主权项 |
1. A method for producing a location-aiding audible signal, the method comprising:
defining a near field location-aiding audible signal comprising audible noise processed by band-pass filters with spectral peaks at about 500 Hz, 4 kHz, and 8 Khz; defining a far field location-aiding audible signal comprising a plurality of simultaneously occurring fundamental tone frequencies, the far field location-aiding audible signal further comprising a plurality of respective harmonic components for each fundamental tone frequency; emitting, during each of a first set of time durations, the near field location-aiding audible signal; and emitting, during a second set of time durations, the far field location-aiding audible signal, the second set of time durations being interleaved with the first set of time durations. |