Module helps synchronisation setup of PCIe digitizers

Module helps synchronisation setup of PCIe digitizers

New Products |
By Nick Flaherty

Spectrum Instrumentation has developed a module to help engineers create multi-channel data acquisition systems with gigahertz speeds.

The Star-Hub option allows up to eight of Spectrum’s PCIe digitizers to be connected together with common clock and trigger signals, which ensures there is minimal phase delay and timing skew between all the channels.

The Star-Hub option is installed by mounting a single piggyback module onto any of the M5i series cards in the multi-channel system. Using accurately matched and shielded coax cabling, the board then distributes the clock to each module and precisely synchronizes the trigger event with the system clock. 

Star-Hub can be used with any of the cards from the M5i.33xx digitizer family. Seven different models are available offering one or two channels, sampling rates from 3.2 to 10 GS/s, 12-bit vertical resolution and bandwidths from 1 to 4.7 GHz. The cards can handle a wide range of signals and feature programmable input voltage ranges, offset control, large on-board memories, advanced trigger functions and a number of different acquisition modes. Together with Star-Hub, the line-up lets you build data acquisition systems with from 2 to 16 channels, sampling at rates of up to 5 GS/s, or up to 8 channels at the maximum sampling rate of 10 GS/s.

Users can also choose to run the Star-Hub system with the digitizer cards internal clock, which offers better than ±1 ppm accuracy, or an external clock, via a front panel SMA input connector. To minimize any channel-to-channel timing skew, there is a programmable skew adjustment available for each connected card. This feature allows time shifts up to 200 ps (10 GS/s) or 312 ps (3.2 and 6.4 GS/s) of the clock of each individual card.

This creates an easy way for users to correct any timing mismatches that may be present in a specific setup for communications, automated testing, aerospace and scientific experimentation where banks of receivers, detectors, sensors or antennas are deployed.

Another advantage of the Star-Hub system is that each of the digitizers retains its own 16 lane, Gen3, PCIe bus, that is capable of transferring data at rates up to 12.8 GB/s. This transfer speed allows continuous transfer at 6.4 GS/s in 12-bit mode, or even 10 GS/s in data-saving 8-bit mode. The bus allows the cards to shift acquired data to PC resources like memory, SSDs and GPUs at exceptionally fast speeds, even though they are all controlled by a single host processor.

“Providing an easy-to-use solution for the multi-channel acquisition of signals in the GHz range is something our customers have been requesting for some time,” said Oliver Rovini, CTO at Spectrum.

“However, when using modular instruments, this is not a simple task. You need to deal with clock systems designed to handle a variety of rates and typically use a phased lock loop (PLL) type architecture. Furthermore, each card has its own trigger circuitry that uses comparators to detect trigger level crossings. At the speeds we are working at, any small differences in these reference levels can easily produce unwanted jitter.”

“Star-Hub takes care of these issues so the user doesn’t have to! The setup is straight forward and, once the cards are connected together, our drivers manage all the necessary clock and trigger distribution conditions for you,” he said. 

The SBench 6 Professional GUI can control all the digitizers connected with Star-Hub. It runs on PCs, using either Windows or Linux operating systems, and provides instrument control, along with display, analysis, storage and documentation capabilities.

The M5i digitizers also ship with a software development kit (SDK) as standard to programme the cards with C, C++, Python, C#, Delphi, VB.NET, J#, Julia, Java, LabVIEW or MATLAB.

The Star-Hub option is available now and can be ordered with any new M5i.33xx series digitizer cards.


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