Campbell Scientific - Model VWIRE 305 - 8-Channel Dynamic Vibrating-Wire Analyzer
From GRANITE Data Acquisition System
Benefits and Features
- Dedicated measurement hardware for simultaneous measurement of each channel
- Interfaces to any standard single-coil vibrating-wire sensor
- Eight simultaneously sampled channels per module; synchronized across multiple modules
- Dynamic measurement rates of 20 to 333 Hz
- Static measurement vibrating-wire and thermistor measurements at 1 Hz
- VSPECT™ spectral interpolation algorithms provide superior noise immunity and measurement resolution compared to time-domain period-averaging approach
- Excitation method providing frequent low-energy pulses to maintain a continuous resonant vibration in the sensor
- Onboard post-processing including frequency conversion, temperature conversion, and rainflow histogram calculation
- CPI DAQ connection for channel expansion
- USB 2.0 interface for PC-based operation
Details
The interface measures the resonant frequency of the wire between excitations using the patented vibrating-wire spectral-analysis technology (VSPECT™). VSPECT provides very fine measurement resolution and limits the influence of external noise by discriminating between signal and noise based on frequency content. Because of this technology, the signal can be carried through longer cables in harsher noise environments, giving you flexibility in your sensor and data-acquisition system siting.
The dynamic vibrating-wire measurement technique is protected under U.S. Patent No. 8,671,758, and the vibrating-wire spectral-analysis technology (VSPECT™) is protected under U.S. Patent No. 7,779,690.
Details
The interface measures the resonant frequency of the wire between excitations using the patented vibrating-wire spectral-analysis technology (VSPECT™). VSPECT provides very fine measurement resolution and limits the influence of external noise by discriminating between signal and noise based on frequency content. Because of this technology, the signal can be carried through longer cables in harsher noise environments, giving you flexibility in your sensor and data-acquisition system siting.
The dynamic vibrating-wire measurement technique is protected under U.S. Patent No. 8,671,758, and the vibrating-wire spectral-analysis technology (VSPECT™) is protected under U.S. Patent No. 7,779,690.
Details
In addition to the dynamic vibrating-wire measurement, the VWIRE 305 makes several auxiliary measurements. A static vibrating-wire measurement is made once each second, along with the dynamic measurements, which provides finer measurement resolution and greater immunity to external noise sources. The VWIRE 305 includes a thermistor input channel paired with each vibrating-wire channel, featuring high-precision 24-bit measurements at a 1 Hz rate. Lastly, a rich set of diagnostic parameters is provided with the vibrating-wire data.
The VWIRE 305 has the capability to simplify post-processing of data by computing common values internally. Vibrating-wire data can be reported as measured frequency or as the frequency squared with a multiplier and offset applied. The thermistor data is reported as resistance or is converted to degrees Celsius using the thermistor’s Steinhart-Hart coefficients. The VWIRE 305 can also internally compile rainflow histograms from the final data and report the values at user-specified intervals.
Vibrating-Wire Inputs
Each channel has two terminals for connecting to the coil of the vibrating-wire sensor. Both vibrating-wire terminals are labeled VW, and the polarity of the wiring is arbitrary. The sensor is excited and measured through the same connections. Sinusoidal excitation is applied for a few cycles of the wire oscillation. The wire is maintained in a continuously vibrating state. Excitation voltage varies automatically to maintain the desired return signal strength.
Thermistor Inputs
Each channel has two terminals for connecting to the thermistor. Both thermistor terminals are labeled T, and the polarity of the wiring is arbitrary. The measurement is a half-bridge configuration with the excitation circuitry and completion resistor integrated into the module.