Java acceleration/tilt/vibration data logger

The DAQ24USB 24-bit analog-digital converter combined with the Accel-70 triaxial accelerometer makes a simple-to-use, low-cost, portable and multi-platform (Linux, Windows) Java data logger. The Accel-70 can log acceleration, tilt or vibration to an ASCII file using the bundled Java data recording software, DAQ-Sys-lab. The logger is supplied with or without an industrial fiberglass enclosure.
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How does NetDAS GPS timing work?

NetDAS “timing” refers to how NetDAS time stamps GRF packets. Note that time-stamping data is more involved than just reading the system clock and using that as the time stamp. This simplistic approach would not work for two reasons. Firstly, the system clock would not have the required resolution, down to the microsecond level and secondly, the analog-digital data stream is asynchronous to the ADC sampling.

GRFd does however use the system clock as a reference to the second. The GPS thread maintains the UTC delta relative to the system clock (along with the GPS lock state). The time stamp is the system time + the UTC delta. Note that this time only resolves the time to the UTC second. The PPS signal (to the ADC board) resolves the time to the microsecond level and these are used together to generate the time stamp.

Assuming that the GPS was locked at some point, the delta was known and the quality was 'good'. When the GPS loses lock, or (perhaps) stops outputting NMEA RMC sentences, the system is free running using the last GPS delta. This will cause time drift so the time quality will be 'poor'. When the GPS regains lock, the UTC delta begins to update again and results in a time tear in the data when the quality goes back to 'good'.

Add GPS timing to legacy (pre-GPS) systems!

Eliminate clock drift for systems with free-running clocks by adding a GPS-NS timing card. If your legacy system has serial and digital input ports and a timer, you can upgrade your timing to GPS with a software-only solution. Simply connect the GPS-NS NMEA output to your serial port and the GPS-NS PPS output to the digital input port which controls a counter. The counter's counts is the time offset from the second (X.00000) and NMEA RMC is the time of that second. With these two numbers the time is determined to the resolution of the counter. For example, if the counter is clocked at 1 MHz, then the time is accurate to one microsecond.

NetDAS 32-channel 24-bit data acquisition

For data acquisition applications (DA) requiring high channel counts, NetDAS-32 is a cost-effective solution. Applications include wired seismic arrays in structures, laboratory sensory DA, seismic surveys or other DA where large numbers of analog sensors need digitization with GPS timing and 24-bit resolution. NetDAS offers TCP/IP connectivity via the NetDAS Tools client/server software (remote data collection, triggering, formatting, performance logging, data concentration). For about $9500, you won't find a better value!

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Watchdog Power Supply

A Watchdog Power Supply (WDPS) is useful for systems that run continuously as a WDPS will automatically reboot the system if it stalls, stops or crashes. The WD is "kicked" every few seconds with a CPU generated pulse. If the pulse is missing (CPU has crashed) the power is recycled. A cold reboot is often the most effective way to recover from software bugs, power glitches, USB stack errors or any other problem that causes the program to halt. To use this WDPS just have it supply the 5VDC to your CPU and have the CPU provide a periodic pulse to the WD. Read Moreā€¦