Exactly, as I mentioned above. CQ requires training (but not much—I have no trouble recognizing it when the signal is only modulated noise), but SOS is another

Exactly, as I mentioned above. CQ requires training (but not much—I have no trouble recognizing it when the signal is only modulated noise), but SOS is another matter altogether, even those not trained in Morse recognize the sound especially if repeated (that 'ring' is unmistakable).