A measurement system includes a receiver configured to receive a measurement signal indicative of a parameter of a measured object. The measurement system also includes a processor configured to iteratively filter the measurement signal using a threshold value. The processor is also configured to adjust the threshold value for each iteration of filtration and determine a signal-to-noise ratio for each iteration of filtration. The processor is also configured to set a filter threshold value to the threshold value for the iteration based on the signal-to-noise ratio.

A measurement system includes a receiver configured to receive a measurement signal indicative of a parameter of a measured object. The measurement system also includes a processor configured to iteratively filter the measurement signal using a threshold value. The processor is also configured to adjust the threshold value for each iteration of filtration and determine a signal-to-noise ratio for each iteration of filtration. The processor is also configured to set a filter threshold value to the threshold value for the iteration based on the signal-to-noise ratio.

A capacitance sensing system can filter noise that presents in a subset of electrodes in the proximity of a sense object (i.e., finger). A capacitance sensing system can include a sense network comprising a plurality of electrodes for generating sense values; a noise listening circuit configured to detect noise on a plurality of the electrodes; and a filtering circuit that enables a filtering for localized noise events when detected noise values are above one level, and disables the filtering for localized noise events when detected noise values are below the one level.

A portable device and associated method are described for use with a system in which a locating signal is transmitted from within the ground during an operational procedure. The locating signal includes a transmission frequency that is selectable from a group of discrete transmission frequencies in a frequency range and the region includes electromagnetic noise that can vary. The portable device includes a receiver having a bandwidth that includes the transmission frequency range and is operable for measuring the electromagnetic noise in the transmission frequency range to establish a frequency content of the electromagnetic noise for use in selecting one of the discrete transmission frequencies that is subsequently transmitted as the locating signal during the operational procedure. The locating signal can be transmitted from a boring tool, a pullback arrangement or an inground cable. A predicted maximum operational depth for a transmitter can be determined prior to the operational procedure.

A portable device and associated method are described for use with a system in which a locating signal is transmitted from within the ground during an operational procedure. The locating signal includes a transmission frequency that is selectable from a group of discrete transmission frequencies in a frequency range and the region includes electromagnetic noise that can vary. The portable device includes a receiver having a bandwidth that includes the transmission frequency range and is operable for measuring the electromagnetic noise in the transmission frequency range to establish a frequency content of the electromagnetic noise for use in selecting one of the discrete transmission frequencies that is subsequently transmitted as the locating signal during the operational procedure. The locating signal can be transmitted from a boring tool, a pullback arrangement or an inground cable. A predicted maximum operational depth for a transmitter can be determined prior to the operational procedure.

A noise detection circuit 100 for a power supply, the noise detection circuit 100 comprising: an impedance element 110 connected to a line 104 for carrying a power supply current having a noise signal component, the noise signal comprising a common mode noise signal and a differential mode noise signal; a filter element 112 coupled to the impedance element 110 and configured to suppress the differential mode noise signal in the noise detection circuit 110; and an evaluation circuit 140 coupled to the impedance element 110 or the filter element 112 and arranged to sense the common mode noise signal and provide an output representative of the common mode noise signal.

A noise detection circuit 100 for a power supply, the noise detection circuit 100 comprising: an impedance element 110 connected to a line 104 for carrying a power supply current having a noise signal component, the noise signal comprising a common mode noise signal and a differential mode noise signal; a filter element 112 coupled to the impedance element 110 and configured to suppress the differential mode noise signal in the noise detection circuit 110; and an evaluation circuit 140 coupled to the impedance element 110 or the filter element 112 and arranged to sense the common mode noise signal and provide an output representative of the common mode noise signal.

A method and system measure a characteristic of a signal under test (SUT) using a signal measurement device. The method includes receiving and digitizing the first and second copies of the SUT through first and second input channels to obtain first and second digitized waveforms; repeatedly determining measurement values of the SUT characteristic in the first and second digitized waveforms to obtain first and second measurement values, which are paired in measurement value pairs; multiplying the first and second measurement values in each of the measurement value pairs to obtain measurement products; determining an average value of the measurement products to obtain an MSV of the measured SUT characteristic; and determine a square root of the MSV to obtain an RMS value of the measured SUT characteristic. The RMS value substantially omits variations not in the SUT, which are introduced by only one of the first and second input channels.

A method and system measure a characteristic of a signal under test (SUT) using a signal measurement device. The method includes receiving and digitizing the first and second copies of the SUT through first and second input channels to obtain first and second digitized waveforms; repeatedly determining measurement values of the SUT characteristic in the first and second digitized waveforms to obtain first and second measurement values, which are paired in measurement value pairs; multiplying the first and second measurement values in each of the measurement value pairs to obtain measurement products; determining an average value of the measurement products to obtain an MSV of the measured SUT characteristic; and determine a square root of the MSV to obtain an RMS value of the measured SUT characteristic. The RMS value substantially omits variations not in the SUT, which are introduced by only one of the first and second input channels.

A current sensor circuit comprises multiple resistive circuit elements of different values of electrical resistance arranged between at least one input terminal of the current sensor circuit and an output terminal; a first plurality of switching circuits coupled between the input terminal and the resistive circuit elements, wherein each switching circuit of the first plurality of switching circuits includes a pair of transistors connected in series; at least one drive amplifier including an output and an input connected to the output terminal; and a second plurality of switching circuits, each switching circuit including a first switch terminal coupled to the at least one drive amplifier output and a second switch terminal coupled to a common connection of a pair of transistors of the first plurality of switching circuits.