Level measuring system

• US 4,135,397 A
• Filed: 06/03/1977
• Issued: 01/23/1979
• Est. Priority Date: 06/03/1977
• Status: Expired due to Term

• Current Assignee: Guss L. Krake
• Original Assignee: Guss L. Krake
• Inventors: Krake, Guss L.
• Primary Examiner(s): Krawczewicz, Stanley T.
• Application Number:
  US05/803,226
• Time in Patent Office: 599 Days
• Field of Search: 324/58.5 B, 73/290 R, 73/304 R
• US Class Current: 73/290.00R
• CPC Class Codes: G01F 23/284 Electromagnetic waves
• CPC Class Codes: G01R 27/06 Measuring reflection coefficients; Measuring standing-wave ratio

Abstract

A system for measuring the height of material in a storage container by generating an incident pulse with a pulse generator and transmitting the pulse through a high impedance transmission line supported in a container. A reflected pulse of opposite polarity is generated at the interface of air and material in the container and is received by a reflected pulse detector which again triggers the pulse generator to continuously monitor the height of the material in the container. The time difference between the transmitted incident pulse and the received reflected pulse of opposite polarity is the indication of the height of the material in the container. A hold off delay disables the reflected pulse detector for a finite period of time so that the reflected pulse detector is not affected by noise signals on the transmission line. If no material is in the container and no reflected pulse of opposite polarity is received, then one automatic start pulse generator retriggers the pulse generator. An auxiliary transmission line of equal length to that in the container is used to calibrate the measuring system.

Claims

1. A measuring system for determining the height of a material in a container comprising:

a. container means for storing a material, a high impedance transmission line means supported in said container means, and load impedance means terminating one end of said high impedance transmission line means;

b. feed line means connected to the other end of said high impedance transmission line means;

2. c. pulse generator means connected to feed line means to generate a train of incident pulses which propagate an external electromagnetic field surrounding said high impedance transmission line means;

d. reflected pulse detector means connected to said feed line means to receive reflected pulses of opposite polarity of said incident pulses from said high impedance transmission line means occurring at an interface of the air and said material in said container means;

e. trigger means connected to said pulse generator means and triggered by each of said reflected pulses from said reflected pulse detector means;

f. start pulse generator means connected to said trigger means;

g. hold off delay means connected between said pulse generator means and said reflected pulse detector means; and

,

h. time interval measuring means connected to said reflected pulse detector means whereby said start pulse generator means triggers said pulse generator means through said trigger means to generate train of incident pulses down said high impedance transmission line means to subsequently propagate an external electromagnetic field surrounding said transmission line means, said hold off delay means disables said reflected pulse detector means during the time of travel of each of said incident pulses from said pulse generator means to a junction of said feed line means and said high impedance transmission line means and time of travel of each of said reflected pulses from said junction to said reflected pulse detector means so that said reflected pulse detector means is not triggered by noise signals during said time of travel, and said time interval measuring means measures the time between said incident pulse and said reflected pulse occurring at the interface of the air and said material in said container, said time interval being directly proportional to said height of said material in said container.

4. The measuring system of claim 2 wherein said pulse generator means comprises a one shot multivibrator whereby said multivibrator is triggered by either said reflected pulse detector means or said trigger means.

5. The measuring system of claim 2 wherein said reflected pulse detector means comprises a high speed pulse amplifier.

6. The measuring system of claim 2 wherein said hold off delay means comprises a one shot multivibrator in series with a delay line connected between said pulse generator means and said reflected pulse detector means.

7. The measuring system of claim 2 wherein said start pulse generator means comprises a one shot multivibrator.

8. The measuring system of claim 6 wherein said time out means comprises a resistor-capacitor network connected to a timing input of said one shot start pulse generator multivibrator whereby said start pulse generator multivibrator triggers said trigger means when said resistor-capacitor network reaches charge.

9. The measuring system of claim 2 wherein said trigger means comprises an OR gate.

10. The measuring system of claim 2 wherein said high impedance transmission line means, said feed line means, and said load impedance means are equal to the characteristic impedance of said high impedance transmission line.

3. A measuring system for determining the height of a material in a container comprising:

a. container means for storing a material, a high impedance transmission line means supported in said container means, and load impedance means terminating one end of said high impedance transmission line means;

b. feed line means connected to the other end of said high impedance transmission line means;

c. pulse generator means connected to said feed line means to generate a train of incident pulses which propagate an external electromagnetic field surrounding said high impedance transmission line means;

d. reflected pulse detector means connected to said feed line means to receive reflected pulses of opposite polarity of said incident pulses from said high impedance transmission line means occurring at an interface of the air and said material in said container means;

e. trigger means connected to said pulse generator means and triggered by each of said reflected pulses from said reflected pulse detector means;

f. start pulse generator means connected to said trigger means to trigger said trigger means;

g. hold off delay means connected between said pulse generator means and said reflected pulse detector means;

h. time out means connected between said reflected pulse detector means and said start pulse generator means; and

,

i. time interval measuring means connected to said reflected pulse detector means whereby said start pulse generator means triggers said pulse generator means through said trigger means to generate a train of incident pulses down said high impedance transmission line means to subsequently propagate an external electromagnetic field surrounding said transmission line means, said hold off delay means disables said reflected pulse detector means during the time of travel of each of said incident pulses from said pulse generator means to a junction of said feed line means and said high impedance transmission line means and time of travel of each of said reflected pulses from said junction to said pulse detector means so that said reflected pulse detector means is not triggered by noise signals during said time of travel, said time interval measuring means measures the time between said incident pulse and said reflected pulse occurring at the interface of the air and said material in said container, said time interval being directly proportional to said height of said material in said container, said reflected pulse detector means retriggers said pulse generator through said trigger means, and said time out means retriggers said start pulse generator means in the event that a reflected pulse is not received by said reflected pulse detector means as the incident pulses are dissipated by said load impedance means when said container is empty of said material.