Accurately measuring bio-impedance is important for sensing properties of the body. Unfortunately, contact impedances can significantly degrade the accuracy of bio-impedance measurements. To address this issue, a method is provided for estimating an impedance matrix of parasitic network disposed between a first network and a second network of a bio-impedance measurement system, the method comprising determining an impedance matrix for the first network (Z.sub.MUX) based on an impedance matrix for the second network (Z.sub.LOAD) for at least one known load condition; fitting Z.sub.MUX values for Z.sub.LOAD for the at least one known load condition to estimate parameters of the impedance matrix of the intervening network.

A method of connecting electrical substation wiring in an electrical substation provides pre-bundled yard cables configured to connect between field devices in the substation and a yard interface connection cabinet. The yard interface connection cabinet has an outside plug bulkhead plate that is accessible from outside of a control house that houses the yard interface connection cabinet. The outside plug bulkhead plate has a plurality of connectors configured to mate with the yard cables. The yard interface connection cabinet further has internal wires extending from an inside plug bulkhead plate and terminating at a terminal block. The connections and wires in the yard interface connection cabinet are tested with the yard cables before installation of the yard interface connection cabinet and yard cables in the substation. The yard cables are connected between the field devices and the outside plug bulkhead plate from outside of the control house.

A test system may be used for obtaining accurate remote sense voltage and/or current values. A measurement instrument may provide a regulated stimulus signal to a device under test (DUT) and measure a DUT signal developed at least partially in response to the stimulus signal. A test circuit may superimpose a test signal over the stimulus signal to cause the DUT signal to be developed further in response to the test signal. The DUT signal may be used to derive a resistance of the path that couples the measurement instrument to the DUT. The measurement instrument may include a source measure unit, the stimulus signal may be a regulated voltage, and the DUT signal may be a sense voltage. The harmonics of the DUT signal may be analyzed to determine a correlation between an amplitude of a measured fundamental frequency of the DUT signal and the resistance of the path.

A test system may be used for obtaining accurate remote sense voltage and/or current values. A measurement instrument may provide a regulated stimulus signal to a device under test (DUT) and measure a DUT signal developed at least partially in response to the stimulus signal. A test circuit may superimpose a test signal over the stimulus signal to cause the DUT signal to be developed further in response to the test signal. The DUT signal may be used to derive a resistance of the path that couples the measurement instrument to the DUT. The measurement instrument may include a source measure unit, the stimulus signal may be a regulated voltage, and the DUT signal may be a sense voltage. The harmonics of the DUT signal may be analyzed to determine a correlation between an amplitude of a measured fundamental frequency of the DUT signal and the resistance of the path.

A method for determining an electrical variable of a component of part of a vehicle electrical system including at least one external current and an electrical impedance unit. A measuring unit is configured to generate a plurality of current and voltage values for each of at least two different operating points of the impedance unit. The method includes: providing the current values of the impedance unit at a first operating point and at least one second operating point; providing the voltage values of the impedance unit at a first operating point and at least one second operating point; corresponding current and voltage values being associated with one another; determining the at least one electrical variable of the component based on a parameter estimation method and an electrical model of the part of the vehicle electrical system and at least part of the corresponding current and voltage values.

A method for determining an electrical variable of a component of part of a vehicle electrical system including at least one external current and an electrical impedance unit. A measuring unit is configured to generate a plurality of current and voltage values for each of at least two different operating points of the impedance unit. The method includes: providing the current values of the impedance unit at a first operating point and at least one second operating point; providing the voltage values of the impedance unit at a first operating point and at least one second operating point; corresponding current and voltage values being associated with one another; determining the at least one electrical variable of the component based on a parameter estimation method and an electrical model of the part of the vehicle electrical system and at least part of the corresponding current and voltage values.

The present disclosure relates to circuitry for driving a load. The circuitry comprises: primary driver circuitry coupled to a primary signal path and operable to drive the load with a playback signal in a first mode of operation of the circuitry, wherein a playback signal comprises a signal that drives the load to generate a desired output; auxiliary driver circuitry coupled to an auxiliary signal path; an auxiliary current sense resistor in the auxiliary signal path; and current detection circuitry coupled to the auxiliary current sense resistor and configured to generate a signal indicative of a current through the load. One of the primary driver circuitry and the auxiliary driver circuitry is operable to drive the load with a pilot signal in a second mode of operation of the circuitry, wherein a pilot signal comprises a signal having a predefined frequency or frequency content and a predefined magnitude.

The present disclosure relates to circuitry for driving a load. The circuitry comprises: primary driver circuitry coupled to a primary signal path and operable to drive the load with a playback signal in a first mode of operation of the circuitry, wherein a playback signal comprises a signal that drives the load to generate a desired output; auxiliary driver circuitry coupled to an auxiliary signal path; an auxiliary current sense resistor in the auxiliary signal path; and current detection circuitry coupled to the auxiliary current sense resistor and configured to generate a signal indicative of a current through the load. One of the primary driver circuitry and the auxiliary driver circuitry is operable to drive the load with a pilot signal in a second mode of operation of the circuitry, wherein a pilot signal comprises a signal having a predefined frequency or frequency content and a predefined magnitude.

A portable nodal impedance analyser. The impedance analyser (100) is configured with an auto best curve-fit application which automatically selects the values for Voltage, Source Impedance and Frequency of the stimulus waveform (best fit values) to generate equivalent circuit and its appropriate V-I traces. The auto best curve-fit application automatically selects one or more input Sinusoidal Patterns (Waveforms) in such a way that the V-I Characteristics of the components present in a Node (the two points across which the input Pattern is driven, and response is received), are best revealed by automatically adjusting the Drive Voltage (0.2V, 4V, 8V and 13V), Source Impedance (10Ω, 50Ω, 100Ω, 500Ω, 1KΩ, 5KΩ, 10KΩ, 50KΩ, 100KΩ) and Frequency (from 1 Hz to 50 KHz) of the input Patterns.

A portable nodal impedance analyser. The impedance analyser (100) is configured with an auto best curve-fit application which automatically selects the values for Voltage, Source Impedance and Frequency of the stimulus waveform (best fit values) to generate equivalent circuit and its appropriate V-I traces. The auto best curve-fit application automatically selects one or more input Sinusoidal Patterns (Waveforms) in such a way that the V-I Characteristics of the components present in a Node (the two points across which the input Pattern is driven, and response is received), are best revealed by automatically adjusting the Drive Voltage (0.2V, 4V, 8V and 13V), Source Impedance (10Ω, 50Ω, 100Ω, 500Ω, 1KΩ, 5KΩ, 10KΩ, 50KΩ, 100KΩ) and Frequency (from 1 Hz to 50 KHz) of the input Patterns.