US Patent 8461978 Wireless ultrasound probe asset tracking

A wireless ultrasound probe has a probe case enclosing a transducer array, an acquisition circuit, a transceiver and a battery. The probe also includes a loudspeaker which produces audible sounds as a function of the range between the wireless probe and a host system. When the probe is within a near field range of the host system, the loudspeaker is silent. But if the probe is moved to an intermediate or a far field range from the host system, the loudspeaker sounds an alert. This audible alert can be used to locate the probe by transmitting a paging signal which, upon reception by the probe, causes the probe to sound its alert. If the probe is moved to an unauthorized location where it is within range of a transmitter or receiver, the reception of a signal by the probe, the transmitter, or receiver will sound an alert signaling the unauthorized presence of the wireless probe.