16 Channels at 1 Million Samples per Second per Channel Simultaneously
Fortis Testing in Lubbock, TX, contacted G Systems to develop a high-speed streaming system for capturing pressure waves generated by explosions during structural blast testing. Requirements included 16 channels, fast sampling and the ability to trigger high-speed cameras with configurable delays to record video documentation of the explosion.
G Systems’ solution is a rugged, high-speed streaming measurement system with the ability to collect 16 channels at 1 million samples per second simultaneously.
A G Systems customer, Fortis Testing, needed a blast test system. Requirements included the ability to record pressure wave measurements during structural testing. The measurement system also had to be remotely configurable, have high-speed cameras with configurable delays to record video documentation of the blast test explosion, and had to reside very close to the blast zone to minimize signal degradation from the sensors.
G Systems developed the solution using pressure sensors that can survive the over-pressure from a 1,200 lb. explosion. The blast wave sensors are mounted at specific locations within the danger zone to precisely measure the pressure wave. Sensors are biased properly while their signals are buffered and sent to a high-performance CompactRIO data acquisition system, which simultaneously measures and records the signals. To meet safety standards, set up and configuration is accomplished through a private LAN connection remotely, at least 1,000 feet away from the blast test.
Signals from the sensor buffer are connected to the 16 BNC inputs on the analog input cards. Digitized samples are routed to the FPGA in the CompactRIO backplane.
The FPGA provides several functions, all of which are configurable through the user interface (UI). FPGA functions including variable sample rate of up to 1 million per second, the number of pre- and post-trigger samples, trigger source and trigger level, the cameras’ trigger polarity and pulse width, and the cameras’ trigger delay.
Fortis Testing needed simultaneous sampling which is achieved with the FPGA. The analog input card’s user-sampling mode gets the throughput up to 1M samples per second. To meet additional requirements, G Systems created a constantly acquiring circular buffer for configurable pre-trigger samples. To provide configurable post-trigger samples, upon triggering, the FPGA sends data to the CompactRIO controller for the prescribed number of post-trigger samples.
For the operator’s safety, real-time data is remotely displayed; data is also saved as a TDMS file on a SD memory card or USB drive depending on the operator’s preference. The captured sample is streamed back over to the UI as a verification that the measurement has succeeded. To allow Fortis Testing to examine and analyze all data, reports in the TDMS file format are tagged with metadata from the configuration page.
The UI is used to configure and arm the measurement system before the explosion is initiated. Each sensor can have unique sensitivity assigned to allow for different sensor models; sensor sensitivity is used to scale the pressure wave readings to Fortis Testing’s desired units. To improve confidence in the measurement system’s readiness — since this type of testing is destructive — the UI monitors the CPU’s four processors and memory available on the CompactRIO.
To reduce the setup time between jobs, multiple users can save and recall configurations. The CompactRIO blinks a front panel LED to notify the operator that the program is functioning, since there is no UI near the blast zone.
Using expertise of embedded FPGA based products and proven architectures, G Systems developed a system quickly and successfully to measure and record pressure waves during structural blast testing. All customer requirements were met including the need for high-speed streaming, flexibility to change the measurement strategy according to different clients’ needs, and minimal signal degradation via the use of ruggedized equipment. Confidence before testing was also achieved by monitoring CPU and memory load remotely.
You may also be interested in G Systems’ automated CSU. With software and hardware designed to be flexible and robust, the CSU is a rugged, portable field test instrument which greatly reduces overall test time through automation and eliminating unnecessary operator tasks. The hardware was designed to withstand the harsh environmental conditions experienced from rapid worldwide deployment.
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