We truly live in the digital era and this is nowhere more evident than in the field of Test and Measurement. Since the development of the earliest electronic computer systems the trend has been to use analog to digital converters (ADC's) in instruments and systems so that they can harness the power of a digital processor when capturing and analyzing electronic signals. Analog Oscillo scopes have been replaced by Digital Oscilloscopes, Multimeters by Digital Multimeters and a variety of Analyzers, once solely using analog technology, have followed the movement and switched to digital. The ADC has been at the heart of this trans formation and in recent times it was the modern digitizer that has led the way and made access to ADC technology easier than ever before.
Digitizers let you harness the full power of the ADC by sur rounding it with a number of key components such as a precision clock, front-end signal conditioning, acquisition memory, software and fast data buses. It's these components that make the ADC more versatile and allow it to be used with maximum performance and in an ever widening range of applications. However, the story hasn't always been that way.
The first digitizers can be traced back to around the 1970's when they used new transistor based ADC technology to capture and digitize transient signals. Known as Transient Recorders these products were often cumbersome, difficult to use and expensive. As such, their application was limited. In the late 80's the Tran sient Recorder was largely replaced by the Digital Oscilloscope. Digital Oscilloscopes offered easy transient capture and came with features such as signal conditioning circuitry, advanced triggering and signal processing. It was a combination that allowed them to be used in a much wider range of applications.
It wasn't until the early 90's and the rise of the Personal Computer that the modern digitizer was revitalized. PC hardware and software moved rapidly and digitizers took advantage by connecting to the new bus and processing capabilities that became available. Digitizers adopted the PC's ISA and PCI technology so that they could be installed right inside the PC. Software tools made using the digitizer much easier. While access to ever faster microprocessors allowed great advances in signal processing and measurement speed. Since then digitizers have continued to flourish. They remain connected to the PC but now appear in an ever expanding array of formats. Modular digitizers are available that go inside the PC (using the latest PCle'>bus) or they can operate outside the PC by being packaged in one of the many industry standards such as PXI, cPCI or LXI.
Digitizers can be used with off-the-shelf software to perform the functions of an Oscilloscope, Transient Recorder, Data Logger, FFT Spectrum Analyzer, Multimeter and many other test instru ments. They can be programmed and customized so that they can be integrated into automated testing systems and they can also be embedded, as the key data acquisition device, in a measurement or analysis instrument.
Table of Contents
Hardware
- General Introduction to Waveform Digitizers
- Advantages of high-resolution in high-bandwidth digitzers
- Proper use of digitizer front-end signal conditioning
- Using Probes and Sensors
- Using acquisition modes
- Triggering and Synchronization
Software
Using
Platforms