Ultrasound-based virus shield

An ultrasound-based virus shield, comprising:

• an ultrasound sonar emitter configured to emit a first sonar signal comprising a header with key data, wherein the key data is unique to the ultrasound-based virus shield;
• an ultrasound sonar receiver configured to receive a plurality of second sonar signals;
• a processor configured to:
• determine, for each respective second sonar signal of the plurality of second sonar signals, whether the respective second sonar signal comprises the key data by identifying a gated key sequence in a header of the respective second sonar signal;
• reject second sonar signals that do not comprise the key data to prevent interference from sonar signals emitted by other ultrasound-based virus shields;
• calculate a distance between the ultrasound-based virus shield and a subject based on a time difference between emission of the first sonar signal and receipt of second sonar signals determined to comprise the key data;
• and
• activate an ultrasound sterilizing emitter in response to determining that the distance calculated is less than a threshold distance;
• and
• the ultrasound sterilizing emitter configured to emit a sterilizing signal.