US4849754A — Remotely calibratable instrument system

Claim 1

Independent Claim 177 words

A two-wire transmitter system comprising: a power supply at one location; a two-wire transmitter at another location interconnected to said power supply by a pair of transmission lines, the transmitter including: an admittance sensing probe for generating an input signal representing the sensed condition and corresponding admittance of materials; an admittance responsive network coupled to said probe for comparing said input signal to a reference signal; output means coupled to said admittance responsive network for generating an output signal based upon said comparison; and admittance calibrating means for sequentially generating calibrating signals on demand which is coupled to said admittance responsive network such that said output means generates said output signal whenever a predetermined relationship exists between said input signal and one of said sequentially generated calibrating signals, said admittance calibrating means thereafter interrupting the sequential generation of calibrating signals and continuously generating said one of said calibrating signals as a new reference signal; and calibration enabling means coupled to said transmission lines for transmitting enabling signals over said transmission lines for enabling said admittance calibrating means.

Claim 2

Dependent Claim 177 words

A two-wire transmitter system comprising: a power supply at one location; a two-wire transmitter at another location interconnected to said power supply by a pair of transmission lines, the transmitter including: an admittance sensing probe for generating an input signal representing the sensed condition and corresponding admittance of materials; an admittance responsive network coupled to said probe for comparing said input signal to a reference signal; output means coupled to said admittance responsive network for generating an output signal based upon said comparison; and admittance calibrating means for sequentially generating calibrating signals on demand which is coupled to said admittance responsive network such that said output means generates said output signal whenever a predetermined relationship exists between said input signal and one of said sequentially generated calibrating signals, said admittance calibrating means thereafter interrupting the sequential generation of calibrating signals and continuously generating said one of said calibrating signals as a new reference signal; and calibration enabling means coupled to said transmission lines for transmitting enabling signals over said transmission lines for enabling said admittance calibrating means.

Claim 3

Dependent Claim 38 words

The system of claim 1 wherein said system further comprises: a load; and wherein said calibration enabling means is adapted to be coupled to said pair of transmission lines at any point between said transmitter and said load.

Claim 4

Dependent Claim 33 words

The system of claim 1 wherein said calibration enabling means comprises: means for monitoring the output signal; and means responsive to said monitoring means for determining when said predetermined relationship has been achieved.

Claim 5

Dependent Claim 35 words

The system of claim 3 wherein said calibration enabling means further comprises: means responsive to said determining means for adjusting said new reference signal whereby preload is provided for use in subsequent condition sensing operations.

Claim 6

Dependent Claim 25 words

The system of claim 1 wherein said calibration enabling means further comprises; means for transmitting an encoded series of enabling signals over said transmission lines.

Claim 7

Dependent Claim 30 words

The system of claim 5 wherein said means for transmitting an encoded series of enabling signals further comprises: means for applying a series of short circuits across said transmission lines.

Claim 8

Dependent Claim 23 words

The system of claim 1 wherein said output means further comprises: means for controlling the output signal to take one of two states.

Claim 9

Dependent Claim 31 words

The system of claim 7 wherein: said calibration enabling means is adapted to be connected to said pair of transmission lines at any point between said transmitter and said power supply.

Claim 10

Dependent Claim 23 words

The system of claim 7 wherein said calibration means comprises: means for monitoring said output signal to detect a change in state thereof.

Claim 11

Dependent Claim 22 words

The system of claim 9 wherein said admittance calibrating means is responsive to said enabling signals for sequentially generating said calibrating signals.

Claim 12

Dependent Claim 47 words

The system of claim 10 wherein: said calibration enabling means continues to supply calibration enabling signals to said admittance calibrating means and said admittance calibrating means continues to sequentially generate said calibrating signals until said calibration enabling means detects a change of state of said output signal.

Claim 13

Dependent Claim 137 words

A condition-monitoring instrument system comprising: a transmitter adapted to transmit an output signal responsive to a monitored condition; and a calibration enabling means, said transmitter and said calibration enabling means being connected by a communication channel, said calibration enabling means having: means for transmitting calibration enabling signals to said transmitter, said transmitter being responsive to said calibration enabling signals by variation of a stored reference signal and by comparison of said varied reference signal to said monitored condition signal and by transmission of said output signal which indicates that said varied reference signal bears a predetermined relationship to the monitored condition signal to said calibration enabling means over said communication channel; means for monitoring said output signal; and means for transmitting additional calibration enabling signals upon change of state of the output signal transmitted by said transmitter.

Claim 14

Dependent Claim 137 words

A condition-monitoring instrument system comprising: a transmitter adapted to transmit an output signal responsive to a monitored condition; and a calibration enabling means, said transmitter and said calibration enabling means being connected by a communication channel, said calibration enabling means having: means for transmitting calibration enabling signals to said transmitter, said transmitter being responsive to said calibration enabling signals by variation of a stored reference signal and by comparison of said varied reference signal to said monitored condition signal and by transmission of said output signal which indicates that said varied reference signal bears a predetermined relationship to the monitored condition signal to said calibration enabling means over said communication channel; means for monitoring said output signal; and means for transmitting additional calibration enabling signals upon change of state of the output signal transmitted by said transmitter.

Claim 15

Dependent Claim 44 words

The system of claim 12 wherein said output signal is bistable and wherein said transmitter further comprises: means for changing the state of said bistable output signal in order to indicate change in the relationship between the reference signal and the monitored condition signal.

Claim 16

Dependent Claim 32 words

The system of claim 13 further comprising: a receiver adapted to be connected to said communication channel, said receiver including means for responding to said bistable output signal transmitted by said transmitter.

Claim 17

Dependent Claim 20 words

The system of claim 14 wherein said communication channel comprises: a two-wire transmission means connecting said transmitter and said receiver.

Claim 18

Dependent Claim 29 words

The system of claim 15 wherein: said communication enabling means is adapted to be coupled to said two-wire transmission means at any point between the transmitter and the receiver.

Claim 19

Dependent Claim 15 words

The system of claim 16 wherein said bistable output signal comprises: a bistable current signal.

Claim 20

Dependent Claim 26 words

The system of claim 17 wherein said calibration enabling means comprises: means for transmitting a series of encoded calibration enabling signals on said two-wire transmission means.

Claim 21

Dependent Claim 24 words

The system of claim 18 wherein said series of encoded calibration signals further comprises: a series of short circuits across said two-wire transmission means.

Claim 22

Dependent Claim 19 words

The system of claim 19 wherein said transmitter further comprises: means for responding to said encoded calibration enabling signals.

Claim 23

Dependent Claim 30 words

The system of claim 20 wherein said means for responding further comprises: means for decoding said encoded signals; and means for comparison of said decoded signals to a stored reference.

Claim 24

Dependent Claim 123 words

A two-wire transmitter system comprising: a power supply at one location; a two-wire transmitter at another location; a pair of transmission lines interconnecting said power supply and said transmitter for carrying a variable signaling current; and a calibrator, said transmitter further comprising: an admittance sensing probe including a probe electrode adapted to sense the condition and corresponding admittance of materials; an admittance responsive network coupled to said probe; output means coupled to said admittance responsive network for varying said signaling current in response to the condition of materials bearing a predetermined relationship to a setpoint stored in said output means, said calibrator being adapted to be coupled to said pair of transmission lines for communicating setpoint calibration enabling signals to said output means.

Claim 25

Dependent Claim 123 words

A two-wire transmitter system comprising: a power supply at one location; a two-wire transmitter at another location; a pair of transmission lines interconnecting said power supply and said transmitter for carrying a variable signaling current; and a calibrator, said transmitter further comprising: an admittance sensing probe including a probe electrode adapted to sense the condition and corresponding admittance of materials; an admittance responsive network coupled to said probe; output means coupled to said admittance responsive network for varying said signaling current in response to the condition of materials bearing a predetermined relationship to a setpoint stored in said output means, said calibrator being adapted to be coupled to said pair of transmission lines for communicating setpoint calibration enabling signals to said output means.

Claim 26

Dependent Claim 30 words

The system of claim 22 wherein said output means further comprises: means for varying said setpoint in a predetermined manner in response to detection of said setpoint calibration enabling signals.

Claim 27

Dependent Claim 18 words

The system of claim 23 wherein said output means further comprises: means for nonvolatile storage of said setpoint.

Claim 28

Dependent Claim 45 words

The system of claim 23 wherein said calibrator further comprises: means for monitoring the signaling current to determine when the output means varies the signaling current in response to the sensed condition bearing said predetermined relationship to said setpoint as varied by said output means.

Claim 29

Dependent Claim 59 words

The system of claim 25 wherein said calibrator further comprises: means for causing said setpoint to be further varied, in order to provide preload for subsequent operations, after said means for monitoring has determined that said sensing current has been varied by said output means in response to said sensed condition bearing said predetermined relationship to said varied setpoint.

Claim 30

Dependent Claim 25 words

The system of claim 22 wherein said calibrator comprises: means for superimposing said setpoint calibration enabling signals on said signaling current on said transmission lines.

Claim 31

Dependent Claim 32 words

The system of claim 27 wherein said means for superimposing comprises: means for placing an encoded series of short circuits across said pair of transmission lines as said setpoint calibration enabling signals.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1992-07-17	1993-01-16	1993-07-18	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1996-07-17	1997-01-16	1997-07-18	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2000-07-17	2001-01-16	2001-07-18	$7700.00	Window Closed / Lapsed

Remotely calibratable instrument system

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