Method and apparatus for cancelling noise in a received signal by signal subtraction
First Claim
1. A method of canceling noise in a communication system having a transmitting unit, a receiving unit and a transmission line connected therebetween, comprising the steps of:
- (a) producing a first signal, which is a first predetermined function of a transmitting signal, in the transmitting unit of the communication system;
(b) producing a second signal, which is a second predetermined function of the transmitting signal, in the transmitting unit of the communication system, said second predetermined function being different from the first predetermined function and said second signals being produced prior to their transmission from said transmitting unit;
(c) transmitting said first and second signals from the transmitting unit to the receiving unit of the communication system through the transmission line of the communication system; and
(d) subtracting one of the first and second signals from the other in the receiving unit to remove noise superposed on the first and second signals during signal transmission, so as to produce a receiving signal corresponding to said transmitting signal.
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Accused Products
Abstract
An industrial measuring apparatus comprises first and second sensors having identical measuring characteristics and arranged close to each other and also close to a common subject of measurement, for measuring the same parameter, a transmitting unit having an adder and a first subtracter respectively connected the sensors through amplifiers, and a receiving unit having a second subtracter connected to the adder and the first subtracter through two transmission lines and constituting a noise canceling device in cooperation with the adder and the first subtracter. The second subtracter produces a receiving signal by subtracting the output of the subtracter representing the difference between the outputs of the first and second sensors from the output of the adder representing the sum of the outputs of the two sensors. Noise superposed on the outputs of the adder and subtracter during transmission is canceled out when the receiving signal is produced, whereby a receiving signal exactly corresponding to the sensor signal is easily obtained.
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Citations
19 Claims
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1. A method of canceling noise in a communication system having a transmitting unit, a receiving unit and a transmission line connected therebetween, comprising the steps of:
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(a) producing a first signal, which is a first predetermined function of a transmitting signal, in the transmitting unit of the communication system; (b) producing a second signal, which is a second predetermined function of the transmitting signal, in the transmitting unit of the communication system, said second predetermined function being different from the first predetermined function and said second signals being produced prior to their transmission from said transmitting unit; (c) transmitting said first and second signals from the transmitting unit to the receiving unit of the communication system through the transmission line of the communication system; and (d) subtracting one of the first and second signals from the other in the receiving unit to remove noise superposed on the first and second signals during signal transmission, so as to produce a receiving signal corresponding to said transmitting signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A device for canceling noise in a communication system, comprising:
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first means, provided in a transmitting unit of the communication system, for producing a first signal which is a first predetermined multiple of a transmitting signal; second means, provided in the transmitting unit, for producing a second signal which is a second predetermined multiple of the transmitting signal, said second predetermined multiple being different from the first predetermined multiple and said first and second signals being produced prior to their transmission from said transmitting unit; and third means, provided in a receiving unit of the communication system, for subtracting one of the first and second signal, supplied thereto through a tramsmission line of the communication system, from the other to remove noise superposed on the first and second signals during signal transmission, so as to produce a receiving signal corresponding to said transmitting signal. - View Dependent Claims (10, 11, 12, 13, 14)
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15. A device for canceling noise in a communication system, comprising:
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first means, provided in a transmitting unit of the communication system, for producing a first signal which is a first predetermined multiple of a transmitting signal; second means, provided in the transmittint unit, for producing a second signal which is a second predetermined multiple of the transmitting signal, said second predetermined multiple being different from the first predetermined multiple and third means, provided in a receiving unit of the communication system, for subtracting one of the first and second signal, supplied thereto through a transmission line of the communication system, from the other to remove noise superposed on the first and second signals during signal transmission, so as to produce a receiving signal corresponding to said transmitting signal, wherein said transmitting unit includes first and second sensors arranged in a facing relation to a common subject of measurement, said first means includes an adder for adding together output signals of said first and second sensors, said second means includes a subtracter for subtracting an output signal of one of said first and second sensors from an output signal of the other, and said third means includes a second subtracter for subtracting an output of one of said adder and said subtracter from an output of the other. - View Dependent Claims (16, 17, 18, 19)
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Specification