|NDT.net||May 2006, Vol. 11 No.5|
PCI version of highest dynamic range digitiser
Design and test engineers can use PCI version of the National Instruments PXI-5922 flexible-resolution digitiser, also known as a PC-based oscilloscope, to make a wide range of dynamic measurements.
The NI PXI-5922 digitiser provides the highest dynamic range of any digitiser on the market. This universal instrument with unprecedented dynamic performance and flexibility is now available in a PCI form factor for applications in a variety of industries including communications, semiconductor, biomedical and ultrasonic nondestructive test (NDT). Unlike traditional oscilloscopes and other PC-based digitisers with fixed resolution for all sample rates, the NI 5922 digitisers use the NI Flex II ADC, which has flexible, user-defined resolution and can sample anywhere from 24bits at 500kS/s to 16bits at 15MS/s.
The NI Flex II ADC is an enhanced multibit delta-sigma converter that incorporates patented techniques to greatly reduce harmonics caused by nonlinearity that is inherent to multibit converters.
This results in an unprecedented dynamic range at even high sample rates, which design and test engineers can use to directly digitise low-level signals without the need for external signal conditioning, such as filters and low-noise amplifiers.
Reduced signal conditioning improves measurement accuracy and reliability while also saving test system development time and cost.
Because of these patented techniques, the PXI-5922 flexible-resolution digitiser has won several awards including the 2006 test product of the year by Test and Measurement World magazine and Hot 100 Products of 2005 by EDN magazine.
Engineers using the NI PXI-5922 digitiser are already solving demanding applications such as high-end audio and ultrasound testing, characterisation of high-resolution digital-to-analogue converters and baseband I/Q analysis. For example, Analog Devices uses the NI PXI-5922 digitiser to characterise settling time of one of its high resolution digital-to-analogue converters (DACs).
'We chose the NI PXI-5922 digitiser because of its unprecedented dynamic range, which we use to measure settling time accurately by filtering out the noise,' said Eoin English, design evaluation engineer for Analog Devices.
'This is the only product on the market with high input impedance and wide dynamic range that we can easily configure and control with NI Labview, which helps us reduce our product development time.' As with other NI digitisers, engineers can use the new flexible-resolution digitisers with arbitrary waveform generators and digital waveform generator/analysers to build mixed-signal applications at any stage in a product's development - from design and validation to manufacturing test.
Design and test engineers can use NI digitisers, such as the NI 5124 200MS/s 12-bit digitisers, the NI 5122 100MS/s 14-bit digitisers and the NI PXI-5114 250MS/s 8-bit value digitiser, to rapidly develop a measurement system with the more than 50 measurements that are built in to the NI-Scope driver software.
All NI digitisers come with this driver, which works with the National Instruments Labview graphical development environment, NI SignalExpress interactive measurement software, NI Measurement Studio for Microsoft Visual Studio .net and the NI LabWindows/CVI Ansi C development environment.