PXIe digitisers enable data transfer speeds up to 1.7Gbyte/s

Article By : Spectrum

The M4x.44xx series devices from Spectrum are packaged in a dual-width 3U module and incorporating a four lane PCI Express Generation 2 interface aimed at high-speed PXIe mainframe systems.

Spectrum has brought to market its first high-speed digitiser product line based on the PXIe (PXI Express) modular instrumentation standard. The M4x.44xx series consists of six products, each packaged in a dual-width 3U module and incorporating a four lane PCI Express Generation 2 interface. The high-performance interface allows data transfer speeds in excess of 1.7Gbyte/s, targeting PXIe mainframe systems, indicated the company.

The digitisers include versions with two and four fully synchronous channels and they come with resolutions of either 14bits, for sampling at rates up to 500MS/s, or 16bits, for sampling at rates up to 130MS/s or 250MS/s. With analogue bandwidth up to 250MHz, the digitisers are suited to use in ATE systems where electronic signals in the 1MHz to 200MHz range need to be acquired and measured with the best possible speed and precision. Typical applications are found in semiconductor and component testing, radar, wireless communications, medical science, automotive, power, physics, surveillance, aerospace and defence.

Designed so that they can be used with the widest range of signals the M4x.44xx series cards feature an oscilloscope style front-end, stated the company. Each channel has its own separate monolithic ADC and low noise signal conditioning circuitry. Fully programmable, the cards provide six gain input ranges (±200mV up to ±10V), selectable input impedance of 50Ω or 1MΩ and AC or DC coupling. Furthermore, an internal bandwidth filter can be activated in situations where high frequency noise, that may mask signals, needs to be suppressed.

The flexible front-end circuitry is complimented by a powerful trigger system and versatile clock. The trigger source can be any of the input channels, either of the two external trigger inputs, any of the eight PXI trigger lines or the PXI star trigger. Trigger modes include positive or negative edge, both edges (window), software and rearm. In addition, logic triggering can be implemented based on the state of the channel and the external trigger inputs.

The clocking system of the digitisers is precise and advanced. The clock can be internally or externally generated (including as source the 100MHz PXIe differential clock and the 10MHz PXI clock). It has a built-in 10MHz reference and, if required, it can be synchronised with other reference sources. A fine-resolution mode is also available that allows clock rates to be selected with 1Hz resolution. The feature makes it possible to program the sampling rate of the digitisers to match that of other devices or to setup acquisitions for specialised input signal conditions.

All the digitisers come with a standard 4Gbyte (two gigasamples) of on-board acquisition memory. The large memory makes it easy to acquire long and complex signals. The capability is further expanded by a host of data acquisition and readout modes. These include single-shot capture (transient recording), streaming (FIFO), segmented (multiple recording), gated (gated sampling), or the combination of segmented acquisition of fast signals in parallel with slow continuous data recording (ABA mode). All trigger events can be time stamped, making it simple to know when they occurred and to determine the time between events.

With their low noise front-ends, high-resolution ADCs and accurate clocks, these PXIe digitisers deliver outstanding dynamic performance, stated Spectrum. For example, signal-to-noise ratios (SNR) are typically over 70dB, spurious free dynamic range (SFDR) is better than 90dB, and total harmonic distortion (THD) is less than -70dB. The combination not only makes it possible to detect small signals on large ones but it also produces better measurement repeatability, precision and accuracy.

The PXIe products are based on Spectrum's M4i line of standard PCIe products and combine the advanced features and signal quality of this series with the industrial standard of PXIe. The M4x products are two slots wide and fit into any PXIe chassis. As Spectrum's M4x platform is based on a modular concept, it will also allow the release of several PXIe products within a short time, all programmed through a common software interface that is compatible to existing PCIe, PCI and LXI products.

Another advantage of sharing technology between platforms is that the PXIe modules can immediately utilise the FPGA based firmware options that already exist for the PCIe cards, added the company. Block averaging and block statistics packages are available for high trigger rate applications that require hardware based processing functions. Block averaging can be used to reduce signal noise and improve measurement resolution while block statistics performs a peak detection process that yields a waveforms maximum, minimum and average values.

To control and operate the digitisers, Spectrum provides its powerful SBench 6 programme. SBench 6 supports all the key functions of the digitiser as well as providing data display, storage, analysis and documentation. The programme offers both oscilloscope and transient recording modes, including data streaming. A base version of SBench 6 is provided free of charge to enable out-of-the box operation of the digitisers.

Customers who want to develop their own programmes can use the proven Spectrumdrivers (available for Windows and Linux), which are included in the delivery. A set of standard programming examples is provided to illustrate the cards main signal capture functions. Extensive support includes Visual C++, Borland C++, Gnu C++, LabVIEW, MATLAB, Visual Basic, VB.NET, C#, J# and Delphi code.

The M4x series cards are available with 4-6 week delivery and come complete with software drivers and a two-year manufacturer's warranty. Technical support, including software and firmware updates, is available free of charge.