ATC Radar System

7/22/2019 ATC Radar System

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ATC Radar System

Laoag MSSR/RCAG Air Navigation Service

[email protected]

Civil Aviation Authority of the Philippines

http://www.caap.gov.ph


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C O N T E N T S

SYSTEM OVERVIEW OF ATC RADAR SYSTEM CONCEPT OF RADAR

RADAR USED IN AIR TRAFFIC CONTROL

FUNDAMENTALS OF SSR/MSSR

QUESTION AND ANSWER


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SYSTEM OVERVIEW OF ATC RADAR

Ja l 6

Aircraft

Satellite

VSAT

VSATRadarAir Traffic Control

RADAR STATION END-USER STATION


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PHILIPPINE RADAR COVERAGE

WEST

NORTH

SOUTH

EAST

LAO

TAG

MAJ


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CONCEPT OF RADAR


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RADAR (Radio Detection And Ranging)

The detection principle is accomplished by

using an echo principle ie, electromagnetic energy

will be beamed at an object and the reflectedenergy will indicate the presence of the object.


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CLASSIFICATION OF RADAR

a. Location Airborne or Ground-based


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b. Usage Search or Precision Radar

c. Principle of Operation


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PRINCIPLE OF OPERATION

a. CW or Continuous Wave Radar

sometimes called as Doppler Radar, primaryused for checking the speed and acceleration

of moving objects.


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b. FM or Frequency Modulated Radar

similar with CW, the transmitted signal is sweptin frequency over a small range about the

carrier. The reflected energy remains at the

frequency with which it left the transmitter.

During the time it takes the energy to return tothe receiver, the transmitter has changed

frequency. The difference in frequency between

reflected signal frequency and the transmitter

frequency upon its return is then detected as

beat frequency and then presented at a suitable

distance measuring device. This indicates the

distance to a fixed target.


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c. Pulse Radar

In a pulse system, the CW transmitter is turned

ON/OFF at a given rate, the time that the

transmitter is turned ON being very short

while the time that is OFF beingcomparatively long. Thus short burst of radio

energy are transmitted while the transmitter

is turned OFF, any echoes returning from a

target may be received easily.

Laoag MSSR/RCAG Air Navigation [email protected]

Civil Aviation Authority of the Philippineshttp://www.caap.gov.ph


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N

Azimuth

a. Primary Surveillance Radar (PSR)

Radiated signal Reflected signal

aircraft

RANGE

Range: 150-500km (depends on radiated power,

line-of-sight system)

Accuracy 2 (Azimuth) : 0.2..0.5

(Range) : 400800 m

Frequency : 3000 MHz

1300 MHz

Radar Pulse Power reaches hundreds of kilowatts or even ones of

megawatts

RADAR USED IN AIR TRAFFIC CONTROL


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b. Secondary Surveillance Radar (SSR)

aircraft

INTERROGATION

1030 MHz

REPLY

1090 MHz

TRANSPONDER

Range: 350-500km (line-of-sight system)

Accuracy, 2 (Azimuth): 0.2..0.5 (MSSR)

0.5..1.0 (SSR)

(Range): 200400 m

Radar


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c. Airport Surface Detection Equipment(ASDE)


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d. Precision Approach Radar (PAR)


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ARSR ASR PAR ASDE

Range 200 NM 60 NM 10 NM 3 NM

Frequency 1250-1350 MHz 2700-2900 MHz 9000-9180 MHz 24.25-24.72 GHz

Power Output 2 MW 500 KW 70 KW 30 KW

Pulse Width 3 sec 1sec 0.25sec 0.02sec

PRF Average 346-349 pps 900 pps 2,400 pps 14,000 pps

Noise Figure Less than 3dB Less than 4 dB Less than 3.5 dB Less than 5 dB

Antenna ( RPM) 6 15 2 sweep/sec 60

Ant. Beam (Hor) 1.25 1.3 Less than 0.8 0.3

Ant. Beam (Ver) Cosec2 Cosec2 Less than 0.5 Cosec2

Polarization Hor. / Circ. Hor. / Circ. Linear Circular

Power Tube Klystron Klystron Magnetron Magnetron

PRIMARY RADARS


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SSR ( Terminal and En-route)

Coverage 100 NM for Terminal; 200 NM for En-route

Frequency Uplink: 1030 MHz Downlink: 1090 MHz

Output Power 0.5 1.5KW

RF PULSE

Pulse Width 0.8 0.1 sec

Rising Time 0.05-0.1 sec

Down Time 0.05-0.2 sec

PRF 200-450 pps

Interval of Mode Pulse Mode A: 8 sec Mode C: 21 sec

Interlace A, A/C,A/A/C

SLS Func-tion RSLS/ISLS

Receiver Sensitivity Less -85 dBm for Terminal less -87 dBm for En-route

Discriminate Level Less -79 dBm for Terminal less -81 dBm for En-route

AccuracyAzimuth: 0.5

Range: 0.2 NM

SECONDARY RADAR


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FUNDAMENTALS OF SSR/MSSRaircraft

INTERROGATION MODE

1030 MHz

REPLY MODE

1090 MHz

Radar

Air-to-ground

Ground-to-air


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a. INTERROGATION MODE and REPLY MODE

1. INTERROGATION MODE

1 FOR MILITARY A/C

2 FOR MILITARY A/C

3A COMMON ATC (IDENT)

B CIVIL A/C

C CIVIL A/C (ALTITUDE)

D RESERVED

3S

P1 P3

5S

P1 P3

8S

P1 P3

17S

P1 P3

21S

P1 P3

25S

P1 P3


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2. REPLY CODE FOR MODE 3/A

SSR= 12bit code = 212 = 4096 Transponder Code

MSSR= 24bit code = 224 = 16 M Transponder Code

EMERGENCY CODE (SPECIAL CODE)

7700 Emergency

7600 Radio Failure

7500 Hijack


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0.45S 1.0S

FF C1 A1 C2 A2 C4 A4 B1 D1 B2 D2 B4 D4 SF SPI

4.35S

2.9S

20.3S

CODE PULSEPOSITIONAL

VALUECODE PULSE

POSITIONAL

VALUE

A1 1000 C1 10

A2 2000 C2 20

A4 4000 C4 40

B1 100 D1 1B2 200 D2 2

B4 400 D4 4


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example


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b. SSR DISPLAY SYSTEM


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c. SSR LIMITATIONS

PROBLEM FACTOR SOLUTION

1. Lost Target

1. Lobing (includes multipathlobing)

2. Differential lobing

3. Shadow blocking by the

body of the aircraft

4. Sitting (blind by building

or lay of land)

5. Main beam killing6. Over interrogation

Sharp cut off antenna

Integral SLS antenna

Antenna diversity (A/C)

Removal of obstruction

Radio wave absorber


Monopulse measurement

2. Split Target (Decline of

azimuth accuracy, decode

miss by data shortage)

1. Lobing and differential

lobing appear partially

2. Resulting from

transponder

When interrogation is

received within reply

suppression time

When interrogation is

received within the

transponder dead time

Sharp cutoff antenna


Use restriction of ISLS

Restriction of interrogator

(number of site, number of

interrogation, transmitted

power)

Transponder Automatic

Overload Control (AOC)

Removal of obstruction


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..SSR LIMITATIONS

PROBLEM FACTOR SOLUTION

3. False Target (Ghost)

1. Reflection from big

building or mountains

2. Transmission from

sidelobe of antenna

(trigger transponder)

receive reply from

sidelobe antenna3. Interference from reply

which responses to

interrogation of other sites

4. Synchronous garble

5. Fruit

6. Synchronous fruit

ISLS

3 pulse SLS


RSLS antenna

Area STC

Degarbling

Defruiter

Stagger Trigger


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-2 -1 0 +1 +2

OBA (DEGREES)

OBA

= "SUM" ANTENNA PATTERN

= "DIFFERENCE" ANTENNA PATTERN

= ERROR PATTERN CHARACTERISTIC

= OFF BORESIGHT ANGLE

DEGREE

+2+1-1-2

DIFFERENCIAL

PHASE-90 (+)

(-) +90

GAIN

IMPROVED PERFORMANCE OF SSR

B

H

K

+1

W

MONOPULSE TECHNIQUE

LARGE VERTICAL

APERTURE ANTENNA

ADVANCED SIGNAL

PROCESSING

ELECTRONIC SCANNING


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INTRODUCTION TO MODE-S SSR

Selective addressing and monopulse technique allows to overcome

majority of conventional SSR problems (fruit and garbling)

MODE-S TRANSPONDER

MSSR MODE-S

Operational compatibility for conventional SSR

Enhanced surveillance and high resolution altitude reporting (25-foot

increment)

Mode S transponder may be locked out from All Call interrogations to

avoid garbling

Mode S transponder has an unique address to provide discrete ident

Search (ALL CALL) Interrogations

Selective (ROLL CALL) Interrogations

Datalink capability


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GROUND STATIONINTERROGATION

TRANSPONDER REPLIESMODE A/C

Transponder

MODE-S

Transponder

SSR

MODE

A/C

MODE A MODE A MODE A

MODE C MODE C MODE C

SSR

MODE S

MODE A only ALL CALL MODE A NO REPLY

MODE C only ALL CALL MODE C NO REPLY

MODE A/S only ALL CALL MODE A MODE S

MODE C/S only ALL CALL MODE C MODE S

MODE S NO REPLY MODE S if addressed

MODE S and MODE A/C COMPATIBILITY


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END OF SLIDE

Laoag MSSR/RCAG Air Navigation Serviced l @ il

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ATC Radar System