DRAFT
ACP WG B-WP-2
Report of the 17th Meeting of
Aeronautical Communications Panel (ACP)
Working Group B
20 to 25 October, 2004
Montreal, Canada
1.
Opening
1.1
The meeting was opened by the Rapporteur, Mr. Donald Willis, from the U.S.
The Secretary for the group was Mr. Robert Witzen from ICAO.
1.2
On behalf of the ICAO Secretariat, the working group was warmly welcomed to
Montreal by Mr. Witzen. His welcome included a brief discussion of working
arrangements and administrative details.
1.3
The agenda, which had been distributed prior to the meeting, was reviewed by the
working group. The agenda was approved by the working group. The approved agenda
is in Appendix 1.
1.4
There were a total of 12 participants to this meeting of WG-B. The list of
participants is in Appendix 2.
1.5
Working papers were submitted prior to as well as during the meeting. The
working papers are listed in Appendix 3.
1.6
A list of action items is in Appendix 4. The list was reviewed by WG-B members
and updated.
1.7
The group agreed on four goals for the meeting: (1) progress the SARPs text for
VDL Mode 2 so that it could be forwarded to ACP/1 or the planned ACP Working Group
of the Whole; (2) finalize VDL Mode 3 frequency assignment criteria so that SARPs text
could be provided at the next WG-B meeting; (3) agree on how to progress the activity on
development of ICAO guidance material on radio frequency interference; and (4) discuss
how to proceed with the onboard compatibility issue in preparation for next week’s joint
meeting with WG-M.
2.
Introductions
2.1
WG-B members were introduced.
3.
Guidance material for VDL frequency assignment planning criteria
3.1
There were no WP’s provided to the meeting for this agenda item.
4.
Final review of ICAO SARPs material (frequency assignment planning criteria)
for VDL Mode 2
4.1
WP-13 was provided by the Secretary to progress this agenda item. This working
paper was the output of AMCP/8 as amended by WG-B/16 in Tokyo.
4.2
WP-13 was thoroughly reviewed with a view to correct inconsistencies and
generally updating the paper to reflect recent developments in testing to establish
frequency assignment planning criteria from WP-8. The new version of this paper is at
Appendix 13.
4.3
The group concluded that further work was needed to complete this document.
This includes VDL Mode 3 to VDL Mode 2 interference, as well as VDL Mode 4 to
VDL Mode 2 frequency planning criteria. Also missing is guidance material on 8.33 kHz
and 50 kHz radios. There are currently no plans to provide further guidance material on
50 kHz radios, unless required.
4.4
The working group agreed that the updated paper should be reviewed by WG-B
members before the next meeting and inputs provided at WG-B/18. The group further
agreed that the paper will then be presented to either ACP/1 or the ACP Working Group
of the Whole for final approval and incorporation in the SARPs.
5.
VDL frequency assignment planning criteria for VDL Mode 3
5.1
WP-6 was presented by the representative from Japan and WP-8 was
presented by the representative from the U.S. to address this agenda item.
5.2
WP-6 addressed recent interoperability testing between Japanese and U.S.
VDL Mode 3 equipment that had been developed independently using the ICAO SARPs
as guidance. The interoperability test was considered to be very successful, even though
there were several minor incompatibility discrepancies noted during the effort. These
discrepancies will be addressed by planned modifications to ICAO Annex 10 SARPs for
VDL Mode 3. Further testing may be planned if needed to validate additional VDL
Mode 3 functionalities.
5.3
WP-8 was presented by the representative from the U.S. This paper presented
results of VDL Mode 3 testing to develop frequency assignment planning criteria. It
included testing with VDL Mode 3 as a victim receiver where the interfering source was
either a DSB-AM transmitter or another VDL Mode 3 transmitter. Several data
formatting inconsistencies were noted in the paper. For example, frequency assignment
planning criteria needed to be modified to express them in meters so that they would be
consistent with existing SARPs. In summary, for VDL Mode 3 adjacent channel
operation to a DSB-AM receiver, the fourth 25 kHz channel can be used without any
restriction. For VDL Mode 3 adjacent channel operation to a VDL Mode 3 receiver, the
second 25 kHz channel can be used.
2
5.4
It was noted that additional data is needed before VDL Mode 3 frequency
planning criteria is complete. This includes criteria for VDL Mode 3 interference to
VDL Mode 2 and also co-channel frequency assignment criteria.
6.
VDL frequency assignment planning criteria for VDL Mode 4
6.1
WP-15, from Eurocontrol, which addressed test planning for VDL Mode 4
frequency assignment criteria was provided to the group but not addressed during the
WG-B meeting. Eurocontrol plans to present this paper to the joint meeting of WG-B
and WG-M.
7.
Compatibility between VDL’s and DSB-AM, including a review of on-board
implementation problems
7.1
WP-5 was presented by the U.S. and WP-9 was presented by Eurocontrol to
address this agenda item.
7.2
WP-5 had been presented and discussed at WG-B/16 in Tokyo. In general,
the paper, prepared by Boeing, concludes that RTCA DO-271B do not adequately protect
some onboard aeronautical systems, such as DME and GNSS, when VDL is
implemented. It should be noted that RTCA DO-271B, DO-281, and DO-186A address
the issue of onboard protection of GPS. Guidance is provided concerning requirements
to protect GPS. Additional work needs to be done, most likely including the
development of draft SARPs (see also section 7.4 below) to further characterize onboard
implementation issues in cooperation with aircraft manufacturers and WG-M. In
addition, the Secretary will request that the Navigation Systems Panel provide WG-B
with interference protection limits for GNSS E1/L1 and E5/L5 signals, DME, and other
onboard navigation systems.
7.3
WG-B members agreed that technology exists to improve performance of new
radio systems, however, in some cases aviation continues to use current standards, such
as for spurious emissions performance, as a baseline for new systems. At some point,
international civil aviation should review existing standards with a view to updating them
to take advantage of new technology.
7.4
The role of ICAO in the onboard compatibility issue was discussed. The
Secretary stated that there is precedent for ICAO establishing standards for use onboard
aircraft to protect aviation systems. For example, the standards developed to protect
GLONASS and GPS from AMSS systems. Likewise, aviation needs VDL standards to
protect other aeronautical systems onboard the same aircraft. This may require
establishing limits for new systems or introducing provisions that state that, “where VDL
is implemented” then a certain level of protection of other systems is needed.
7.5
WP-9. Eurocontrol presented the meeting with an assessment of the VDL Mode2 airborne co-site interference in the Link2000+ framework (WP# B1709 & M902). The
paper discussed several scenarios of potential airborne co-site interference between VHF
3
voice services and VDL Mode-2 services. It also discussed examples of interference on a
laboratory aircraft under various scenarios.
7.6
The three main scenarios were (1) an Airborne VDL Mode-2 transmitter
interfering on DSB-AM voice reception, (2) an Airborne AM-DSB voice transmitter
interfering on VDL Mode-2 reception, and (3) an Airborne AM-DSB voice transmitter
delaying a VDL Mode-2 transmitter (this was a theoretical case in the event that a VDL
Mode-2 channel was sensed to be busy due to out-of-band emissions from DSB-AM
voice)
7.7
The paper also addressed combinations of the various scenarios. The meeting
heard several recordings of interference and its effect on intelligibility. There was a
discussion by the meeting on “VHF Sensitisation Modification”. The meeting was
referred to a working paper (WGB1103) on the ICAO website. The meeting was
reminded that de-sensitization may bring the VHF-DSB AM receiver below the
specification as contained in the relevant SARPs, which is not acceptable.
7.8
The meeting concluded that this study shows that VDL Mode-2 airborne co-site
interference is not affecting voice nor data link performance to a detrimental extent when
operating on the 2nd adjacent channel. It was agreed that the VDL Mode-2 frequency
planning criteria established in 2001 at the ICAO level are not impacted by airborne cosite interference. The maximum round-trip delay of the VDL Mode-2 messages,
excluding ground network delays, was assumed to be 8 seconds.
7.9
It was agreed by the meeting that the study demonstrated that in a Link2000+
framework, VDL Mode-2 airborne co-site interference does not affect voice service, nor
data-link performance. It was also agreed by the meeting that the study further
demonstrates that this still holds true if DSB-AM voice operations and VDL Mode-2
operations on an aircraft use the respective media where the channel loading of the RF
Channel for both DSB-AM voice and VDL Mode-2 is 20 times greater than foreseen in a
Link2000+ scenario. In fact, the study demonstrates that these conclusions are
extendable to any CPDLC-like application over VDL Mode-2, without specific
operational assumptions. The study shows that the single real impact of airborne co-site
interference is a slight reduction of the total capacity per channel. This is quantified in
the study. It was agreed that the paper was mature and comprehensive.
8.
Guidelines for the introduction of VDL in the VHF band
8.1
WP-6 presented by Japan under Agenda Item 4 (VDL frequency assignment
planning criteria for VDL Mode 3) was also attributed to this agenda item. WP-6 was not
discussed separately for this agenda item.
9.
Global signaling channel for VDL Mode 4
9.1
The representative from Sweden introduced WP-14 that addressed ongoing
planning for introduction of VDL Mode 4 signaling channels in Europe.
4
9.2
The current plan for implementation of regional signaling channels in Europe
focuses on the 136-136.975 MHz band. The initial VDL Mode 4 signaling channel in
Europe is to be 136.925 MHz. The frequency 136.825 MHz is planned to become the
second regional signaling channel in Europe and is currently being coordinated. Sweden
has also applied to use this frequency in Sweden for ADS-B ground surveillance
applications. It was concluded that this is a significant development in the
implementation of a global signaling channel for VDL Mode 4. As a next step, the
Secretary will inform other ICAO Regions of this development, and recommend that
136.925 MHz be considered in those Regions that plan implementation of VDL Mode 4.
9.3
Future planning for VDL Mode 4 signaling channel implementation includes
introduction of VDL Mode 4 into the 112-117.975 MHz. It was noted that this is
consistent with the WRC-2003 allocation which limited AM(R)S systems providing air
navigation applications to operate above 112 MHz until compatibility with FM Broadcast
was studied. Also, studies on compatibility with ILS and VOR still have to be
completed, in coordination with the NSP.
10.
ICAO guidance material on radio frequency interference
10.1
WP-7 and WP-10, presented respectively by the representatives from France
and the U.S., provided material to be used to progress this agenda item.
10.2
WP-7 provided information concerning radio frequency interference to
aeronautical systems in France. France records the total amount of time of air traffic
delays that are attributed to radio frequency interference and divides that time into seven
categories. It was noted that in 2001 a majority of ATC delays were due to interference to
a primary airport radar. It was noted that another piece of data that may be useful is the
number of air traffic delays that are caused by radio frequency interference incidents.
The total delay time is easily converted into economic losses for the airlines.
10.3 France considers that a good objective to solve heavy interferences emanating
from its own territory is a maximum delay of 5 days. The solution of heavy interferences
emanating from foreign countries often takes longer. A better coordination between
ATCs, spectrum regulators and justice would be welcome. The hardest cases may last
more than one year.
10.4 The French member stated that as priority is given to heavy interferences, the
satisfactory threshold for light or sporadic interferences resolution is one month. That
member also pointed out that an important category of interference is due to stuck
microphones that should be easy to prevent but are not, although each individual case is
generally solved in less than one hour. It was noted that this problem obviously exists
elsewhere and statistics would be interesting.
10.5 WP-10 addressed the resolution of radio frequency interference. This paper
included common sources of radio frequency interference as well as operational issues
5
that can result in radio frequency interference complaints from users, such as using
frequencies outside of their designated operational areas. The paper also provided a
methodology to identify, locate, and eliminate radio frequency interference, and included
several case studies of various types of interference. Future aspects of this activity
should include personnel training issues.
10.6 The Secretary noted that there are growing cases of radio frequency interference
to GNSS. These include, for example, States that allow fixed links in the GNSS radio
spectrum 1559-1610 MHz, until 2015 in some cases.
10.7 A discussion followed of how to progress this activity. The Secretary stated that
there have been several useful inputs made on this issue. The ANC view is to move
technical material out of Annex 10 and into a “technical manual” arrangement. This is
also the Secretariat’s goal for the radio frequency interference material. Toward that end,
the Secretary will prepare an outline of the ICAO guidance material on radio frequency
interference for WG-B review, on the basis of the submissions received to date.
11. Any other items WG-B members identify/future meeting
11.1 The Secretary provided an update on Secretariat activities that impact the group.
A new CNS Director has been selected to replace Judimar Chagas. He is Jim Nagle from
the U.S. and will arrive at ICAO in November. Alessandro Capretti is now the Secretary
for the Navigation System Panel and Torsten Jacob and Robert Witzen will share
responsibilities for the Aeronautical Communications Panel.
11.2 The group was informed that the meeting of the Air Navigation Commission
adjusted the dates of some meetings. It is expected that ACP/1 will now meet in 2006
and that an ACP Working Group of the Whole will meet in June/July 2005.
11.3
The Secretary noted that the Secretariat is developing a new website for ACP.
The temporary URL is http://www.icao.int/anb/panels/newacp/. Comments from
members are welcome. [Ed note: this site has since been changed to
http://www.icao.int/anb/panels/acp/.]
11.4
The group was informed that it is planned to have the next WG-B meeting as
a joint meeting with WG-F and, likely, the Spectrum Subgroup of the Navigation
Systems Panel. Among other things, it is hoped to address the WG-B task to address the
development of ICAO guidance material on radio frequency interference. This meeting
is tentatively planned for late February/early March and would be immediately before the
APT Preparatory Group meeting to be held in Bangkok.
12.
Closing
12.1
The meeting concluded on October 25.
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Appendices
1. WP-1: Agenda
2. WP-2: List of Participants
3. WP-3: List of Working Papers
4. WP-4: List of Action Items
5. WP-5: VDL Mode 3 Onboard Interference Testing Summary
6. WP-6: Report of FAA-JCAB VDL Mode 3 Interoperability Testing
7. WP-7: Radio Interferences
8. WP-8: VDL Mode 3 to VDL Mode 3 Avionics Interference Testing
9. WP-9: Assessment of VDL Mode-2 Airborne Co-site Interference in Link2000+
Framework
10. WP-10: Radio Frequency Interference Resolution
11. WP-11: Updated Plan for Frequency Testing of VDL Mode 4 for the
Development of Frequency Planning Criteria
12. WP-12: VDL Operational Requirement Criteria
13. WP-13: Frequency Assignment Planning Criteria for VDL Modes 2, 3 and 4
14. WP-14: Signaling Channels for VDL Mode 4
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