above, N1 and N2 are the levels (dBm) of the two VHF FM sound broadcasting signals at the VHF data broadcast (VDB) receiver input. Neither level shall exceed the desensitization criteria set forth in paragraph (c). Delta f = 108.1 - f1, where f1 is the frequency of N1, the VHF FM sound broadcasting signal closer to 108.1 MHz. Section 87.169 is amended to read as follows: § 87.169 Scope. This subpart contains class of station symbols and a frequency table which lists assignable frequencies. Frequencies in the Aviation Services will transmit communications for the safe, expeditious, and economic operation of aircraft and the protection of life and property in the air. Each class of land station may communicate in accordance