Integrated threshold arming method and apparatus

Intervalometer apparatus for determing the arrival time of a bandwidth limited pulse of ultrasonic energy passing through a fluid medium comprising

• pulse transducer receiving means for generating an electrical signal output in response to undulations of the pulse incident thereon,
• integrated threshold arming means comprising
• a rectification circuit for rectifying said transducer electrical signal output, and
• an integration means responsive to said rectification circuit output for generating an arming signal when the integrated value of said rectification circuit output for a pulse crosses a threshold value, and
• threshold crossing recognition means responsive to said arming signal and said transducer electrical signal for detecting a permitted threshold crossing of said transducer electrical signal, said permitted threshold crossing determining the time of arrival of said pulse.

A method for determining the arrival time of a bandwidth limited energy pulse comprising the steps of:

• generating, in response to said pulse, an electrical receive signal representing the undulations of the pulse,
• electrically rectifying the receive signal for generating a rectified received signal,
• generating, in response to the rectified received signal, an arming electrical signal representative of an armed condition, said second generating step comprising the step of integrating the rectified received signal for generating the arming signal when an integrated value, dependent upon the rectified received signal, crosses a threshold value, and
• detecting, in response to said arming signal entering said armed condition, a zero-crossing occurring in the receive signal during the armed condition, the zero-crossing determining the arrival time of the bandwidth limited pulse.

An interval measuring method for determining the arrival time of a bandwidth limited pulse of ultrasonic energy passing through a fluid medium comprising the steps of

• generating an electrical received signal output in response to the pulse undulations incident upon a receiving element,
• rectifying the electrical signal output,
• integrating said rectified signal,
• generating an arming signal when the integrated value of the rectified signal for a pulse crosses a threshold value, and
• detecting, in response to the arming signal, a selected threshold crossing in the electrical signal, said threshold crossing determining the time of arrival of the pulse.

Intervalometer apparatus for determining the arrival time of a bandwidth limited energy pulse in a flare stack system, comprising

• a plurality of processing stations,
• each processing station having associated therewith a safety discharge conduit and a safety discharge valve connected for controlling gaseous discharge from said processing station to said conduit,
• a header conduit connected to a plurality of said discharge conduits,
• a first transducer at a first location of said header conduit,
• a second transducer at a second location of said header conduit, said first and second transducers defining between them an interrogation path,
• means for measuring an upstream transit time and a downstream transit time for the propagation of said energy pulse between said transducers in an upstream and a downstream direction respectively, said measuring means including means for determining the arrival time of received energy pulses comprising
• pulse receiving means responsive to each said received pulse for generating an electrical receive signal representing the undulations of the pulse,
• arming means responsive to said receive signal for generating an arming electrical signal representative of an armed condition, said arming means comprising
• a signal integrator responsive to said receive signal for generating said arming signal when an integrated value, dependent upon said receive signal for a said energy pulse, crosses a threshold value, and
• event recognition means responsive to said arming signal and said receive signal for detecting an event occurring in said receive signal during said armed condition, said event determining the arrival time of said bandwidth limited pulse.

A method for determining the arrival time of a bandwidth limited pulse in a flare stack system, said flare stack comprising

• a plurality of processing stations, each processing station having associated therewith a safety discharge conduit and a safety discharge valve connected for controlling discharges from said processing station to said conduit, and
• a header conduit connected to a plurality of said discharge conduits, said method comprising the steps of
• exciting a first and a second transducer for emitting acoustic energy therefrom, and
• measuring an upstream transit time and a downstream transit time for the propagation of a received energy pulse between said transducers in an upstream and a downstream direction respectively, said measuring step determining the arrival time of said pulse and including the steps of
• generating, in response to said pulse, an electrical receive signal representing the undulations of the received pulses,
• generating, in response to the receive signal, an arming electrical signal representative of an armed condition, said second generating step comprising the step of integrating the receive signal for generating the arming signal when an integrated value, dependent upon the receive signal, crosses a threshold value, and
• detecting, in response to said arming signal, an event occurring in the receive signal during the armed condition, the event determining the arrival time of the bandwidth limited pulse.

Intervalometer apparatus for determining the arrival time of a bandwidth limited energy pulse of ultrasonic energy comprising

• pulse receiving means responsive to said pulse for generating an electrical receive signal representing the undulations of the pulse,
• arming means responsive to said receive signal for generating an arming electrical signal representative of an armed condition, said arming means comprising
• a signal integrator responsive to said receive signal for generating said arming signal when an integrated value, dependent upon said receive signal for a said energy pulse, crosses a threshold value,
• said integrator further comprising a deadband threshold circuitry for blocking said receive signal prior to integration when said signal has a value within a predetermined range, and
• event recognition means responsive to said arming signal and said receive signal for detecting an event occurring in said receive signal during said armed condition, said event determining the arrival time of said bandwidth limited pulse.