Meeting Report - International Civil Aviation Organization



Report of the 20th Meeting of

Aeronautical Communications Panel (ACP)

Working Group B

29-31 May, 2006

Montreal, Canada

1. Opening of Meeting

The Rapporteur, Mr. Robert Frazier, opened the meeting at 10 am. The Secretary of the meeting was Mr. Robert Witzen.

2. Introduction

Introductions of participants were made. There were a total of 9 participants, with one new member, Mr. Yuji Matsukubo, from Japan. The list of participants is in Appendix 2.

3. Review of Agenda

The working group reviewed and approved the agenda. The approved agenda is in Appendix 1.

4. Initial Introduction of Working Papers and Attribution

Attribution of the nine working papers was made to the appropriate agenda items. The Working Papers are listed in Appendix 3. There were no papers for agenda items 8 (VDL Mode 4 Global Signaling Channel) and 11 (ICAO guidance material on radio frequency interference).

5. Guidance material for VDL frequency assignment planning criteria

5a VDL frequency assignment planning criteria for VDL mode 3

WP 5

Mr. Frazier introduced Working Paper 5, Frequency Assignment Planning Criteria for VDL Mode 3, which was prepared by Mr. Nakatani and Mr. Matsukubo of Japan and Mr. Coleman of the USA. The paper contains editorial modifications to the section on VDL Mode 2 and a new VDL Mode 3 section which is now complete. The material on VDL Mode 3 was based on data taken by the FAA and by ENRI. Since it was, for the most part, new material, it was not accepted by this meeting, but is to be presented for adoption at the next WG B meeting.

5b VDL frequency assignment planning criteria for VDL mode 4

WP 6

WP6, Recommendation for Frequency Planning Criteria for VDL Mode 4, introduced by Larry Johnsson, presents the results from the radio measurement campaign that LFV has undertaken in 2005/2006. The measurement procedures defined by ICAO ACP WG-B has been followed. The results, based on tests of one VDL M4 radio, indicate that there should be four guard channels between VDL Mode 4 and DSB-AM in a ground scenario and two guard channels in an air scenario. The protection distance between VDL Mode 2 and VDL Mode 4 and between VDL Mode 4 and VDL Mode 4 should be one guard channel for both scenarios. These results will be used when ACP is defining the Frequency Planning Criteria for VDL Mode 4. The group agreed that the results from these tests could be used to begin populating the VDL M4 section of the Frequency Assignment Planning Criteria document. A question was raised as to how close was the emission spectrum of the VDL Mode 4 transmitter to the ICAO mask. This may be important when developing frequency planning criteria from this one radio.

A sub-working group was established to take this data and update the Frequency Assignment Planning Criteria document section on VDL Mode 4, which is currently blank. The group will use the VDL M2 and VDL M3 sections as a template for the format of the VDL M4 section and populate it with the data from this paper. As additional data is collected and approved, the VDL M4 criteria can be updated. Volunteers to participate include Mr. Johnsson, Eurocontrol and the WG B Secretary. No volunteer was found to lead this sub working group. The group is to provide updates to the VDL Mode 4 frequency assignment planning criteria to be reviewed at a future WG B meeting, not later than February 2007.

6. Compatibility between VDL and DSB-AM on-board implementation problems

WP 7

WP 7, Operational Experience of Operating VDL Mode 4 On-board Aircraft, introduced by Larry Johnsson, presents the results from an investigation of the operational experience with respect to on-board co-site interference when operating a VDL Mode 4 system together with DSB/AM analogue voice on-board medium sized aircraft. None of the pilots had experienced any interference on the DSB/AM voice radio. The report concludes that VDL Mode 4 interference on DSB/AM voice is a non-issue when operating a medium sized aircraft in an area supported by a VHF ground infrastructure like in Sweden. The meeting was invited to consider the availability of an environment supporting VHF voice as well as data link services in airborne installations that can be used for further analysis of co-site issues. The meeting agreed that the information in this paper is interesting but must be characterized as anecdotal because it lacks basic technical data needed in order for any conclusions to be drawn. For instance, the meeting noted that information on the channel separation between VDL and DSB-AM was lacking as was the antenna being used by the ATC DSB-AM radio and the coupling loss between them. Mr. Johnsson stated that he would try to provide this data at the next meeting of WG B.

7. Guidelines for the introduction of VDL into the VHF band

WP 8

WP8, Status of Implementation of VDL Mode 4 in Sweden, presented by Larry Johnsson, gives information on the on-going implementation of services based on VDL Mode 4 in Sweden. At the airport in Kiruna (the most northern city in Sweden) ADS-B based surveillance services are being implemented using VDL Mode 4. A VDL Mode 4 ground station and display equipment in the tower are in place. Operational service is expected to commence in December 2006. The Swedish regulator (Luftfartsstyrelsen) has approved that ADS-B data from the VDL Mode 4 system is merged with surveillance data from the traditional ground movement radar system at Stockholm/Arlanda, the busiest airport in Sweden. This enhanced surveillance facility will be in operation from June 2006. LFV (the ANS provider in Sweden) is installing a ground infrastructure that covers the whole country and consists of initially 12 ground stations. The project will last until November 2007 when all stations will be in place and interconnected through a ground network.

WP 9

WP 9, Brief VDL 4 Progress Report, was presented by Patrick Delhaise, Eurocontrol. The paper presented the Eurocontrol plan to complete testing on VDL Mode 4. The Eurocontrol VDL Mode 4 Project will end at the end of 2006, Eurocontrol recently shared the results with the VDL Mode 4 community. It is intended that these results will be provided to ICAO ACP WG B. It was felt by the meeting that this work may help in understanding the on-board compatibility issues. It was noted that the radio tested under this program is the same unit tested for WP 6.

8. Global signaling channel for VDL mode 4

No contributions were submitted for this agenda item.

9. Review of Draft Report of WG-B 18th and 19th meetings

The meeting reviewed the WG B portion of the combined report of WG B, WG M, WG F and NSP SSG which covered the 18th meeting of WG B. It also reviewed the draft report of WG B 19th meeting. Both reports were approved with minor changes. The following questions were raised concerning the Report of the 19th meeting. Why is the FAA S/P=20 in Table 1, but the required channel separation is the largest at 4 in Table 2? Are the values in Table 2 guard band channels or the next usable channel? A reference is needed for paragraph 9. Paragraph 10.2 is an addition to WG B work program.

10. Review of Open Action items

A list of action items is in Appendix 4. The list was reviewed by WG-B members and updated.

11. ICAO guidance material on radio frequency interference

No contributions were submitted for this agenda item.

12. PEDs – Compatibility with aviation systems

12a. UWB

WP 3

WP 3, Ultra WideBand, Update on the European Situation and Testing Carried Out Within the UK, was presented by John Mettrop. The report highlights that with respect to the UWB communications applications ECC TG3 have produced a draft ECC decision which has been adopted by the ECC (See Appendix B). There was however concern over the draft decision from the European Commission as well as a number of States [which wanted higher power flux density limits] with respect to the limits proposed between 3.1 & 4.4 GHz and hence a second consultation has been initiated [by the ECC] with respect to the power flux density limits within this band.

The work on Ground Penetrating Radar (GPR), Wall Penetrating Radar (WPR), & Building Material Analysis (BMA) is continuing with ECC TG3 and is due to report in July this year. The draft report states that the main concern is not with respect to the GPR and WPR since both systems will have limited use, be licensed, required to co-ordinate their activities and aviation has many years of practical experience of these operations without an incident. The BMA however does cause some concern since it is intended to be license exempt and aim at the tradesman/serious home do-it-yourself enthusiast. The theoretical analysis has shown that UWB can potentially cause interference to aeronautical systems. The conclusions of this theoretical analysis have been confirmed by the testing carried out so far with simulated UWB sources. Whether practical UWB sources will present less or more of a challenge has yet to be determined but by the time the results of this testing have been finalized UWB regulation in Europe will already be in place. The report concludes with a table of recommended power flux density limits for protection of aeronautical radionavigation, communications and surveillance systems from UWB interference. The meeting recommended that GPR and WPR operation be coordinated with relevant aviation authorities.

12b GSM

WP 2

WP 2, GSM On-board Aircraft, Update on the European Situation and Issues to be Addressed, was presented by John Mettrop. The use of mobile phones on-board aircraft has been a topic for discussion within aviation for some time. Recently with advances in technology a number of companies including OnAir have re-ignited the debate proposing that mobile phones could be used on aircraft if a pico-cell were fitted within the cabin reducing the radiated power of the phone. The conclusion of the technical analysis by SE7 is that provided there is a minimum separation of 3,000 metres (10,000 feet) between the aircraft and the ground then the on-board systems would not have an adverse effect on the ground GSM network. The onus is now on aviation to give clear guidance as to whether mobile phones can be used safely on-board aircraft. The paper listed six areas issues that need attention by aviation:

1) The need for Globally Harmonized Advice/Regulation?

2) Acceptance of the 3,000 metre (10,000 feet) Radio Regulatory Limit

3) Differences Between Regions

3a) Different mobile phone systems

4) Differences Between Aircraft

5) Potential Increased Risk of Air-rage

6) Interference to Aircraft Systems

It was noted that EUROCAE WG 58 and RTCA Inc. SC 202 are working together to arrive at a joint set of recommendations with respect to the operation of T-PEDs on aircraft which includes guidelines on phases of flight as well as human factors. The paper recommends that WG B recommend to the Air Navigation Bureau that action be taken by the appropriate bodies within ICAO to address these issues such that clear guidance/regulation can be provided on a global basis. ICAO should seek assistance from States and other aeronautical bodies such as EASA and IATA. During the discussion, the Secretary stated that he will bring this material to the attention of the ICAO Medical Section and Air Worthiness Section for possible comment and action. The meeting highlighted several issues that seem to be “falling through the cracks.

WP 4

WP 4, Subject: Licensing and operation of GSM base stations on board aircraft, was presented by the Secretariat. This contribution contains comments of the International Civil Aviation Organization (ICAO) on the text for a Draft ECC Decision on the harmonised use of airborne GSM systems in the frequency bands 1710 – 1785 and 1805 – 1880 MHz. ICAO concluded: “This Decision needs significant further work. Technical issues regarding the protection of avionics from mobile phone use on board aircraft are currently addressed, inter alia, by RTCA Special Committee 202 and Eurocae WG 58. It is suggested that this Draft Decision governs only the assignment process of frequencies from the bands 1710 – 1785 and 1805 – 1880 MHz to airborne GSM base stations. The use of the System together with the passenger mobile phones on board aircraft needs to be regulated by aviation authorities of the State of registry. This draft Decision is a further step which may result in raising the interference levels for aeronautical safety communication and navigation.”

After a discussion the group agreed to the following recommendation on the use of cellular phones in aircraft. “The use of cellular phones in aircraft raises many safety issues, ranging from radio frequency interference to aircraft systems to passenger rage. ICAO should recommend that States oppose such use unless these issues are thoroughly studied, and vetted within the aviation community, and well thought out conclusions are drawn. Some issues that require study include the operation of so-called pico cells. These are classified as installed aircraft systems, but with one significant difference from all other such aircraft systems. That difference is that they will have to control passenger cell phones. Thus not only is the pico cell operation important to safe flight, but their ability to control cellular phone emissions is a safety of flight issue. For instance, when the pico cell is turned off below 10000 ft altitude to protect the cellular phone ground infrastructure, what happens to the passenger cellular phones that are either overtly left on or are accidentally left on? Furthermore, a pico cell can only operate with one cellular phone system. How are the passenger phones using another system managed? Can jammers (noise floor lifters) keep them from transmitting (provided that their operation can be legalized). Also, each pico cell can only handle a few calls. What happens to the other phones on the system that it can handle, but that it does not have the capacity for? Will passenger rage result from passengers that can’t get through even when they have the “correct” phones?

Unless these and all other questions are answered satisfactorily to the aviation community, WG B recommended that ICAO should oppose the use of such devices on aircraft as potential hazards to safe flight. WG B further recommends that ICAO should pursue one global rule applicable to all phases of flight; i.e., that the use of phones is either permitted for all phases of flight or not permitted for any phases of flight. ”

The meeting noted that Assembly Resolution A29-19, Legal Aspects of “Global Air-Ground Communications” needs to be taken into consideration for further work.

13. WG-B Accomplishments.

The WG B accomplishments were reported to the Working Group of the Whole in June 2005. This current meeting is the first one since that time. This meeting produced material for VDL Mode 3 frequency planning as well as material which can be used to begin populating the VDL Mode 4 frequency planning criteria. The VDL Mode 3 frequency planning criteria are planned finalized by February 2007.

14. WG-B goals/where we are going

• Completion of the frequency assignment planning criteria for VDL Modes 3 and 4 for approval by ICAO by February 2007, including issues related to the VDL Mode 4 spectrum emission mask (i.e. actual transmission mask vs. transmission mask as per Annex 10. (An ad-hoc group was formed for this activity)

• Developing of a methodology for compatibility assessment of VDL with DSB-AM when both are used simultaneously on the same aircraft by February 2007. (On-board compatibility)

• Follow the activities of RTCA and EUROCAE in their assessment of the technical and human factor aspects of the effects of use of cellular phones on board aircraft (in relation to a draft ECC decision on this matter) and draw our conclusion based on available information by February 2007

• Continue development of material related to the protection of aeronautical radiocommunication systems from interference from non-aeronautical sources (Ongoing)

• Assist (WG F) in the development and completion of FM-immunity and FM interference considerations for GBAS and VDL Mode 4 (2007)

• Specific technical issues as per list of action items (February 2007)

15. Any other items.

The meeting was addressed by the President of the Air Navigation Commission, Mr. Adrian Sayce, the Director of the Air Navigation Bureau, Mr. Bill Voss, the Chief of the Communications, Navigation and Surveillance Section, Mr. Jim Nagle and the Secretary of the Aeronautical Communications Panel, Mr. Robert Witzen. They stressed the need for a more transparent process in the ANC, when reviewing the activities of the panels . A method being implemented to help achieve this is an annual review of the status of the work in all panels The first such review will take place during the fourth quarter of this year. This new approach will require the panel Secretaries to produce a brief status report on the ongoing activities of the panel, including a planning for the completion of various tasks and a well thought out rationale for why the work is being carried out. It was also clarified that the work of the panels should concentrate on the strategic objectives of ICAO (these are available on the ICAO website icao.int) and the ICAO Global Plan and Global Plan Initiatives. The latter will be linked to the specific tasks and activities of the Organization. Of paramount importance is that ICAO responds to aviation problems in a timely manner. In these activities, ICAO is streamlining its activities and moving from a standards generating body to a global aviation problem solving body.

16. Next Meeting Date and Location.

The next meeting will be held at ICAO Headquarters, Montreal Canada. It is to be scheduled for early next year (exact date TBD).

The meeting concluded at 1130 hours on May 31.

Appendices

1. Agenda

2. List of Working Papers

3. List of Participants

4. List of Action Items

5. Report of the 19th Meeting

6. Updated Frequency Assignment Planning Criteria for VDL

APPENDIX 1

WG B/WP-1

Agenda

1. Opening of Meeting

2. Introduction

3. Review of Agenda

4. Initial Introduction of Working Papers and Attribution

5. Guidance material for VDL frequency assignment planning criteria

5a VDL frequency assignment planning criteria for VDL mode 3

WP 5

5b VDL frequency assignment planning criteria for VDL mode 4

WP 6

6. Compatibility between VDL and DSB-AM on-board implementation problems

WP 7

7. Guidelines for the introduction of VDL into the VHF band

WP 8, 9

8. Global signaling channel for VDL mode 4

9. Review of Draft Report of WG-B 18th and 19th meetings

10. Review of Open Action items

11. ICAO guidance material on radio frequency interference

12. PEDs – Compatibility with aviation systems

12a. UWB

WP 3

12b GSM

WP 2, 4

13. WG-B Accomplishments

14. WG-B goals/where we are going

15. Any other items

16 Next Meeting date and location.

APPENDIX 2

List of Working Papers

|Agenda Item |Working Paper |Title |

|3 |1 |Agenda |

|12b |2 |GSM On-board Aircraft, Update on the European Situation and Issues to be Addressed |

|12a |3 |Ultra WideBand, Update on the European Situation and Testing Carried Out Within the UK |

|12b |4 |Subject: Licensing and operation of GSM base stations on board aircraft |

|5a |5 |Frequency Assignment Planning Criteria for VDL Mode 3 |

|5b |6 |Recommendation for Frequency Planning Criteria for VDL Mode 4 |

|6 |7 |Operational Experience of Operating VDL Mode 4 On-board Aircraft |

|7 |8 |Status of Implementation of VDL Mode 4 in Sweden |

|7 |9 |Brief VDL 4 Progress Report |

APPENDIX 3

List of Participants

|Name & Company |Address |Telephone/ |E-Mail |

| | |Fax | |

|Mr. John Mettrop |K6 G6 |Tel: +44 (0) 20 7453 6531 |john.mettrop@dap.caa.co.uk |

|Technical Manager |CAA House | | |

| |45-59 Kingsway |Fax: +44 (0) 20 7453 6565 | |

| |London WC2B 6TE | | |

| |United Kingdom | | |

|Mr. Robert Witzen |International Civil Aviation Organization |Tel: + 1 (514) 954-8219 |rwitzen@icao.int |

|Technical Officer |999 University Street |Ext. 6714 | |

|CNS Section |Montreal, Quebec |Fax: + 1 (514) 954-6759 | |

|Air Navigation Bureau |Canada H3C 5H7 | | |

|Patrick Delhaise |DAS/CSM |Tel +32 2 7293478 |patrick.delhaise@ |

|Eurocontrol |Rue de la Fusee 36 |Fax +322 729 3811 |eurocontrol.int |

| |B-1120 Brussels | | |

| |Belgium | | |

|Torsten Jacob |International Civil Aviation Organization |Tel: + 1 (514) 954-8219 |tjacob@icao.int |

| |999 University Street |Ext. 8136 | |

| |Montreal, Quebec |Fax: + 1 (514) 954-6759 | |

| |Canada H3C 5H7 | | |

|Robert Frazier |Air Traffic Organization Technical |Tel |robert.frazier@ |

|FAA |Operations |+ 1 202-267-9722 | |

| |800 Independence Avenue |Fax | |

| |Washington, DC 20591, USA |+ 1 202-267-5901 | |

|Loftur Jónasson |Gufunes Telecom Centre |Tel |loftur@gannet.is |

|Gannet ATS Com |Soleyjarima 6 |+354-563-6538 | |

| |IS-112 Reykjavík | | |

| |Iceland | | |

|Larry Johnsson |LFV Group |Tel |Larry.johnsson@lfv.se |

| |ANS ATM Development |+46 40 6131381, +46 708 | |

| |Box 52 |151381 | |

| |SE-230 32 Malmo-Sturup | | |

| |Sweden | | |

|Yuji Matsukubo |ENRI |Tel |mailto:matsukubo@enri.go.jp |

|ENRI |Researcher |+81-422-41-3180 | |

| |7-42-43 Jindaiji-Higashimachi, |Fax | |

| |Chofu-shi Tokyo |+81-422-41-3182 | |

|Victor Nagowski |VJN Enterprises, Inc. |Tel |vnagowski@ |

| |1125 Crestview Drive |410-991-6521 | |

| |Annapolis, MD 21409 | | |

APPENDIX 4

AERONAUTICAL COMMUNICATIONS PANEL (ACP)

WORKING GROUP B-20

Montreal, Canada 29 – 31 May 2006

List of Action Items

1. (WG-B/16) The WG-B participant from Sweden will determine the status of work on identifying VDL Mode 4 global signaling channels.

Status: Open.

2. (WG-B/20) A question was raised as to how close was the emission spectrum of the VDL Mode 4 transmitter to the ICAO mask. This may be important when developing frequency planning criteria from this one radio. Mr. Johnsson will provide emission characteristics of the VDL Mode 4 receiver used in WP 6.

Status: Open

3. (WG-B/20) A subgroup was established to update the FPC Document with VDL Mode 4 material. The data in WP 6 will be used to begin populating this section. As additional data is collected and approved, the VDL M4 criteria can be updated. Volunteers to participate in this group include Mr. Johnsson, Eurocontrol and the WG B Secretary. No volunteer was found to lead this sub working group. The group is to provide updates to the VDL Mode 4 frequency assignment planning criteria to be reviewed at a future WG B meeting, not later than February 2007.

Status: Open

4. (WG-B/20) With respect to WP 7, the meeting noted that information on the channel separation between VDL and DSB-AM was lacking as was the antenna being used by the ATC DSB-AM radio and the coupling loss between them. Mr. Johnsson stated that he would try to provide this data at the next meeting of WG B.

Status: Open

5. (WG-B/20) Report of the 19th meeting. Why is the FAA S/P=20 in Table 1, but the required channel separation is the largest at 4 in Table 2? Are the values in Table 2 guard band channels or the next usable channel? A reference is needed for paragraph 9. Paragraph 10.2 is an addition to WG B work program. Mr. Frazier agreed to investigate these issues and have answers by the next WG B meeting.

Status: Open

APPENDIX 5

Report of the 19th Meeting of

Aeronautical Communications Panel (ACP)

Working Group B

26 – 31 May, 2005

Montreal, Canada

1. Opening

. The Rapporteur, Mr. Donald Willis, sent his regrets for not being able to attend the meeting. Mr. Robert Frazier acted as Rapporteur. The Secretary for the group was Mr. Robert Witzen from ICAO.

. The working group reviewed the agenda, and after a slight rearrangement of items, was approved. The approved agenda is in Appendix 1.

. There were a total of 6 participants to this meeting of WG-B. The list of participants is in Appendix 2.

. There was one working paper, and one information paper. It was listed in Appendix 3.

. A list of action items is in Appendix 4. The list was reviewed by WG-B members and updated.

. The group agreed on four goals for the meeting: (1) approval of the Report of 17th Meeting. [Note: The 18th meeting was held in conjunction with WG F. A joint report was produced. That report is available for review. See Agenda Item 8 of the Joint Meeting Report]; (2) Investigate the proposed new interference criteria for VDL Modes 2 and 3 which was presented by Japan (WP-5), and (3) update and reorganize the Action Items

. Introductions were not necessary since all participants, except for the Rapporteur, were in attendance at WG M (May 23-26, 2005).

2. Guidance material for VDL frequency assignment planning criteria. There were no contributions for this agenda item.

3. Final review of ICAO SARPs material (frequency assignment planning criteria) for VDL Mode 2. There were no contributions for this agenda item.

4. VDL frequency assignment planning criteria for VDL mode 3.

. Mr. Nakatani of Japan presented WP-5. The Electronic Navigation Research Institute (ENRI) has carried out radio interference tests between DSB-AM and VDL Mode 3 to examine impact of interference to VDL Mode 3 on voice quality using a voice quality tester (VQT). This paper describes the test setup and presents the test results. One of evaluation tools installed in the VQT is described in ITU-T Rec P.862 Perceptual Evaluation of Speech Quality (PESQ). The VQT system is a computer employing specialized software. The VQT feeds the desired signal generator with a voice phrase. It then records the audio output of the victim receiver under test. A comparison is made between the two audio files, and a score between 1 (worst) and 4.5 (best) is assigned. The score indicates receiver voice quality. The higher score, the more exact a replica the VDL output is to the original. Tests were made for VDL Mode 3 receiver as the victim, with both VDL and DSB-AM as interference sources. Also, testing was conducted with VDL as the interferer and an analog DSB-AM receiver as victim. Co-channel and adjacent channel testing was conducted.

. The results were discussed and it was agreed that the co-channel D/U for interference to DSB-AM agreed with the S/P criteria. An acceptable PESQ score for co-channel interference to VDL produced a D/U of approximately 15 dB. For adjacent channel interference, VDL interference to VDL produced only small reduction in the PESQ score even for a one-channel separation. However, DSB-AM interference to VDL seemed to require 2 channels. For VDL interference to DSB-AM, three channels seemed to produce an acceptable score.

. Material was submitted by Yasuyoshi Nakatani, which was prepared to compare test results based on PESQ scores, bit error rate (BER) and signal to pulse ratio (S/P). The material is contained in Tables 1 and 2

Table 1. Comparisons of Co-Channel Test Results based on PESQ, BER and S/P for Radio Interference between DSB-AM and VDL Mode 3

|Interferer Tx |Victim Rx |Method |Result |Conducted by |

|VDL3 |VDL3 (GND) |PESQ |14 dB |ENRI |

| | |BER |17 dB * |ENRI |

|VDL3 |VDL3 (AIR) |PESQ |14 dB |ENRI |

| | |BER |17 dB * |ENRI |

| | |BER |18 dB |FAA |

|DSB-AM |VDL3 (GND) |PESQ |15 dB |ENRI |

| | |BER |17 dB * |ENRI |

|DSB-AM |VDL3 (AIR) |PESQ |15 dB |ENRI |

| | |BER |17 dB * |ENRI |

| | |BER |18 dB |FAA |

|VDL3 |DSB-AM (AIR) |PESQ |35 dB |ENRI |

| | |S/P |32 dB ** |ENRI |

| | |S/P |20*** |FAA |

Note) *: Received level of desired signal was set to -88 dBm

**: Received level of desired signal was set to -82 dBm

*** Based on test of only one DSB-AM receiver. Previous U.S. test resulted in a D/U of 30 dB.

Table 2. Required Channel Separation for 2000 ft.Distance Between Interferer and Victim.

|Interferer Tx |Victim Rx |Method |Required Channel |Conducted by |

| | | |Separation | |

|VDL3 |VDL3 (AIR) |PESQ |1 channel |ENRI |

| | |BER |2 channel |ENRI |

| | |BER |2 channel |FAA |

|VDL3 |DSB-AM (AIR) |PESQ |3 channel |ENRI |

| | |S/P |2 channel |ENRI |

| | |S/P |4 channel |FAA |

|DSB-AM |VDL3 (AIR) |PESQ |2 channel |ENRI |

| | |BER |2 channel |ENRI |

| | |BER |2 channel |FAA |

1. References for Tables 1 and 2.

WG-B/12 WP8 VDL Mode 3 to DSB-AM Interference Test (ENRI)

WG-B/14 WP5 Impacts of Radio Interference on VDL Mode 3 (ENRI)

WG-B/16 WP17 VDL Mode 3 to DSB-AM Interference Testing (FAA)

WG-B/17 WP8 VDL Mode 3 to VDL Mode 3 Avionics Interference Testing (FAA)

WG-B/19 WP5 Report of VDL Mode 3 Voice Quality Test with Radio Interference (ENRI)

. It was noted that PESQ is appropriate for voice communication, not for data. A comparison between voice qualities using both techniques (PESQ and BER) is needed. The PESQ technique requires specialized computer software, which is patented technology. The VQT must be leased or purchased. It was concluded that PESQ technique needs additional study. However the following was agreed to. The co-channel results for PESQ consistently gave smaller D/Us than did BER. For co-channel interference to DSB-AM, PESQ gave a larger D/U requirement than did S/P. The wide variation between results for DSB-AM as victim (20 dB to 35 dB) requires further study. For adjacent channel test, PESQ and BER give virtually identical results. However, for S/P testing, PESQ testing gave results that are straddled by those from U.S. and Japan using S/P. In general, for VDL as the victim, the larger value of D/U for co-channel and channel separation for adjacent channel, is preferable to use since VDL Mode 3 is to be used for both voice and data. For the case where DSB-AM is the victim, the answer is more muddy, with a significant variation in the results indicated in both tables

5. VDL frequency assignment planning criteria for VDL mode 4. Eurocontrol submitted IP-1. It states that: “Provided that the [VDL Mode 4] avionics improvement is confirmed by the tests, it is expected that implementable frequency planning criteria could be proposed taking into account ground-station tests already achieved and avionics tests to be redone.” …”Eurocontrol has developed in the last months a VDL Mode 4 co-site testing plan that will be applied for these tests. This work plan is published on the Eurocontrol VDL Mode 4 web pages ()”.

6. Compatibility between VDL’s and DSB-AM, including a review of on-board implementation problems. There were no contributions for this agenda item.

7. Guidelines for the introduction of VDL into the VHF band. There were no contributions for this agenda item.

8. Global signaling channel for VDL mode 4. There were no contributions.

9. ICAO guidance material on radio frequency interference. There were no contributions for this agenda item. The Secretary indicated that WG-B may be taking on additional frequency interference work outside the VHF Comm band. This work may include HF on Power Line Carrier (PLC), cable TV, SSR/Mode S self-interference due to ADS-B and ACAS. Further discussion must be held on this addition to the WG-B work program.

10. Any other item WG-B members identify and location of next meeting.

Mr. Nakatani proposed that WG-B and WG-M be merged, because recent WG-B activities were not very active. The secretary responded that such a proposal was rejected at the AMCP/8 meeting by some panel members as well as the ANC. However, considering the experience gained with separate meetings of WG-B and WG-M, he expressed his support for this proposal and agred to undertake to bring a relevant proposal to the WG of the Whole meeting in June 2005.

The Secretary stated that there is a need to address the number of channels in Annex 10 allowed for digital links. Currently there are four at the top of the 136-137 MHz band.

11. Next Meeting and Closing. The next meeting of WG-B is scheduled as a joint meeting with WG-M during the week of November 7-11, 2005 at ICAO Headquarters, Montreal Canada.

12 The meeting concluded on May 30.

Appendices

7. WP-1: Agenda

8. WP-2: Draft Report of the 17th Meeting

9. WP-3: List of Working Papers

10. WP-4: List of Action Items

11. WP-5: Report of VDL Mode 3 Voice Quality Tests with Radio Interference

12. WP-6: List of Participants

13. IP-1: VDL Mode 4 work program at Eurocontrol

14. Flimsy: WG-B 2004 Activities

15. Flimsy: Comparisons of Test Results based on PESQ, BER and S/P

APPENDIX 6

WP-WG-B/20 WP-5

Agenda Item 6: FREQUENCY ASSIGNMENT PLANNING CRITERIA FOR VDL MODE 3

Prepared by

Yasuyoshi Nakatani, ENRI

SUMMARY

This paper provides an update for the Frequency Assignment Planning Criteria for VDL Mode 2, 3 and 4 by incorporating a VDL Mode 3 section into the current version of the criteria. It also corrects some errors in the VDL Mode 2 section.

0

Yuji Matsukubo, ENRI

Ed Coleman, FAA

1. Introduction

The material for Frequency Planning Criteria for VDL Mode 2 and VDL Mode 3 is presented in the Attachment. The Attachment provides an update for the Frequency Assignment Planning Criteria for VDL M ode 2, 3 and 4 by incorporating a VDL Mode 3 section into the current version of the criteria. It also corrects some errors in the VDL Mode 2 section.

2. Recommendation

The group is to consider the material in the Attachment as an upgrade to the Frequency Assignment Planning Criteria for VDL Mode2 and 3.

Attachment to WP 5

FREQUENCY ASSIGNMENT PLANNING CRITERIA FOR VDL MODE 2, 3 AND 4

This material is intended to be published in the ICAO Handbook on aviation spectrum requirements; material should be included in Annex 10 to refer to this Handbook. Also, ICAO Regions should be invited to include this material in their frequency planning process.

1. INTERFERENCE THRESHOLDS

The interference threshold for the VHF digital link (VDL) is specified (Annex 10, Volume III, Part I, paragraph 6.3.5.1) as follows:

a) VDL Mode 2 maximum corrected bit error rate (BER) is 1 in 104;

Note. The uncorrected BER value of 1 in 103 is to be used in the testing of equipment. The forward error correction method used in VDL Mode 2 (see Annex 10, Volume III, Part I, paragraph 6.4.3.1.2.1) translates an uncorrected BER of 1 in 103 into a corrected BER of 1 in 104 (see also MOPS for VDL Mode 2).

b) VDL Mode 3 maximum uncorrected bit error rate is 1 in 103; and

c) VDL Mode 4 maximum uncorrected bit error rate is 1 in 104.

Note. The BER value for VDL Mode 4 corresponds to a message error rate (MER) of approximately 2 in 102 using the formula MER=1-(1-BER)216 and assuming a one-slot message with 216 bits of data. VDL Mode 4 does not provide forward error correction of the data.

2. SIGNAL PARAMETERS

The values for the radio frequency signal in Table 1 are to be used in the testing of equipment and the development of separation criteria for VDL.

The VDL interference immunity criteria (D/U* ratio) which are identified in these VDL frequency assignment planning criteria and developed in accordance with the test methods in section 4 are defined as follows:

“The protection parameter (as specified in section 3, e.g. an S/P ratio of 6 dB) shall be met with the specified minimum desired signal level (dBm) at the receiver input (as specified in Table 1) and an undesired signal with a signal level (dBm) at the receiver input causing interference not exceeding the protection parameter; the D/U* ratio is the ratio between the two signal levels as measured on their transmitted frequency (either co- or adjacent channel to the desired frequency).”

Table 1 Values for the Radio Frequency Signal

|Parameter |DSB-AM |DSB-AM |VDL M2 |VDL M2 |VDL M3 |VDL M3 |VDL M4 |VDL M4 |

|TRANSMITTER |Airborne |Ground |Airborne |Ground |Airborne |Ground |Airborne |Ground |

|Output power transmitter |44 dBm |50 dBm |42 dBm |44 dBm |44 dBm |44 dBm |42 dBm |45 dBm |

| |(25 W) |(100 W)1) |(16 W) |(25 W) |(25 W) |(25 W) |(15 W) |(32 W) |

|Feeder loss (assumed) |-3 dB |-3 dB |-3 dB |-3 dB |-3 dB |-3 dB |-3 dB |-3 dB |

|Antenna gain (assumed) |0 dB |2 dB |0 dB |2 dB |0 dB |2 dB |0 dB |2 dB |

|EIRP |41 dBm |49 dBm |39 dBm |43 dBm |41 dBm |43 dBm |40 dBm |44 dBm |

| |(12.5 W) |(80 W) |(8W) |(20 W) |(12.5 W) |(20 W) |(10 W) |(25 W) |

|Adjacent channel emission (Transmitter) for VDL specified in Annex 10, Vol. III, Part I, paragraph 6.3.4 |

|1st adj. ch. (16 kHz bandwidth) |Not specified in Annex 10 |-18 dBm |-18 dBm |-18 dBm |-18 dBm |-18 dBm |-18 dBm |

|2nd adj. ch. (25 kHz bandwidth) |Not specified in Annex 10 |-28 dBm |-28 dBm |-28 dBm |-28 dBm |-28 dBm |-28 dBm |

|4th adj. ch. (25 kHz bandwidth) |Not specified in Annex 10 |-38 dBm |-38 dBm |-38 dBm |-38 dBm |-38 dBm |-38 dBm |

|8th adj. ch. (25 kHz bandwidth) |Not specified in Annex 10 |-43 dBm |-43 dBm |-43 dBm |-43 dBm |-43 dBm |-43 dBm |

|16th adj. ch. (25 kHz bandwidth) |Not specified in Annex 10 |-48 dBm |-48 dBm |-48 dBm |-48 dBm |-48 dBm |-48 dBm |

|32nd adj. ch. (25 kHz bandwidth) |Not specified in Annex 10 |-53 dBm |-53 dBm |-53 dBm |-53 dBm |-53 dBm |-53 dBm |

|RECEIVER |

|Min. signal 2) at receiver antenna |75 μV/m |20 μV/m |75 μV/m |20 μV/m |75 μV/m |20 μV/m |35 μV/m |35 μV/m |

|Annex 10, Vol. III |(-82 dBm) |(-93 dBm) |(-82 dBm) |(-93 dBm) |(-82 dBm) |(-93 dBm) |(-88 dBm) |(-88 dBm) |

| |part II |part II |part I |part I |part I |part I |part I |part I |

| |2.2.1.2 |2.3.1.2 |6.2.2. |6.3.2 |6.2.2. |6.3.2 |6.9.5.1.1.1 |6.9.5.1.1.1 |

|Feeder loss |-3 dB |-3 dB |-3 dB |-3 dB |-3 dB |-3 dB |-3 dB |-3 dB |

|Antenna gain |0 dB |2 dB |0 dB |2 dB |0 dB |2 dB |0 dB |2 dB |

|Min. signal at receiver input |-85 dBm |-94 dBm |-85 dBm |-94 dBm |-85 dBm |-94 dBm |-91 dBm |-89 dBm |

|Out-of-band immunity performance of receiver 3) as per Annex 10, Volume III, Part I, paragraph 6.3.5.3 (VDL) and Volume III, Part II, paragraph 2.3.2.8 (DSB-AM). |

|1st adj. ch. | | |-40 dB |-40 dB |-40 dB |-40 dB |-40 dB |-40 dB |

|4th adj. ch. |-50 dB |-50 dB |-60 dB |-60 dB |-60 dB |-60 dB |-60 dB |-60 dB |

1) Output power: for calculating separation distances in section 7, 100 W was assumed for the output power of the DSB-AM (voice) ground based transmitter. Typical values of these stations of 25 W or 50 W will result in smaller separation distances.

2) Minimum signal level: conversion from input power (dBm) to field strength (μV/m and v.v.) was done on the basis of the following formula: Pr = E - 20logF - 167.2; where Pr is isotropically received power (dB(W)), E is the electric field strength (dB(μV/m) and F is the frequency (GHz) (ITU-R Recommendation PN.525-2 refers). This formula can be converted in 10logPr = 20logE – 20logF-77.2; where Pr is signal at receiver antenna (in space) in mW, E is the field strength at the antenna in µV/m and F is the frequency f in MHz.

3) Out-of-band immunity: values for the out-of-band immunity performance in section 5 (interference susceptibility of the receiver tested) are based upon actual measurements on a number of receivers. [Where receivers are used with different characteristics, adjustments in the separation distances are required. For VDL Mode 2, reference is made to working paper 5 submitted to the 11th meeting of WG B of the Aeronautical (Mobile) Communications Panel A(M)CP which is available on ]

3. TESTING PARAMETERS

. Interfered Station: DSB-AM (Air and Ground Receiver)

. Minimum (desired) signal levels at DSB-AM receiver input to be used in the test measurements are:

a) Ground stations: -94 dBm; and

b) Aircraft stations: -85 dBm

. Characteristics of the interfering (undesired) signals

Table 2 Characteristics of the Interfering Signals

|Interfering station |VDL M2 |VDL M3 1) |VDL M4 |

|S/P ratio 2) |6 dB |18 dB 1) |12 dB |

|Channel load |2% |1 timeslot 3) |Various |

| | |4 timeslots 3) |(see table 6 below) |

1) Only aircraft DSB-AM receivers are to be considered.

2) Accepted values after evaluation of audio samples of interference.

3) 1 timeslot operation used for all tests, except squelch break for which 4 slots are operating simultaneously.

Note. Either the 6 dB (S+N)/N ratio needs to be confirmed for VDL Mode 3 and 4 or it needs to be demonstrated that the S/P ratio is more constraining than the required (S+N)/N ratio.

. Interfered Station: VDL Mode 2 (Air and Ground Receiver)

Minimum (desired) signal levels at VDL Mode 2 receiver input to be used in the test measurements are:

a) Ground stations: -94 dBm; and

b) Aircraft stations: -85 dBm

Channel loading of the VDL Mode 2 is 20 % (for testing with VDL Mode 4 the channel loading of the VDL Mode 2 is 100 %).

Protection parameter: The bit error rate for VDL Mode 2 shall not exceed 1 in 103 (uncorrected).

Characteristics of the interfering (undesired) signals

Table 3 Characteristics of the Interfering Signals

|Interfering station |DSB-AM |VDL M2 |VDL M3 |VDL M4 |

|Channel load |Voice with 30% modulation |2 % |4 timeslots |100 % 2) |

| |depth 1) | | | |

1) See paragraph 4.3.2.a

2) Correction factors need to be applied to relate these values to particular operational scenarios. These are under development.

Note. The application of a channel loading of 2 % when VDL Mode 2 is the interfering (undesired) signal needs further clarification..

. Interfered Station: VDL Mode 3 (Air and Ground Receiver)

. Minimum (desired) signal levels at VDL Mode 3 receiver input to be used in the measurements are:

a) Ground stations: -94 dBm; and

b) Aircraft stations: -85 dBm

Protection parameter: The bit error rate for VDL Mode 3 shall not exceed 1 in 103 (uncorrected).

Characteristics of the interfering (undesired) signals

Table 4 Characteristics of the Interfering Signals

|Interfering station |DSB-AM |VDL M2 |VDL M3 |VDL M4 |

|Modulation depth or |Voice with 90% peak | |4 timeslots | |

|channel load |modulation depth 1) | | | |

1) This corresponds to 30% modulation with 1 kHz toneSee paragraph 4.3.a.

. Interfered Station: VDL Mode 4 (Air and Ground Receiver)

Minimum (desired) signal levels at VDL Mode 4 receiver input to be used in the test measurements are:

a) Ground stations: -89 dBm; and

b) Aircraft stations: -91 dBm

Channel loading of the VDL Mode 4 is 100 %.

Protection parameter: The message error rate (MER) for VDL Mode 4 shall not exceed 2 in 102 (which corresponds to a uncorrected bit error rate of 1 in 104).

. Characteristics of the Interfering Signals

Table 5 Characteristics of the Interfering Signals

|Interfering station |DSB-AM |VDL M2 |VDL M3 |VDL M4 |

|Modulation depth or |Voice with 90% peak |2 % | |Various 2) |

|channel load |modulation depth 1) | | | |

1) This corresponds to 30% modulation with 1 kHz tone.See paragraph 4.3.a

2) Correction factors need to be applied to relate these values to particular operational scenarios. These are under development. (see paragraph 3.4.5 and 3.4.6 below)

. VDL Mode 4 Interferer Channel Loading

Table 6 Channel Loading of Interferer

| | |

|Channel type |Channel Loading of Interferer |

| | | | |

| |Scenario 1 |Scenario 2 |Scenario 4 |

| |Aircraft on ground vs |Aircraft on ground vs ground station |Aircraft vs aircraft both |

| |aircraft on ground | |airborne |

| | | | | |

| | |Case A - ground station as |Case B - aircraft station as | |

| | |interferer |interferer | |

| | | | | |

|ADS-B |6.7% |3.3% |6.7% |0.44% |

| | | | | |

| |5 x 1-slot per second |3 x 1-slot and 1 x 2-slot per|5 x 1-slot per second |1 x 1-slot |

| | |2 seconds | |per 3 seconds |

| | | | | |

|Point-to-point |1.7% |40% |1.7% |0.33% |

|communication | | | | |

| | | | | |

| |5 x 1-slot and 5 x 2-slot per|10 x 1-slot and 20 x 2-slot |5 x 1-slot and 5 x 2-slot per|1 x 1-slot and 1 x 2-slot per|

| |12 seconds |per second |12 seconds |12 seconds |

| | | | | |

|TIS-B |0% |90% |0% |0% |

| | | | | |

| |- |22 x 3-slot per second |- |- |

. VDL Mode 4 Victim Loading

Table 7 Channel Loading of Victim

| | |

|Channel type |Channel Loading of Victim |

| | | | |

| |Scenario 1 |Scenario 2 |Scenario 4 |

| |Aircraft on ground vs |Aircraft on ground vs ground station |Aircraft vs aircraft both |

| |aircraft on ground | |airborne |

| | | | | |

| | |Case A - ground station as |Case B - aircraft station as | |

| | |victim |victim | |

| | | | | |

|ADS-B |1.3% |1.3% |3.3% |0.44% |

| | | | | |

| |1-slot per second |1-slot per second |3 x 1-slot and 1 x 2-slot per|1 x 1-slot per 3 seconds |

| | | |2 seconds | |

| | | | | |

|Point-to-point |0.33% |0.33% |40% |0.33% |

|communication | | | | |

| | | | | |

| |1 x 1-slot and 1 x 2-slot per|1 x 1-slot and 1 x 2-slot per|10 x 1-slot and 20 x 2-slot |1 x 1-slot and 1 x 2-slot per|

| |12 seconds |12 seconds |per second |12 seconds |

| | | | | |

|TIS-B |0% |0% |90% |0% |

| | | | | |

| |- |- |22 x 3-slot per second |- |

4. TEST METHODS

Test setup for testing of interference into a DSB-AM receiver caused by VDL Mode 2, 3 and 4 signals and for testing of interference into a VDL receiver caused by DSB-AM or VDL signals is given in Figure 1.

[pic]

Figure 1 Test Setup

. Impact of VDL Signal on DSB-AM Receiver (measuring of D/U ratio)

The test methods in 4.2 to 4.34 below can be used to assess the impact of VDL signals into a DSB-AM receiver and are based on measuring the ratio of power of the interfered (desired) and interfering (undesired) signal levels at the receiver input.

Tests on adjacent channels were made with 25 kHz increments. Measurements made with 25 kHz equipment at a given frequency separation (kHz) would also apply to 8.33 kHz equipment with the same frequency separation (kHz). The results are presented with reference to the adjacent 25 kHz channel number. Further work is necessary to identify if the frequency separation for 8.33 kHz equipment can be reduced. Also, material needs to be developed with regard to the separation between VDL and DSB-AM with 50 kHz channel spacing.

. Test Procedure for Measuring the Squelch Break of the DSB-AM Receiver (all VDL modes)

a) No desired DSB-AM signal is present; and

b) Co- and adjacent channel operation. The undesired VDL signal source is tuned to the same frequency as the DSB-AM receiver or the 1st, 2nd, 3rd, 4th, 5th, 10th, 20th and 40th adjacent channel with increments of 25 kHz. The undesired VDL signal level is increased until the squelch is lifted. The level is recorded.

. Test Procedure for Measuring the D/U Ratio on the Desired DSB-AM Channel by the Interfering (undesired) VDL Mode 3. (Evaluation of the effect of the interference on the audio output of the receiver)

a) The desired DSB-AM signal source is set to produce a signal level of -85 dBm (for aircraft receiver testing) or -94 dBm (for ground equipment testing) at the DSB-AM receiver input, 90% peak amplitude modulation with ATC phrases at the input of the DSB-AM receiver. This corresponds to 30% modulation with a 1 kHz tone;

b) The undesired VDL Mode 3 signal source is set to give a 30 dB D/U at the centre frequency of the desired AM signal. The DSB-AM receiver is tuned to the same frequency. A recording is made of the audio output from the receiver for each adjacent channel;

c) The undesired VDL Mode 3 signal is then increased to give a 30 dB D/U in the pass band of the DSB-AM receiver on the first and subsequent adjacent channels and a recording is made of the audio output from the receiver for each adjacent channel; and

d) A listening panel then assesses the quality of the audio results recorded, scoring each.

Note. The D/U in this section is the ratio (dB) between the desired and undesired signal in the DSB-AM receiver pass band.

. Test Procedure for Assessing the Impact of an Undesired VDL Signal on a Desired DSB-AM Receiver. (Signal + Noise to Noise ratio (S+N)/N and Signal to Pulse (S/P) ratio)

The test methods in 4.4.2 and 4.4.3 below can be used to assess separately The test methods for measuring the (S+N)/N ratio degradation and signal-to-pulse(S/P) ratio can be used to assess separately the effects of a digital signal on a DSB-AM receiver. By separating the effects of the pulse modulation and continuous modulation of a digital signal on the audio signal, these two objective parameters can be separately measured and tested. In the presence of a desired signal, the signal + noise to noise ((S+N)/N) ratio and signal to pulse (S/P) ratio as specified in Table 2 are considered at the audio output of the receiver. The level of acceptability of these (S+N)/N ratios and S/P ratios was established through varying the ratios level and through conducting subjective tests with audio samples. The various (S+N)/N and S/P ratios in Table 2 were developed with this method.

Test Method for Measuring the (S+N)/N Ratio Degradation

a) The desired DSB-AM signal source is set so as to produce a signal level as indicated in Table 2 of paragraph 3.1 at the DSB-AM receiver input, 30% amplitude modulated with 1 kHz tone;

b) Co- and adjacent channel operation. The undesired VDL signal source is set in continuous mode 1) with a centre frequency equal to that of the DSB-AM receiver or the 1st, 2nd, 3rd, 4th, 5th, 10th, 20th or 40th adjacent channel. The level of undesired VDL signal source at the input of the DSB-AM receiver is varied until a (S+N)/N degradation consistent with Table 2 is measured at the audio output receiver. The level of the undesired VDL signal at the receiver input is noted. The audio distortion is checked to ensure that it is less than 10%. If this is not the case then the undesired VDL signal which is level required to achieve 10% audio distortion is measured and noted.

1) Continuous mode refers to a continuous transmission of data. This is obtained by removing the ramp up and ramp down sequence in the VDL, which results in VDL Mode 3 having the same continuous mode characteristics as VDL Mode 2 since these two systems have the same modulation scheme.

. Test Method for Measuring the Signal-to-Pulse (S/P) Ratio

a) The desired DSB-AM signal source is set so as to produce a signal level as indicated in paragraph 3.1.1, with a 30% modulated 1 kHz tone at the input of the DSB-AM receiver as reference signal S. The level of this reference signal is measured at the audio output of the receiver;

b) After removal of the reference signal, the undesired VDL signal is added to the receiver input and set to achieve S/P ratios not greater than those specified in Table 2, where S is the level of the reference signal and P is the peak level of the pulsed signal measured at the audio output of the DSB-AM receiver; and

c) Co- and adjacent channel operation. The undesired VDL signal source is set in pulse (burst) mode with a centre frequency equal to that of the DSB-AM receiver or the 1st, 2nd, 3rd, 4th, 5th, 10th, 20th and 40th adjacent channel. The level of the undesired VDL signal source at the input of the DSB-AM receiver is varied until the S/P ratios in Table 2 are met. This level is noted.

d) Audio pulses are the remaining pulses on the interfered (desired) audio signal and are caused through the ramp up and ramp down sequence of the VDL.

Note. When testing the interference from VDL Mode 2 into the DSB-AM receiver, it was observed that the D/U ratio obtained when measuring the (S+N)/N ratio is within the same range or lower than those obtained when measuring the S/P ratio. Therefore only the channel rejection characteristics obtained when measuring S/P ratios were considered when developing protection requirements and separation distances.

. Test Procedure for Assessing the Impact of Either an Undesired DSB-AM Signal or Undesired VDL Signal on a Desired VDL Mode2, Mode 3 or Mode 4 Receiver

. Test Method for Measuring the Bit Error Rate of the VDL

a) The desired VDL signal source is set so as to produce a signal level as indicated in paragraph 3.2 (VDL Mode 2), paragraph 3.3 (VDL Mode 3) or paragraph 3.4 (VDL Mode 4) at the input of the desired VDL receiver. The VDL receiver is tuned to the same frequency as the desired VDL signal source;

b) Co- and adjacent channel operation. The undesired VDL or DSB-AM signal source is tuned to the same frequency as the desired VDL receiver or the 1st, 2nd, 3rd, 4th, 5th, 10th, 20th and 40th adjacent channel. The level of the undesired signal VDL or DSB-AM signal source is increased until the bit error rate, as specified in Annex 10 (see paragraph 1.1) is reached but not exceeded. The level of the undesired signal source at the input of the VDL receiver is noted. The protection parameters of the undesired signal source are as specified in section 3.

. Test Procedure for Assessing the Impact of an Undesired VDL Mode 4 Signal on VOR or ILS Receiver

. VOR Receiver Testing

a) Test Setup

[pic]

Figure 2 Test Setup

b) Characteristics of the VOR and test method;

1) Channel spacing for VOR receiver is 50 kHz;

2) Co- and adjacent channel interference shall be investigated (1st, 2nd, 3rd and 4th adjacent VDL Mode 4 channel with 25 kHz increments);

3) A change in VOR bearing of 0.3E due to the interference of VDL Mode 4 shall be considered as interference threshold. (A change of 0.3E in the selected VOR bearing corresponds to a deviation in the VOR course indicator of 4.5 μA);

4) VOR frequency 112 MHz, 115MHz and 117.95MHz shall be tested;

5) The level of the VOR signal at the input of the VOR receiver shall be set at -79dBm.

c) Characteristics of the VDL Mode 4 signal;

1) The VDL Mode 4 interference source shall be incremented in steps of 25 kHz;

2) The following VDL Mode 4 duty cycles shall be investigated:

– 1.3% duty cycle (one sync burst transmission in one slot every second), simulating the worst case co-site (onboard aircraft) scenario;

– 2.7% duty cycle (two-slot burst transmission in every second), simulating the worst case co-site (onboard) scenario for transmission of e.g. TCP-information;

– 50% duty cycle (sync burst transmissions in every other slot), simulating a medium dense scenario of interferers at equal distance;

– 50% duty cycle (two slot transmissions in every other two slots), simulating a medium dense scenario of interferers at equal distance;

3) The undesired VDL Mode 4 signal is then increased to produce a change in the VOR bearing of 0.3 degree. This corresponds to a change in the course deflection current of 4.5 μA.

Note. 50% duty cycle leads to a beat frequency of 37 Hz. VOR’s are rather sensitive against low beat frequencies in the order of 30 Hz. This scenario should be considered as a medium dense scenario with interferences at equal distance.

. ILS-Localizer Receiver Testing

a) Test Setup

Test setup is equal to the test for VOR receiver.

b) Characteristics of the ILS-localizer and test method;

1) Channel spacing for ILS-localizer receiver is 50 kHz;

2) Co- and adjacent channel interference shall be measured (1st, 2nd, 3rd, and 4th adjacent VDL Mode 4 channel with 25 kHz increments);

3) A change in the ILS-localizer difference in depth of modulation (DDM) of 0.093 due to the interference of VDL Mode 4 shall be considered as interference threshold. (A change of 0.093 in the DDM corresponds to a deviation in the ILS course indicator of 4.5 μA);

4) ILS-localizer frequencies 111.95 MHz shall be tested;

5) The level of the ILS-localizer signal at the input of the localizer receiver shall be set at -86 dBm.

c) Characteristics of the VDL Mode 4 signal;

1) The VDL Mode 4 interference source shall be incremented in steps of 25 kHz;

2) The following VDL Mode 4 duty cycles shall be investigated:

– 1.3% duty cycle (one sync burst transmission in one slot every second), simulating the worst case co-site (onboard aircraft) scenario;

– 2.7% duty cycle (two-slot burst transmission in every second), simulating the worst case co-site (onboard) scenario for transmission of e.g. TCP-information;

– 50% duty cycle (sync burst transmissions in every other slot), simulating a medium dense scenario of interferers at equal distance;

– 50% duty cycle (two-slot burst transmissions in every other two slots), simulating a medium dense scenario of interferers at equal distance;

3) The undesired VDL Mode 4 signal is then increased to produce a change in the ILS-localizer bearing of 0.093 DDM. This corresponds to a change in the course deflection current of 4.5 μA.

5. OUT-OF-BAND IMMUNITY PERFORMANCE

Note. When in this section reference is made to adjacent channels, this reference is to the actual adjacent channel with 25 kHz separation.

. VDL Mode 2

. The following interference scenarios have been analyzed:

a) Interference caused by VDL Mode 2 into DSB-AM system;

b) Interference caused by DSB-AM system into VDL Mode 2; and

c) Interference from VDL Mode 2 into VDL Mode 2

. Interference Caused by VDL Mode 2 into DSB-AM System

. Co-channel Interference

No measurements addressing the co-channel interference from DSB-AM into VDL Mode 2 and from VDL Mode 2 into DSB-AM have been developed, as the same channel should not be used for VDL Mode 2 and DSB-AM. To avoid the need for interregional coordination, globally harmonized frequencies should be used for VDL Mode 2. Where possible, the band 136-137 MHz should be reserved for VDL operations. Coordination with ICAO regional office has been conducted to ensure that the band is reserved. Coordination of specific assignments still needs to be conducted in particular regions.

. Adjacent Channel Interference

Annex 10, Volume III, Part II, paragraph 3.2.8.2 contains the immunity criteria for DSB-AM receiving systems against interference from any VDL station.

It has been observed, on the basis of testing results of a number of aircraft DSB-AM receivers in accordance with the test method described in section 4, that the immunity performance characteristics in Annex 10 would result in overly pessimistic frequency assignment criteria to protect DSB-AM systems when interfered with a VDL Mode 2 signal. The DSB-AM receivers tested, which were considered to be representative for the airborne receivers currently in use (with 25 kHz characteristics), showed significantly better immunity performance characteristics than those given in Annex 10.

Considering the worst case test results for each of these receivers, the following interference immunity performance characteristics for DSB-AM systems when interfered with a VDL Mode 2 signal D/U ratios were developed:

Table 8 D/U Ratios (S/P = 6 dB)

for Desired DSB-AM and Undesired VDL Mode 2 signals

|Adjacent channel |D/U ratio (dB) |

|1 |-34 |

|2 |-53 |

|3 |-60 |

|4 |-63 |

|5 |-65 |

|10 |< -65 |

|20 |< -65 |

|40 |< -65 |

Note. These interference immunity characteristics need to be incorporated in Annex 10 and their compliance with MOPS needs to be assessed.

. Squelch Break

The squelch break for DSB-AM receivers required a VDL Mode 2 signal level greater than 0 dBm on the second and beyond adjacent channel. It was therefore considered that squelch break is not a parameter to be considered in frequency assignment planning.

. Interference Caused by DSB-AM System into VDL Mode 2

. Co-channel Interference (see paragraph 5.1.2.1)

. Adjacent Channel Interference

Annex 10, Volume III, Part I paragraph 6.3.5.3 contains the immunity criteria for VDL aircraft receiving systems against interference from any source (VDL or DSB-AM).

It has been observed, on the basis of testing results in accordance with the test method described in section 4.5, that the immunity performance characteristics in Annex 10 would result in overly pessimistic frequency assignment criteria to protect VDL Mode 2 system when interfered with a DSB-AM signal. The VDL Mode 2 receivers tested showed significantly better immunity performance characteristics than those given in Annex 10.

Considering these test results, the following interference immunity performance characteristics for VDL Mode 2 systems when interfered with a DSB-AM signal D/U ratios were developed:

Table 9 D/U Ratios (Uncorrected BER 1 in 103)

for Desired VDL Mode 2 and Undesired DSB-AM signals

|Adjacent channel |D/U ratio (dB) |

|1 |-33 |

|2 |-60 |

|3 |-60 |

|4 |-66 |

|5 |-69 |

|10 |< -69 |

|20 |< -69 |

|40 |< -69 |

Note. These interference immunity characteristics need to be incorporated in Annex 10 and their compliance with MOPS needs to be assessed.

It was concluded that the D/U ratio for VDL Mode 2 being interfered with DSB-AM systems is better that when DSB-AM systems are being interfered with VDL Mode 2. Therefore the calculation of minimum geographical separation distances concentrates on the protection of DSB-AM systems.

. Interference Caused by Undesired VDL Mode 2 into Desired VDL Mode 2

. Co-channel Interference

. The MOPS for VDL Mode 2 specifies that the co-channel D/U protection ratio is 20 dB.

Note. This needs to be incorporated in Annex 10.

. Adjacent Channel Interference

Measurements on an airborne VDL Mode 2 receiver (in accordance with the test method in section 4.45) showed the following D/U.

Table 10 D/U Ratios (Uncorrected BER 1 in 103)

for Desired VDL Mode 2 and Undesired VDL Mode 2

|Adjacent channel |D/U ratio (dB) |

|1 |-29 |

|2 |-66 |

|3 |-68 |

|4 |-67 |

|5 |-67 |

The channel loading on the desired signal is defined in paragraph 3.2.21 and on the undesired signal in paragraph 3.2.42.

. VDL Mode 3

. The following interference scenarios have been analyzed:

a) Interference caused by VDL Mode 3 into DSB-AM system;

b) Interference caused by DSB-AM system into VDL Mode 3; and

c) Interference from VDL Mode 3 into VDL Mode 3

. Interference Caused by VDL Mode 3 into DSB-AM System

. Co-channel Interference

Although the same channel should not be used for VDL Mode 3 and DSB-AM, impact of VDL Mode 3 signals on DSB-AM signals was assessed on the same frequency (channel) at S/P ratio 18 dB. Considering the worst case test results, the following interference immunity performance characteristic for DSB-AM systems when interfered with a VDL Mode 3 signal was developed.

[Table 11 D/U Ratios (S/P = 18 dB)

for Desired DSB-AM and Undesired VDL Mode 3 signals

|Channel |D/U ratio (dB) |

|Co-channel |20 |

Note: This interference immunity characteristic is based on the test result conducted by the FAA. However D/U ratio 33 dB was obtained from the worst case test results carried out by the ENRI. Therefore the value in Table 11 needs to be reviewed.]

. Adjacent Channel Interference

Annex 10, Volume III, Part II, paragraph 2.3.2.8.2 contains the immunity criteria for DSB-AM receiving systems against interference from any VDL station.

[It has been observed, on the basis of testing results of a number of aircraft DSB-AM receivers in accordance with the test method described in section 4, that the immunity performance characteristics in Annex 10 would result in overly pessimistic frequency assignment criteria to protect DSB-AM systems when interfered with a VDL Mode 3 signal. The DSB-AM receivers tested, which were considered to be representative for the airborne receivers currently in use (with 25 kHz characteristics), showed significantly better immunity performance characteristics than those given in Annex 10.]

Considering the worst case test results for each of these receivers, the following interference immunity performance characteristics for DSB-AM systems when interfered with a VDL Mode 3 signal were developed:

Table 12 D/U Ratios (S/P = 18 dB)

for Desired DSB-AM and Undesired VDL Mode 3 signals

|Adjacent channel |D/U ratio (dB) |

|1 |-22 |

|2 |-36 |

|3 |-49 |

|4 |-54 |

Note. These interference immunity characteristics need to be incorporated in Annex 10 and their compliance with MOPS needs to be assessed.

. Interference Caused by DSB-AM System into VDL Mode 3

. Co-channel Interference

Although the same channel should not be used for VDL Mode 3 and DSB-AM, impact of DSB-AM signals on VDL Mode 3 signals was assessed on the same frequency (channel) at uncorrected BER 1 in 103. Considering the worst case test results, the following interference immunity performance characteristic for VDL Mode 3 when interfered with a DSB-AM signal was developed.

Table 13 D/U Ratios (Uncorrected BER = 1 in 103)

for Desired VDL Mode 3 and Undesired DSB-AM signals

|Channel |D/U ratio (dB) |

|Co-channel |18 |

. Adjacent Channel Interference

Annex 10, Volume III, Part I paragraph 6.3.5.3 contains the immunity criteria for VDL aircraft receiving systems against interference from any source (VDL or DSB-AM).

It has been observed, on the basis of testing results in accordance with the test method described in section 4.5, that the immunity performance characteristics in Annex 10 would result in overly pessimistic frequency assignment criteria to protect VDL Mode 3 system when interfered with a DSB-AM signal. The VDL Mode 3 receivers tested showed significantly better immunity performance characteristics than those given in Annex 10.

Considering these test results, the following interference immunity performance characteristics for VDL Mode 3 systems when interfered with a DSB-AM signal D/U ratios were developed:

Table 14 D/U Ratios (Uncorrected BER 1 in 103)

for Desired VDL Mode 3 and Undesired DSB-AM signals

|Adjacent channel |D/U ratio (dB) |

|1 |-52 |

|2 |-52 |

|3 |-61 |

|4 |-65 |

Note. These interference immunity characteristics need to be incorporated in Annex 10 and their compliance with MOPS needs to be assessed.

. Interference Caused by Undesired VDL Mode 3 into Desired VDL Mode 3

. Co-channel Interference

Measurements on an airborne VDL Mode 3 receiver (in accordance with the test method in section 4.4) showed the following D/U.

Table 15 D/U Ratios (Uncorrected BER = 1 in 103)

for Desired VDL Mode 3 and Undesired VDL Mode 3 signals

|Channel |D/U ratio (dB) |

|Co-channel |18 |

. Adjacent Channel Interference

Measurements on an airborne VDL Mode 3 receiver (in accordance with the test method in section 4.4) showed the following D/U.

Table 16 D/U Ratios (Uncorrected BER 1 in 103)

for Desired VDL Mode 3 and Undesired VDL Mode 3

|Adjacent channel |D/U ratio (dB) |

|1 |-48 |

|2 |-60 |

|3 |-65 |

|4 |-66 |

The channel loading on the undesired signal in paragraph 3.3.3

. VDL Mode 4

6. INTERFERENCE MODEL

. Propagation Model

Separation distances shall be calculated on the basis of free space propagation.

The transmission loss (Lbf) using free space propagation characteristics can be calculated as follows:

Lbf (dB) = 20log(f) + 20log(d) + 32.4 (Re. ITU-R Recommendation 525-2) (1)

where: f = MHz

d = km

. Interference Model

[pic]

Pd - Pu = D/U = Pd - {(Tu +Lu + Gu) -Lbf}

where: Pd, Pu and Tu are expressed in dBm (2)

Lu, Gu and Lbf are expressed in dB

From (1) and (2) the separation distance can be calculated by:

20log(d) = D/U - Pd + Tu + Lu + Gu - 20log(f) - 32.4 (3)

The EIRPu of the undesired transmitter equals Tu + Lu + Gu which converts formula (3) into

20log(d) = D/U* - Pd + EIRPu - 20log(f) - 32.4 (4)

Note. The factor 20log(f) introduces a variation of 1.24 dB in the results of calculating 20log(d). 20log(f) is for the frequency 136 MHz 42.67 and for 118 MHz 41.43; therefore minimum separation distances are at the lower band edge slightly larger than at 136 MHz.

7. SEPARATION DISTANCES FOR VDL MODE 2

The tables provided in this chapter cover the following six (2+2+2) possible interference pairs.

a) VDL Mode 2 aircraft into DSB-AM aircraft and ground stations (2)

b) DSB-AM aircraft into VDL Mode 2 aircraft and ground stations (2)

c) VDL Mode 2 aircraft into VDL Mode 2 aircraft and ground stations (2)

However, in total, there are 16 interference pairs, not six. The table below maps the 16 cases to the separation distance tables provided in this document and provides explanation for the cases not explicitly treated in the tables:

Table 17171711 Interference Pairs (A/C: aircraft; GS: ground station)

| |Victim Station |

| |VDL M2 A/C |VDL M2 GS |DSB-AM A/C |DSB-AM GS |

|Undesired|VDL M2 A/C |Table 117-C, left |Table 117-C, right |Table 117-A, left |Table 117-A, right |

|Station | | | | | |

| |VDL M2 GS |Note 1 |Note 2 |Note 3 |Note 2 |

| |DSB-AM A/C |Table 117-B, left |Table 117-B, right |Note 5 |Note 5 |

| |DSB-AM GS |Note 4 |Note 2 |Note 5 |Note 5 |

Note1: This is the opposite direction of the case treated in (Table 117-C, right). Calculations (not provided in the document) show that the distances calculated in (Table 117-C, right) are more stringent than those calculated in the opposite direction. Hence no data is provided for the opposite direction in the document.

Note2: This is a ground-to-ground case (no separation distances discussed in the document – only generic statement in 7.52.13).

Note3: This case is analogous to Note 1, with reference to (Table 117-B, right).

Note4: This case is analogous to Note 1, with reference to (Table 117-A, right).

Note5: This case is already covered by Annex 10 (DSB-AM vs DSB-AM).

When using the interference model as in paragraph 6.2 and formula (4), the following separation distances were calculated, using the relevant information from Table 1, 8, 9 and 10 as follows.

Minimum protection distance for interference from VDL Mode 2 aircraft stations (undesired signal) into desired DSB-AM aircraft stations and desired DSB-AM ground stations with the following parameters:

a) EIRPu of undesired VDL Mode 2 aircraft station is 39 dBm;

b) Pd of desired DSB-AM aircraft station is -82 dBm at the VDL Mode 2 antenna (signal in space); and

c) Pd of desired DSB-AM ground station is -93 dBm at the VDL Mode 2 antenna (signal in space)

Table 171-A Minimum separation distance for protecting DSB-AM (GS, A/C) from VDL M2 (A/C) harmful interference

|Channel Separation |D/U (dB) |Minimum separation distance for protecting: |

| | |DSB-AM aircraft station |DSB-AM ground station (see note 2) |

| | |119 MHz |

| | |VDL M2 aircraft station |VDL M2 ground station (see note) |

| | |119 MHz |

| | |VDL M2 aircraft station |VDL M2 ground station (see note 2) |

| | |

| |VDL M3 A/C |VDL M3 GS |DSB-AM A/C |DSB-AM GS |

|Undesired|VDL M3 A/C |Table 18-C, left |Table 18-C, right |Table 18-A, left |Table 18-A, right |

|Station | | | | | |

| |VDL M3 GS |Note 1 |Note 2 |Note 3 |Note 2 |

| |DSB-AM A/C |Table 18-B, left |Table 18-B, right |Note 5 |Note 5 |

| |DSB-AM GS |Note 4 |Note 2 |Note 5 |Note 5 |

Note1: This is the opposite direction of the case treated in (Table 18-C, right). Calculations (not provided in the document) show that the distances calculated in (Table 18-C, right) are more stringent than those calculated in the opposite direction. Hence no data is provided for the opposite direction in the document.

Note2: This is a ground-to-ground case (no separation distances discussed in the document – only generic statement in 8.5.3).

Note3: This case is analogous to Note 1, with reference to (Table 18-B, right).

Note4: This case is analogous to Note 1, with reference to (Table 18-A, right).

Note5: This case is already covered by Annex 10 (DSB-AM vs DSB-AM).

When using the interference model as in paragraph 6.2 and formula (4), the following separation distances were calculated, using the relevant information from Table 1, 8, 9 and 10 as follows.

Minimum protection distance for interference from VDL Mode 3 aircraft stations (undesired signal) into desired DSB-AM aircraft stations and desired DSB-AM ground stations with the following parameters:

a) EIRPu of undesired VDL Mode 3 aircraft station is 41 dBm;

b) Pd of desired DSB-AM aircraft station is -82 dBm at the antenna (signal in space); and

c) Pd of desired DSB-AM ground station is -93 dBm at the antenna (signal in space)

Table 18-A Minimum Protection Distance (VDL M3 (A/C) > DSB-AM (GS, A/C))

|Channel Separation |D/U (dB) |Minimum separation distance for protecting: |

| | |DSB-AM aircraft station |DSB-AM ground station |

| | |119 MHz |

| | |VDL M3 aircraft station |VDL M3 ground station |

| | |119 MHz |

| | |VDL M3 aircraft station |VDL M3 ground station |

| | |119 MHz |

|VDL -3 A/C interfering with a DSB-AM A/C |568 |-54 |

| |(from Table 18-A) |(from Table 18-A) |

|DSB-AM A/C interfering with a VDL-3 A/C |160 |-65 |

| |(from Table 18-B) |(from Table 18-B) |

As stated in section 7.4.3.1, the minimum separation distance for two aircraft on the ground can be expected to be between 50 and 100m. The distances in the table above are far in excess of these “typical” distances, however, if the aircraft is on the ground it can be presumed that the desired signal level will be significantly stronger than the -82dBm used to calculate the above distances.

Section 7.4.3.3 states that a -70dBm desired signal level is “achievable in most operational conditions on the ground”. Given this desired signal level, the separation distances can be recalculated with the results summarized in the table below:

Desired Signal Level = -70, D/U Ratio = -54 which yields a -16dBm undes signal level.

Considering a 44dBm undes TX, 3dB feedline loss, 0dBi antenna gain yields a free space path loss requirement of 57dB. 57dB of pathloss equates to approx 150m (Changing the D/U ratio to -65dB yields 40m)

|Scenario (-70dBm des sig lvl) |Sep. Dist (m) |D/U (dB) |

|VDL -3 A/C interfering with a DSB-AM A/C |150 |-54 |

| | |(from Table 18-A) |

|DSB-AM A/C interfering with a VDL-3 A/C |40 |-65 |

| | |(from Table 18-B) |

. Interference between Aircraft on the Ground and Ground Station

The data contained in tables 18-A, 18-B, and 18-C show that the following separation distances should be maintained to ensure interference free communications at the 4th adjacent channel:

|Scenario (-93dBm des sig lvl) |Sep. Dist (m) |D/U (dB) |

|VDL -3 A/C interfering with a DSB-AM GS |2016 |-54 |

| |(from Table 18-A) |(from Table 18-A) |

|DSB-AM A/C interfering with a VDL-3 GS |568 |-65 |

| |(from Table 18-B) |(from Table 18-B) |

We cannot use the same -70dBm desired signal argument from section 8.4.3 since the victim receiver is a ground station which might be receiving a signal from a far away aircraft. If distances closer than above are required cavity filters can be installed at the ground station.

. Interference between Ground Transmitting Station and Ground Receiving Station

Normally, ground transmitters are geographically separated from ground receiver stations. Transmissions from ground DSB-AM stations may interfere with the (ground) reception of VDL Mode 3 signals and transmission from ground VDL Mode 3 signals may interfere with the (ground) reception of DSB-AM signals. This should be considered in the design of ground station characteristics. Also here, the use of special cavity filters may assist in securing proper functioning of the various communication systems.

. Required Channel Separation for VDL Mode 3 versus VDL Mode 3

. Interference to Aircraft in Flight (air-to-air interference)

The required protection distance for two aircraft in flight is 600 m. Table 18-C shows that this distance is reached at the 2nd adjacent channel with a very large margin. Therefore, to assign a VDL Mode 3 channel in the same service volume as another VDL Mode 3 channel, a single channel guard band is necessary.

. Interference between Aircraft on the Ground

Experimental data (see tables 18-A, 18-B, and 18-C) for aircraft to aircraft interference in a mixed VDL3 – DSB-AM environment indicates the following is necessary to ensure interference free communications at the 4th adjacent channel.

|Scenario (-82dBm des sig lvl) |Sep. Dist (m) |D/U (dB) |

|VDL -3 A/C interfering with a VDL -3 A/C |143 |-66 |

| |(from Table 18-C) |(from Table 18-C) |

Using the same logic regarding the desired signal level as in section 8.4.3 yields the following table:

|Scenario (-70dBm des sig lvl) |Sep. Dist (m) |D/U (dB) |

|VDL -3 A/C interfering with a VDL -3 A/C |40 |-66 |

| | |(from Table 18-C) |

. Interference between Aircraft on the Ground and Ground Station

The data contained in tables 18-A, 18-B, and 18-C show that the following separation distances should be maintained ensure interference free communications at the 4th adjacent channel:

|Scenario (-93dBm des sig lvl) |Sep. Dist (m) |D/U (dB) |

|VDL -3 A/C interfering with a VDL -3 GS |506 |-66 |

| |(from Table 18-C) |(from Table 18-C) |

We cannot use the same -70dBm desired signal argument from section 8.5.2 since the victim receiver is a ground station which might be receiving a signal from a far away aircraft. If distances closer than above are required cavity filters can be installed at the ground station

8. SEPARATION DISTANCES FOR VDL MODE 4

9. SUMMARY OF VDL FREQUENCY ASSIGNMENT PLANNING CRITERIA

Table 19191912 25 kHz Guard band channels between aircraft transmitting stations and aircraft or ground receiving stations

|Vs. |Receiving station |

| |DSB-AM |VDL M2 |VDL M3 |VDL M4 |

|A/C |GS |A/C |GS |A/C |GS |A/C |GS | |Aircraft transmitting station |DSB-AM |- |- |1 |1 |2 |3 | | | | |VDL M2 |1 |4 |1 |1 | | | | | | |[VDL M3 |3 |Note 3 | | |1 |2] | | | | |VDL M4 | | | | | | | | | |

Note1: The numbers provided in table 195 are guard channels. The next channel that can be used without frequency assignment planning constraints is 1 higher (e.g. A desired DSB-AM station that is interfered by a VDL Mode 2 aircraft station, requires one 25 kHz guard band channel. The next channel, 50 kHz away, can be used in the same designated operational coverage without constraints.

[Note3: The guard band is more than 40 channels based on the test results.]

-----------------------

International Civil Aviation Organization

20th Meeting of Aeronautical Communications Panel Working Group B (ACP WG-B)

Montreal, Canada

29-31 May 2006

International Civil Aviation Organization

20th Meeting of Aeronautical Communications Panel Working Group B (ACP WG-B)

Montreal, Canada

29 – 31 May 2006

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