Comparison of 14 Decibels Versus 20 Decibels Desired to Undesired SignalProtection Ratios

摘要

Due to a shortage of very high frequency (VHF) communications frequencies, theFAA must use the same frequencies in different airspaces across the country. The geographical separation between ground transmitters is engineered to provide a desired signal that is at least 14 decibel (dB) above any co-channel signal the receiver may receive. The International Civil Aviation Organization (ICAO) recommends a greater 20-dB separation. This difference between the two signals is known as the desired to undesired (D/U) ratio. Tests performed on eight avionics receivers at the FAA Technical Center to compare receiver performance when