PULSE DISCRIMINATOR AND TELEMETERING SYSTEMS USING SAME

• US 3,742,473 A
• Filed: 08/12/1970
• Issued: 06/26/1973
• Est. Priority Date: 08/12/1970
• Status: Expired due to Term

• Current Assignee: Detector Electronics Corporation
• Original Assignee: David M. Hadden
• Inventors: Hadden, David M.
• Primary Examiner(s): Caldwell, John W.
• Assistant Examiner(s): Mooney, Robert J.
• Application Number:
  US05/063,178
• Time in Patent Office: 1,049 Days
• Field of Search: 340/203 307/234,235,246 328/109,115,111 329/109,106
• US Class Current: 340/870.2
• CPC Class Codes: G01R 29/0273 the pulse characteristic being duration, i.e. width (indicating that frequency of pulses is above or below a certain limit)
• CPC Class Codes: G08C 19/26 by varying pulse repetition frequency

Abstract

A telemetering system is disclosed having a transmitter located at an outlying station for generating a train of pulses having a certain parameter which is a function of a quantity to be measured. The pulses are transmitted over a two wire transmission line to a receiver located at a base station. The receiver includes a pulse discriminator for discriminating both the minimum height and the minimum pulse width of the pulses to be metered by the receiver. The pulse discriminator includes a pulse generator, such as a unijunction transistor, having a storage capacitor connected across its input terminals. The capacitor is charged up through a resistor such that the time to reach the triggerable level for the pulse generator is equal to the minimum pulse width to be discriminated. The charging cycle for the capacitor is controlled through a switching transistor biased such that input pulse to be discriminated must have a certain pulse height to cause the transistor to switch current to the capacitor and the switching transistor is held '"'"''"'"''"'"''"'"'on'"'"''"'"''"'"''"'"' only so long as the pulse height exceeds the minimum level. The capacitor charging cycle is reset each time the input pulse falls below the predetermined pulse height reference level.

Claims

1. In a telemetering system, transmitter means to be located at an outlying station for generating a train of pulses, said pulses having a predetermined fixed width and being of a repetition rate which is a function of a quantiy to be metered, receiver means to be located proximate a base station for receiving the transmitted train of pulses and being responsive to the repetition rate of said pulses for producing a metering output which is a measure of the quantity to be metered, two conductor transmission line means for interconnecting the base station and the outlying station and over which the train of transmitted pulses is to be transmitted from said transmitter means to said receiver means, the improvement wherein, said receiver means includes a pulse discriminator means for discriminating the pulses to be metered by said receiver means as received over said transmission line means from said transmitter means and for converting only such discriminated pulses into an output which have an amplitude in excess of a predetermined threshold value for a predetermined Minimum threshold time, whereby noise is effectively suppressed in the metering output of said receiver means.

2. In a telemetering system, transmitter means to be located at an outlying station for generating a train of pulses having a certain parameter which is a function of a quantity to be metered, receiver means to be located proximate a base station for receiving the transmitted train of pulses and being responsive to the certain parameter thereof for producing a metering output which is a measure of the quantity to be metered, two conductor transmission line means for interconnecting the base station and the outlying station and over which the train of transmitted pulses is to be transmitted from said transmitter means to said receiver means, the improvement wherein, said receiver means includes a pulse discriminator means for discriminating the minimum height and minimum width of the pulses to be metered by said receiver means as received over said transmission line means from said transmitter means, and for converting only such discriminated pulses into an output which meet both the minimum requirements of pulse width and height, whereby noise is effectively suppressed in the metering output of said receiver means, and wherein said pulse discriminator means includes, a storage capacitor and a resistor through which said capacitor is to be charged, means for charging said capacitor from a source of current through said resistor, a triggerable pulse generator means for generating an output pulse when an input trigger signal to said triggerable pulse generator exceeds a reference amplitude, said storage capacitor being connected across the input to said triggerable pulse generator for building-up an input trigger signal voltage to said pulse generator in accordance with the charge on said capacitor, said resistor and capacitor having values to provide a time constant such that the time to charge the said capacitor to the voltage level thereacross which will trigger said pulse generator means is determinative of the minimum pulse width to be discriminated, switching means responsive to the pulse height of the input pulse to be discriminated for switching to a first state to feed the charging current into said storage capacitor through said resistor and for maintaining the flow of charging current to said capacitor only so long as the pulse height of the input pulse to be discriminated does not fall below a predetermined threshold amplitude, said switching means also being arranged so that when the input pulse does fall below the predetermined amplitude said switching means switches to a second state to rapidly discharge the charge stored on said capacitor, and means for setting said certain predetermined pulse height threshold amplitude of said switching means.

3. The apparatus of claim 2 wherein said switching means comprises a single transistor having base, emitter and collector electrodes, said capacitor being connected across said emitter and collector electrodes, and means for applying pulses to be discriminated across the base and emitter electrodes of said transistor.

4. The apparatus of claim 2 wherein said triggerable pulse generator means comprises a unijunction transistor having a pair of base electrodes and a gate electrode, said capacitor being connected across one of said base electrodes and said gate electrode.

5. The apparatus of claim 3 including a source of potential applied across said collector and said emitter electrodes of said transistor, a voltage divider means having first and second resistive means with a node therebetween connected in series between the source of potential and said base electrode of said transistor, and means for coupling the pulses to be discriminated between said node of said voltage divider and said emitter electrode of said transistor, said voltage divider serving to establish the minimum pulse height for pulses to be discriminated by said pulse discriminator means.

6. The apparatus of claim 1 wherein said two conductor transmission line means comprises an unshielded pair of conductors.

7. The apparatus of claim 1 wherein said two conductor transmission line means comprises a pair of unshielded wires.

8. The apparatus of claim 1 wherein said two conductor transmission line means comprises a single wire strung through an electrical conduit which forms the second conductor of said transmission line.

9. The apparatus of claim 1 wherein said two conductor transmission line comprises a wire and a spaced hollow conductive pipe.

10. The apparatus of claim 1, including, power supply means to be connected to said transmission line means at the base station for energizing said pair of conductors with dc current and voltage, and wherein said transmitter means includes, means for pulse modulating the dc voltage on said transmission line at the outlying station for producing the train of output pulses traveling over said transmission line from said transmitter means to said receiver means.

11. The apparatus of claim 1 wherein said transmitter means produces a train of pulses of reduced potential on said transmission line.

12. In a method for telemetering, generating a train of pulses at an outlying station, said pulses having a certain predetermined fixed pulse width and being of a repetition rate which is a function of a quantity to be measured, transmitting the train of pulses over a two conductor transmission line to a base station, receiving the transmitted train of pulses at the base station, producing a metered output from the received pulses which is a measure of the quantity to be metered at the outlying station, discriminating the pulses as received over the transmission line from the outlying station for a minimum pulse height and a minimum pulse width such that only such pulses having an amplitude in excess of a predetermined threshold value for a predetermined minimum threshold time are metered, whereby noise is effectively suppressed in the telemetering of the signals from the outlying station to the base station.

13. The method of claim 12 wherein the step of discriminating the pulses as received over the unshielded transmission line includes the step of discriminating against the pulses which are not wider than a few microseconds.

14. In a pulse discriminator apparatus, storage capacitor means and a resistor means through which said storage capacitor is to be charged, means for charging said storage capacitor from a source of current through said resistor, triggerable pulse generator means for generating an output pulse when an input trigger signal to said triggerable pulse generator exceeds a reference amplitude said storage capacitor being connected across the input to said triggerable pulse generator for building-up an input trigger signal voltage to said pulse generator in accordance with the charge on said capacitor, said charging resistor and storage capacitor having a time constant such that the time to charge the said capacitor to the voltage level thereacross which will trigger said triggerable pulse generator means is determinative of the minimum pulse width to be discriminated, switching means responsive to a certain predetermined threshold pulse height of the input pulses to be discriminated for switching to a first state to feed the charging current through said resistor means into said storage capacitor and for maintaining the flow of charging current to said capacitor only so long as the input pulse to be discriminated does not fall below the predetermined threshold pulse height, said switching means also being arranged so that when the pulse height of the input pulse does fall below the predetermined amplitude said switching means switches to a second state for rapidly discharging the charge stored on said capacitor, and means for setting said certain predetermined threshold pulse height of said switching means.

15. The apparatus of claim 14 wherein said switching means comprises a single transistor having base, emitter and collectoR electrodes, said storage capacitor being connected across said emitter and collector electrodes, and means for applying pulses to be discriminated across the base and emitter electrodes of said transistor.

16. The apparatus of claim 14 wherein said triggerable pulse generator means comprises a unijunction transistor having a pair of base electrodes and a gate electrode, said storage capacitor being connected across one of said base electrodes and said gate electrode.

17. The apparatus of claim 15 including, a source of potential applied across said collector and emitter electrodes of said transistor, voltage divider means having first and second resistive means with a node therebetween connected in series between said source of potential and said base electrode of said transistor, and means for coupling the pulses to be discriminated between said node of said voltage divider and said emitter electrode of said transistor, said voltage divider serving to establish the minimum pulse height for pulses to be discriminated by said pulse discriminator means.