Wireless Data Acquisition.

The Center for Geotechnical Modeling at the University of California, Davis has developed a custom wireless data acquisition system (WiDAQ) to augment and extend its data acquisition infrastructure. The premise to the WiDAQ system is to provide freedom from traditional wired instruments and offer the flexibility of using a small self-contained package controlled by an intuitive user interface.Wireless data acquisition network

QTM-8524 RF modem modules operate in the 2.4GHz ISM band and can reach speeds up to 57.6 kbps. As a spread spectrum system they can be used alongside other radio systems with minimal signal conflict. Further, as the modules use GMSK (Gaussian Minimum Shift Keying) modulation, they have a very low bit error rate, which is ideal for use in factories and other high-noise environments. Additional advantages of the DSSS implementation are high throughput, and a noise-like signal that is particularly resistant to deliberate or accidental interception, demodulation and jamming. No license is necessary for operating wireless QTM-8000 systems. Wireless data acquisition systems

If you're just starting to think about wireless data acquisition for your facility, read the points below. If you're already committed to wireless -- even if you have a wireless system in place -- you might want to skip ahead to FEDD's Wireless Solutions.

By now you're probably wondering what this has to do with data acquisition. Although Wi-Fi devices are used primarily as wireless Internet or LAN access points, their applications are far ranging. A Wi-Fi network can be used to access a DATAQ Instruments' Ethernet device from up to 150 feet away! Wi-Fi capability allows you to monitor your WinDaq data from virtually anywhere in the building without the bother of running back and fourth or laying cable, all for around $150. Wireless Lab data acquisition

For wireless data acquisition and control communications, the system utilizes Z-Wave, a low bandwidth wireless protocol that specifically targets residential control applications. HIP also provides 802.11 WiFi support, for communicating with PCs and PDAs. Since the system is fully wireless, remodeling installations require no additional wiring or "hole drilling," Lagotek says. Wireless PDA Data acquisition

The output power of the radio transmitter in each station is made low ([approximate]10 mW) to minimize interference. The range of each station is 300 feet (about 90 m) with a small whip antenna and can be increased by use of a directional antenna. The system is based on a spread-spectrum transceiver and uses an in-house developed algorithm to central communication over more than 100 frequency pairs on a 433- or 918-MHz base frequency. The wireless links currently operate at a data rate of 19.2 kb/s, but are capable of 115 kb/s. Wireless Rfid Data acquisition

A system that acquires seismic data using cellular wireless technology is similar to a cellular telephone system in a large city. Inside the hypothetical city limits shown in Figure 1a, several radio towers create overlapping reception/broadcast areas that combine to cover the city. Through a connection of radio towers, a cellphone user at A can talk to, or transmit digital information to, a second cellphone user at B. The diagram implies that A and B exchange information via pass-along communication links 1, 2, 3, and 4, which span many miles.

Communications between the application and master radio are transmitted over a standard TCP/IP network. The TCP packet payload transmitted between the master radio and the application is custom-formed for controlling the WiDAQ system. Using this custom-formed packet the library coordinates the transfer of instructions, status updates, sampled data, etc. Since the intricacies of forming/reading these packets are encapsulated within the library (DLL), the application is simplified and is instead composed only of the logic necessary for operating a data acquisition system. The following outlines the operation of this application.

A wireless data acquisition system has been developed for the quick, efficient measurement of strain. The wireless system can be set up in a matter of seconds at a particular measurement location and does not require wires to connect the sensors to a central data acquisition system. The system can operate with conventional strain gauges that are bonded or welded to a structure. Alternatively, these systems can use a clamp-on strain gauge that can be quickly applied without surface preparation. Data can be monitored in a near real-time fashion while testing is in progress.

Deflection measurements are also possible with the wireless data acquisition system, but the wireless system has the same requirement for reference locations under the bridge as does conventional instrumentation. Consequently, the method used to easily measure deflections remotely is a laser radar system that precisely measures the distance to a remote target.

The laser radar system is placed at one location under the bridge, and a laser beam is scanned over multiple points on the bridge to remotely measure deflections. Neither surface preparation nor the mounting of targets on the bridge is required. The main advantages of this type of instrumentation are the quick setup time, the large number of measurement locations possible, and the elimination of the need for scaffolding or access below the structure. When used together, the wireless data acquisition system and the laser radar system have the potential to rapidly measure the load capacity of bridges, and that could result in a more precise estimate of the number of structurally deficient bridges.

All data acquisition systems generally operate in a similar fashion. They receive an external input from some type of sensing device, condition and/or convert the input to a format suitable for transmission, as necessary, and transmit it to another piece of equipment usually a monitor or controller, which may be a computer, and more specifically, a personal computer. The external input is generally an analog signal, although digital signals, frequently on-off switching, pulse-width modulation, or serial data protocols, are also involved. The inputs, though, come in many forms with many different characteristics, be they pneumatic, hydraulic or electronic, to list a few. Modern applications, control schemes and devices usually necessitate the use of electronic inputs in one form or another. For example, electronic analog inputs may have ranges of 4-20 mA, +/-5 volts, +/-15 volts, or microvolts to millivolts.

That's all there is to it! In a matter of minutes you can be up and running at sample rates as high as 186,000 samples per second with little or no help from your network administrator. So take a few minutes out of your day, set it up, and enjoy the convenience of wireless data acquisition.

Radio frequency (RF) wireless data acquisition systems can convert the input to a conditioned electronic signal which is used to modulate a carrier frequency which is then transmitted as a radio frequency signal to equipment in another location. The conditioned signal is encoded with data corresponding to the status of the input. In the United States the Federal Communications Commission (FCC) regulations govern RF transmissions, and similar agencies regulate RF transmissions in other countries, specifically as to the frequency band that can be utilized to transmit the signal and the strength of the signal. Other data transmission means, such as infrared, optical, or any means which does not require a mechanical connection is understood to offer similar advantages as RF transmission.

Manufacturer of wireless and broadband data acquisition and communication systems for government applications. Types of data communication and acquisition systems include electro optic polymer modulators and millimeter wave wireless communication system.

The laser system is capable of sub-millimeter measurements over a maximum range of about 30 meters. This instrument differs from other remote, distance measurement devices in that it can resolve sub-millimeter measurements without requiring a special retroreflective target.

To optimize the performance of their cars, students at The University of Akron use wireless data acquisition technology to monitor on-board data while the cars are on the track. For example, one such measurement is shock absorber travel, measured using linear potentiometers. This data is collected using a DATAQ Instruments DI-720EN and is then transmitted via an SMC Networks wireless access point to a laptop computer.

This example has only one WCM and therefore, only one data acquisition configuration. However, when using multiple WCMs, different data acquisition configurations can be created for each WCM. For instance, if the user is using three WCMs and would like one WCM to sample at 4096 Hertz and the other two at 2048 Hertz, simply add two different data acquisition events to the list, configure them appropriately, and assign them to the respective WCMs as previously described.

Designer and developer of engineered test, measurement and automation systems including data acquisition systems for wireless applications. Regulatory compliance and standards RF verification, wireless ATE, radio test, manufacturing functional test, LabVIEW toolkits, test system development & consulting.

Three deflection measurements and one strain measurement were made on the girders at the mid-span of the structure. The installation of these sensors and the configuration of the wireless data acquisition system were completed in approximately one hour.