Ultrasound speed measurement of temperature and pressure

An apparatus for calculating an automatically calibrated gas velocity vector in external pressure-temperature, the apparatus comprising:

• first and second transmitters adapted to transmit ultrasonic pulses, wherein the first transmitter is in an open configuration and the second transmitter is in a first ventilated tube, such that the second transmitter is positioned along a first axis;
• third and fourth transmitters adapted to transmit ultrasonic pulses, wherein the third transmitter is in an open configuration and the fourth transmitter is in a second ventilated tube, such, that the fourth transmitter is positioned along a second axis, the second axis perpendicular to the first axis;
• a receiver adapted to receive ultrasonic pulses from the transmitters, whereby the first and second transmitters are each positioned a first distance from the receiver, the third and fourth transmitters are each positioned a second distance from the receiver and are each positioned at a 90 degree angle from the first and second transmitters;
• means for transmitting a first ultrasonic pulse from the first transmitter to the receiver;
• means for calculating a first transit time vector for the first pulse to reach the receiver;
• means for transmitting a second ultrasonic pulse from the second transmitter to the receiver;
• means for calculating a second transit time vector for the second pulse to reach the receiver;
• means for transmitting a third ultrasonic pulse from the third transmitter to the receiver;
• means for calculating a third transit time vector for the third pulse to reach the receiver;
• means for transmitting a fourth ultrasonic pulse from the fourth transmitter to the receiver;
• means for calculating a fourth transit time vector for the fourth pulse to reach the receiver;
• means for calculating a first transit time differential vector by taking a first difference between the calculated first transit time vector and a first predetermined time transit vector;
• means for calculating a second transit time differential vector by taking a second difference between the calculated second transit time vector and a second predetermined time transit vector;
• means for calculating a third transit time differential vector by taking a third difference between the calculated third transit time vector and a third predetermined time transit vector;
• means for calculating a fourth transit time differential vector by taking a fourth difference between the calculated fourth transit time vector and a fourth predetermined time transit vector;
• means for calculating a first automatically calibrated gas velocity component vector by taking a first differential difference between the calculated first and second transit time differential vectors;
• means for calculating a second automatically calibrated gas velocity component vector by taking a second differential difference between the calculated third and fourth transit time differential vectors;
• and
• means for determining the automatically calibrated gas velocity vector by combining the first automatically calibrated gas velocity component vector and the second automatically calibrated gas velocity component vector.