Product Notes

Two of the key specifications of digitizers are bandwidth and amplitude resolution. These specifications are not independent - with increasing resolution available with decreasing bandwidth. Users must make a tradeoff in selecting a digitizer to meet their measurement needs. This article discusses the advantages and limitations of high resolution in high bandwidth digitizers. Where high resolution is greater than 12 bits and high bandwidth is greater than 20 MHz.

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Analog Boxcar Averaging (sometimes referred to as Gated Integration) is a technique that has been used by engineers and scientists for more than 50 years to reduce unwanted noise on signals. In more recent times, with the development of fast high-resolution digitizer technology, digital Boxcar Averaging has been used to achieve the same type of results. Furthermore, digital Boxcar Averaging brings with it additional benefits in that it can improve a digitizer?s overall resolution and its dynamic performance. This white paper shows how digital Boxcar Averaging can be used to reduce signal noise, even on single shot events. Read more

Arbitrary waveform generators (AWG's) are among the most powerful signal sources available for testing. They offer an extensive range of waveshapes which can be created and selected to rapidly provide a broad range of test events.

This article shows how to use SBench 6 equations to generate waveforms

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The Arbitrary Waveform Generator (AWG) is a powerful and flexible signal generator capable of outputting any wave shape within the bandwidth of the generator. Once you have the AWG you will need to populate it with waveforms. The cost of creating, capturing, modifying, and transferring test waveforms can easily match the cost of the generator. This application note is intended to make the process easier by providing examples of creating, capturing, modifying, and transferring waveforms to your AWG. Read more

For nearly 30 years Spectrum Instrumentation has been designing and manufacturing PC based instruments, typically digitizer and generator products, for the electronics Test and Measurement market. The company recently decided that it was time to replace its popular M2i.49xx series of digitizer cards, that were first designed over ten years ago Read more

Electronic test and measurements equipment can be classified into two major categories; measurement instruments and signal sources. Instruments such as digital multi-meters, digitizers, oscilloscopes, spectrum analyzers, and logic analyzers measure electrical characteristics of an input signal, most typically electrical potential difference or voltage. Signal sources are required to provide signals to be used as a test stimulus. In many test situations the devices being tested do not generate signals on their own. Take for example an amplifier. Without a signal source to provide an appropriate input signal no significant electrical measurements can be made. It is the combination of measurement instruments and signal sources that make electrical testing possible. In this note we will be discussing the use of arbitrary waveform generators (AWGs), signal sources that can create test stimuli with a variety of wave shapes.

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Introduction to modular digitizers explaining history, digitizer terms and selection criteria. The product note also elaborates the question when a digitizer iand when an oscilloscope should be used.

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PCI eXtensions for Instrumentation or PXI is a computer based hardware and software platform for test and measurement systems. Developed in the late 1990?s as an open industry standard based on the compact PCI (cPCI) computer bus, PXI provides a basis for complex, rugged, modular instrumentation systems. The PXI standard is governed by the PXI systems Alliance (PXISA) which maintains and controls the evolution of the standard to insure interoperability of instruments from hundreds of vendors. Read more

In this article we will discuss the key features of the digitizerNETBOX, an LXI digitizer instrument, and demonstrate how it can make real world measurements on an air compressor. We?ll show how to install and connect the instrument and then set up the measurement with the included software - all within a few minutes. Read more

The trend for multi-channel testing has never been stronger as more electronic devices use array and parallelization methods to increase system speed and performance. Requirements can be found in almost every field, such as testing MIMO (Multiple-Input Multiple-Output) antennas that are used for radio links in communication, or the transmitter and receiver arrays employed in advanced radar, sonar, and ultrasound systems. Even in general electronics the need for multi-channel testing is expanding. Components continue to increase in complexity, coming with higher pin counts, while micro controller and processing systems utilize faster and more complex logic circuitry and bus systems.

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Modular digitizers and similar measuring instruments such as the Spectrum Instrumentation model M4i.44xx series shown in Figure 1, need to match a wide variety of signal characteristics to the fixed input range of the internal analog to digital converter (ADC) Read more

Modular digitizers are typically small compact devices that allow the capture and conversion of analog electronic signals into digital data. The data can then be stored in on-board memory or transferred to a PC. As digitizers are "blind" instruments they do not normally have an integral display to view, measure or analyze the data they collect. Instead, these functions are usually performed by a PC.

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Although modular digitizers can be considered computer hardware they require suitable firmware and software in order to be integrated into the host computer system. Digitizers use embedded software and require device drivers, maintenance software and operational applications to control, view and transfer the digitizer's data. Software can be supplied or it can be custom developed, this application note provides an overview of the software required to support modular digitizers

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Self-excited electronics like power supplies, oscillators, transmitters, and signal generators can often be tested using a measuring instrument (digitizer, oscilloscope, spectrum analyzer, etc.) alone. Externally excited electronic devices like amplifiers, filters, receivers, and digital interfaces require a signal source and a measuring instrument for testing. Modular Arbitrary Waveform Generators (AWG's) and modular digitizers are available with multiple source and measurement channels that can be configured in bandwidth, sample rate, and memory.

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Digitizers are used to convert electrical signals into a series of measurements that are then output as a numerical array of amplitude values versus time. To make this information useful the time information is typically related to a specific reference point which is most commonly the trigger position. The trigger point can be something that occurs within the measured signal or it can be from other external sources. The function of triggering is to link the time measurements to a specific known point in time. For repetitive signals the trigger must be stable in order to enable measurements from one acquisition to be compared with others. When multiple digitizers or related acquisition instruments are integrated into a multi-channel system meaningful data can only be obtained when all channels are referenced to a common time axis. This requires time synchronization of the data acquisition elements of the system with all the digitizer channels normally being triggered by the same event. This application note will focus on the related topics of triggering and synchronization. Read more

One of the great powers of Arbitrary Waveform Generators (AWG?s) is that they can generate an almost infinite number of waveform shapes. The AWG?s operating mode controls the timing of how these waveforms are output. In this application note we will investigate the effective use of the operating modes for the Spectrum M4i.66xx series of AWG?s, concentrating on the sequence mode which offers the ability to control the selection of the output waveshapes in near real-time.

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Modular digitizers like the Spectrum Instrumentation M4i.44xx models shown in Figure 1, offer many acquisition features matched to the primary application of acquiring multiple channels of input data and transferring that data at high rates to analysis computers. They also offer multiple acquisition modes that are intended to use on-board memory efficiently and decrease the dead time between acquisitions. This is especially true with signals that occur at low duty cycles in such applications as echo ranging (including radar, sonar, lidar, and ultrasound), and transient data collection applications (such as time of flight spectrometry and other stimulus-response based analysis). Read more

Probes convert signal levels, change impedance levels, or offer convenient connection methods. Sensors or transducers convert physical phenomena to electrical signals. Examples include current probes, accelerometers, and photomultipliers. Both types of input devices are supported by Spectrum digitizers. This application note deals with using both probes and sensors with Spectrum modular digitizers.

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The block, or segmented memory, averaging mode is used with Digitizers for different applications where incoherent noise needs to be removed from a signal. Independent of the manufacturer of the digitizer all FPGA based hardware implementations of the block averaging mode limit the maximum size of the segment to be averaged. The limit depends on the capacity of the FPGA and usually ranges from 32k up to 500k samples.

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