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1. 975 600 600 2800 8700 11800 12400 18800 24300 24600 30800 33400 36800 62800 94800 100800 120800 amp 1266700 ft Control The correct contents in the replies DF 11 CA 0 4 5 or 6 depending on the capability AA XPDRs address PI 0 if YES DF 04 F82 1 DR 0 UM 0 AC x AP XPDRs address DF 20 FS 1 DR 0 UM 0 AC2 x MB 0 AP XPDRs address x Gilham conversion of the ground altitude and 1000 ft if altitude is switched off if NO idem with x each of Gilham conversion of the various altitudes set on the variator Transponder Test Benches Procedure 77 Verification Mode A Report Performance specifications MS 2 5 1 3 5 6 3 20 2 11 MT 5 4 13 4 protocol procedure 11 Interrogation reply sequences UF 05 PC 2 0 RR 20 DI 0 SD 0000 AP the address DF 21 reply The pilot manipulates the control box switches to follow a list of the 66 combinations containing 2 ONEs and 10 ZEROs plus 66 others with 2 ZEROs and 10 ONEs Control The correct replies for each of the successives codes X introduced by the pilot DF 05 FS 1 DR 0 UM 0 AC X AP XPDRs address DF 21 FS 1 DR 0 UM 0 AC X MB 0 AP XPDRs address Reduced version if available time is too short only the 1642 code is used Procedure 72 Verification RI Acquisitio
2. where SD contains subfields IIS 0 RRS DF 20 FS 1 DR 0 UM X AC altitude 0 MB message AP XPDRs address Control Depending on the level of the transponder its DataLink possibilities and the evolution of the situation concerning BDS in the future standards DF 20 FS 1 DR 0 UM X AC altitude 0 MB message AP XPDRs address Transponder Test Benches 4 2 RAMP TEST PROGRAM 4 2 1 Operation The installation of the test procedures in the Ramp test set is based on a set of successive software modules that control the sequences developed in paragraph 4 1 The execution of the tests are dependant of aknowledgement approval continue interrupt or re start buttons These buttons may be physically installed in front of the equipment or touch screen operation 4 2 2 Modules Each module controls a succession of displays and waiting periods for any order given by the buttons Figure 3 Module for one procedure 1 module for 1 procedure basic schematics IL display procedure name ves Next buttons display settings to enter data in XPDR fixed data data in ADLP one button start or continue procedure modifie data settings modifie setting end display PASS FAILED SHOW RESULTS ves buttons display EXIT MODULE DP Transponder Test Benches 33 4 2 3 34 display the procedure name and tests content
3. 05 06 07 1 0 2 0 4 0 4 3 44 45 5 0 5 1 5 2 5 3 6 0 gt The transponder must be linked to the corresponding interfaces ADLP that will input the relevant information in the corresponding register 255 x 56 bit buffer d Control j The DF 20 or 21 contains the following fields j DF 20 FS 1 DR 0 UM X AC altitude 0 MB message AP XPDRs address DF 21 FS 1 DR 0 UM X ID a c code A MB message XPDRs address For each of the desired register the MB message rmust be converted following the contents as defined in the Mode 5 Specific Service Manual For example for register 4 0 Aircraft Intention the message content is bit 1 to 13 selected altiude in steps of 16 ft bit 1 staus bit 2 MSB bit 14 to 24 selected altiude rate in steps of 32 ft mn bit 14 staus bit 15 MSB bit 25 to 35 selected magnetic course 0 heading 1 in steps of 360 512 deg bit 25 2 switch 0 or 1 bit 26 status bit 27 sign bit 28 MSB bit 36 to 47 selected airspeed 0 mach number 1 in steps of 0 5 kt or Mach 0 004 bit 36 switch 0 or 1 bit 37 status bit 38 MSB bit 48 to 56 status and selection bits Conversion software have already been developed by EUROCONTROL EEC and could be obtained from this souce Example of the display of these converted BDS are shown in the EEC note Mode S Specific Services and Data Link Tes
4. corresponding to GICB registers 0 5 0 6 0 7 or 0 8 where z 56 bits of data defined in the Mode S Specific Service Manual average rate of 2 sec down to 1 10 sec depending on the register and the aircraft movement with a Surface Position Squitter that may vary if so determined by register 0 7 Squitter Status For some registers the transponder must be set to fictitious AIRBORNE status it is not sure whether this is possible on all aircraft see the remark above d Control The correct contents of DF 11 and DF 17 the random transmission rate a diagram N Number of events vs time in ms between messages for the following registers the list is valid today and may vary DF 11 atarateof 1 sec limits 0 8 to 1 25 register 0 5 2 sec limits 0 4 to 0 6 s aircraft being set AIRBORNE register 0 6 1 5s limits 4 8 to 5 2s aircraft NOT set AIRBORNE register 0 7 register 0 8 1 55 limits 4 8 to 5 2s if aircraftis set AIRBORNE 1 10 s limits 9 6 to 10 4 s if aircraft is left stationnery Transponder Test Benches 27 Procedure 9 a Verification Mode 5 Address Performance specifications MS 3 17 1 3 20 2 1 2 811 MT 5 4 13 4 extract of protocol procedure n 9 Interrogation reply sequences UF 05 PC 0 RR 0 DI O SD F000 UF 11 PR 0 ll 1 amp 14 zeros AP X i where X the 552 combinations of 2 ONEs amp 22 ZEROs and
5. vs input power MTL interrogator s level when reply rate crosses 90 i for MTL dB and higher the reply rate must be 99 Procedure P 868 a Verification i Intermode amp C Acceptance vs P4 Width b Performance specifications i MS 3 9 4 MT 54 52 Fixed settings i Interrogator at nominal setting no P2 i XPDR code 1642 altimeter at zero if possible if not the altimeter will correspond to the ground altitude d Test progress Level at input 21 40 amp 60 dBm i P4 varying from 1 0 3 0 us per 25 ns steps 100 interrogation reply sequences for each step amp each input level e Measurement amp display Diagrams reply 96 vs P4 width tolerance areas shown i for both Intermode amp C and for each of the input levels Transponder Test Benches 23 Procedure 87 a Verification Intermode amp Acceptance vs P4 Spacing Performance specifications 5 3 9 3 5 4 5 2 Fixed settings Interrogator at nominal setting 2 i XPDR code A 1642 altimeter at zero if possible j if not the altimeter will correspond to the ground altitude Test progress Level at XPDR input 21 40 amp 60 dBm P3 spacing varying from 1 4 2 7 us per 25 ns steps 100 interrogation reply sequences for each step amp each input level Measurement amp display Diagrams reply vs spacin
6. Mode S is now included in these equipment limited to electrical parameters and some protocols Transponder Test Benches 3 1 6 1 7 TRANSPONDER PERFORMANCE ANALYSERS Starting in 1984 two successive mobile test installations have been built for measuring transponders either on the bench or aboard moving aircraft on airports the MTPA first and then the DATAS were built into a half trailer with electrical power supply in order to have complete electrical autonomy installed beside the main runway of European airports where they could measure the operational transponders of aircraft just before take off or after landing and sometimes also on the main taxi way Thousands of transponders have been measured and statistical data collected served as support for ATC surveillance plannings Information on the defective tranponders was also transmitted to administrations and companies but the follow up of this procedure was not really engaged During the same period the equipment served as a very useful tool for transponder problem analysis and for development investigations and pre certification of the first European Mode S transponders Altough the technology and the use of these equipment were obsolete in 1995 it is a good basis for the present task PRESENT SITUATION IMEE Table 1 TOOL S AVAILABILITY Certification Maintenance amp operational validation Investigations simulations BENCH test unit RAMP test unit Te
7. change code to 0400 gt P52 again change code to 1642 and switch off the altimeter gt sequence P53 P58 P62 P66 P71 P72 i P77 P78 P86 P87 P88 print result Other Possibilities The system built for the ramp test set nead some flexibility one must be able to modify the characteristics of the tests It is an obligation to allow the evolution of maintenance rules these being adapted to the ATC SSR problems and to manufacturing changes the research and developments of administrations and airliner maintenance services the easy building of the laboratory test set variant This implies the availability of the modules one must be able to access the measurement parameters number of iterations succession of Mode S formats etc with the sole limitations that only authorised technicians may control these elements and that in any case the default values are set back for the usual operator Unauthorised values too large unpossible message subfield for the test parameters are announced to the operator and the system wait for new entry Results Management Memory All results are automatically written in memory it contains the date the transponder under test references serial number aircraft regitration Mode S address each successive test protocol n name the conditions of the test settings the resulting data whatever the form even if no display was asked by the operator du
8. followed by 0 975 5 rest d 2interrogations Mode A uniformily mixed with 4 UF 05 interrogations 0 0016 s followed by 0 9984 s rest note if the is equiped for long replies respectively 16 of the 50 6 of the 18 i 4 of the 8 and 2 of the 4 interrogations must require long replies Measurement amp display The XPDR must reply to ALL these interrogations Procedure P 77 a 22 Verification Intermode amp C Sensitivity MTL Performance specifications i MS 3 2 4 MT 5 4 1 2 Fixed settings Interrogator at nominal setting XPDR code A 1642 altimeter at zero if possible if not the altimeter will correspond to the ground altitude Test progress 100 interrogation Intermode DF11 sequences level at XPDR input 60 80 dBm 1 dB steps i this repeated for Intermode Measurement amp display Diagrams reply vs input power MTL interrogator s level when reply rate crosses 90 MTL difference Intermode C displayed Transponder Test Benches Procedure 78 Verification Mode 5 Sensitivity MTL b Performance specifications MS 3 2 4 MT5 4 11 Fixed settings Interrogator at nominal setting i XPDR code A 1642 d Test progress 100 interrogation UF 11 with PR 0 DF 11 sequences level at XPDR input 60 80 dBm per 1 dB steps e Measurement amp display Diagrams reply
9. in 11 3 2 Latest 11 3 3 List of Tests and 11 3 4 Suggested List of Procedures for The Ramp Test set 12 3 5 List of Procedures for The Laboratory Test set 14 RAMP TEST SET nie in Ira 17 4 1 Procedures Analysis 17 4 2 Ramp Test 33 4 35 Jechnical Data nnt ett 37 4 4 X Testing Environment 37 LABORATORY TEST eode perte OR eee RR 39 5 1 Procedures 5 2 Bench Test Program eese nnne 5 3 Technical Data er t ER me 5 4 Testing Environment essent REFERENGES cit Ka puduit eus 41 TABLE of CONTENTS vii blank page viii 1 1 1 2 1 2 1 1 2 2 1 2 3 1 2 4 Preamble PRESENT SITUATION amp NEEDS THE TOOLS Figure 1 Laboratory bench for XPDR amp ADLP Figure 2 Ramp tester for Airborne chain Er cw Gay C Simulator THE REASONS References We refer mainly to an information paper called Off line tools for Airborne Equipment see reference 1 developed by DED 3 dated Feb 96 philosophy in support of the IIMSES requesting a coherent bench policy for these equipment compatible with the future ATN Concerning the measurements to be executed in Mode A C t
10. of 2 ZEROs amp 22 ONEs plus the known the sole address of the transponder in test in the aircraft Control non reply to x 552 combinations to UF 05 to UF 11 with II 1 to UF 11 with Il 14 the correct contents the replies to the 3 interrogations to be accepted i DFOS FS 1 DR 0 UM 0 ID code 7377 AP XPDRs address DF 11 CA 0 4 5 or 6 depending on the capability AA XPDRs address II 1 DF 11 CA 0 4 5 or 6 depending on the capability AA XPDRs address Il 14 Procedure P 70 a 28 Verification Altitude Report Performance specifications MS 2 5 1 3 5 6 3 17 1 b MT 5 4 13 4 extract of protocol procedure n 10 Interrogation reply sequences Intermode Mode C S All call P1 P3 P4 DF 11 reply with AA XPDRs address UF 04 PC 0 RR 0 DI 2 0 SD 0000 AP the address DF 04 reply f UF 04 PC 0 RR 20 DI 0 SD 0000 AP the address DF 20 reply Two options depending on whether or not a pressure altitude variator is available 1 sufficient time for these repeated sequences is acceptable if YES test only the ground altitude and if possible to switch off the altitude data 0000 value if NO install the altitude pressure variator at the relevant captor output and introduce succes sively a series of defined altitudes such arranged as to give a diversity of bit patterns
11. short P1 amp P3 pulses 200 ns X XX XXX increasing importance FAR 43 mandatory biennal Ramp test included in STFTV S STFTV addition to the FAR 43 rrequirements for Ramp testing Sg STFTV supplementary addition for Bench testing Transponder Test Benches IMEE Table 3 PRESENT RAMP TESTER CAPABILITIES Transmission parameters 1090 Mhz Mode A C emer nies 1 reply frequency 4 pulse positions mean offset 5 pulse width mean of all pulses 8 ge ay time delay time jitter 1 15 diversity isolation 21 MTL all Mode s 25 sidelobe suppression vs P1 P2 level ratio inModeS vs P5 P6 level ratio 31 reduced Intermode A amp C Only All Call 32 Intermodes acceptance vs P3 P4 spacing 33 Mode S acceptance vs P2 SyncPh Rev spacing uplink address control long squitter UF4 UF5 limited 2 limited 2 LEGEND Y yes available na not applicable to this Mode 1 should not reply 2 inoctal Comm A only MA field programmable limited and uneasy Comm B difficult to extract the GICB registers BDS 8 Transponder Test Benches Table 4 MOPS ED 73 PROTOCOL PROCEDURES Procedures MOPS XPDR level Laboratory number tests error protection interrogation acceptance CA verification non selective lockout 2 FS amp VS protocol code PI verification in all tests gt address verification altitude report 10 4096 code
12. testing in the STFTV report see 2 1 2 protocol tests necessary for long squitter GICB register extraction as recently required The following keys are used in the Tables 5 and 6 shown at end of this chapter 3 i in italics test presently available on most ramp test sets with dual border test mandatory on ramp by present rules plus those in the STFTV recommendations plus those similar in Mode 5 amp Intermode with bold border to be executed in lab but which are also proposed for the ramp test sets being considered as important for ATC see 2 1 1 in bold oblique the procedures proposed for ramp test sets Transponder Test Benches The numbering scheme is the following electric tests are numbered 1 for Modes A amp C T1 for Intermodes S1 for Mode 5 TS1 when combined see also note on bottom of page 6 i protocol tests are listed 1 as in Table 4 amp as in the MOPS The procedures are listed P1 P89 starting with the protocol ones to keep the same numbers as in the MOPS document 3 4 3 The tests choosen for the Ramp tool 3 4 3 1 Modes A amp C parameters In addition to present equipment s capability one adds the tests pulse amplitude variation delay time difference Mode vs Mode A code validity Mode height validity on the ground value j reply rate at various PRF instead of only 235 or 500 hz Mode amp acceptance vs 1 spa
13. want to tests many problems encountered in various now unkmown situations etc Therefore no limitations should be applied to the test lists and all the procedures developed in the Tables 5 amp 6 should be available to the technician Transponder Test Benches IMEE Table 5 MAXIMUM TEST LIST ELECTRIC PARAMETERS All XPDRs Mode S XPDRs only Mode A C Intermode Mode S interrogations interrogations interrogations Transponder s transmission test proce characteristics 1090 Mhz dure 1 reply frequency 2 mean output power 3 pulse amplitude variation during a reply 4 pulse positions max amp mean offset A4 A5 i 5 pulse width mean of all pulses TS 5 9 delay time difference Mode A vs Mode C A9 10 delay time vs input level 11 squitter unsolicited replies Bom 12 reply pulse rise amp decay times 13 reply rate vs PRF 13 reduced reply rate 500 hz 25 sidelobe suppression vs P1 P2 level ratio in Mode S vs P5 P6 level ratio E 525 i P82 QUE ern 29 Mode A amp C accep vs P1 spacing 29 for Mode S in Intermode A amp C T 30 Mode A amp C acceptance vs P1 amp P3 width A30 P67 BT Zn 29 P85 31 Intermode A amp C acceptance vs P4 width T31 i P86 31 reduced Intermode A amp C only All Call 32 Intermode A amp C accep vs P3 P4 spacing 33 Mode S accept vs P2 SyPh Rev spacing see page 10 3 4 2 for pres
14. 11 acquisition amp maximum airspeed 12 PR reply probability stochastic acquisition 13 Comm A interface amp information contents 15 broadcast All Call formats uplink 16 downlink interface DF 0 DF 16 17 in 18 Comm B protocol 18 b directed Comm B Comm B broadcast downlink interface storage design buffer rate d ARE uplink interface ELM Comm C Comm D protocol directed Comm D sensitivity level operation RA report to Mode S ground interrogator transmission of ACAS capability information coordination ACAS broadcast message XPDR replies to incoming ACAS R messages XPDR ACAS throughput XPDR communication timing Numbers in brackets means the parameter can be tested during another procedure this reduces the total measurement time lt Transponder Test Benches 9 10 blank page Transponder Test Benches 3 3 1 3 2 3 3 3 3 1 3 3 2 PROPOSED TESTS LIST GLOBAL PROPOSAL To develop new ramp amp lab test benches one has to consider the following points the tests tool will have two variants used in the laboratory one operated on the ramp the ramp tool shall be a reduced version of the lab tool for both economical reason and homogeneity of the measurements the lab tool shall be able to test ALL the parameters defined in ICAO Annex 10 document as j well as in the various MOPS mentioned above concerning transponders the ramp tool shall be ab
15. Benches 29 Procedure 73 a 30 Verification Stochastic Acquisition Performance specifications MS 3 18 4 23 3 20 2 21 MT 5 4 13 4 protocol procedure n 13 Interrogation reply sequences UF 11 PR X II 0 0000 0000 0000 0000 AP XPDRs address where X is varying from 0 to 15 with 100 interrogations each 1 with no lockout set 2 with one lock out set Control The correct of replies in each case with a tolerance of 30 for the values other than 99 or 0 1 PR 088 1 amp 9 2 amp 10 3811 4812 other gt 50 25 99 35 65 18 32 125 9 15 62 4 6 0 if2 PR 8 9 10 11 12 other gt 99 50 35 gt 65 25 18 gt 32 12 5 9215 62 42 6 0 Transponder Test Benches Procedure 77 Verification GICB Register Extraction b Performance specifications MS 3 21 1 12 a b c amp f Ref 6 Mode S Specific Services Manual ATTENTION THE SPECIFICATIONS MAY VARY In any case refer to the latest version of both Mode S Specific Services Manual see ref 6 Interrogation reply sequences UF 04 or 05 PC 0 RR x DI 7 SD 0y00 AP XPDRs address DF 20 or 21 replies where hexadecimal numbers vary to extract all desired GICB register x sum of 16 BDS1 subfield y RRS subfield BDS2 subfield The present list of registers is
16. EUROPEAN ORGANISATION FOR THE SAFETY OF AIR NAVIGATION Tw EUROCONTROL EUROCONTROL EXPERIMENTAL CENTRE Mode S TRANSPONDERS TEST BENCHES USER REQUIREMENTS version 1 EEC Note 21 98 EEC Task C07 EATCHIP Task SUR 3 E1 Issued September 1998 The information contained in this document is the property of the EUROCONTROL Agency and no part should be reproduced in any form without the Agency s permission The views expressed herein do not necessarily reflect the official views or policy of the Agency REPORT DOCUMENTATION PAGE Reference Security Classification EEC Note N 21 98 Unclassified Originator Originator Corporate Author Name Location EEC COM EUROCONTROL Experimental Centre Communications B P 15 F 91222 BRETIGNY SUR ORGE Cedex France Telephone 33 0 1 69 88 75 00 Sponsor Sponsor Contract Authority Name Location EATCHIP Development Directorate EUROCONTROL Agency DED 3 Rue de la Fus e 96 B 1130 BRUXELLES Telephone 32 0 2 729 9011 MODE S TRANSPONDER TEST BENCHES USER REQUIREMENTS VERSION 1 Author Date Pages Figures Tables References Michel BIOT 9 98 viii 41 5 6 7 EATCHIP Task EEC Task No Task No Sponsor Period Specification SUR 3 E1 C07 DED 3 Distribution Statement a Controlled by Head of COM b Special Limitations None c Copy to NTIS YES NO Descriptors keywords Mode S Test benches Avionics maintenance Abstracts This note pres
17. a function of the required accuracy For the protocol tests it is a series of necessary transactions Procedures Up to now each test sequence was devoted to one characteristic or action but it is possible to group several parameter measurements in one reply or on the mean of n replies see above to gain time It is especially useful for the Ramp test set So the new procedures proposed in this paper will combine several measurements automatically The way choosen for this grouping allows separation between the tests compulsorily executed by the ramp test sets and those done in the laboratory or workshop A grouping that is not mandatory just a proposed improvement Transponder Test Benches 11 3 3 3 3 4 3 4 1 3 4 2 12 Tests in different Modes The way the characteristic is measured in Mode A amp C or Intermode or Mode S may differ not only in the interrogations patterns and reply data but also in the importance for ATC or by the fact that the parameter measured under one Mode is already verified in another This is to explain that some tests are present in Mode A and or in Mode 5 and not in Intermode the propositions for ramp testing differ the regrouping of tests procedures differs between Mode A amp C Intemodes and 5 electric tests generally use Mode or Intermode except in sets 53 58 66 67 77 85 86 amp 87 where both Modes or Intermodes interrogations are gener
18. andard shock proof Transponder Test Benches 37 38 blank page Transponder Test Benches 5 1 5 2 5 3 5 4 LABORATORY TEST BENCH PROCEDURES ANALYSIS BENCH TEST PROGRAM E T E T TECHNICAL DATA TESTING ENVIRONMENT Transponder Test Benches 39 40 blank page Transponder Test Benches 6 REFERENCES Ref 1 Ref 2 amp 3 Ref4 Ref5 Ref6 Rete s Transponder Test Benches Off line Tools for Airborne Equipment EUROCONTROL DEDOS information paper for the SSGT meeting October 1996 GTVS Ground Transponder Verification Verification Two Feasibility Studies ordered by EUROCONTROL terminated in 1993 1 INTERSOFT ELECTRONICS Olen Belgium 2 THOMSON CSF SDC Meudon la for t France STFTV Surveillance Team Task Force on Transponder Verification Report EEC note 20 95 A Field Study of Transponder Performance in General Aviation Aircraft Report FAA Tech Center DOT FAA CT 97 7 December 1997 Mode S Specific Services Manual ICAO Doc 9688 AN 952 June 1997 Mode S Specific Services and Data link Test bench EEC note 11 98 April 1998 41
19. ated Mode A C transponders only need to be verified by tests in the first tests procedures dual column the Mode S types are to be checked versus all tests procedures SUGGESTED LIST OF PROCEDURES FOR THE RAMP TEST SET Preamble The fact that a test or a procedure is proposed for the ramp test set does not automatically make it mandatory for Maintenance rules these last are defined by other regulation bodies JAR or others The test sets here defined must at least be able to execute the present ramp imposed tests plus those recently proposed see above chapters Besides it must be recalled here that the ramp test set objective is not to replace the ramp part of the certification of a transponder type Neither to replace the long test procedure defined in the Eurocae MOPS to verify the the transponders performance But some of their measurement principle MOPS 5 4 are reproduced or used as a basis Presentation Some of the tests listed in the Tables 5 and 6 are already executed on the present generation of ramp test sets Naturally they include at least all what is mandatory in FAR43 for Mode A amp C The objective is to enlarge the capacity of these equipment to j all tests proposed to be mandatory on ramp in the STFTV report similar tests Mode 5 Intermodes A amp C whenever it applies some tests considered as important see 2 1 and generally already executable on lab test sets and or suggested for bench
20. cing all these tests that can be easily implemented if not already executed in some ramp equipment Remark test A4 is presently limited to the F2 position the offset of ALL pulses should be verified and the maximum value in fact the worst displayed 3 4 3 2 Intermodes A amp C parameters The Intermode A amp C acceptance vs P4 short or long pulse test 21 is enlarged to a complete test T31 the acceptance vs P4 width Important also is the test T32 Intermode A amp C acceptance vs P3 P4 spacing 3 4 3 3 Mode S electric parameters Are added to the present test sets possibilities pulse positions mean offset is enough here pulse amplitude variation from the 1st to the 56th 112th mean pulse width mixed reply rate capability a complex series of various interrogations at various rates Mode S acceptance vs P1 Sync Phase Reversal spacing All these tests are important for a correct decoding a 112 bit long message is much more sensitive to a deviating clock than a 12 bit in the Mode A reply including the Sync Phase Reversal where the acceptance of the P2 P6 spacing should be verified inside a large window and not just limited to YES or NO at nominal time Besides the squitter verification in Mode S is transfered to the protocol procedures list see next paragraph because the squitter generation in recent transponders e g Mark 4 types is a complex combination of short and long squitter
21. code A 7377 repeated with successively gt gt codes A 4000 and A 0400 Measurement amp display Reply code displayed for each code power mean value of all pulses mean value of lowest pulse maximum variation between all pulse in a reply min max position of ALL pulses vs F1 1 45 us mean value of each pulse and the maximum offset that is the offset of the worst pulse pulse width mean value of all pulses Procedure 53 a 18 Verification Delay Time Delay Time Jitter Delay Time Difference Mode CodeC Performance specifications MS 3 7 1 Annex 10 Gilham conversion MT 5 4 3 3 Fixed settings Interrogator at nominal setting level at input 50 dBm Test progress 100 interrogation reply sequences Mode A idem Mode i 4 code A 1642 altimeter switched out if possible if not the altimeter will correspond to the ground altitude Measurement amp display Delay time F1 mean value Mode are compared jitter on delay time of 100 replies reply altitude decoded either C 0000 or xxxx corresponding to 1000 ft or to ground altitude Transponder Test Benches Procedure 57 a a Verification Reply Rate vs PRF Performance specifications MS 3 4 1 5 4 2 5 Fixed settings Interrogator at nominal setting level at XPDR input 50 dBm i XPDR cod
22. data Transponder Test Benches A planned sequence is a list established depending on the user needs planned maintenance repair research 4 2 4 Fast trials In order to fasten the trial one can adopt a succession of test sequences each sequence being arranged in such a way that the same settings are used for all the tests contained and no interrupt messages appears during or between tests like modify settings display results exit data all data are stored in memory and printed at the end if wanted The only interruption in the trial is then the necessary change of settings between two sequences see the following Figure 5 Fast trial Combination of Procedures fast trial planified combination of test procedures basic schematics enter date XPDR n aircraft registration 5 000000000 000000000 entry 000000000 000000000 start group of procedures display group settings to enter data in XPDR fixed data data in ADLP c Gone button execution of all the test modules of the group NO last group YES print exit data print exit data Transponder Test Benches 35 4 2 5 4 2 6 4 2 6 1 4 2 6 2 4 2 7 36 Example of succession of sequences Set code to 7377 SPI gt sequence P51 P57 P75 52 change code to 4000 gt P52 again j
23. e A 7377 SPI Test progress PRF 500 interrogations per sec during one sec followed by 5 or 10 sec rest j then idem at 600 700 1500 interrogations per sec Measurement amp display Diagram reply vs Procedure 58 Verification Mode A amp Sensitivity MTL Performance specifications MS 3 2 4 MT 5 4 12 Fixed settings Interrogator at nominal setting XPDR code A 1642 altimeter at zero if possible if not the altimeter will correspond to the ground altitude Test progress 100 interrogation reply sequences level at XPDR input 60 80 dBm per 1 dB steps first with Mode A then repeated using Mode C Measurement amp display Diagram reply vs input power MTL interrogator s level when reply rate crosses 90 MTL difference Mode A amp C displayed Transponder Test Benches Procedure 62 Verification Sidelobe Suppression vs P1 P2 Level Ratio b Performance specifications MS 3 8 2 MT 5 4 4 2 Fixed settings Interrogator at nominal setting i XPDR code A 1642 altimeter at zero if possible j if not the altimeter will correspond to the ground altitude d Test progress With P2 at nominal position amp width P2 P1 ratio varying from 12 dB per 1 dB steps 100 interrogation reply sequences for each step repeated for the level at XPDR input 50 dBm amp MTL 3 e Measurement a
24. eillance environment Concerning parameter testing during lifetime the following priorities were established to test on RAMP every year the transponder on the BENCH every 2 years the RAMP tests should follow the FAR 43 regulations an Europeanised JAR version that is completed F1 F2 spacing Mode A and C accept vs P1 amp P3 spacing the BENCH tests should follow all FAR 43 measurements with the addition of sidelobe suppression vs P1 P2 spacing reply delay time reply at PRF 500 Mode A and C acceptance vs P1 amp P3 width width of ALL pulses Additionally after each passage on the bench whatever its reason and periodicity the characteristics had to be restored to the NOMINAL value And transponders older than 12 years should pass every year a visit on the bench Transponder Test Benches 5 2 1 4 2 2 2 2 1 2 2 2 Recent FAA field study see ref 5 A recent field study of transponders aboard General Aviation aircraft in the USA was made using the modified FAA DATAS equipment made on 548 flying aircraft the test covered 31 parameters those executed by the EEC plus some additional ones The percentage of failures are significantly high if one considers the strict norms but they refer to General Aviation and in particular to aircraft rarely flying IFR so the figures will not be analysed If we compare the relative importance of each parameter linked as in our studies
25. entation keys Transponder Test Benches 15 IMEE Table 6 MAXIMUM TEST LIST PROTOCOLS Procedures MOPS number error protection interrogation acceptance CA verification use instead test P 2 gt non selective lockout selective lockout squitter verification PR reply probability stochastic acquisition Comm A interface amp information contents broadcast All Call formats uplink downlink interface use instead test P 18 gt GICB register extraction Comm B protocol AIS flight ident protocol amp interface bili Comm B broadcast Comm C protocol uplink interface ELM Comm C Comm D protocol directed Comm D Comm D interface Comm U uplink interface sensitivity level operation coordination ACAS broadcast message XPDR replies to incoming ACAS R messages XPDR ACAS throughput XPDR communication timing Note IM Intermode interrogations in addition to the UF s see page 10 3 4 2 for presentation keys Transponder Test Benches 4 RAMP TEST SET 4 1 PROCEDURES ANALYSIS 4 1 1 Legend 1 MS Eurocae MOPS for SSR transponders performance specifications 3 2 2 test procedures data 5 4 3 Mean in the 3 paragraphs 4 1 1 to 4 1 3 all values are computed as the mean of 100 replies 100 identical interrogation reply sequences 4 Time spacings are coun
26. ents user requirements for test tools for Mode 5 and Mode A C transponders Past experiences in transponder verification mandatory maintenance rules are shown a first series of tests is developed for what should be a common Ramp Test bench A next note will develop the tests for a Laboratory unit conceived as an extension to this Ramp version This document has been collated by mechanical means Should there be missing pages please report to EUROCONTROL Experimental Centre Publications Office 15 91222 BRETIGNY SUR ORGE Cedex France EEC Note N 21 98 EEC Task N C07 Issued September 1998 Mode S TRANSPONDERS TEST BENCHES USER REQUIREMENTS version 1 by Michel BIOT Summary Ramp test equipment for Mode A C transponders exist at present but generally perform only the mandatory tests to assure the safe behaviour of these avionics There is a need for standardised test tools that would execute defined sets of measurements in defined test conditions so as to give comparable results for Mode A C and Mode S transponders A Ramp version would be necessary for maintenance and a Laboratory version for repair and research and development Based on multiple experiences of transponder performance measurements as well as on actual test tools the present paper develops the test needs for both versions followed by the user requirements for the Ramp version that could be accepted as a base for technical s
27. f all Mode 5 pulses Procedure P 72 a Verification Mean Output Power Pulse Amplitude Variation Mean Pulse Positions Mean Pulse Width b Performance specifications MS 3 3 3 3 6 1 gt 3 6 6 MT 5 4 2 2 5 4 3 2 Fixed settings Interrogator at nominal setting level at XPDR input 50 dBm XPDR code 1642 Test progress 100 interrogation UF 05 or 21 DF 05 or 21 sequences i or Intermode A reply DF11 sequences e Measurement amp display i Power mean value of all Mode S pulses i diagram m amplitude of each reply data pulse 1st 56 or 112 pulse position mean offset nominal vs 1st pulse 0 5 us pulse width mean value of separately the preamble pulses the 0 5 us pulses amp the 1 us pulses note depending on the capability of the XPDR Transponder Test Benches 21 Procedure 75 a Verification Mixed Reply Rate Capability Performance specifications MS342 MT5425 Fixed settings Interrogator at nominal setting level at XPDR input 50 dBm i code A 7377 SPI Test progress 4 separated sequences lasting 1 sec a 500 interrogations Mode A uniformily mixed with 50 UF 05 interrogations in 15 b 120 interrogations Mode A uniformily mixed with 18 UF 05 interrogations in 0 1 s followed by 0 9 s rest 30 interrogations Mode A uniformily mixed with 8 UF 05 interrogations in 0 0255
28. g tolerance areas shown for both Intermode A amp C and for each of the 3 input levels Procedure P 88 a Bo Transponder Test Benches Verification Mode 5 Acceptance vs P2 6 Sync Phase Reversal Spacing Performance specifications j MS 1 6 5 3 9 5 MT 5 4 5 2 Fixed settings j Interrogator at nominal setting i XPDR code A 1642 Test progress P2 Sy Ph Rev spacing varying from 2 4 3 1 us per 25 ns steps level at input MTL 3 and 50 dBm 100 interrogation reply sequences for each step for each power level Measurement amp display Diagrams reply vs P2 Sync Phase Reversal spacing tolerance areas shown both level curves shown 4 1 4 Mode 5 Protocol Procedures For all these protocol tests the interrogator is at nominal regarding electric values no pulse P2 is i used level at input is 50 dBm uplink address is the XPDR address code is A 7377 i Unless especially mentioned Some test are only applicable to some types of XPDRs depending on their level or whether they are Mark 4 or not see the double asterisks Diversity operation must be inhibited to avoid unequal unknown reception by the XPDR and jumping problems the power and delay differ and worse the upper antenna be totally invisible to the test set located on the ground or simplier the test set ignores which antenna i
29. h the MOPS procedure tests that follow Transponder Test Benches IMEE Table 2 FIRST SERIES of MODE A C TESTS MTPA DATAS STFTV Transponder s transmission mean failure i impor require occurence tance ments characteristics 1090 Mhz 84 88 91 93 1 reply frequency 2 mean output power 3 pulse amplitude variation during a reply 4 pulse positions max offset mean offset 5 pulse width mean of all pulses 6 Mode A code validity 7 Mode altitude report the ground 8 delay time delay time jitter 9 delay time difference Mode A vs Mode C 10 delay time vs input level 11 squitter periodicity no interrogations 12 reply pulse rise amp decay times 13 reply rate vs PRF 13 reduced form reply rate 235 hz 500 hz 21 MTL Mode A Mode MTL difference Mode A vs Mode C 22 dead time 23 suppression time 24 receiving frequency acceptance 25 sidelobe suppression vs P1 P2 level ratio 26 sidelobe suppression vs P1 P2 spacing 27 sidelobe suppression vs P2 pulse width 28 interference additional P1 P1 P3 29 Mode A acceptance vs P1 P3 spacing idem Mode C i 30 Mode A amp C acceptance vs P1 amp P3 width 0 3 16 3 LEGEND not measured a few measurements only not statistically significative b old series of transponder showed some strange behaviour c oneortwo old series of transponder reacted to very
30. he following documents are also used j the GTVS Ground Transponder Verification System feasibility see ref 2 amp 3 the STFTV Task Force on Transponder Verification see ref 4 an FAA report Field Study of Transponder Performance in General Aviation Aircraft see ref 5 Laboratory tests Several test benches exist for Mode A C but new bench tools are needed for Mode 5 XPDRs to analyse new errors to investigate new problems new developments j to examine protocols to help certify the airborne installation Ramp tests Several ramp test sets exist for Mode A C amp Mode S but they are outdated they are not yet adapted to rapid testing of protocols to the increased set of tests data link functions Concerning tests in both situations Data link function that add new domains of investigation that are only partially fulfilled European Harmonisation is necessary for both tools and maintenance requirements for Mode A C amp S airborne equipment based on the same EUROCAE MOPS Transponder Test Benches 1 1 3 1 3 1 1 3 2 1 3 3 1 3 4 THE LABORATORY TEST BENCH A need for aeronautical administrations research and technical services In support of the Initial Implementation Mode 5 Enhanced Surveillance Programme IIMSES which requests a coherent policy be developed for bench testing of airborne equipment Data link ADLP TCAS CMS developers in various European industries
31. hout P2 Mode Intermodes A S 5 A Only Only with P2 P2 level P1 pulse included the same ones i Mode S UF 0 with RL 0 1 11 PR 11 0 address FF FFFF hex UF 4 5 with RR 0 15 16 17 18 amp 19 PC DI SD 0 UF 20 21 with RR 0 15 16 17 18 19 PC DI SD 0 7 UF 16 with RL 0 1 UF 24 with RC 2 Control The correct reply in each of the Modes Transponder Test Benches Procedure 6 Verification Squitter Extended Squitter b Performance specifications MS 3 20 2 6 modified MT 5 4 13 4 protocol procedure n 6 already modified ATTENTION THE SPECIFICATIONS MAY VARY GICB sequences and repetition rate are not definitive and the AIRBORNE GROUND status may not be varied as desired Interro ation reply sequences Unsollicited replies in Mode S There no interrogations To obtain valuable result in terms of periodicity at least 400 different unsollicited replies must be observed for each of the following cases 1 XPDRs with SHORT SQUITTER ONLY the short squitters DF 11 are transmitted at an average rate of 1 sec i contents CA 1 0 PI address in clear 2 XPDRs with EXTENDED SQUITTER a not controlled mixture of short amp long squitters DF11like above DF 17 FS 1 DR 0 DI 7 SD 0x00 MB z PI XPDRs address where x is the subfield BDS2 and equals 5 6 7 or 8
32. landing aircraft The required list of tests took into account 1 the results of 5 years of measurements with the reporting in particular fault percentage 2 the theoretical consequences of malfunctions 3 the real consequences observed during combined MTPA campaigns where MTPA result was linked to simultaneous radar observations 4 the administrations reports Central Transponder File 5 the possibility of automatic measuring and realistic field results Trials and theoretical works executed by the study contractors showed that a set of additional measurements could probably be executed in their GTVS proposal However variable opinions existed about the possibility to execute these tests on moving aircraft with valid and operational results These lists of tests are shown in Table 2 For the BENCH or RAMP test sets we are dealing in this paper the aircraft position is not a problem and time is not limited at least it is not a question of seconds RAMP means here that the transponder is in a stationary aircraft e g in or better out of its hangar Therefore we may consider that the best solution would be to execute ALL the tests developed in Table 2 and to take care of the 5 considerations above STFTV priorities see ref 4 The Task Force for Transponder Verification issued in 1995 96 a report that developed considerations and propositions concerning the verification of transponder behaviour in the ATC surv
33. le to test all the IMPORTANT parameters based on the earlier tools and studies as shown in the above chapter JAA43 STFTV and MOPS protocols list contains obligations for ramp testing but we feel this is far from being enough in order to preserve the future the tools will be able to enlarge their capabilities at least in the protocol domain the ramp tool will be built first see 1 4 3 LATEST REQUIREMENTS i In order to support the Enhanced Surveillance program see POEMS the ramp tool must analyse long squitters extract amp display clear all parameters contained in the registers as defined in the Mode 5 Specific Service Manual extract amp display in clear AICB messages the lab tool must in addition test all protocols for DATA LINK be able to vary the interrogator s frequency LIST OF TESTS AND PROCEDURES List structure The following Tables 5 amp 6 are built by combining all tests in Tables 2 3 amp 4 above plus the equivalent tests in other Modes whenever it applies A subset of this maximum list is then proposed for the Laboratory test set a further reduced list is then eventually proposed for the Ramp test set Each procedure will describe a set of interrogation gt reply sequences that must be carried out to verify each characteristic or action of the transponder For the electric tests it corresponds to n identical sequences where n is
34. lse sequences all Mode A C Intermode A C that is all combinations of two following P1 P2 P3 P4 trains Mode S UF DF 00 04 05 11 16 17 20 21 24 with any field and subfield contents time delays up to 30 sec use in lockout tests if these test are added repetition rate PRF 1 to 100 hz in Mode S to 2000 hz in the other Modes physical output both channels to connecting cable connector one channel to antenna 10 W maximum antenna directional on a tripod to connecting cable connector 4 3 2 Input Downlink Two channels to allow in the bench variant the diversity measurements frequency 1070 1110 Mhz resolution 0 01Mhz power upto 0 1W 17 dBm at input to antenna with a resolution of 0 5 dB pulse miminum width 200 ns resolution 25 ns or shorter with intervals of 200 ns between one pulse decay and the next pulse rise pulse rise and decay times measurable 4 3 3 Display Active matrix for confortable external natural light 9 inch screen 800 x 600 pixels either 20 lines of text or diagram X Y dialog windows with on screen buttons data result presentation powers peak pulse value mean values as defined in the procedure paragraphs in dB amp in W altitude available in feet 4 4 TESTING ENVIRONMENT The equipment will be used essentially on external Power input 90 to 240V 45 440 hz Temperature 0 to 455 C in operation 40 to 470 storage Humidity 95 96 St
35. may take advantage of the availability of such common instrument Existing test benches either measure only Mode A C amp S electric characteristics or some protocol but always off line The proposed bench go further in testing systematically all electric parameters and protocols on line giving way to up down sequences each reply influencing the next interrogation these protocols include Comm A B C amp D messages Test set up for a complete test bench Basically the tests will be executed on the bench but finally a ramp installation is necessary to validate situ the complete airborne chain incl antenna that is with TCAS CMC a real environment on the ground or simulated in the air For this purpose some extension towards ramp use power antenna physical support has to be envisaged In addition to this operational validation acceptance of the maintenance procedures will also use this variant Finally mixed installations combining specific laboratory with the bench and a connected ground station be use to investigate special or new problems setup of this kind exist already between the EEC and French and UK technical services Objectives of the bench validation of SARPS validation in view of equipment certification not the certification itself validation for maintenance before delivering certificate of conformity and to prepare the main
36. mp display Diagrams we reply vs P2 P1 ratio tolerance areas shown for the 2 input power levels Reduced version if available time is too short replace the diagrams by the reply at 9 dB and 0 dB only Procedure P 66 a Verification Mode amp C Acceptance vs P1 Spacing b Performance specifications MS 3 9 3 MT 5 4 5 2 Fixed settings Interrogator at nominal setting no P2 level at XPDR input MTL 10 dB i XPDR code 1642 d Test progress 1 spacing varying from 6 5 9 5 us 19 5 22 5 us per 25 ns steps 100 interrogation reply sequences for each step e Measurement amp display Diagrams reply vs P1 spacing tolerance areas shown for both Mode 6 10 us and Mode C 19 2 23 us Reduced version if available time is too short replace the diagrams by a set of values reply at 7 0 7 8 8 2 9 0 us and 20 0 20 8 21 2 22 0 us only 20 Transponder Test Benches 4 1 3 Modes 5 electrical and Intermode A amp C Procedures Procedure 77 Verification Reply Frequency b Performance specifications MS 3 3 1 MT 5 4 2 1 Fixed settings Interrogator at nominal setting PRF 50 hz level at XPDR input 50 dBm i XPDR code A 1642 d Test progress 100 interrogation UF 05 reply DF 05 sequences or Intermode A DF11 sequences Measurement amp display Frequency 1090 Mhz mean value o
37. mp C transponders but contained here in a Mode S downlink messages the importance is therefore the same Maximum airspeed and identification flight plan or a c registration of the aircraft are useful data to the air traffic controller stochastic behaviour of the transponder appears as important for a smooth radar behaviour those two characteristics are easily tested in procedures 12 19 amp 13 Comm B messages are important in the data link exchanges between ground and aircraft for various reasons including ADS but they are not mandatory for all versions levels of these transponders more some characteristics are not yet adopted neither definitive But many BDS see Mode S Specific Services are already defined Therefore following the latest requests see 3 2 both a new procedure P 17 concerning the GICB registers and the easily applicable procedure P 20 will be kept for ramp testing Proposed List of Procedures Finally the following list of procedures is proposed for the Ramp Test set Mode A amp C procedures P 51 52 53 57 58 62 amp 66 Mode S and Intermode A amp C procedures P 71 72 75 77 78 86 87 amp 88 Mode S Protocol procedures P 2 6 9 10 11 12 13 17 19 amp 20 LIST OF PROCEDURES FOR THE LABORATORY TEST SET This version of the test set is of course much more complete as well as more flexible because different types of users are interested Research and developments the operator may
38. n and Maximum Airspeed Performance specifications MS 3 18 4 25 amp 29 3 23 1 5 MT 5 4 13 4 protocol procedure n 12 Interrogation reply sequences Depends whether the is ACAS compatible not 1 NOT ACAS compatible UF 00 RL 0 000 AQ 0 amp 1 000 000 AP the address DF 00 replies 2 The XPDR is ACAS compatible the same UF 00 plus UF 00 000 RL 1 000 AQ 0 amp 1 000 000 AP the address DF 16 replies UF 16 000 RL O 000 AQ 0 amp 1 000 000 O AP address DF 00 replies UF 16 RL 1 000 AQ 0 amp 1 000 000 MU O AP address DF 16 replies Control The correct replies i ifi DF 00 replies VS 1 SL 0 RI x AC altitude on the ground XPDRs address where x 8 to 14 depending on the max airspeed when bit AQ was 0 0 when bit AQ was 1 if2 see MS 3 23 1 5 i DF 00 replies VS 1 SL 0 to 7 depending on the ACAs level or the a c RI x AC altitude of the ground AP XPDRs address 0 2 3 4 depending on the ACAS capability of the a c when bit AQ was 0 8to14 depending on the max airspeed when bit AQ was 1 DF 16 replies same contents plus MV filled with zeros where x Remark More complete tests of the ACAS exchange protocol are executed in Bench test set procedures 31 Transponder Test
39. nt of tests developed in Table 2 is not available or desirable on this sort of tool 1 RTCA EUROCAE documents Mode S Intermode RTCA MOPS DO 181A and EUROCAE MOPS ED 73 describe the Mode S transponder and the tests procedures to ensure the transponder is complying with the ICAO specifications defined in the Annex 10 chapter 3 contains the minimum performance specifications chapter 5 tests procedures to be executed in the laboratory chapter 6 some additional ones executed on the ramp Altough not being a maintenance document but a manufacturing verification certification test description it is used as a main source document for establishing maintenance procedures and rules The document being a mandatory reference for the definition of the characteristics it will serve as such in the present paper more in order not to reinvent the wheel we will use the protocol procedures directly as they are listed and e g use their number sequence procedures 1 to 37 these protocol procedures are shown in Table 4 NOTE 1 For the sake of comparison a numbering common to all tables including those in next chapter has been used this explains the holes in the number sequences n 1 19 electrical characteristics of the transponder s transmission 1090 Mhz n 21 39 electrical characteristics transponder s reception capability 1030 Mhz no numbers for the message protocol tests as they will be regrouped wit
40. pecifications The user requirements for the Lab version will follow in the second version ADLP BDS BDS x x CMC CMS GDLP GICB GTVS MOPS STFTV TCAS XPDR LIST of ACRONYMS and ABBREVIATIONS Aircraft Data Link Processor Binary Data Store subfield in MB downlink field now renamed GICB register x x Central Maintenance Computer of the aircraft Central Maintenance System of the aircraft Ground Data Link Processor Ground Initiated Comm B Ground Transponder Verification System Minimum Operating Performance Specifications of the Transponders edited by EUROCAE Surveillance team Task Force for Transponder Verification Traffic alert and Collision Avoidance System Transponder Mode A C and Mode 5 vi 1 Preamble PRESENT SITUATION amp 1 1 1 The TO00ls nr ER ee ee es 1 1 0 Pe dre ni dee 1 1 3 Laboratory Test 2 1 4 The Ramp Test 3 1 5 Short Historie net Seen 3 1 6 Transponder Performance 4 1 7 Present Situation kennen an 4 GURRENT EISTS OF TESTS ni De e ere e Re 5 2 1 Mode A amp C Possible and Necessary 5 2 2 Mode S Characteristics 6 PROPOSED TESTS LIS Tine en d 11 3 1 Global Proposal e obe ERR
41. ring the test To avoid to the risk of field failure hard disk should be replaced by any other memory system Result transfer The contents of the memory must be transferable by any actual means floppy disk or equivalent GPIB bus RS232 to another computer base or local network Printer output is required Autotest The system must contain an autotest device that is automatically launched before any operation starts This autotest verifies the input and output of the system and can control the exactness of the measurements through a reference transponder It must be possible to introduce the distance ramp tool aircraft antenna before starting the tests in order to the apply the corresponding time delay correction Transponder Test Benches 4 3 TECHNICAL DATA The equipment must be able to generate all the tests described in the test lists above and therefore must have the following capacities 4 3 1 Output Uplink Two channels to allow in the bench variant the diversity measurements frequency 1020 1040 Mhz steps of 0 2 Mhz power for measurements at 2 to 25 or 15 meters up to 37 or 44 dBm 5 or 25 W at output of antenna in steps of 0 5 dB difference between channels upto pulse miminum width 250 ns steps of 25 ns or shorter with intervals of 200 ns between one pulse decay and the next pulse rise pulse rise and decay times respecting ICAO Annex 10 DPSK modulator for uplink P6 pulses idem pu
42. s replying Therefore the top channel must be terminated by its characrteristic impedance Successive signs 1 mean a sequence containing more than 1 interrogation followed by 1 reply ATTENTION the Mode 5 Specific Services as well as the squitter protocol may still change in the near future so in some of the protocol tests see ATTENTION THE SPECIFICATIONS MAY VARY the BDS definition use sequences and repetition rate if applicable may be different from what is developed but the princip of the measurement remains Always refer to the latest version of th Mode S Specific Services ref 6 and Mode S Subnetwork SARPS The formats used in these tests are the following Uplink Formats 1 99 EJNM Wo YY x means x bits are devoted to this field YY 0000 show a series of zeros between fields Transponder Test Benches 25 Downlink Formats ore eas Lors VS P 76 55 24 kes ND 4 0 24 means x bits are devoted to this field 0000 show series of zeros between fields Procedure P 2 a 26 Verification Interrogation Acceptance Performance specifications MS 3 20 2 2 amp 3 3 21 1 1 amp 4 3 23 MT 5 4 13 4 protocol procedure 2 Interrogation reply sequences Wit
43. s waite for approval or stop or next procedure display the settings the data to enter in the transponder via its control box e g the code or if applicable to the external equipment linked to it ADLP waite for execution order start of the procedure stops whenever a new Setting has to be applied during the procedure e g change of code waite for continue order stops at end of testing display of the information PASSED or FAILED wait for order display result or go to the next procedure if result display button has been pushed the successive results are presented in the form _ corresponding to the measurement a data e g Pulse Width 455 ns mean of 100 replies 14 pulses the tolerances is 350 550 ns X Y diagram e g reply vs P3 width with the tolerance areas in grey a list of reply messages e g DF11 CA 7 808080 I 0 with the text correct_ wrong after which the system switches over to another module Trial Modules A trial is a planified sequence of procedures defined by the above modules see this Figure 4 1 module for 1 trial a series of planified procedures basic schematics enter date XPDR n aircraft registration 000000 keyboard 000000 P 000000 entry 000000 000000 000000 start first procedure execution of the module see module description DED von next repeat print exit data print exit
44. s whose contents vary in accordance to GICB Mode S Specific Service Manual Finally altough desirable it is not possible to test on the ramp that is without cable connections the diversity parameters the two antennas receiving simultaneously the signals albeit with very small time delay and power difference Transponder Test Benches 13 3 4 3 4 3 4 4 3 5 14 Mode 5 protocols The test procedure n 1 P1 Error Protection is not possible with a installed in an aircraft the address being cabled in the rack Only the correct address will be verified as part of any other tests Test procedure n 3 the capability and procedure n 8 the PI verification are checked in the replies DF11 in procedure P 2 Squitter verification protocol n 6 the squitter protocols have changed since their increasing use in ADS simple and extended squitter are now part of the proposed and or mandatory elements of the future Mode S transponders Therefore in order to saveguard the future the test bench shall be built such as to accept and analyse the various squitter contents and periodicity P 6 Mode S addresses are tested in various combinations to discover e g incorrect cabling or bad contact in the transponder rack mounting procedure 9 Procedure 10 verifies the altitude reports but this depends on the installation possibilities Procedure 11 corresponds to the Mode A code validity executed on Mode A a
45. st centres amp administrations JAA Test centres amp aircraft operators electric electric protocols protocols electric electric protocols protocols existing 1 to upgrade NOT existing NOT existing NOT existing NOT existing existing to upgrade existing 1 to upgrade NOT existing NOT existing NOT existing existing 2 to upgrade NOT existing existing 2 to upgrade existing 1 to upgrade NOT existing specific bench NOT existing existing to upgrade NOTE 1 some equipment can test most of the parameters wanted see next chapter on the bench but operation is both long and semi automatic NOTE 2 simple ramp test sets exist but they test few parameters and their precision do not always follow the improved accuracy that is wanted in the future ATC environment New ramp test sets are in preparation that include automatic sequences it is highly probable that their increased capabilities will join our present request at least partially The present document is then a way of standardising these tools to reach the minimum commonality 4 Transponder Test Benches 2 1 2 1 1 2 1 2 CURRENT LISTS OF TESTS MODE A amp C POSSIBLE AND NECESSARY TESTS GTVS Test lists see ref 2 amp 3 Some years ago a feasilbility study was submitted for an equipment called GTVS Ground Transponder Verification System to be installed on airports for measuring the transponders aboard the
46. sting in real conditions of Enhanced Surveillance transponders the RAMP test bench has to be developed first the laboratory equipment being an extension of the ramp unit Test conditions Testing is based on ICAO Annex 10 the relevant RTCA amp EUROCAE MOPS signals in space reply capability messages exchange protocols test conditions The transponders will be tested in real situation that is aboard stationary aircraft preferably out of the hangar to avoid reflection SHORT HISTORIC The ramp equipment for XPDR maintenance testing did evolve from the early tools totally manual test sets only capable of fixed Mode A C interrogations only the spacing P1 P3 was variable fixed PRF and SLS conditions and few reply analyses frequency rough power of reply pulse position of F2 only and acceptance window for other ones up to the present generation in use capable of measuring under variable interrogation parameters pulses SLS most of the pulse characteristics including frequency variations with a higher accuracy The tendency is now to produce test tools digitally controlled e g touch screen or remote control by PC through GICB links but through long procedure semi automatic and used mainly in lab Most ramp tools in use are variants with capabilities reduced on both interrogations and replies characteristic and display part of the problem is linked to the time limits to user technicity to price
47. t Bench reference 7 Transponder Test Benches 31 Procedure 79 a Verification AIS Flight Identification Protocol Performance specifications MS 3 18 4 14 amp 27 3 21 1 13 amp 17 MT 5 4 13 4 protocol procedure n 19 Ref 6 Mode S Specific Services Manual Interrogation reply sequences UF 04 or 05 0 RR 18 DI 7 SD 0000 AP XPDRs address i DF 20 or 21replies j where SD contains subfields 115 0 RRS 0 the rest 0 too Control correct contents of the replies DF 20 or 21 DF 20 FS 1 DR 0 UM X AC altitude 0 MB message XPDRs address or i DF 21 FS 1 DR 0 UM X ID a c code A MB message AP XPDRs address j where the 56 bit message MB is BDS 2 0 charac 1 charac 2 charac 3 charac 4 charac 5 charac 6 charac 7 charac 8 the characters giving with ICAO international alphabet n 7 the aircraft s registration tail number Procedure P 20 a 32 Verification Capability Report Performance specifications MS 3 18 4 14 amp 27 3 21 1 12 amp 17 3 23 1 2b MT 5 4 13 4 protocol procedure n 20 j ATTENTION THE SPECIFICATIONS MAY VARY io In any case refer to the latest version of both Mode S Specific Services Manual see ref 6 and the Mode S subnetwork SARPS Interrogation reply sequences UF 04 0 RR 17 DI 7 SD 0 AP XPDRs address
48. ted from the pulses front edge at half amplitude 5 Here on ramp when maximum load is requested Mode A code is set to 7377 the SPI if necessary because the highest load code A 7777 could mislead safety on radars in the vicinity when a variation between successive bits is desirable A 1642 is used 6 Unless otherwise stated PRF is 450 hz for Mode A amp C and 50 hz for Intermodes and Mode S 7 The sign means in a sequence the interrogation followed by its reply 8 The sign shows settings on the transponder side fixed and or modified during the test entered executed by the pilot 4 1 2 Mode A amp C Procedures Procedure P 57 a Verification Reply Frequency b Performance specifications MS 3 3 1 MT 5 4 2 1 Fixed settings Interrogator at nominal setting level at XPDR input 50 dBm Mode A code A 7377 SPI d Test progress 100 interrogation reply sequences e Measurement amp display frequency 1090 Mhz mean value of all pulses Transponder Test Benches 17 Procedure 52 a Verification Mean Output Power Pulse Amplitude Variation Mean Pulse Width Pulse Positions Mode A pulse decoding Performance specifications MS 3 3 3 3 5 1 2 4 5 amp 6 MT 5 4 2 2 5 4 3 1 Fixed settings Interrogator at nominal setting level at XPDR input 50 dBm Mode A Test progress 100 interrogation reply sequences with XPDR set to
49. tenance procedure to be adopted for each version of airborne set up i e new investigations amp operational evaluations Test conditions Testing is based on ICAO Annex 10 the relevant RTCA amp EUROCAE MOPS signals space reply capability messages exchange protocols test conditions Altough some equipment will be connected to the XPDR amp ADLP they will not be tested by the proposed tool they are only in and output to XPDR amp ADLP e g they could be replaced by a bench controled airborne data simulator but the validity of the complete chain will be tested Transponder Test Benches 1 4 1 4 1 1 4 2 1 4 3 1 4 4 1 5 THE RAMP TEST BENCH A need for aircraft operators maintenance services Existing Ramp test sets are more or less outdated and cannot support all the requirements of complete set Mode A C tests all Mode S protocols squitter and long squitter validations and the economy of fast and automatic testing A need for administrations technical services administartions must control the validity of the proposed maintenance requirement i the execution of this maintenance They need also a mixed form of testing for validation of different equipment in a pseudo real environment a set up of this kind exist presently but this subset is not the purpose of the present document Objectives of the bench The first objective being the te
50. to the effect of a corresponding failure on ATC functionis between this study and the other ones one may point out altitude errors or failure to report it and delay difference A vs not measured sidelobe suppression P1 P2 ratio Mode vs P1 amp width which were measured but showed errors only in old transponder series now out of use A first list of tests in Mode A C Rebuilding the lists of parameters to test mentioned in the above paragraphs with more coherence including all the tests executed during MTPA amp DATAS campaigns and the recent FAA study we get in Table 2 a first list for a Bench Test System concerning Mode A C only 1 It incudes two columns revealing the importance of the measured parameter theoretical consequences of malfunctions the occurence of faults during 1984 1988 and 1991 1993 MTPA DATAS campaigns and the duration of the test MODE S CHARACTERISTICS The emergence of Mode S engaged the equipment manufacturers to develop Mode S transponder test sets some years ago this generation of tools allows a series of electric characteristics to be tested combined with a few essential protocol exchange verifications Ramp test set capabilities in all Modes The possibilities of presently available ramp test sets are given in Table 3 Due to time limits and some other considerations economy technical difficulties and unawareness of some misbehaviour the full amou

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