System for measuring the time for a signal to pass between two spaced points in a fluid
AssigneeBritish Gas Corporation
InventorMichael J. Gill
Life of this patent
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Abstract
A measurement system for measuring the time for a signal to pass between two transducers TDR1,2 to allow fluid speed or flow to be determined in a gas meter for example. Each transducer can transmit or receive signals. The system is controlled by a microcontroller 31 and a signal with a phase change acts as a marker which is transmitted from transmitter 21 via matching stage 22,23 from one transducer and is received by the other. On receipt via the matching stage and amplifier 24 it is sampled by capacitor array 25 and detected in detector 29. Amplitude information from array 25 is made available to the microcontroller to compute time of signal travel and hence flow rates.
Claims31
A system for measuring the time for a signal to pass between two spaced points in a fluid comprising:
- transmitter means for generating a signal including a plurality of cycles or pulses with a phase change provided therein acting as a marker;
- first transducer means for transmitting the generated signal with the marker therein;
- second transducer means spaced from the first transducer means for receiving the transmitted signal;
- and
- means for sensing the received signal, said sensing means including means for detecting the phase change marker and means for retaining amplitude information on the received signal to assist in measuring the time period for the signal passage through the fluid.
A system as claimed in any preceding claim, wherein timer means are provided to generate periodical standby and operational conditions, the standby condition being long relative to the operational condition to reduce power requirements.
A system as claimed 8, wherein the computation means includes timer means for initially determining the elapsed time between transmission and reception of the marker to allow this information to be used in combination with the phase information to more accurately determine this elapsed period.
A method of measuring the time for a signal to pass between two spaced points in a fluid comprising:
- generating a signal including a plurality of cycles or pulses with a phase change provided therein acting as a marker;
- transmitting the generated signal with the marker wherein through the fluid via a first transducer;
- receiving the transmitted signal from a second transducer after passage through the fluid;
- and
- sensing the received signal, said sensing step including detecting the phase change marker and retaining amplitude information on the received signal to assist in measuring the time period for the signal passage through the fluid.
A method as claimed 19, wherein the determining step initially determining the elapsed time between transmission and reception of the marker to allow this information to be used in combination with the phase information to more accurately determine this elapsed period.
A fluid speed measurement device comprising:
- first and second spaced transducer means;
- transmitter and receiving means for transmitting and receiving signals in both direction between said transducer means;
- switching means for allowing each transducer means to be periodically used for either transmission or reception;
- and matching means commonly used for both transmission and reception to ensure that transducer characteristics are substantially constant for both transmitting and receiving modes of operation.
A fluid speed measurement device comprising:
- first and second spaced transducer means;
- transmitter and receiving means for transmitting and receiving signals in both directions between said transducer means;
- switching means for allowing each transducer means to be periodically used for either transmission or reception;
- and
- matching means for transmission and reception to ensure that transducer characteristics are substantially constant for both transmitting and receiving modes of operation;
- wherein the matching means includes a substantially constant low impedance path for each transducer both during transmission and reception;
- wherein the low impedance path includes a network having a transformer with one winding for receiving an induced transmission signal for driving the transducer, said transformer winding also forming a series connection to the reception circuit when connected thereto;
- and
- wherein the network includes a matching resistor in series with the transformer winding and a capacitor connected across the transducer to optimize phase coherance.
Dependencies are inferred from the claim text.