International Civil Aviation Organization WORKING PAPER FREQUENCY SPECTRUM MANAGEMENT PANEL (FSMP) (AERONAUTICAL COMMUNICATIONS PANEL (ACP)) THIRTY SECOND MEETING OF WORKING GROUP F (FREQUENCY) Cairo, Egypt 16 – 24 February 2015 Agenda Item 6 Development of material for ITU-R meetings Liaison Statement from ITU-R WP5B “Characteristics of ADS-B Receivers on-board Satellite” and a draft response, developed by the Technical Sub-group (TSG) of the Aeronautical Surveillance Panel (ASP) (Presented by the Secretary) SUMMARY Attachment 1 to this paper is a Liaison Statement from ITU-R WP5B, asking specific questions in order to facilitate their on-going compatibility studies with incumbent systems in the frequency band 1 088.7 – 1 091.3 MHz. This Liaison Statement was addressed by the ASP TSG during their meeting 26 – 30 January. Attachment 2 to this paper contains their suggested response to the first of two questions contained in the Liaison Statement. ACTION Using the attached material as basis, FSMP WG-F is invited to draft a response to the Liaison Statement from ITU-R WP5B. Attachment 1: Liaison Statement from ITU-R WP5B: “Characteristics of ADS-B Receivers on-board Satellite” Attachment 2: Preliminary draft response from ASP TSG
It should be noted that the proposed baseline interference scenario is a simplification from a realistic scenario but as pointed out above can be used to compute interference rates at a satellite location and apply assumptions about the receiving antenna and receiver. It is assumed that the instantaneous aircraft count (IAC) is a result of a uniform aircraft density across a defined region. The following figure contains measurements that are the basis for aircraft density assumptions: Based on the aircraft count measurements over the New York Northeast corridor region in 2011, the following represents the aircraft density, DAC, for the measured number of aircraft (NAC), DAC = NAC / (π * R2), where NAC is 1200 within range R = 300 NM. DAC = .0042 aircraft per sq NM For the purposes of converting density to area represented in earth center (EC) degrees, assuming 60 NM is 1 EC degree, DAC * 3600 = 15.3 aircraft per sq EC degrees If the New York high density area is represented by a 300 NM east-west and 900 NM region with uniform density, the IAC is: IAC = 300 * 900 * .0042 = 1134 aircraft The message transmission rates per aircraft are determined based on the measured message rates averaged over the number of aircraft. Actual measured aircraft count is 1218 aircraft within 300 NM. The average reply/broadcast rates per aircraft from the measurements are: 63.9 Mode A/C replies/second 12.2 Mode S replies/second The Mode S reply rate for this baseline scenario includes 5% that are extended squitter broadcasts. As extended squitter equipage increases, the Mode S reply rate would need to reflect the increase in equipage. Other assumptions that can be used for interference and desired signal computation: Assume transponder transmit power of 54 dBm. Desired signal power is based on equipage class of extended squitter aircraft. Minimum power is either 51 dBm or 54 dBm. Antenna diversity operation needs to be reflected in signal power at the satellite receiver. For