Data acquisition system and analog to digital converter therefor
AssigneeWestinghouse Electric Corp.
InventorGyorgy I. Vancsa
Life of this patent
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Abstract
From a plurality of parallel channels of communication, each including a voltage-to-frequency (V/F) converter, a central clock synchronously timed for each channel, the derivation of a train of pulses having a number of pulses representative of the magnitude of an analog signal inputted to the V/F converter. The central clock also times the multiplexing at the measuring point of either the analog input signal or a bias voltage for calibration or a voltage reference for scaling. The central processor receives the counts from each train of pulses, combines them and threats them to provide a corrected count in each channel separately. Clocking and pulsing are effected through an isolation transformer associated with each channel, to and from the central processor.
Claims2
A method of deriving through a channel of communication including an anlog-to-digital (A/D) converter, a corrected value C.sub.XC applicable to any count C.sub.X derived from said (A/D) converter through said channel of communication in relation to an analog input signal of magnitude V.sub.X applied from at least one measuring point, comprising the steps of:
- (1) applying a bias voltage V.sub.B at the input of said channel of communication and deriving a count C.sub.B at the output of said A/D converter;
- (2) applying a known voltage reference V.sub.REF at the input of said channel of communication and deriving a count C.sub.REF at the output of said A/D converter;
- (3) applying the analog input signal of magnitude V.sub.X of the measuring point and deriving a count C.sub.X at the output of said A/D converter;
- (4) computing C.sub.XC with the formula:
- ##EQU8## where "RES" is the Resolution C.sub.RES of measurement and "Range" is the spread of the input signal V.sub.X in magnitude;
- the deriving steps (1) and (2) of counts C.sub.B and C.sub.REF being refreshed from applied voltages V.sub.B and V.sub.REF from time to time before deriving counts C.sub.X and computing C.sub.XC under steps (3) and (4).
Dependencies are inferred from the claim text.