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- AERONAUTICAL COMMUNICATIONS PANEL (ACP) EIGHTEENTH MEETING OF WORKING GROUP F Montréal, Canada 12 – 22 May 2008 Agenda Items : 2 b, 5 and 6
- Considerations on video streams for the work of the WRC-11 A.I. 1.3.
- Introduction
- Spectrum issue related to the video streams
- 3- Action by the meeting
AERONAUTICAL COMMUNICATIONS PANEL (ACP) EIGHTEENTH MEETING OF WORKING GROUP F Montréal, Canada 12 – 22 May 2008 Agenda Items : 2 b, 5 and 6
(Presented by Didier PETIT, Sylvain GERMAINE and Alain DELRIEU)
To date, only a few U.A (unmanned air vehicles) fly in very specific segregated airspaces. The scope of the WRC-11 A. I. 1.3 invites studies to be performed within ITU-R to identify under what conditions future U.A could be granted access to all kinds of airspace unrestrictively . The resolution 421 invites to study the requirements for UA ‘’command and control’’ (C2) as well as the ‘’sense and avoid ‘’(SAA) functions. For the flight of the U.A. in conventional airspace, the UA operator, i.e. the remote pilot may need to receive a real-time visual picture of the airspace environment in the immediate vicinity the unmanned aircraft, if confirmed as an operational safety requirement, with respect to both conventional piloted aircraft and to persons and facilities on ground. It is worth noting that today’s experience with UAS operated in segregated airspace has established :
Furthermore experience with ACAS (Airborne collision avoidance systems) design and operations for conventional piloted aircraft has repetitively shown that the reaction time needed to perform an evasive manoeuvre to avoid a perceived collision with either a neighbouring aircraft or approaching ground obstacle is much shorter than the time required for the tactical surveillance and control loop between aircraft and ground control ATC ; and accordingly such a threat requires an immediate evasive action under automatic on-board implementation, with evasive action reporting to ground control facilities as a second priority. The informative document ‘’ACP-WGF-IPXX_UAS_Links’’ submitted in parallel to this meeting indicates the technical possibility to transmit real time video from the U.A to the remote piloting centre under C2(Command and Control) or SAA (sense and avoid) functions. It shows also that there may be a requirement to do so for the payload but not necessarily on a real time transmission basis . These transmissions could occur directly or could be relayed by satellite or aircraft.
Below is a highly preliminary sizing of the considered UA video transmission capabilities that may be employed between the UA and its remote pilot control (RPC) station needed for its command and control (C2). Further study work is needed to :
Considering a current standard definition video stream (720 x 576 pixels) with a frame rate of 20 images/s and 256 colours (8 bits) of each pictures, this leads approximately to a bit rate of : 720 x 576 x 20 x 8 = 66.4 Mbits/s Knowing that the current spectrum efficiency used for aeronautical telemetry is around 1bit/s/Hz, the above rough video requirement leads to a spectrum need of around 66 MHz. Future spectrum efficiencies figures greater than 1 bit/S/Hz achievable at the time of UAS deployment into unsegreagated airspace, should also be considered Such a value is for one U.A. only. Data and video compression method could significantly reduce this value by several tens of percent and lead to final spectrum requirements in the order of several MHz instead of several tens of MHz. On the opposite, these compressions methods bring some drawbacks such as important processing workloads and significant latency. Essential characteristics of such video data transmission and compression would need to be determined as part of the aeronautical C2 and SAA telecommunications standards mentioned above. Latency in the order of a few seconds may probably be unacceptable for the video if confirmed to be required for the safety C2 or SAA functions identified in Res 421, contrary to video radio links operated for the UA mission payload which may very well accept such a latency or even a greater one. The interest of this simple example is to show that the scarce spectrum resource could not be sufficient if video streams, in both up and down direction from the RPC are ultimately confirmed to be needed for the SAA or C2 functions of the UAS. as part of UAS air-worthiness certification mandated for their safe design and flight operations in unsegregated airspace. This is particularly true in ICAO classes E to G airspaces as well as in the unclassified ones.
The ACP WGF is invited:
1 This in line with the EUROCONTROL-SPEC-01 -02 :
( pages) ACP WG-F/18 WP04 Directory: safety -> acp -> acpwgf -> acp-wg-f-18 acp-wg-f-18 -> Information paper acpwgf -> Joint meeting of the acpwgf -> Working paper acpwgf -> Amcp wgm/WP19 19 August 2002 Aeronautical Mobile Communication Panel (amcp) Working Group-m meeting Fifth Meeting Saint Petersburg, Russia, 19 to 23 August 2002 Agenda Item 4: satcom acpwgf -> Acp wgf/16 wp 27 Rev. 1 International Civil Aviation Organization acpwgf -> Working paper acpwgf -> Working paper acpwgf -> Airborne collision avoidance systems working group-a acpwgf -> Aeronautical communications panel (acp) Download 20.27 Kb. Share with your friends:
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