of ground clutter. Target information in the air-to-air modes is presented as synthetic video on a "clean scope" display, both on a head-up display (HUD) and a head-down display, the Radar/Electro-Optical Display. Air-to-surface modes provide extensive mapping, target detection and location, and navigational capabilities.

The radar consists of six functional line replaceable units (LRUs) which are organized for autonomy, logical function, minimum interconnection, ease of maintenance, and co-production potential.

A digital multiplex bus system provides a "party line" interface between the radar computer and the other line-replaceable units, with the exception of the digital signal processor. A separate high-speed data bus connects the radar computer with the digital signal processor. All radar LRUs are mounted in the nose of the F-16 aircraft and are accessible from ground level, except for the radar control

panel installed in the cockpit. The primary means of communication with the other F-16 avionic systems is by use of MIL-STD-1553B Multiplex System.

This manual has been designed as a supplementary manual to TO BMS 1TO BMS 1F-16CM-34-1-1

Designation

AN = Antenna/Aerial or Army Navy A = Airborne

P = Radar G = Fire Control

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Specification

Range: 296.32km, 184 miles

Range for 5m2_{aerial target 105km}[4] Search cone: 120 degrees × 120 degrees

Azimuth angular coverage: ±10 degrees / ± 30 degrees / ± 60 degrees Volume 3-6 FT3_{(0.102 m}3₎

Weight 295 lb (134.3 Kg)

Frequency X Band Pulse Doppler.

Starting Envelope frequency around 9.86 GHz. as high as 26 GHz Air Cooling 12 lb/min

Peak Transmit power 17.5 kW at low duty (0.03 max) 1.75 kW at high duty (0.45 max) Beam width 3.25 deg azimuth, 4.55 deg elevation

Maximum scan rate 65 deg/s for RWS (horizontal scan) 84.6 deg/s for ACM 10x40 (vertical scan) Noise figure 3.25 dB

Power 5,600 VA Transmitter Gridded, multiple peak power traveling wave tube Antenna Planar array, 740 × 480 mm

Azimuth scan ±10 deg, ±25 deg, ±30 deg, ±60 deg Elevation coverage 1, 2, 3 or 4 bar

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Radar Overview and Activation

Radar System Components

Figure 2 AN/APG68 Components The AN/APG 68 radar consists of the following major componetnts

 ANTENNA The planar array antenna, provides high gain and low sidelobes over all scan angles. It includes a lightweight balanced electric drive system to drive the two axes gimbals between +/- 60 degrees. The transmitted and received pulses are controlled in time by the PMW (Pulse Modulated Wave) radar design, and the waveguide duplexer assembly. Internal to the antenna are Uniphaser Assemblies (used for quadrature phase control), Phase Shifters (used of quadrature I/Q data).

 TRANSMITTER The transmitter contains an air-cooled traveling wave-tube (TWT), a solid-state grid pulser, high voltage power supplies and regulators, and protection and control circuitry. The entire transmitter is solid state, except for the final TWT output tube. The pilot may select among four of the 16 available APG-66 operating frequencies in any given F-16 aircraft (N/I).

 LOW POWER RF The power radio frequency unit contains a receiver protector, low-noise amplifier, receiver, analogue/digital converters, stable local oscillator (STALO), and the system clock generator. All needed analogue processing of the radar return signal is

performed in this LRU. The LPRF also provides frequency agility for certain air-to-surface modes.

 DIGITAL SIGNAL PROCESSOR Clutter rejection and other radar signal processing is performed by the digital signal processor. Digital radar techniques have been used

extensively to replace contemporary analogue hardware. The digital signal processor uses standard integrated circuits mounted in dual-in-line packages.

 COMPUTER The radar computer configures the radar system for the various operating modes, directs the digital signal processor to embed symbols in the video output, makes calculations, routes data to the fire control computer, interfaces with other F-16 avionic systems as well as other radar LRUs and controls all of the self-test and built-in-test functions of the radar. The computer is equipped with 48,000 16-bit words of programmable, semiconductor read-only memory.

RCP Antenna Computer LPRF Processor Transmitter TWT Pulser HVPS Protection & Control LVPS I/O Power Supply Mode Freq. Range PRF Antenna Scan Power Supply Uniphasor Driver Servo Power

Supply CPU a/c inter I/O Mem Missile _Inter

Controller Rec Video & A/D Conv Staio Power Supply Power Supply Synchroniser

I/O Proc Scan

Conv A rr ay DC Inputs Syncho Inputs F-16 MUX Bus Analog to SMS (AIM 9) Video IQ Bus DSP Bus

Triggers and Timing

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©Page 7 o Temporary scratchpad memory requirements are met using volatile, semi-conductor

random access memory.

o Memory reserve exists for introduction of new features and modes. Information from the radar returns is initially placed into a storage area called the ‘bin’, this information is kept until the radar has enough information to be sure that the return is actually a target. Target classification and screening is also accomplished at this stage, screening to remove ground targets and other unwanted returns. The system then passes the information to the PSP, where it is interpreted and passed onto the Fire Control Computer (FCC). The FCC in the F-16

receives this information, and displays the appropriate information in the Radar MFD, and the HUD if required.

The radar uses a filter to remove ground clutter and enable lookdown operation. The filter is centred in velocity at the F-16 ground speed and covers a band of velocities. The velocities filtered

constitute a Doppler notch. When a contacts is tracked manoeuvres so its closure rate on the F-16 is within this velocity band it is said to have entered the notch. The FCR has a number of techniques it uses to reduce the impact of targets entering the notch, described further in the Single Track Target Mode of the radar (STT).

Modes Overview

The FCR has a number of different modes and sub modes dependent on the detection requirements. Modes can generally be switched through either using the TMS on the side-stick or through

operation of the FCR page on the MFD.

The two major modes of the Air-to-Air radar are Combined Radar Modes (CRM), or Air Combat Manoeuvring (ACM). Each of these modes have further sub modes shown diagrammatically below.

Figure 3 Available A/A Radar Modes and Sub Modes All Air-to-Air radar display a B-Scope video of the detection.

AN/APG 68 Air-to-Air

Range While Scan (RWS)

Track While Scan (TWS)

Ultra Long Scan (ULS)

Velocity Scan (VS) Combined Radar Mode (CRM) Air Combat Manoeuvre (ACM) 30x20 10x60 BORE SLEW Situation Awareness Mode (SAM)

Single Track Target (STT)

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©Page 8 Ground radar has a number of master modes:

 GM Ground Mapping Radar  GMT Ground Moving Target  SEA (Sea)

There are two further sub modes: SP Snow Plow and FZ Freeze. Ground Radar are all Pie Scope.

FCR Activation and BIT

To ensure that the Fire Control Radar is powered by the Main Generator through the Non Essential bus and will not function unless the Main Generator is operating. Input power of the FCR is 5.6kW. The radar generates a significant amount of heat. The F-16 removes the heat through an air cooling at a rate of 12lb/minute. This is achieved when the AIR SOURCE on the AIR COND PANEL is turned to NORM. Failure to set the AIR SOURCE correctly will result in the radar automatically shutting down.

Figure 4 Air Condition Panel (Starboard Console)

The video output of the FCR is shown on the MFD Multi Function Displays, that must be turned on using the AVIONICS POWER panel.

Figure 5 Avionics Power (Starboard Console)

To feed power to the FCR, the SNSR PWR switch must be set to ON. This will initiate the FCR BIT (described below).

Figure 6 Sensor Power (Starboard Console)

COOL WARM MED TEMP COOL WARM MED TEMP OFF A I R C O N D AIR SOURCE RAM DUMP NORM OFF + MMC ST STA MFD UFC DL GPS ATT IN FLT ALIGN NAV OFF

OFF OFF OFF OFF

OFF OFF INS + STOR HDG NORM A V I O N I C S P O W E R FCR S N S R P W R OFF OFF OFF OFF STBY RDR ALT RIGHT HDPT LEFT HDPT +

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Fire Control Radar Built in Test

The Fire control radar will initial a built in test (BIT). The test ensures that all line replaceable units are operating, that the buses are connected and that the array can gimbal through the ±60° both in Azimuth and Elevation.

The following are the BIT error codes:

BIT Code Description

FCR 004 Antenna digibus wraparound test failed

FCR 005 System waveguide pressure failed FCR 007 Azimuth and elevation motor FCR 008 Antenna ARC- computer count FCR 020 MLPRF digibus wraparound test FCR 021 Receiver protector fail

FCR 024 Reference oscillator lock bit FCR 084 DMT digibus wraparound test FCR 085 Low voltage power supply fault FCR 088 Hi voltage power supply fault FCR 089 Transmitter OK on

FCR 095 Hi voltage wraparound test

FCR 214 PSP digibus external wraparound test

The Radar will enter a Non Radiation condition and NO RAD is displayed in the HUD on one of the following conditions:

 Weight on Wheels (WOW) to prevent ground personnel being injured  Entry to Air Combat Manoeuvre Mode (ACM)

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Air-to-Air

The radar cannot scan the entire volume of space in front of the air-craft at the sametime. Hence to enable the detection the antenna will scan the volume in front of the aircraft.

To gimbal the array and scan a large volume of space takes time. Hence the pilot has a number of options to alter the volume. These are described below.

Bar Scans

The radar scans the volume through a number of bars. These can either be adjusted through the pilot, or will be adjust automatically dependent on sub mode.

The scan patterns are described below.

Figure 7 Bar scans

Azimuth Gates

It takes time to move the radar across the scan zone of ±60°. This can be reduced by setting up azimuth gates. The reduce the length of time for the radar to traverse the azimuth and increase refresh time of contact.

The azimuth gates can be set from ±10°, ±30° or ±60° and are either pilot controlled, or the gate will be set dependent on modes and submodes of the radar.

Elevation

In normal operation the phase array will be gimballed around the boresight by ±60°. This however means that any target that is outside the scan volume of the radar will not be detected.

Figure 8 Boresighted Radar and Contact out of scan area (not to scale)

2.2° 2.2° 2.2° 60° 1 bar 2 bar 4 bar

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©Page 11 To pick up targets that are outside the scan pattern of the radar, the pilot can adjust the radar antenna through the antenna knob on the throttle.

Moving this has the effect of pointing the radar at the area of sky that the pilot wishes to search for contacts.

Figure 9 Decreased Antenna elevation (not to scale) The radar can be moved through ±60°

FCR Video Display used in the F-16

Through the era of radar there have been a variety of displays, depending on the antenna and technology available. The traditional display is a “pie” display where the angle of the contact is represented by the angle on the display, and the range is represented by the distance from the origin.

The display for the Air-to-air modes of the radar, uses a B-scope display. The difference is that the nose of the aircraft is stretched along the bottom axis of the display. This can assist with determining threats, however it can take a little practice to be able to use the display well. The key point to remember is that contacts moving directly down the B-scope display are coming straight towards you.

An example of a pie scope and B-scope display are below for the following contacts:

Contacts

Bearing Range

45° 50 nm -30° 50 nm

0° 60 nm

The contacts are displayed as B scope below:

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©Page 12 However as a pie scope the contacts would be displayed as below:

Figure 11 Pie scope display of contacts

Radar Screen Key components

The radar MFD has a number of key components. Figure 12 depicts an MFD showing the key elements of the display

Figure 12 Key components of the A/A Radar MFD  Radar Gain – cannot be adjusted in A/A

 Radar ranged scale. It can be altered through using OSB 20 (up arrow) and OSB 19 (down arrow). The figure shows 40 which means the number of miles from the bottom of the display to the top of the display

 The Antenna Elevation is represented by the T symbol  The Bullseye Position of the Radar Cursor

 Ownship Bullseye will be displayed only if set through the relevant LIST page in the Up front Controls. If the Bullseye is not shown, the steerpoint steering cue is displayed showing the direction to steer for the next steerpoint.

Horizon Line 30 045 40 020 40 20 -01 Radar Cursor Radar Range Antenna Elevation

Radar Cursor Bullseye Ownship Bullseye Antenna Azimuth ECM Detection Radar Contact Radar Gain Active Steerpoint Bullseye

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©Page 13  The Radar Cursors are the two vertical lines and can be slewed through the TQS slewable

control. The Cursors have two numbers which display the altitude (Search Altitude Display) that the radar can detect at the cursor location. If the radar is beam would take it below ground the number is displayed in red and has a negative sign

 Contacts are shown as white squares.

o The contact position is approximately 18 miles from the aircraft. o The line from the contact indicates the direction of the contact.

o The light square shows the history of the contact, where the contact was on any prior sweeps. The number of history squares can be updated through the radar control page.

 Electronic Counter Measures (ECM) will mean that the radar cannot display nor lock onto the contact until the radar is powerful enough to “burn through” the ECM. Although the Radar will not be able to lock on to contact, the video will display chevrons at the azimuth where the ECM is being shown

 The bottom of the radar screen shows the current antenna azimuth. The bottom of the radar display represents the nose of the aircraft

The FCR can be controlled through various options on the MFD.

Figure 13 MFD Options

 Master Mode Select: will select between CRM (Combined Rader Modes) and Air Combat Model (ACM)

 Sub Mode select. Example shows Range While Scan. For full details below.  View will enable the radar to expand the area around the cursor. This can also be

completed through use of the Stick pinky switch  OVRD will turn the radar to Standby

 CNTRL shows Radar control page

 Data Link controls enables the FCR to send data via the data link

CRM 20 045 RWS NORM OVRD CNTRL ASGN 1 2 3 4 FCR DCLT SWAP 4 B A 6 40 020 10 20 -01 Select Master Mode

select

Sub Mode Select View _{Display Control Page} Override Mode

Data Link Control Select Azimuth Gate

Bar Scan Select

Declutter display

Multi Functional Display Options

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©Page 14  DCLT Declutter removes symbology from the MFD display

 The bottom MFD buttons are the same as all MFD screens in the F-16 and will not be covered here.

Radar Options

Depressing the CNTL option on the MFD (OSB 5) the display will show the Control options for the Radar.

The Radar Options are as follows:

CHAN 1 changes the radar channel to avoid interference from other aircraft (NI)

MK INT 1 is the Marker intensity button and ranges from 1 to 4. This allows a different intensity for the range markers than the overall symbol intensity set through the SYM rocker (NI).

BAND WIDE is used to select the radar band from narrow to wide (NI)

BCN DLY is an option to set the beacon delay from 0.00 to 99.9 through the data entry display (NI). PM OFF is the Power management and alternates between PM ON & PM OFF (NI).

LVL 1 toggles between ECCM level 1 and level 2 (NI).

TGR HIS 1 toggles between the target history and is the option working for A-A FCR. History can be set from 1 - 4 providing a trail for radar targets in A-A.

ALT TRK is Altitude Liner blanker option ON or OFF (NI).

MTR 1 is the declutter option on A-G & A-A radar, rejecting targets below certain radial velocities (NI). CRM 20 045 RWS NORM OVRD CNTL CHAN 1 MK INT 1 BAND WIDE BCN DLY 0.00 PM OFF FCR DCLT SWAP 020 10 20 -01 MTR HIGH ALT TRK OFF TGR HIS 2 LVL 1

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Combined Radar Modes

Range While Search

Range While Search is a general purpose Air-to-Air search mode. It is designed to scan the largest volume possible however this is at the expense of time it takes to complete the update for

information. However RWS will paint a target for a brief period of time, and hence there is a reduced change to be detected by any Radar Warning Receiver equipment.

Generally the information provided is limited. Each contact is displayed a square which corresponds to its azimuth and range.

Further information can be gained on the contact by slewing the radar cursors to bug the contact contacts. The radar will then display the altitude of the contact.

The Radar can be moved to Spotlight scan through TMS FORWARD. This will place Azimuth Gates and reduce the gimbal scan of the radar.

The elevation and bar scans coverage are summarised below:

Elevation Scan (RWS / LRS) thousands feet

Range 1 bar 2 bar 4 bar

10 nm 5 10 20 20 nm 10 14 24 40 nm 20 28 48 80 nm 40 56 96 160 nm 80 112 192 CRM 20 045 RWS NORM OVRD CNTRL ASGN 1 2 3 4 FCR DCLT SWAP 4 B A 3 40 020 10 20 -01 15

Azimuth Gate Altitude of bugged

target Non bugged target

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©Page 16 Azimuth coverage is summarised in the following table:

Azimuth Scan (RWS / LRS) nm Range ±10° ±25° ±30° ±60° 10 nm 3.5 8.8 10.2 17.3 20 nm 7.0 17.5 20.0 34.6 40 nm 13.9 34.8 40.0 69.3 80 nm 27.8 69.5 80.0 138.6 160 nm 55.6 139.0 160.0 272.2

TMS Forward over a bugged target will change the Radar mode to Range While Search Situation Awareness Mode (see below).

Figure 14 TMS Controls in RWS

Ultra Long Range Scan

This is the same as RWS but is optimised for finding targets at long range.

Track While Scan

TWS tracks multiple targets while searching for others. It is limited to tracking 10 targets. Targets are detected in TWS as they are in RWS, and contact symbols are displayed at the target range and azimuth.

TWS can acquire and track contacts either manually or automatically. Automatic acquisition will take place if the contact is above the speed gate. This is prevents the use of a track slot for a low threat target or a potential false alarm. Contacts whose ground speed along the radar line of sight is greater than 200 knots will automatically be acquired and tracked by the radar as described above. Targets whose speed is slower than 200 knots can be acquired manually by placing the acquisition cursor over the target and designating.

It will begin to form track files automatically from RWS radar returns. Radar returns from RWS is placed into a “bin”, if the radar detects something twice within 6.5 seconds the track files are formed automatically. Tracks are prioritized by range and the order in which they were detected.

<1s SAM (Cursors on target) >1s SPOTLIGHT SCAN

>1s Enter TWS Nothing

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©Page 17 Figure 15 Track While Scan

TWS is limited to tracking 10 targets simultaneously. As the radar does not dwell on a target to continue to track a return (compare with STT mode) contact track positions are extrapolated in between radar paints.

TWS will dump a track file if:

 If a target is not updated, within 13 seconds

 The target moves out of the radar’s current scan, (azimuth scan, and/or elevation scan)  If the pilot is tracking 10 targets and decides to designate on a search target, the radar will

dump the lowest priority track and automatically upgrade the search target into a track file.  If the radar has not received a hit on a track on its return scan, if the contact is not where

the radar has predicted the contact to be (calculated from the target’s last heading and speed)

If a contact is no longer detected then:

 The contact will turn red and extrapolate for the position for a further 13 seconds total.  The last 5 seconds before the radar dumps the track, the track will begin to flash. If the track is detected again, the contact will turn back to yellow.

TWS. Support three scan patterns: ± 60, 2 bar ± 25, 3 bar ± 10, 4 bar CRM 20 045 TWS NORM OVRD CNTRL ASGN 1 2 3 4 FCR DCLT SWAP 4 B A 3 40 020 10 20 -01 08 Azimuth Gate 15 15 1 13 09 18 11 12 18 A tracked target

Non Tracked Target

(Red) Extrapolated Track File

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©Page 18 Elevation Scan (RWS / LRS) thousands feet

Range 3 bar 4 bar

10 nm 12 15

20 nm 24 30

40 nm 48 60

80 nm 96 60

160 nm n/a n/a

There are two ways to bug targets.

 Slew the cursors over to a track file (or a search target) and designate using TMS forward  TMS-right to bug the closest track file.

o Further TMS-right’s will step the bug to the next highest priority track file. o The pilot may enter Single Target Track (STT) by slewing the cursors over the bug

and pressing TMS-forward.

o This will erase all search targets and tracks from the radar, although the tracks will extrapolate for 13 seconds.

If the pilot returns to search (TMS-aft) to return to TWS, the extrapolated tracks will reappear and the target will be bugged. If TMS-aft is commanded again, the pilot will drop the bug and the radar will continue to TWS. If TMS-aft is commanded a third time, the radar will dump all tracks and begin rebuilding tracks automatically. If TMS aft is commanded a fourth time, the radar will go back into CRM-RWS.

Without a bugged target, the azimuth scan centres on the cursors and elevation is controlled manually. When a target is bugged, the azimuth is biased to keep the bugged target in the scan and the elevation is centred on the bugged target. If the antenna elevation is tilted while the pilot has a bugged target, upon dropping the bug, the elevation scan will move according to what the pilot commanded to reflect the position set by the antenna elevation controls.

Figure 16 TMS controls TWS

Velocity Search

Velocity search interleaves a high PRF mode with a mediuam PRF mode to extend the ranging capabilities and provide a lower false alarm rate. VS is designed to detect contacts with a head-on aspect displays contacts are displayed based on their relative speed. Note tis mode will only display contacts that are closing, contacts that are moving away are not displayed.

<1s SAM (Cursors on target)

Erase tracks (rebuild track file)

Bug highest priority target then Step Bug >1s return to RWS

Nothing

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©Page 19 Figure 17 VRS Display

Contact detection and display in VS is a two-step process consisting of a high PRF scan followed by a medium PRF scan. The first scan is called the Alert scan during which a contact is first detected and its azimuth and velocity are stored. Immediately after a Confirm scan is initiated with which the range is determined. After the contact has been detected in both Alert and Confirm scans, the target is displayed. No new search targets are displayed in the alert scan.

The display shows fast contacts at the top of the display (representing 1500 knots closure rate), and slower contacts at the bottom of the display.

Situation Awareness Mode

The Situation Awareness Mode (SAM) provides the capability to track a single target, while simultaneously continuing to search for other targets. The search volume is controlled by the pilot through the MFD or the through the antenna controls.

The azimuth may be reduced to maintain the track on the selected contact. SAM is a RWS sub mode and is entered:

 From RWS or LRS when the target acquisition cursor is over a contact and the contact is designated by TMS forward

 Mode transitions from TWS (single or multiple track), the bugged target becomes the SAM, and other TWS are extrapolated for 13 seconds

 Transition from RWS or LRS from ACM or VSR from single target track through return to search via TMS aft

CRM 20 045 VSR NORM OVRD CNTRL ASGN 1 2 3 4 FCR DCLT SWAP 4 B A 3 40 020 10 20 -01 Contact Contact

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©Page 20 The HUD changes its symbology to assist the pilot in visually acquiring the target:

Figure 18 Target Designation in FOV STT Mode

Figure 19 Target Designation Outside Field of View STT Mode

5 5 1.0 C 45 40 35 30 13,5 13,0 12,5 32 33 34 5 5 NAV 0.82 3.7 ARM AR AL B006.2 000:29 006>02 100 13,0200

Target Designation Box

5 5 1.0 C 45 40 35 30 13,5 13,0 12,5 32 33 34 5 5 NAV 0.82 3.7 ARM AR AL B006.2 000:29 006>02 100 13,0200 Target Designation Outside Field of View

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©Page 21 Figure 20 SAM Mode

Further information is displayed on the MFD display including:

 Intercept Steering Cue that provides the Steering Cue to the pilot for a pure pursuit course to intercept the bugged target (horizontal cue only)

 Target Azimuth and Elevation Indicator, this assists the pilot in requiring the bugged target if the target tracking is lost. When tracking is lost, the target last known Azimuth and Elevation are displayed to enable the pilot to slew the antenna to require acquire the lock

 Target heading, Speed and closure rate are displayed

Note that the MFD will automatically change display settings to keep the target in the upper the portion of the MFD and in the centre.

Locked targets may be one of many of symbols and are described below.

The antenna may be slewed through the antenna controls to ensure that the radar can maintain the track.

SAM can be exited in one of the following ways:

 Transition to single target track (TMS forward) with the acquisition over the contact. The SAM bugged contact then becomes the STT target

 Mode transition to TWS. The SAM target becomes the bugged target n TWS. If SAM was originally entered from TWS multiple target track and the extrapolated files have not expired they are restored as system targets

 Return to search while in SAM (TMS aft)

 The Intercept Steering Cue gives a heading cue to the pilot so that a pure intercept course can be flown CRM 20 045 RWS NORM OVRD CNTRL ASGN 1 2 3 4 FCR DCLT SWAP 4 B A 3 40 020 10 Bugged Target 09 Target Azimuth Indicator Target Elevation Indicator Intercept Steering Cue 305° 350 +120K Target Magnetic Heading Target Calibrated Air Speed Closure Rate Search Contact

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Dual Target Track (SAM sub mode)

Two targets can be tracked simultaneously within SAM. Once a single contact has been bugged in RWS, the radar wil go to SAM mode. To bug another target move the target acquisition cursors over the new contact and designate through TMS forward.

The radar will now attempt to gimbal to keep both targets illuminated simultaneously.

Figure 21 TMS Actions

Single Target Track

Other target is blanked from the MFD to assist the pilot in planning and executing the intercept.

Figure 22 Single Track Target Display

In STT mode, the radar will run Non Cooperative Target Recognition (NCTR) algorithms to identify the aircraft locked. The NCTR analyses the returns and compares them to a stored profiles. The NCTR relies on the turbine blade return from each aircraft, and hence will only work if the radar can gain a return from the air-intakes.

The radar filters ground clutter to enable lookdown operation. The filter is centred in velocity at the F-16 ground speed and hence constitute a Doppler notch. When a tracked contact tracked

Return to SAM Swap Target Nothing Enter STT Mode CRM 20 045 RWS NORM OVRD CNTRL ASGN 1 2 3 4 FCR DCLT SWAP 4 B A 3 40 020 10 Bugged Target 09 Target Azimuth Indicator Target Elevation Indicator Intercept Steering Cue 305° 350 +120K Target Magnetic Heading Target Calibrated Air Speed Closure Rate

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©Page 23 manoeuvres so its closure rate on the F-16 is within this velocity band it is said to have entered the notch.

When this occurs the radar may not see the target, as those signals in the notch are filtered out and incorrectly rejected as clutter. At this point the radar initiates a memory track operation called COAST. However if the contact is determined to be able to compete against the clutter, the main beam clutter notch is shifted in frequency and the contact is tracked normally (track through notch). If the contact cannot compete against the clutter the radar will enter COAST. In COAST the contact position is extrapolated from the last known information. The radar remains in COAST for 4 seconds. If the target is reacquired in this time, period the normal track will resume.

Contact and Target Symbols Summary

Below are the various symbols that are displayed in the radar scope:

Figure 23 Radar Track File Symbology

09 09 09 09 09 09 09 09 LOSE LOSE (White) Search Contact

(Yellow) System Track File Red Extrapolated Track File (Yellow) Bugged/Priority Target

(Red) BTF with active MPRF (HPRF no \) AMRAAM in flight

09 (Purple) Track File (TF) with (inactive) AMRAAM in flight (Purple) Bugged Track File (BTF) with (inactive) AMRAAM in flight

(Red) TF with active MPRF (HPRF no \) AMRAAM in flight (Red) BTF at AMRAAM predicted time of impact (Red) TF at AMRAAM predicted time of impact

(Red) with Lose AMRAAM in flight (Red) BTF with Lose AMRAAM in flight

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©Page 24

Air Combat Manoeuvring Modes

Air Combat Mode can be entered through either positioning the DOGFIGHT/missile override switch on the TQS, or through selecting OSB 1 and select ACM.

ACM is ranged to 10 nm, and no target information is displayed on the MFD prior to lock on. The ACM mode will automatically lock onto the first target that is illuminated. If two targets are detected in the same area, the closest target will be acquired.

When ACM is first selected the radar will automatically go to the 30x20 mode with the radar non radiating. Radiation then commences upon a selecting a specific scan pattern.

Scan patterns can be selected through the use of the TMS switch, and SLEW can be enabled through the slewing of the cursors.

Figure 24 TMS Switch options ACM mode

ACM 30x20

This radar scan pattern is designed to match the view from through the HUD. The can pattern is set to 30° azimuth and 20° elevation.

Figure 25 30x20 Scan Pattern The scan pattern is as follows:

+4°

-10°

0°

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ACM 10x60

The 10 degree by 60 degree scan pattern may be entered into directly from the 30x30 pattern. On selection a cue will be shown in the HUD from the gunsight cross to the bottom of the HUD

Figure 27 10x60 Scan Pattern The bar scan is as follows:

20° 30° 30x20

10°

+53°

-7°

0°

+4°

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ACM BORE

The boresight scan pattern can be entered from any scan patter by moving the TMS switch forward. The boresight is the width of the beam out to 10 nm.

Figure 29 BORE Scan Pattern The beam shape is as follows:

Figure 30 BORE Beam +52° 10° -6° 60° 4.6° 3.3° -3° elevation 0° azimuth

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ACM SLEW

Slew can be entered from any of the ACM submodes by slewing the acquisition cursor controls. On selection a body stabilised cue it presented in the HUD with MIN/MAX altitudes shown on the HUD out to 5 nm.

Figure 31 Slewable Scan Pattern

Figure 32 HUD Slewable ACM Mode The bar scan is as follows:

30° +60° +30° (left) 30° 0° (Slewable) +10° -10° +40° +40° Slewable Cue 5 5 1.0 C 45 40 35 30 13,5 13,0 12,5 32 33 34 5 5 NAV 0.82 3.7 ARM AR AL B006.2 000:29 006>02 100 13,0200 20 10

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20°

60° Slewable ACM

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Ground Radar

The Ground Radar offers three modes for weapon delivery:  GM – Ground Mapping Mode

 GMT – Ground Moving Target Mode  SEA – Ship mode

The radar has a further sub-modes: Snow Plow and freeze. The major features of any display are shown below:

Ground Radar modes are all displayed as a “pie-scope”. The Ground Radar modes are generally ground stabilised over the Sensor Point of Interest (SPI). This will mean that the radar will gimbal to keep the radar picture consistent, regardless of the position of the radar.

If the radar gimbals do not allow the full radar picture to be shown, the radar will become blank. If the radar cannot gimbal to illuminate the steerpoint, the radar display will be blank.

Key features of the display are as follows:

 Radar Gain enables control of the radar gain, and increases the amount of energy used to detect the surface

 Radar return is general clutter, however more features of the terrain can be viewed by increasing the radar gain either through the OSB, or through use of the Range knob on the TQS

 Contacts are shown as brighter returns,

 An artificial horizon is displayed to assist in situation awareness when pilots are heads down  The Radar Cursors show the SPI. The cross shows the area that will be displayed when the

FOV is expanded. The cursors can be slewed, however not when the cursor is slewed it enters a delta into the SPI

 SPI flight time shows the flight time to reach the Sensor Point of Interest GM AUTO NORM OVRD CNTL

B A R O F Z S P C Z S T P 20 045 SWAP FCR DCLT 000:33 A 6 40 Radar Gain Contact Radar Return (clutter)

SPI flight time Artificial Horizon

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Key features of the display are as follows:

 Radar Mode enables radar mode selecton  AUTO automatic ranging of the display

 NORM selects expansion options (described below in detail)  OVRD puts the radar to stand-by

 CNTL shows the control page (same as for AA mode)  BARO back-up bombing sensor (N/I)

 FZ freezes the radar display and turns the radar to a non-radiating state, however the radar view will be updated through the inertial navigation system

 CZ returns the SPI to current steerpoint and removes any SPI deltas  STP is the sighting point rotary.

o STP in NAV mode

o TGT in A-G Master Mode,

o OA1 or OA2 if data has been entered for the applicable SPI, o RP if VRP is mode selected

o IP if VIP mode has been selected.

o Note: TMS right changes the sighting point rotary selection as well.  Multi function display options direct access etc remain as per each MFD.  Azmuth Select enables the pilot to reduce the scan azimuth of the radar  Range enables the pilot to change the display range of the radar

 Radar gain increases/decreases the gain of the radar (useful for picking out additional terrain features)

Target designation is through TMS forward. To undesignated the target use TMS aft. GM AUTO NORM OVRD CNTL

B A R O F Z S P C Z S T P 20 045 SWAP FCR DCLT 000:33 A 6 40 Radar Gain Radar Mode

Ranging Expand Override Control Page

Back-up bombing sensor Freeze Snow plow Cursor Zero Range

Multi Functional Display Options

Sighting Mode Azimuth select

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Ground Moving Target

The Ground Moving Target Indicator (GMT) mode is used to detect targets that are moving >5 knots <100 knots. Detected targets are displayed as small synthetic video squares. Since the radar must accomplish moving target detection and produce a video map as well, the GMT display is produced using multiple scans. For example, in all expanded modes and +/- 10 degree scan unexpanded mode, the radar uses the first scan to produce the background map and the next three scans to detect moving targets. Only two scans are needed for the remaining unexpanded modes. The first scan is used to produce the background map and the second scan produces the moving target detections.

Snow Plow Mode

Snowplow mode is entered though selecting SP. Snow plow removes the ground stabilisation, and commands the radar to scan the terrain in front of the pilot. The focus of the radar beam will be the location of the cursors.

TMS forward, will ground stablise the current location of the cursors. A further TMS forward will designate a target.

Freeze Mode

Map video can be frozen to assist in cursor positioning or to improve SA when a silent

(non-radiating) radar mode of operation has been selected. Freeze mode can only be selected when the FZ mnemonic is displayed at OSB 7. Freeze can be exited using OSB 7 or by changing the FCR mode or field of view.

When in freeze mode, the present position indicator moves about the display format depicting aircraft position and heading relative to the video map. A continuously updated magnetic course and ground range from present position to cursor position is displayed in the lower left corner of the MFD. A continuously updated cursor latitude and longitude is displayed in the upper right corner of the MFD.

Depressing and holding TMS-aft blanks the cursor lat/long for as long as it is held. The sighting point option cannot be changed while freeze mode is selected.

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NORM EXP, DBS1,2

The radar video can be expanded by selection of the OSB 3NORM. The initial expansion will provide a more detailed view at the cursor location. The MFD will show a quarter mile bar bottom left to assist with SA.

GM Radar mode has two further expansion modes for Doppler Beam Sharpening. This improves the radar return at the location of the radar by making use of the radar antenna as a Synthetic Aperture. DBS1 level of expansion is identical to the expansion mode but with increased resolution. DBS2 increases the level of view.

In general DBS2 is double the magnification of DBS1. The summary of the expansion areas are displayed below:

Range EXP/DBS1 (x2) DBS2 (x4)

10 nm 2.5nm x 2.5 nm 1.25 nm x 1.25 nm

20nm 5 nm x 5 nm 2.5nm x 2.5 nm

40 nm 10 nm x 10 nm 5nm x 5 nm

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Glossary

AA Air to Air

ACM Air Combat Manoeuvring

AG Air to Ground

BTF Bugged Track File

DBS Doppler Beam Sharpening

DTT Dual Track Target

FCR Fire Control Radar

FOV Field of View

FZ Freeze

GHz Giga Hertz (cycles per second)

HUD Head Up Display

Hz Hertz (cycles per second)

Km Kilometre

MFD Multi Function Display

Nm Nautical mile

OSB Option Soft Button

PRF

RF Radio Frequency

RWS Range While Scan

SAM Situation Awareness Mode

SP Snow plow

SPI System Point of Interest

STT Single Track Target

TF Track File

TMS Target Management Switch

TQS Throttle Quadrant System

TWS Track While Scan (pronounced TWIZ)

VS Velocity Search

WOW Weight in Wheels

Links

http://duotechservices.com/apg-66-and-apg-68-support http://www.designation-systems.net/usmilav/electronics.html

Picture Credits

Front page Northrop-Grumman website Line drawing of F-16,Wikicommons