Transducer system for continuous monitoring liquid levels in _storage tanks and the like

Method of generating a digital code indicative of liquid level within a storage tank or the like upon receipt of a square wave interrogation signal from a transmitter receiver of a tank gauging system located at a central station remote from said storage tak under survey but electrically connected to said transponder network through an INTERROGATION, a MARK and a SPACE line of said tank gauging system, comprising the steps of:

• (A) encoding, as a updated, stored digital code, a series of input signals representative of liquid level within said storage tank in response to said interrogation signal;
• (B) generating a microcircuit rest signal after said encoded digital code has been generated and stored at a series of memory addresses;
• (C) generating in response to said reset pulse, sets of square wave pulses of differing repetition rates and pulse widths;
• (D) in response to selected sets of said square wave pulses of (C) logically scanning said series of memory addresses and forming a synthetic digital code at microcircuit signal levels directly equivalent to said encoded digital code of (A);
• and
• (E) as a function of said synthetic digital code, driving said MARK and SPACE lines to generate a MARK-SPACE digital code at said central station equivalent--in detail--to said encoded digital code of (A) whereby said liquid level condition within said storage tank can be indicated.

Transducer system for generating a digital code indicative of liquid level within a storage tank or the like, upon receipt of a square wave interrogation signal from a transmitter/receiver of a tank gauging system located at a central station remote from said storage tank but electrically connected to said transducer system through an INTERROGATION, a MARK and a SPACE line of said tank gauging system comprising:

• (A) means for providing a series of input signals representative of liquid level within said tank, said means being in circuit with a series of look-up read-only-memories (ROM's);
• (B) I/O network for receiving said interrogation signal and connected to (A) for generating a reset signal therefrom in response to said interrogation signal;
• (C) an oscillator/ripple counter formed essentially of MSI's connected to (A) and including at an input a network for receiving said reset pulse from (A), said oscillator/ripple counter generating, in response to said reset pulse, sets of square wave pulses of differing repetition rates and pulse widths;
• (D) a multiplexer and multi-segment decoder/driver means connected to each other and to (B) responding to selected sets of said square wave pulses to generate a synthetic digital code indicative of liquid level at microcircuit signal levels at an output means of said decoder/driver means;
• (E) isolator/driver means having one or more inputs connected to said decoder/driver means of (D), and one or more output means connected to said MARK and SPACE lines controllable as a function of said synthetic digital code to drive said MARK and SPACE lines between tank gauging operating potentials for generating said digital code of interest at said central station whereby said liquid level condition within said storage tank can be indicated.