Mode S related researches
in ENRI
Tadashi Koga
Electronic Navigation ResearchInstitute, JapanEIWAC 2009
Tokyo, Japan, 5‐6March, 2009

Introduction:
Secondary Surveillance Radar(SSR) Mode S•Enhanced surveillance capability•Datalink capability
Aircraft
Transponder

Interrogation

ReplyAntenna

Tranceiver
Processor
SSR Mode SGS

ATC facilities

ENRI has started R&D of SSR Mode S with two
new functions since 2006 in order to prepare
future deployment of new Mode S in Japan.
Part I
Downlink Aircraft Parameters(DAPs) function
Part IIInterrogator Identifier code coordinationfunctionPart IDownlink Aircraft Parameters（DAPｓ）

1. Background• European states
launches DAPs
project in 1990s.
• DAPs is mandatory
in some Europeanstates.
• The percentage ofaircraft with DAPs isincreasing in Japan.

regis
terELS

EHS-

24bit address

*

*

-

Mode 3/A**-

25 ft altitude

*

*

-

Flight status**

10Datalink capability report**

17GICB**

20Aircraft identification

*

*

30RA*

*

40

Selected Vertical intention*

50

Track and turn report*60

Heading and speed report*2. GICB protocol
GICB downlinks 56bits data fromtransponder.

Transponder

GICB
requestGICB
reply#Contents

00‐‐‐‐‐‐‐‐‐‐

05

Airborne position20

Aircraft ID

FMS

Altimeter…
40

Sensor
Vertical intention…
255

Requests(ID)

HMI‐‐‐‐‐‐‐‐‐‐‐‐

Network
Network

GPSATM
ATM
Systems
Systems

DAPs application
Improve
Air picture
Of controllers

Enhanceconflict
detection
algorithm

3. Experimental System
44

CHOFU GSIWANUMA
GS

Year

April 2008

March 1995

Power

Max 1.5kw

Max 1.5kw
200NM

Period4seconds

10seconds

40

Longitude[degree]

Covera 250NM
ge

42

Iwanuma
38

Chofu

36

34

32

30
134

136

138

140
142
Latitude[degree]

144

We validate new functions through real aircraft
monitoring.

146

148

4. DAPs monitoring
Downlink procedure
All Mode S aircraft in air

Mode S aircraft Acquisiton
GICB 10 Request
GICB 17 Request

GICB20 Requst

Daps Capability?

Surveillance Only

Num. of DAPs
requesting AC > N
Targetis in coverage?

GICB05,40,50,60 Request

Stop Request

GICB controller
picks up 6 aircraft
and monitor theirparameters.

Results of GICB capability monitoring
961 aircraft
Register
NumberData Content

Number ofaircraft%05

Extended squitter airborne position

569

59.206

Extended squitter surface position

563

58.6

07

Extended squitter status602

62.608Extended squitter identification and type

581

60.5

09

Extended squitter airborne velocity

592

61.6

0A

Extended squitter event-driven
information

14

1.5

20

Aircraft identification

591

61.5

21

Aircraft registration number

248

25.8

40

Selected vertical intention

584

60.8

50

Track and turn report

611

63.6

60

Heading and speed report

588

61.2

60 % of aircraft have DAPs capability

4. DAPs monitoring
Downlink procedure
All Mode S aircraft in air

Mode S aircraft Acquisiton
GICB 10 Request
GICB 17 Request

GICB20 Requst

Daps Capability?

Surveillance OnlyNum. of DAPs
requesting AC > NTarget
is in coverage?

GICB05,40,50,60 Request

Stop Request

GICB controller
pick up 6 aircraftand monitor theirparameters.

Parameter monitoring(1) GICB 40 Selected vertical Intention
MCP/FCU selected altitude
FMS selected altitude
Barometric pressure setting
MCP/FCU Mode bits•
••
•
–•
•

(Range: 0 to 65520 ft)(Range: 0 to 65520 ft)(Range: 800‐1210mb)

VNAV Mode, ALT Hold Mode or Approach Mode

Target alt source
Status bits

Examples of GICB 40 monitoring
Arrival aircraft
44GICB40 Monitoringx 10Altitude
MCP/FCU selected altitude
FMS selected altitude

3.5
3altitude[ft]

2.5
2
1.5
1
0.5
0
0200

400

600

800

1000
Time[sec]

1200

1400

1600

1800

2000

Departure aircraft
4x 10

4

3.5

Altitude(ft)

3

2.5

2

1.5

1

0.5

0
3.62

3.64

3.66

3.68

3.7

3.72

3.74

3.76

3.78

3.8

3.82
x 10Time[sec]4

(2) GICB 50 Track and turn report••••••

Roll Angle(Range:
True track angle (Range:
Track angle rate (Range:
Ground speed (Range:
True airspeed (Range:Status bits

‐90 to 90 degrees)‐180 to 180 degrees)‐16 to +16 degrees/second)
0‐2046knots)
0‐2046knots)

Aircraft Track
36

35.5

Point#4

Latitude[Degree]

35

Point#3
Point#2

34.5

34

Point#1

33.5

33
136.5

137

137.5

138
138.5
139
Longititude[Degree]

139.5

140

140.5

Roll Angle

50

Point#1

Angle[Degree]

GICB50monitoring

Point#2

Point#3

Point#4

0-50

0200

400

600

800

1000

1200

1400

1600

1800

2000

1200

1400

1600

1800

2000

1200

1400

1600

1800

2000

True Track Angle

Angle[Degree]

300
200
100
00200400600800

True angle rate

5Angle[Degree]

1000

0-50200400

600

800

1000
Speed

600

Ground Speed
True Airspeed

Speed[kt]50040030020010000200400

600

800

1000
Time[sec]

1200

1400

1600

1800

2000

Part II.
Interrogator Identifier
Code Coordination

1. Background
Airport Surveillance Radar (ASR)

MLIT home pageAir Route Surveillance Radar(ARSR)
Yokotsudake ARSROga ORSR

Yokotsudake

KushiroKushiro ARSR

Hirata ARSR

Hachinohe

Oginojo ARSR

Hachinohe ARSR

Oga
Fukue ORSR

Jobonzan

Sangunzan ARSR

Oginojo
HirataSangunzan
Fukue

Kaseda ARSRImanoyama

Iwaki
Jobonzan ARSR

MikawaMikunisan

YamadaHakoneIwaki ORSR

KasedaHachijojima
Mikawa ARSR

Amami

Hakone ARSR
Imanoyama ARSR

Yaedake

LEGEND

Miyakojima
Amami ARSR

Hachijojima ORSR

Miyakojima ARSR

Radar covering area(15,000ft)
Radar covering area(30,000ft)

Yaedake ARSR

ARSR：Air Route Surveillance Radar
ORSR：Oceanic Route Surveillance Radar

Dual radar covering area
(15,000ft)

MLIT home pageInterrogator Identifier(II) code allocation problem•ICAO defined only fifteen II codes.
•II code should be allocated without conflicts between
neighbor ground stations(GS) .
Many GS are deployed.
Run short of II codes.
Allocate the same II code between neighbor GS.
GS are not able to achieve continuous aircraftsurveillance in overlapping area.

II code coordination function

2. II code coordination methods
There are several solutions.
We decide to develop two methods.
• The Independent Coordination(2006‐2008)– Stochastic Lockout Override (SLO)– Lockout coverage restriction (LCR)• The network‐aided Coordination(2008‐2010)

(1)Stochastic Lockout Override(SLO) TechniqueAB

Override Interrogation:
Transponders must reply all-call replies in spite of lockout
condition with designated probability (1, ½ , ¼ , 1/8, 1/16).

(2)Lockout Coverage Restriction(LCR)TechniqueAB

GS A controls lockout coverage by using coverage map.

SLO + LCR

A

B

With combination of SLO and LCR,
the independent coordination achieve continuous
surveillance in overlapping area.

5.2 Experiment for function test
Chofu GS settings

41

SLO: 120 degrees(-45 to 75degree)

40

Lockout Map 15000ft

39

RR : 1, ½ , ¼
PRF: 113pps
Lockout map:
3D Cell
5NM×5NM×200ft(9km×9km×60m）

Latitude[degree]

38

37

36

35

34

33
137

138

139

140
141
142
Longitude[degree]

143

144

Lockout Map at 15,000ft

1455.3 Results of tests
All-Call replies and SLO area

41

We observed
a lot of all-call replies
in SLO area

40

39

Latitude[degree]

38

37

SLO is working correctlyboth in transponders
and in GS.

36

35

34

33

32

31
135

136

137

138

139
140
141
Longitude[degree]

142

143

144

145

Aircraft track passing overlap coverage
38.5

38

Cyan: all-call replies
Blue: roll-call replies

Latitude[degree]

37.5

37

Chofu GS acquire aircraftin overlap area.

36.5

3635.5138.5

139139.5

140
Longitude[degree]

140.5

141141.5

Conclusion
We developed Mode S with two functions.
• DAPs– 60% of aircraft have DAPs capability.
– Aircraft are sending reasonable values.

• II code coordination– Independent Coordination achieves continuous
aircraft surveillance in overlapping area