Signal measurement and processing method and apparatus

Apparatus for generating an output dependent upon the impedance or at least one component of the impedance of a device, the apparatus comprising:

• a load component having a known impedance or at least one component thereof for connection in series with said device;
• a signal generating arrangement for generating a time-varying electrical signal for application to the series connected load component and device;
• a measurement channel for measuring voltages;
• a switch arrangement connected to said measurement channel for switching the measurement channel to sequentially measure a first voltage on a first side of said load component, and one of a second voltage on a second side of said load component or a voltage difference between said first side and a second side of said load component;
• and
• a processing arrangement connected to said measurement channel for processing the sequentially measured voltages to generate an output dependent upon said impedance or said at least one component of impedance of said device;
• wherein said processing arrangement is adapted to generate said output as an indication of whether or not a factor related to the impedance or at least one component thereof is above or below a threshold without determining an absolute measure of impedance.

A method of generating an output dependent upon the impedance or at least one component of the impedance of a device, the method comprising:

• connecting a load component having a known impedance or at least one component thereof in series with said device;
• applying a time-varying electrical signal to the series connected load component and device;
• using a measurement channel to sequentially measure a first voltage on a first side of said load component, and a voltage difference between said first side and a second side of said load component;
• and
• processing the sequentially measured voltages to generate an output dependent upon said impedance or at least one component of the impedance of said device.

A method generating an output dependent upon the impedance or at least one component of the impedance of a device, the method comprising:

• connecting a load component having a known impedance or at least one component thereof in series with said device;
• applying a time-varying electrical signal to the series connected load component and device;
• using a measurement channel to sequentially measure a first voltage on a first side of said load component, and one of a second voltage on a second side of said load component or a voltage difference between said first side and a second side of said load component;
• and
• processing the sequentially measured voltages to generate an output dependent upon said impedance or at least one component of the impedance of said device;
• wherein the processing generates said output as an indication of whether or not a factor related to the impedance or at least one component of the impedance is above or below a threshold.

Apparatus for generating an output dependent upon the impedance or at least one component of the impedance of a device, the apparatus comprising:

• a load component having a known impedance or at least one component thereof for connection in series with the device to allow for the measurement of a voltage drop across the load component;
• a generator arrangement for applying a signal having a voltage to the series connected load component and device;
• a measurement arrangement adapted to measure a first voltage one side of said load component, and one of a second voltage on the other side of said load component or a difference voltage comprising the voltage difference across said load device;
• and
• a signal processing arrangement for processing the measurements to generate an output dependent upon the impedance or at least one component of the impedance of the device, wherein said processing arrangement is adapted to:
• determine a first parameter indicative of the complex amplitude of the first voltage on a first side of said load component connected to said device, and a second parameter indicative of the complex amplitude of said difference voltage or a calculated difference voltage comprising the difference between the first and second voltages;
• multiply each of the first and second determined parameters by the complex conjugate of the second determined parameter to generate third and fourth parameters respectively;
• and
• compare said third and fourth parameters to generate an output or compare one or more components or derivatives of the third parameter and said fourth parameter to generate said output.

A method of generating an output dependent upon the impedance or at least one component of the impedance of a device, the method comprising:

• connecting a load component having a known impedance or at least one component of the impedance in series with the device to allow for the measurement of a voltage drop across the load component;
• applying a signal having a voltage to the series connected load component and device;
• measuring a first voltage one side of said load component, and a second voltage on the other side of said load component or a difference voltage comprising the voltage difference across said load device;
• and
• processing the measurements to generating an output dependent upon the impedance or at least one component thereof, wherein said processing comprises:
• determining a first parameter indicative of the complex amplitude of the first voltage on a first side of said load component connected to said device, and a second parameter indicative of the complex amplitude of said difference voltage or a calculated difference voltage comprising the difference between the first and second voltages;
• multiplying each of the first and second determined parameters by the complex conjugate of the second determined parameter to generate third and fourth parameters respectively;
• and
• comparing said third and fourth parameters to generate said output or comparing one or more components or derivatives of the third parameter and said fourth parameter.

Apparatus for generating an output in dependence upon the impedance or at least one component of the impedance of a device, the apparatus comprising:

• a load component having a known impedance or at least one component of impedance for connection in series with the device to allow for the measurement of a voltage drop across the load component;
• a generator arrangement for applying a time-varying voltage signal to the series connected load component and device;
• a measurement channel for measuring voltage;
• a switch arrangement for switching the measurement channel to sequentially measure a first voltage a first side of said load component and a difference voltage between said first side and a second side of said load component;
• and
• a signal processing arrangement for processing the measurements to generate an output in dependence upon the impedance or at least one component of the impedance.

A method of generating an output in dependence upon the impedance or at least one component of the impedance of a device, the method comprising:

• connecting a load component having a known impedance or at least one component of the impedance in series with the device to allow for the measurement of a voltage drop across the load component;
• applying a time-varying voltage signal to the series connected load component and device;
• sequentially measuring a first voltage on a first side of said load component and a difference voltage between said first side and a second side of said load component using a measurement channel;
• and
• processing the measurements to generate an output in dependence upon the impedance or at least one component of the impedance.

A method of identifying a device having an impedance characteristic as a function of frequency, the method comprising:

• applying signals of a first and second frequency to said device;
• obtaining measurements indicative of a first voltage one side of said load component, and one of a second voltage on the other side of said load component or a difference voltage comprising the voltage difference across said load device, the measurements being obtained at both said frequencies;
• determining a value dependent on the impedances for said device at said frequencies using said measurements, including the steps of:
• determining first and second parameters indicative of the complex amplitude, at said first and second frequency respectively, of the first voltage on a first side of said load component connected to said device;
• determining third and fourth parameters indicative of the complex amplitude, at said first and second frequency respectively, of said difference voltages or a calculated difference voltage comprising the difference between the first and second voltages;
• multiplying each of the first and third determined parameters by the complex conjugate of the third determined parameter to generate fifth and sixth parameters respectively;
• multiplying each of the second and fourth determined parameters by the complex conjugate of the fourth determined parameter to generate seventh and eighth parameters respectively;
• and
• performing a comparison using said fifth, sixth, seventh and eighth parameters to determine said value or performing a comparison using one or more components or derivatives of said fifth, sixth, seventh and eighth parameters to determine said value;
• using said value to identify said device;
• and
• generating an output identifying said device.

A method of identifying a device having an impedance characteristic as a function of frequency, the method comprising:

• applying signals of a first and second frequency to said device;
• obtaining first and second parameters indicative of the complex amplitude, at said first and second frequency respectively, of the first voltage on a first side of said load component connected to said device;
• obtaining third and fourth parameters indicative of the complex amplitude, at said first and second frequency respectively, of said difference voltages or a calculated difference voltage comprising the difference between the first and second voltages;
• multiplying each of the first and third parameters by the complex conjugate of the third determined parameter to generate fifth and sixth parameters respectively;
• multiplying each of the second and fourth parameters by the complex conjugate of the fourth determined parameter to generate seventh and eight parameters respectively;
• comparing at least one of said parameters for said device with corresponding at least one parameters for at least one other device to identify said device;
• and
• outputting a value indicative of said identity of said device.

A proximity sensor for sensing the proximity of a target comprising:

• an electrical component for sensing the proximity of the target, said electrical component having electrical properties that vary with the proximity of the target;
• an impedance component having a known impedance and a first end connected to a first end of said electrical component;
• an analog difference amplifier connected to said first end and a second end of said impedence component;
• a switch connected to switch between said first end of said impedance component and an output of said analog difference amplifier;
• a signal generator connected to said second end of said impedance component for generating an electrical signal for application to the impedance component and electrical component;
• an analog-to-digital converter for receiving an electrical signal and for generating a digital signal;
• and
• a processor connected to the analog-to-digital converter for receiving a digital voltage signal and for generating a proximity signal, wherein said processor is adapted to control said switch to switch to connect to said first and second ends of said impedance component sequentially.

Apparatus for generating an output dependent upon the impedance or at least one component of the impedance of a device, the apparatus comprising:

• a load component having a known impedance for connection in series with the device to allow for the measurement of a voltage drop across the load component;
• a generator arrangement for applying a time-varying voltage across the series connected load component and device;
• a measurement arrangement adapted to sequentially measure a first voltage on a first side of said load component, and a difference voltage comprising the voltage difference between said first side and a second side of said load device;
• and
• a signal processing arrangement for processing the measurements to generate an output dependent upon the impedance of said device;
• wherein said signal processing arrangement is adapted to monitor said measurements to detect fault conditions in said device and to output a warning output if a fault condition is detected.

A method for generating an output dependent upon the impedance or at least one component of the impedance of a device, the method comprising:

• connecting a load component having a known impedance in series with the device to allow for the measurement of a voltage drop across the load component;
• applying a time-varying voltage across the series connected load component and device;
• sequentially measuring a first voltage on a first side of said load component, and a difference voltage comprising the voltage difference between said first side and a second side of said load device;
• processing the measurements to generating an output dependent upon the impedance of said device;
• monitoring said measurements to detect fault conditions in said device and outputting a warning output if a fault condition is detected.

A method of identifying a device having an impedance characteristic as a function of frequency, the method comprising:

• applying at least two frequency signals to said device;
• obtaining measurements indicative of the voltage across said device and the current flowing through said device at said frequencies;
• processing said measurements in a multiplicative and non divisional manner to determine if a first impedance or part of the impedance of the device at a first frequency has a predefined inequality relationship with a second impedance or part of the impedance of the device at a second frequency, without calculating either impedance;
• identifying the device in dependence upon the predefined inequality relationship;
• and
• outputting a value indicative of said identity of said device.