In some implementations, an automatic gain control (AGC) circuit comprises: a pre-divider circuit operable to pre-divide an input signal according to a pre-divider circuit setting and output a pre-divided signal; a pre-amplifier operable to pre-amplify the pre-divided signal and output a pre-amplified signal; a post-divider circuit operable to post-divide the pre-amplified signal according to a post-divider circuit setting; an analog-to-digital converter (ADC) operable to generate a digital data stream from the post-divided signal; logic operable to sample the digital data stream; determine a pre-divider circuit setting and a post-divider circuit setting based on the sampled data stream; set the pre-divider circuit and the post-divider circuit based on the determined settings; and generate a received signal strength value based on the pre-divider circuit setting and the post-divider circuit setting.

Controlling a switching element in accordance with a voltage output from a signal amplifying circuit enables adjusting a voltage to be received by a current calculation circuit. Even when a range of a air volume to be used is wide and a range of output of a DC motor is wide, or a current flowing through the DC motor has a wide range, a resistance value of a shunt resistor and an amplification factor of a signal amplifying circuit are not required to be reduced, and thus current detection accuracy of the DC motor can be improved.

Controlling a switching element in accordance with a voltage output from a signal amplifying circuit enables adjusting a voltage to be received by a current calculation circuit. Even when a range of a air volume to be used is wide and a range of output of a DC motor is wide, or a current flowing through the DC motor has a wide range, a resistance value of a shunt resistor and an amplification factor of a signal amplifying circuit are not required to be reduced, and thus current detection accuracy of the DC motor can be improved.

An autoranging ammeter with fast dynamic response allows improved dynamic measurement of rapidly changing direct electrical currents. The ammeter utilizes a low-cost dual threshold comparator mechanism coupled with an analog-to-digital converter and digital processing to rapidly select the appropriate current shunt resistor.

The present invention relates to a device and a method for measurement of electrical signals in an industrial automation and control system. The device comprises an input circuit, configured to receive an electrical input signal (100), scale the electrical input signal by a scaling factor and to set the scaling factor according to a scaling signal (110), an Analog-to-Digital Converter, ADC (220), which is electrically connected to the input circuit, wherein the ADC is configured to convert the scaled electrical input signal (103) into an intermediate digital signal (120), and a first signal path (211), connected to an digital end of the ADC, configured to create the scaling signal (110) and to send the scaling signal (110) to the input circuit, wherein, based on the intermediate digital signal of a sample period and the scaling factor of the sample period, the scaling factor for a subsequent sample period is set.

A measuring circuit for determining the magnitude of a current flowing through a conductor, the measuring circuit having an input terminal pair that can be connected to the current transformer, with a first switch, which connects a measuring resistor between the input terminals in a current measuring position, and which, in a voltage measuring position, separates the measuring resistor from at least one of the input terminals, and having an output terminal pair, at which, alternatively, a voltage-dependent measuring voltage present at the input terminal pair or a current-dependent measuring voltage present at a first measuring point of the measuring resistor can be tapped. The invention also discloses a changeover switch which can be switched synchronously with the switch. The changeover switch is used to connect an output terminal to the first measuring point in the current measuring position, and to the second measuring point in the voltage measuring position.

The present invention relates to a device and a method for measurement of electrical signals in an industrial automation and control system. The device comprises an input circuit, configured to receive an electrical input signal (100), scale the electrical input signal by a scaling factor and to set the scaling factor according to a scaling signal (110), an Analog-to-Digital Converter, ADC (220), which is electrically connected to the input circuit, wherein the ADC is configured to convert the scaled electrical input signal (103) into an intermediate digital signal (120), and a first signal path (211), connected to an digital end of the ADC, configured to create the scaling signal (110) and to send the scaling signal (110) to the input circuit, wherein, based on the intermediate digital signal of a sample period and the scaling factor of the sample period, the scaling factor for a subsequent sample period is set.

A measurement apparatus has a current sensor and at least one A/D converter, which current sensor has at least two channels (CH1, CH2), via which channels (CH1, CH2) the current sensor (30) respectively provides a measurement signal (CH1_SIG, CH2_SIG) characterizing the current. The at least two channels (CH1, CH2) include a first channel (CH1) and a second channel (CH2), which second channel (CH2) is designed to measure a greater maximum current than the first channel (CH1). Also described is a method for measuring a current flowing through a conductor by way of the measurement apparatus.

Load current consumption measured using a first resistor having a high resistive value and a second resistor having a low resistive value. Differential amplifiers, the outputs of which are coupled to analog-to-digital converters and to a processing circuit unit, are connected to each of the nodes of the resistors. Depending on the current level, the processing circuit unit advantageously selects one of the analog-to-digital converters to estimate the present consumption of current in the load. Each input terminal of a resistor is advantageously power supplied from a power amplifier and each power amplifier is advantageously driven by a control loop. For low load currents, the first amplifier associated with the first resistor power supplies the load through the resistors while, for high load currents, when this first amplifier saturates, the second amplifier associated with the second resistor, takes over from the first amplifier to continue to power supply the load.

An auto ranging ammeter that allows improved measurement of rapidly changing, high-dynamic range electrical currents. The ammeter computes current during range switches by using digital signal processing to combine voltage measured over both a variable shunt resistor and a fixed shunt resistor. The ammeter uses fast comparators and digital processing to select the appropriate shunt resistor. The auto ranging ammeter includes a voltmeter which enables the device to output current, voltage, power, charge, and energy consumed by a target device under test.