Data Recording for Dynamic Signals
While many manufacturers provide long term data recording functions on various hardware platforms, it is difficult to find a good data recording instrument that meets following requirements:
- For dynamic data acquisition and data recording, the samples of all input channels must be accurately synchronized. The time synchronization accuracy must be better than 100ns (or 1 degree phase match at 20kHz).
- The sampling rate of each channel for data recording functions must be as high as 100kHz to cover the useful frequency range of sound and vibration applications.
- The data storage media for data recording must be reliable, anti-shock, and vibration. Regular hard-drives using electrical spindles cannot be used for this application.
- Data storage in data recording devices must have a minimum of a few hundred gigabytes
- Data must be stored without losing dynamic range. A 32bit floating point format is preferred.
- Some customers may require a portable data recording solution
- Some customer may require hundreds of input channels for their data recording needs.
- The data recording module must have input channels that accommodate various vibration and acoustic sensors.
- The data recording action is triggered by various events, such as level or edge trigger, timer, alarm or abort limiting events etc.
- Post processing software for data recording must be capable of handling very large files efficiently to playback, process and export the data files.
Crystal Instruments provides two solutions for long term data recording that meets all the requirements described above.
With various excitations, the characteristics of the UUT system are measured experimentally. These characteristics include:
HANDHELD DATA RECORDING SOLUTION
The first data recording solution is the CoCo-80 and CoCo-90 for portable applications. The long time waveform from each channel simultaneously records into the internal flash memory or external SD card. A dedicated REC hard button equipped with the handheld, portable data recording instruments make recording as easy as pushing a button.
DATA RECORDING FOR HIGH CHANNEL COUNT SYSTEM
The second data recording solution is the Spider-NAS. It is the ideal data recording solution for high channel count data acquisition and data recording.
The Spider-NAS (Network Attached Storage) is a dedicated data recording storage device that works with front-end modules from Crystal Instruments, including the Spider-80X, Spider-81, and Spider-DAQ. Eight high-speed data buses interface directly with each Spider front-end module. An Ethernet port is used to configure and control the Spider-NAS during data recording operations.
A high-performance removable Serial ATA (SATA) 2.5-inch hard disk is used as a storage media. When recorded, data will be written in the NTFS file format. Data is transferred from the Spider-NAS to the PC using Crystal Instruments Engineering Data Management software. Another option is to remove the SATA hard disk connect it to a PC.
A second SATA hard disk can be attached to Spider-NAS. This disk can serve the same purpose as the first disk. Users can plug in their own 2.5-inch hard drive.
The Spider-NAS is shipped from the factory with a solid state hard-drive installed, containing a capacity of 250GB. The solid state drive performs very well in the high shock and vibration environment.
Each dedicated data port can reach a theoretical speed of 480 Mbits/second. In practice, the system can store data simultaneously for all dynamic measurement channels at 100 kHz sampling rate enabled.
A special error checking algorithm is developed to detect and avoid any errors occurring during data transfer and storage.