High-speed 5 Gsample/sec PCIe digitiser cards

September 28, 2014 // By Graham Prophet
Spectrum is offering a solution to engineers and scientists looking to capture and analyse fast electronic signals in the DC to 1 GHz frequency range. The company has extended the performance of its PCIe based instruments by adding nine new models to its M4i series of digitisers.

These cards have real-time sampling rates up to 5 Gsample/sec and high bandwidth making it possible for them to measure signals, edges and pulses down into the sub nanosecond realm.

Models are available with one, two or four channels, and come with 4 GB on-board memories, advanced acquisition modes, and software tools that allow easy integration into any system. The cards can replace conventional test instruments (such as digital oscilloscopes and spectrum analysers) whenever measurement speed, flexibility, size or channel density becomes an issue. They can be used inside a PC, when the technology needs to be embedded or outside the PC (with an expansion box) if bench-top access is required.

Spectrum's M4i series is based on the PCIe bus and the products are designed to allow the fastest possible data transfer. For example, using the cards PCI Express x8 Gen2 interface data can be transferred directly to a host PC at speeds of up to 3.4 GBytes/sec. All Spectrum digitisers support transient recording and data streaming modes. Streaming allows the capture of extremely long signals that are passed directly into the PC, where they can be stored or analysed, without the loss of vital information. The M4i series also includes on-board FPGA technology so that optional firmware packages can perform on-the-fly functions such as signal averaging and peak detection. Pre-processing waveforms reduces data transfer times and greatly improves measurement speeds.

The digitisers are equipped with fully calibrated front-end signal conditioning circuits that offer input ranges from ±200 mV up to ±2.5 V full scale. Further signal conditioning can also be provided through the use optional amplifiers. Signal conditioning allows signals to be scaled correctly so that they use the full 8-bit dynamic range of the digitiser, optimising measurement accuracy and resolution.

To allow the capture of complex and rare events, the cards also feature an array of flexible trigger modes. Triggering is possible on any channel or either of the two external trigger inputs. All the trigger sources can be logically combined to enable conditional triggering on specific input patterns. The trigger modes are further complimented by a variety of acquisition modes that allow memory segmentation as well as fast trigger time stamping. The re-arm time between triggers can be as low as 80 samples (16 nsec @ 5 Gsample/sec) making it possible to capture and time stamp pulses and signal bursts even when the events are extremely close together.