System for remote sensing of a physical parameter
First Claim
1. Dual-channel modulation system, for remote measurement of a physical parameter at a plurality of measurement points, havinga central evaluation unit (10);
- a plurality of sensing units (32-38);
data bus means (12, 14;
26,
28) interconnecting said evaluation unit and said sensing units;
each of said sensing units (32-38) comprising a first sensor (52) associated with a respective one of said measurement points, a first modulation circuit (54) connected to the output of said sensor and generating a pulse-interval-modulated signal, representing a first data channel, and a phase modulator (60), for the pulses generated, each respective modulator being adjusted differently for each of said sensing units (32-38),wherein,each sensing unit further comprises at least one additional modulation circuit (58) having an input for a control signal (62) and modulating at least one of the width and amplitude of said pulses, as a function of said control signal (62), thereby providing a second data channel.
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Accused Products
Abstract
A temperature remote-measurement system features a central evaluation unit 10 for all measuring points connected to two conductors 12, 14, forming a main data bus. In the embodiment shown, three addressable bus switches 18-1, 18-2, and 18-3 are connected to the data bus. To each bus switch 18 are connected respective conductors 26, 28. These together form an auxiliary bus, which is either connected to, or disconnected from, the main data bus formed by conductors 12, 14, depending upon the position of breaker 20. To the auxiliary buses formed by conductors 26, 28 are connected sensing units 32-38, which can modulate (as measurement pulses) the current carried by the conductors 26, 28 and which respond to specific voltage pulses (control pulses) generated by the control unit 10 and carried over these conductors. Each of the sensing units 32-28 has a temperature sensor 39, a pulse generator 40 controlled by the frequency of the sensor output signal, and a switching stage 41 activated by the sensor signal, so that the sensing unit altogether generates a sequence of pulses, whose interval represents the temperature at the sensing unit. The system also includes a modulator 58 which uses at least one of pulse width modulation and pulse amplitude modulation.
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Citations
15 Claims
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1. Dual-channel modulation system, for remote measurement of a physical parameter at a plurality of measurement points, having
a central evaluation unit (10); -
a plurality of sensing units (32-38); data bus means (12, 14;
26,
28) interconnecting said evaluation unit and said sensing units;each of said sensing units (32-38) comprising a first sensor (52) associated with a respective one of said measurement points, a first modulation circuit (54) connected to the output of said sensor and generating a pulse-interval-modulated signal, representing a first data channel, and a phase modulator (60), for the pulses generated, each respective modulator being adjusted differently for each of said sensing units (32-38), wherein, each sensing unit further comprises at least one additional modulation circuit (58) having an input for a control signal (62) and modulating at least one of the width and amplitude of said pulses, as a function of said control signal (62), thereby providing a second data channel. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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Specification