INTRODUCTION TO FIREFINDER RADAR

1
INTRODUCTION TO FIREFINDER RADAR
2
MISSION

• PRIMARY
• TO LOCATE HOSTILE ROCKET, MORTAR AND ARTILLERY
  WEAPONS AND TO PROCESS THOSE LOCATIONS IN A
  TIMELY MANNER FOR COUNTERFIRE AND INTELLIGENCE
  PURPOSES
• SECONDARY
• ADJUST OR REGISTER SUPPORTED ARTILLERY UNITS
• ASSIST SUPPORTED UNITS S-2/3 IN PROCESSING
  COUNTERFIRE AND INTELLIGENCE DATA

3
WHAT IS RADAR
Radio Detection And Ranging Ra refers to the
RF(Radio Frequency) used in the electromagnetic
spectrum. D refers to detection of an object
based on RF(Radio Frequency) signal return. R
refers to range based on speed and time it takes
for return of the RF signal. Radar
3
4
What is RF (Radio Frequency)?

• Radio Frequencies are best described as Energy
  that has been emitted into space (Radio Wave)
• Radio waves have several characteristics to take
  into consideration
• Speed
• Wave Length
• Frequency

5
REFLECTED RADIO WAVES
Similar to sound wave reflection. Process
usually requires the measurement of range and
bearing. Works on line-of-sight
principle. Thick moisture such as snow, heavy
rain or fog, may reduce max range, disrupts
transmitted and received signals.
6
6
6
SPEED

• All frequencies travel the speed of light.
• Travels 300,000 Km per second
• RF energy travels out, strikes an object and
  returns which give us the term Radar Mile (6.66
  Micro Secs)
• Speed of light Frequency (in Hz)
• Wavelength

7
What is Wavelength?
A wavelength is the space occupied by one full
cycle of a radio wave at any given instant.
Wavelengths are expressed in meters (one meter is
equal to 3.28 feet).
EXAMPLE
A wavelength of 300 meters would be 984 feet.
29
8
Wavelength
For example, if a radio wave could be frozen in
place and measured, its wavelength would be the
distance from any one point on a cycle to the
corresponding point on the next cycle. The
higher the frequency, the shorter the wavelength.
9
Frequency

• Frequency is the rate at which the wave length
  cycles past a fixed point per second

10
Radar Track Functions
11
PRF
Pulse Repetition Frequency (PRF) The number of
pulses of RF energy transmitted per second.
Pulse Repetition Frequency or PRF
7
7
12
PRT
Pulse Repetition Time (PRT). The time between the
start of two consecutive pulses.
Pulse Repetition Time or PRT
8
13
PULSE WIDTH
Pulse Width (PW) The time from the start to the
end of one pulse. May be referred to as transmit
time. Higher frequencies give shorter pulse
width which allow the radar to detect smaller
objects at longer ranges. The AN/TPQ-36(V)8
Radar utilizes X-Band which 10 GHZ(3cm in
length).
9
14
REST TIME
Rest Time. The time between pulses. Rest time
PRT - PW. This is the time from the end of a
pulse to the start of the next pulse. May be
referred to as off time or listen time. The
radar cannot transmit and receive (listen)
simultaneously.
10
10
15
BLOCKS OF A BASIC RADAR
Synchronizer - Timer or keyer for the RADAR.
Basically creates the Frequencies needed and the
Exciter from within amplifies the frequencies.
Transmitter - Generates electromagnetic energy.
Inputs from synchronizer, continues its final
amplification process necessary based on search
range.

66
16
RADAR System Block Diagram
Transmitter
Amplified RF
Exciter Key Timing Signals
Synchronizer
RF Channel Switch
S788 Shelter
69
17
BLOCKS OF A BASIC RADAR
Duplexer/Circulator - Allows the same antenna to
be used for transmitting and receiving. Inputs
from the transmitter and the antenna, outputs to
the receiver. Its an RF energy directional
switch.
Antenna - Radiates electromagnetic energy, and
receives return echoes. Inputs from the
transmitter via the duplexer/circulator and
return RF from the targets. Outputs to the
receiver.

67
18
RADAR System Block Diagram
Transmitter
Antenna
Amplified RF
Exciter Key Timing Signals
Synchronizer
Duplexer
RF Channel Switch
S788 Shelter
69
19
BLOCKS OF A BASIC RADAR
Receiver - Accepts return echoes, amplifies and
processes target data. Inputs from the antenna
via the Duplexer/ circulator. Outputs to the
indicator.
Indicator - Produces a visual, audible or both
indications of the received data. Inputs from the
synchronizer and receiver. Output is to the
system operator.

68
20
RADAR System Block Diagram
Transmitter
Antenna
Amplified RF
Exciter Key Timing Signals
Synchronizer
Duplexer
Receiver
RF Channel Switch
Indicator
TARGET
TARGET
TARGET
S788 Shelter
69
21
Radar Characteristics
22
AN/TPQ 46AFIREFINDER RADAR

• It is designed to locate shorter-range,
  high-angle, low-velocity indirect firing systems.
  However, it will locate high-velocity artillery
  and rockets within its capabilities.
• USMC FIRE FINDER is considered a Division asset
  and resides at the Arty Regiment. Operational
  control and logistics are coordinated at the Arty
  Regt.

23
SYSTEM CONFIGURATION
ANTENNA TRANSCEIVER GROUP (ATG) PLGR ANTENNA
24
SECTION REQUIREMENTS

• EMPLACEMENT MCCRE STANDARDS/
  TRAINED
  SECTION
• -- WITHOUT NETS 20 MINUTES / 9 1/2 MINUTES
• -- WITH NETS 60 MINUTES / 30 MINUTES
• DISPLACEMENT
• -- WITHOUT NETS 10 MINUTES / 7 MINUTES
• -- WITH NETS 30 MINUTES / 15 MINUTES

25
AN/TPQ-46A CAPABILITIES

• MAX RG 24KM(METT-T)
• MIN RG 750M
• 15 Km Planning Range
• Search Sector
• 230 - 1600 mils
• Crew 9
• 4 HMMWV Section
• Q-46 3-6 km Behind FLOT

• MAX OF 9 ACTIVE ZONES
• ACCURACY 1 OF RANGE

26
TRACKING CAPABILITIES LIMITATIONS SEARCH SECTOR
1600 mils MAX SEARCH SECTOR
MAXIMUM RANGE Q46 24km Q37 50km
MIN SEARCH Q46 230 mils Q37 300 mils
PLANNING RANGES Q46 14.5km (Arty)
18KM (Mtrs) 24km (Rkts)
Q37 30km (Arty Mtrs) 50km (Rkts)
MINIMUM RANGE Q46 750m Q37 3km
27
HOSTILE MODE OPERATIONS
28
HOSTILE MODE TRACKING PARAMETERS

• Radar only detects objects on their ascending
  trajectory.
• The object must be big enough to create a radar
  return in order for the radar to see the
  object.
• The speed of the object must be within the
  velocity parameters of the radar in order for the
  radar to see the object.
• Q46 50 - 1500 meters per seconds
• Q37 130 -1500 meters per seconds
• Radar must track the object long enough to
  achieve a solution
• Q46 3 - 5 seconds
• Q37 5 - 8 seconds

29
EXTRAPOLATES PROJECTILE TRAJECTORY TO HOSTILE
WEAPON LOCATION
MATHEMATICAL COMPUTATION OF TRAJECTORY
PROJECTILE TRACKED
ENEMY WEAPON
INITIAL ALTITUDE DISPLAYED FOR THE WEAPON SYSTEM
IS THE LOW DATUM PLANE
RADAR
30
HOW THEY ACQUIRE
TRACK BEAMS
VERIFY
SEARCH
31
RADAR BEAM CROSS-SECTION
RADAR TRACK CLUSTER
4 x Beams
32
HIT

• When at least one beam in the track cluster, but
  not all, detect the object
• Insufficient data is collected to constitute a
  plot

33
MISS
When none of the beams in the track cluster are
stuck by the object
34
PLOT

• All four beams of the track cluster detect the
  object
• The detected range of the projectile is within 75
  meters of the predicted range
• The detected azimuth is within 20 mils of the
  predicted azimuth (Q36), 15 MILS (Q37)
• The detected elevation is within 15 mils of the
  predicted elevation (Q36), 10 MILS (Q37)

35
HOSTILE MODE TRACKING PROCESS

• 1. Object breaks the search fence beam
• 2. Radar determines the objects
• Speed
• Elevation
• Range
• Azimuth

RADAR BEAM SEARCH FENCE
36
HOSTILE MODE TRACKING PROCESS

• 1. Radar predicts the objects next location and
  sends out verification beams to determine if the
  object has ballistic characteristics.
• 2. Object must successfully pass 15 discriminate
  tests for the computer to verify that it has a
  ballistic trajectory.
• 3. There are three possibilities for
  verification beam
• Hit
• Miss
• Plot

VERIFICATION BEAM
RADAR BEAM SEARCH FENCE
37
HOSTILE MODE TRACKING PROCESS
1. If ballistic trajectory is verified, radar
sends out a series of tracking beams. 2. Track
beams provide the computer information about the
objects ballistic arc to mathematically
extrapolate a predicted launch and impact point.
38
SUMMARY OF THE HOSTILE MODE TRACKING PROCESS
MISS
1. Object breaks the radars search fence. 2.
Radar verifies that object has ballistic
characteristics 3. Radar tracks object along
its predicted trajectory 4. Computer
extrapolates grid location to the objects point
of origin and point of impact
HITS
PLOTS
39
MULTIPLE TRACKS

• CAN TRACK 10 TARGETS SIMULTANEOUSLY

40
TRACK TERMINATION

• The radar stops sending out verification beams
  when
• Radar computes a solution to the acquisition.
• 3 sequential misses happen (Q36), 5 misses for
  (Q37)
• The predicted azimuth of the next track update is
  outside the left or right limits of the radars
  search sector
• The predicted elevation of the next track is
  above or below the radars min or max search
  elevation (outside the search box)

41
MINIMUM Q-46AACQUISITION REQUIREMENTS

• 3-5 seconds of good tracking time
• If tracking is terminated for 3 sequential misses
  the number of plots required for a solution
  varies from 6 to 15 based on initial detection
  range.
• If tracking is terminated for other than 3
  sequential misses the number of plots required
  for a solution varies from 3 to 10 based on
  initial detection range.

42
MINIMUM Q37 ACQUISITION REQUIREMENTS

• 5 - 8 seconds of good tracking time
• If tracking was terminated for 5 sequential
  misses
• At ranges less than 30km at least 12 plots are
  required for a solution.
• At ranges greater than 30km at least 15 plots are
  required for a solution.
• If tracking was terminated for reasons other than
  5 sequential misses
• From 3kms - 7kms the minimum plot requirement is
  5
• From 7kms - 16 kms the minimum plot requirement
  increases at a linear rate from 5 to 12 and then
  remains constant until 30 kms.
• At 30 kms the minimum plot requirement jumps to
  15 for the remaining portion of range.

43
Friendly Fire
44
FRIENDLY FIRE MODE

• FF mode has the same range limitations and
  probabilities of detection as in the hostile
  mode.
• FF search fence is focused to 440 mils, through
  which the round must pass
• The best probable angle-T is 400 mils with
  acceptable angles from 0800 to 1200 mils using
  1000mils as the optimum.

45
FRIENDLY FIRE REQUIREMENTS
1. SUBMODE OF MSN (i.e. ARTY IMPACT-PREDICT)
5. TARGET LOCATION 6. TARGET NUMBER
2. QUADRANT ELEVATION
4. MAX ORD ABOVE THE GUN
3. FIRING UNIT GRID LOCATION
46
False Targets
47
THREE CATEGORIES OF TARGETS

• Normal Targets Mortars, artillery, and rockets
  detected, verified, and tracked by the main beam
  of the radar.
• False Targets Information that causes the radar
  to report a target to the operator when there is
  no actual targets.
• Electronically induces signals
• Side lobe tracks (helicopters, aircraft,
  vehicles, other ground clutter)
• Unwanted Targets Targets other than mortar,
  artillery, or rocket which the radar reports to
  the operator. These are objects which pass
  through the beam and behave in a ballistic
  manner.
• Tank rounds, especially skips / ricochets
• Individual rounds as small as 50 caliber
• Bursts of small arms
• Shrapnel or other material from explosions
  (spall)

48
False Weapon Location Report Test Data

• H. E. Bailey Highway Traffic at Apache Gate, Ft.
  Sill
• Engineering Test Based on 4 Hours Minimum Test
  for Each Version

49
MDS (Minimum Discernible Signal)
MDS is defined as the lowest level signal that
can be detected as a target or return. This
signal must be recognizable above the Radar
Receivers noise.
Receivers have an established level of noise.
Threshold detection allows detection of any
signal that breaches the average receiver noise
by a set amount.
62
50
MDS (Minimum Discernible Signal)
MDS is an indication of receiver sensitivity and
along with transmitter power out, aids in
establishing the maximum range of a RADAR
Only targets B and D would be detected.
MDS Level is a set amount above Ave
Average Noise
RADAR Noise
63
51
DOPPLER EFFECT
When RF energy transmitted from a radar strikes
an object that is either moving toward or away
from the radar, the frequency of the reflected
energy is changed. This is the Doppler effect.
20
52
DOPPLER EFFECT
Negative Doppler (outgoing target) FRIENDLY FIRE
(RADAR REGISTRATION)
Received frequency is LOWER than transmitted
frequency.
21
53
DOPPLER EFFECT
Positive Doppler (incoming target) HOSTILE FIRE
OPERATIONS
Received frequency is HIGHER than transmitted
frequency.
22
54
Questions?