Method for operating a metal detector and metal detector
AssigneeMettler-Toledo Safeline Ltd.
InventorYifei Zhao
Life of this patent
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Abstract
The method and system are disclosed for operating a metal detector having a balanced coil system with a drive coil that is connected to a transmitter unit which provides a transmitter signal with at least one operating frequency (fTX), and with first and second detection coils that provide an output signal to a receiver unit that processes a related receiver signal which includes an imbalance signal, and that provides digital in-phase and quadrature components (dI, dQ) of the demodulated imbalance signal.
Claims20
A method for operating a metal detector having a balanced coil system with a drive coil that is connected to a transmitter unit which provides a transmitter signal (s1) with at least one operating frequency (fTX), and with a first detection coil and a second detection coil that provide an output signal (s2) to a receiver unit that processes a related receiver signal (s3) which includes an imbalance signal, and that provides digital in-phase and quadrature components (dI, dQ) of a demodulated imbalance signal, the method comprising:
- processing the digital in-phase and quadrature components (dI, dQ) of the imbalance signal in a signal controller for providing control data to a compensation unit that is configured for compensating the imbalance signal,
- applying the digital in-phase components (dI) of the imbalance signal to a first control unit (41I) which provides an in-phase control component (dCI) for the imbalance signal, and applying the digital quadrature components (dQ) of the imbalance signal to a second control unit (41Q) which provides a quadrature control component (dCQ) for the imbalance signal;
- synthesizing, in the compensation unit, a digital compensation signal (dCOMP) with a frequency of the imbalance signal which corresponds to the at least one operating frequency (fTX), with a phase and magnitude according to the in-phase and quadrature control components (dCI, dCQ) provided for the imbalance signal;
- converting the digital compensation signal (dCOMP) into an analogue compensation signal (aCOMP);
- and
- applying the analogue compensation signal (aCOMP) to the balanced coil system or to the receiver signal (s2, s3) for compensating the imbalance signal.
A metal detector comprising:
- a balanced coil system with a drive coil that is connected to a transmitter unit configured to provide a transmitter signal (s1) with at least one operating frequency (fTX);
- a first detection coil and a second detection coil configured to provide an output signal (s2);
- a receiver unit configured to receive the output signal and to process a receiver signal (s3) which includes an imbalance signal, and to provide digital in-phase and quadrature components (dI, dQ) of a demodulated imbalance signal;
- and
- a signal controller configured to receive the demodulated imbalance signal to provide control data to a compensation unit which is configured for compensating the imbalance signal, wherein
- a) a first control unit configured to receive the digital in-phase components (dI) of the imbalance signal and to provide an in-phase control component (dCI) for the imbalance signal, and a second control unit configured to receive the digital quadrature components (dQ) of the imbalance signal and to provide a quadrature control component (dCQ) for the imbalance signal;
- b) the compensation unit being configured to:
- synthesize a digital compensation signal (dCOMP) with a frequency of the imbalance signal which corresponds to the at least one operating frequency (fTX), with a phase and magnitude according to the in-phase and quadrature control components (dCI, dCQ) provided for the imbalance signal;
- convert the digital compensation signal (dCOMP) into an analogue compensation signal (aCOMP);
- and
- apply the analogue compensation signal (aCOMP) to a compensation coil of the balanced coil system, or to the input signal (s2) of the receiver unit, or via a summation module or subtraction module to the receiver signal (s3) in a signal path of the receiver unit for compensating the imbalance signal.
Dependencies are inferred from the claim text.