Methods and apparatus for removing cyclic noise from the output signal of a magnetic sensor
AssigneeDaikin Industries, Ltd.
InventorKen-ichi Sata
Life of this patent
Estimating the term…
Abstract
A cyclic noise removing method first generates a template of a cyclic noise caused by a cryogenic refrigerator, which template is generated by arithmetically averaging the output signal from a magnetic sensor by every vibration cycle of the cryogenic refrigerator, the magnetic sensor being cooled by the cryogenic refrigerator, then removes noise included in the output signal of the magnetic sensor by subtracting the template from the output signal of the magnetic sensor.
Claims14
A method for removing cyclic noise from an output signal from a magnetic sensor which removes cyclic noise caused by vibration of a refrigerator from said output signal from said magnetic sensor which is cooled by said refrigerator to an operable low temperature so as to obtain an object signal, said method comprising the steps of;
- (a) arithmetically averaging said output of said magnetic sensor for every integral fundamental period of noise caused by vibration of said refrigerator so as to generate a template of a cyclic noise, said template substantially omitting said object signal for measurement and other noise;
- and
- (b) subtracting said template from said output of said magnetic sensor so as to obtain said object signal.
A method for removing cyclic noise from an output signal from a magnetic sensor which method removes cyclic noise caused by vibration of a refrigerator from said output signal from said magnetic sensor which is cooled by said refrigerator to an operable low temperature so as to obtain an object signal, said method comprising the steps of;
- (a) arithmetically averaging said object signal using said object signal as a trigger signal prior to starting measurement, so as to obtain an arithmetically averaged signal,
- (b) performing actual measurement so as to obtain said output of said magnetic sensor, and subtracting said arithmetically averaged signal from said output signal of said magnetic sensor so as to obtain a difference signal;
- (c) arithmetically averaging said difference signal for a predetermined number of prior cycles so as to obtain an averaged noise signal, said prior cycles being determined with respect to a position corresponding to a portion of said output signal of said magnetic sensor, which portion is to have cyclic noise removed therefrom;
- (d) subtracting said averaged noise signal from said portion of said output signal of said magnetic sensor;
- and
- (e) repeating processings in steps (c) and (d) when said output signal of said magnetic sensor is obtained for every new cycle.
An apparatus for removing cyclic noise from an output signal from a magnetic sensor which apparatus removes cyclic noise caused by vibration of a refrigerator from said output signal from said magnetic sensor which is cooled by said refrigerator to an operable low temperature so as to obtain an object signal, said apparatus comprising;
- noise template generating means for generating a template of said cyclic noise excluding said object signal for measurement and other noise by arithmetically averaging said output of said magnetic sensor for every integral fundamental period of noise caused by vibration of said refrigerator;
- and
- cyclic noise removing means for obtaining said object signal by subtracting said template from said output of said magnetic sensor.
An apparatus for removing cyclic noise from an output signal from a magnetic sensor which apparatus removes cyclic noise caused by vibration of a refrigerator from said output signal from said magnetic sensor which is cooled by said refrigerator to an operable low temperature so as to obtain an object signal, said apparatus comprising;
- first arithmetically averaging means for obtaining an arithmetically averaged signal by arithmetically averaging said object signal using said object signal as a trigger signal prior to starting measurement;
- first subtracting means for obtaining a difference signal by performing actual measurement so as to obtain said output of said magnetic sensor, and by subtracting said arithmetically averaged signal from said output signal of said magnetic sensor;
- second arithmetically averaging means for obtaining an averaged noise signal by arithmetically averaging said difference signal for a predetermined number of prior cycles, said prior cycles being determined with respect to a position corresponding to a portion of said output signal of said magnetic sensor, which portion is to have cyclic noise removed therefrom;
- second subtracting means for subtracting said averaged noise signal from said portion of said output signal of said magnetic sensor;
- and
- repetition control means for operating said
Dependencies are inferred from the claim text.