Wireless Data Collection System Across a Large Area

Author(s):
Chris Cahoon - B&B Technologies, an NTS Division

Industry:
Government/Defense, Aerospace/Avionics

Products:
Vision, PXI/CompactPCI, LabVIEW

The Challenge:
Testing custom electronic equipment across a large geographical area (more than 25 square miles) and wirelessly sending the data to a centralized database for analysis and future storage, while the system employs up to 40 data collection units that simultaneously acquire data.

The Solution:
Acquiring data with USB DAQPads and custom National Instruments LabVIEW software, relaying the data to high-speed wireless access points via 802.11g wireless communication, and transferring the data to a centralized SQL database, while a PXI chassis with NI hardware monitors the health of each of the wireless access points.

Our customer needed to perform outdoor tests of military equipment in a rugged environment across a large geographical area. The data needed to be simultaneously sent to a central database for storage and subsequent viewing. To achieve this, we built portable wireless access points (APs) that can communicate with a network and database at the central data processing center using high-speed wireless LOEA radios communicating at 1 Gb/s. Each AP also has its own local 802.11g wireless network to communicate with the numerous data collection units (DCUs).

Testing

The DCUs consist of either a durable laptop or tablet PC connected to a USB DAQPad 6015 and a wireless 802.11g antenna. The DAQPad works well because of its combination of portability, variety of relatively high-speed signals, and low cost. Using LabVIEW, I created flexible modular software in a small amount of time. The software can measure up to eight analog voltages, read or output to eight digital lines, implement two counter/timer channels for either event counting, frequency measurements, or pulse train output, and can read from RS-232 serial ports. Using the LabVIEW Database Connectivity Toolkit working with Microsoft’s SQL Server, I saved data directly to the database without making complex network connections.

Each AP consists of a LOEA high-speed wireless radio, an 802.11g local network, power provided by large solar panels and a propane generator, and a health monitoring system to ensure that the AP is working properly. The best choice for this health monitoring system was a combination PXI/SCXI chassis due to its compactness and high density of instrumentation. Each SCXI chassis contains an 1162HV module for reading high voltage digital signals and an 1102 thermocouple module connected to a PXI-6251 M Series MIO DAQ card to read up to 32 thermocouples.

A pan-tilt-zoom camera connected to each AP allows users in the central data processing center to view each AP and its surroundings in real time. To implement this, I used a PXI-1411 IMAQ card to capture video from the camera and a PXI 8421/4 RS-485 card to control the camera’s pan-tilt-zoom functions. Using the built-in TCP connectivity functions in LabVIEW, I established two-way communication between the central data center and each AP to send compressed live video data from the AP to the data center, as well as send camera control commands from the data center to each camera.

Data Storage and Viewing

An LOEA radio in the central data processing center connects the SQL database to the high-speed wireless network. The database consists of two terabyte servers connected to a domain controller running Microsoft’s SQL Server. The overall storage of the system is approximately 6 terabytes of data. I used LabVIEW and the Database Connectivity Toolkit to create an application to allow the user to read the data from the database, reassemble the data, and view the data. With the power of SQL queries, I can store large amounts of data and find the data the user needs quickly.

Additional Utilities

The application also includes several additional utilities including the camera controller utility, a network pinging utility, and the AP health monitoring utility. With the camera controller, the user can view live camera data from any of the connected APs and to remotely control the camera’s pan, tilt, and zoom functions. The network pinging utility allows the user to send a network “ping” to devices on the network, verifying that devices are connected to the network. This utility is useful when trying to diagnose potential problems with network connectivity. With the AP health monitoring utility, the user can view live data transmitted from the APs to the central database. From here, the user can monitor AP input and output voltages, power consumption, and temperatures.

Software Configurability

The power of the database helps the user to independently configure settings for each DCU and store them in the central database. These settings include the types of measurements to take, the settings of each data acquisition channel, and the speed of data acquisition. Because the DCU retrieves its settings from the database each time it is powered on, users in the central data center can change settings locally so that users in the field in difficult environments do not need to make any adjustments while testing.

Advantages of LabVIEW and NI hardware

The fact that National Instruments hardware integrates so well with LabVIEW was a huge advantage while integrating the hardware with the software. Using NI-DAQ instrument drivers made it quick and easy to configure and use the hardware. The modularity of NI-DAQ also made it possible to use the same software in my DCUs and APs despite the fact that the DCUs use USB based DAQPads while the APs use PXI-based hardware. The only instrument driver I needed to write was for camera, which is really impressive considering the variety of hardware the system used.

For more information, contact:

Timothy R. Brooks

NTS

5200 Pasadena Ave NE

Albuquerque, NM 87113

Tel: 505-345-9499

E-mail: tim.brooks@ntscorp.com

 

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