Chapter 3 System Overview

Measurement Input

Signal Conditioning, Ranging, and Amplification Analog input signals are multiplexed into the internal DMM’s signal-conditioning section typically comprising switching, ranging, and amplification circuitry. If the input signal is a dc voltage, the signal conditioner

is composed of an attenuator for the higher input voltages and a dc amplifier for the lower input voltages. If the input signal is an

ac voltage, a converter is used to convert the ac signal to its equivalent dc value (true RMS value). Resistance measurements are performed by supplying a known dc current to an unknown resistance and measuring the dc voltage drop across the resistor. The input signal switching and

ranging circuitry, together with the amplifier circuitry, convert the 3 input to a dc voltage which is within the measuring range of the

internal DMM’s analog-to-digital converter (ADC).

You can allow the instrument to automatically select the measurement range using autoranging or you can select a fixed measurement range using manual ranging. Autoranging is convenient because the instrument automatically decides which range to use for each measurement based on the input signal. For fastest scanning operation, use manual ranging for each measurement (some additional time is required for autoranging since the instrument has to make a range selection).

Analog-to-Digital Conversion (ADC) The ADC takes a prescaled dc voltage from the signal-conditioning circuitry and converts it to digital data for output and display on the front panel. The ADC governs some of the most basic measurement characteristics. These include measurement resolution, reading speed, and the ability to reject spurious noise. There are several analog-to-digital conversion techniques but they can be divided into two types: integrating and non-integrating. The integrating techniques measure the average input value over a defined time interval, thus rejecting many noise sources. The non-integrating techniques sample the instantaneous value of the input, plus noise, during a very short interval. The internal DMM uses an integrating ADC technique.

You can select the resolution and reading speed from 6 digits (22 bits) at 3 readings per second to 4 digits (16 bits) at up to 600 readings per second. The Advanced menu from the 34970A front panel allows you to control the integration period for precise rejection of noise signals.

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Agilent Technologies 34970A manual Measurement Input

34970A specifications

Agilent Technologies 34970A is a versatile data acquisition and measurement system that has gained popularity in various industries, including research and development, manufacturing, and education. The primary purpose of the 34970A is to offer an efficient solution for data collection, monitoring, and analysis, which can significantly enhance productivity and accuracy in testing applications.

One of the main features of the 34970A is its modular design, allowing users to customize the system according to their specific measurement needs. The mainframe can accommodate up to three plug-in measurement modules, which can include various types of measurements such as analog, digital, temperature, and frequency. This modularity provides flexibility for users to tailor the system to their requirements, making it highly adaptable to different applications.

Another notable characteristic of the Agilent 34970A is its impressive channel configuration. The system can support up to 120 measurement channels when fully configured, enabling extensive data acquisition without the need for multiple devices. This capability is essential for applications requiring simultaneous monitoring of multiple parameters or locations.

The 34970A utilizes advanced signal processing technologies to ensure high-accuracy measurements. The internal 6.5-digit resolution multimeter provides precise readings, while the device also supports various input types, such as thermocouples and RTDs for temperature measurements. The ability to perform mathematical functions, such as summation and averaging, on the acquired data further enhances its usability.

For data storage and management, the Agilent 34970A features built-in memory for storing up to 20,000 readings. Users can also easily transfer data to a PC through the RS-232 interface or GPIB (IEEE 488) for further analysis and reporting. Additionally, it offers the capability to program automatic data logging and scheduling of measurements, which streamlines the testing process and reduces manual intervention.

In terms of user interface, the 34970A is equipped with a large graphical display that provides clear visualization of measurement data and easy navigation through settings and options. The menu-driven interface makes it accessible for users of all skill levels, simplifying the setup and operation of the device.

Overall, the Agilent Technologies 34970A stands out for its modularity, high channel capacity, advanced measurement technologies, and user-friendly interface. As a reliable and efficient data acquisition system, it is well-suited for a wide range of applications, making it an essential tool for engineers and technicians looking to enhance measurement precision and efficiency.