An Examination of the Feasibility of Ultrasonic Communications Links

Abstract : A study is performed to consider the feasibility of using the ultrasonic band just above the normal adult audio frequency range (20-25 kHz) for low data rate signaling. In this band several features of interest are explored and a potential application (Identification Friend-or-Foe [IFF]) is highlighted. A key finding is that the data transmission rate is restricted in the presence of multipathing effects. Data transmission rates in the 300-baud range are possible when Rician noise statistics dominate. For non-line-of-sight cases when Rayleigh statistics dominate, a data link may not be possible. However, in the presence of a dominant reflecting path data may be transmittable, but at greatly reduced rates, due to multipathing. To study the potential of this technology a series of measurements were performed to determine signal losses with range, angular emission properties of a series of horns as a function of frequency, and Amplitude Modulation (AM) and Frequency Modulation (FM) data encoding methods.

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