22Radiated signal characteristics

22 Radiated signal characteristics

AM radio band (1) An AM radio service carrier: (a) must be amplitude modulated to a maximum of 125 per cent positive and 100 per cent negative modulation by the sum signal (L+R); and (b) if the transmission of the signal is a stereo transmission – the carrier must be phase modulated to a maximum of 1.26 radians by the combination of the difference signal (L‑R) and a 25 Hz pilot signal. (2) An emission caused by the transmission of an AM radio service on a frequency more than 9 kHz, but not more than 18 kHz, from the carrier, must be attenuated at least 25 dB below the level of the carrier. (3) An emission caused by the transmission of an AM radio service on a frequency more than 18 kHz, but not more than 27 kHz, from the carrier, must be attenuated at least 35 dB below the level of the carrier. (4) An emission caused by the transmission of an AM radio service on a frequency more than 27 kHz from the carrier either: (a) must be further attenuated at a rate of 1 dB per kHz; or (b) must not exceed a level of 200 μV/m at a distance of 1 km from the transmit antenna. (5) For the purposes of subguidelines (1) to (4) and this subguideline (5):

baseband signal means the modulating signal applied to produce amplitude modulation of the main carrier or amplitude and phase modulation in the case of a stereo transmission.

Note: In mono transmissions, the baseband signal is the sum of the left (L) and right (R) audio signals.

carrier means the MF signal modulated by the baseband signal.

L means the left audio channel of a stereo audio signal.

MF has the meaning given by the interpretation determination.

R means the right audio channel of a stereo audio signal.

FM radio band (6) In relation to an FM radio service: (a) the main carrier must be frequency modulated by the baseband signal; (b) the maximum frequency deviation of the main carrier must not exceed 75 kHz; and (c) a positive value of the baseband signal must correspond to a positive frequency deviation of the main carrier.

Note: There is a positive value of the baseband signal when the signal crosses the time axis with a positive slope.

(7) An emission caused by the transmission of an FM radio service on a frequency removed from the main carrier by more than 120 kHz, but not more than 240 kHz, must be attenuated at least 25 dB below the level of the unmodulated main carrier. (8) An emission caused by the transmission of an FM radio service on a frequency removed from the main carrier by more than 240 kHz, but not more than 600 kHz, must be attenuated at least 35 dB below the level of the unmodulated main carrier. (9) An emission caused by the transmission of an FM radio service on a frequency removed from the main carrier by more than 600 kHz must be attenuated either: (a) at least 43 + 10log P dB (where P is transmitter power in watts) below the level of the unmodulated main carrier; or (b) at least 80 dB below the level of the unmodulated main carrier; whichever is the lesser attenuation. (10) For the purposes of subguidelines (6) to (9) and this subguideline (10):