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
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
FSMP-WGF32-WP04__ITU-R_ADS-B_Liaison_and_ASP-TSG_response.docx