DME/TACAN Interruptions Caused by Electromagnetic Interferences

ACP-WGF16/IP-09 International Civil Aviation Organization 05/12/06

WORKING PAPER

AERONAUTICAL COMMUNICATIONS PANEL (ACP)

SIXTEENTH MEETING OF THE WORKING GROUP F

Montreal, Canada 11 – 15 December 2006

Agenda Item 4: Interferences from non-aeronautical sources – other issues

DME/TACAN INTERRUPTIONS CAUSED BY ELECTROMAGNETIC INTERFERENCES

(Presented by M. Ito, Japan)

SUMMARY This contribution informs the meeting on potential risk of radio interference may be widely spread in aeronautical radio apparatus. ACTION WG-F members are invited to pay more attention to the operational risk. Similar experiences of other entities would be helpful to mitigate future occurrences.

1. INTERFERENCE CASE 1

1.1 On 21st October 2005, four DME ground stations in South Kanto Area went down simultaneously due to unknown interference signals and other two DME affected. In spite of the effort, the actual cause of the incident could not be identified.

1.2 In order to improve the robustness, signal strength of built-in pseudo DME interrogator was realigned to ensure that there is no harmful interference with DME and TACAN. Original setting was to secure ICAO requirement on sensitivity with substantial margin.

1.3 Secondly, obsolete analog external- noise-based skitter generator still used in some of the DME/TACAN stations were replaced by digital skitter generator unit to stabilize the number of nominal skitter pulse pairs regardless the fluctuation of receiver noise floor.

(2 pages) 036706db01190bb1669a30930b0044ff.doc ACP-WGF16/IP-09 2

2. INTERFERENCE CASE 2

2.1 From May 2006, a DME at Kansai International Airport was intermittently affected by interference from unlawful wireless ITV camera. Engineers stationed at the Kansai International airport identified that the signal contain video information through the analysis of wave form and spectrum. Then engineers identified the place of interference source with direction of interference signal and demodulated video scene.

2.2 Engineers stationed at other airport offices were informed of the results of interference incident to enable them to tackle possible re-occurrence of interference caused by unlawful wireless ITV cameras.

2.3 Many unlawful wireless TV cameras seem to use L-band (900-1200MHz) are sold widely and easily purchased. As a sample, some camera was sold with 1.2 GHZ transmitter, with 300m coverage and some seems to have much higher transmitter power.

3. ACTION BY THE MEETING

3.1 WG-F members are invited to communicate well with radio spectrum management agency and other relevant agencies to detect and eliminate the suspected radio source.

3.2 WG-F members are invited to pay more attention to increasing potential risks of radio interference to L-band aeronautical systems (e.g. DMEs, GNSS, SSR, AMSS, etc.).