Tests Explore Factories' Wireless Difficulties
Wireless systems offer great promise inside factories for communications, monitoring, and machine control, but while they are more flexible and less expensive than wired systems, they aren't easy to use. Recent tests conducted by the National Institute of Standards and Technology have confirmed why: Industrial plants can be highly reflective environments, scattering radio waves erratically and interfering with or blocking wireless transmissions.
The latest NIST tests were done in August at an engine plant and a metal stamping plant in partnership with the U.S. Council for Automotive Research. The manufacturing plants NIST tested were crowded with stationary and mobile metal structures, such as fabrication and testing machinery, platforms, beams, conveyors, forklifts, maintenance vehicles, and autos in various stages of production. NIST monitored frequencies below 6 gigahertz (GHz) for 24-hour periods to understand the background ambient radio environment and found that interference from heavy equipment ("machine noise") can impair signals for low-frequency applications such as those used to in some controllers on the production floor. A detailed analysis of a common wireless LAN frequency band (channels from 2.4 to 2.5 GHz) found heavy, constant traffic by data-transmitting nodes, wireless scanners, and industrial equipment, the agency said in an Aug. 30 technical note.
NIST researchers will use the data in studies trying to pre-qualify wireless devices for use in industrial environments. They already have identified some ways to minimize radio interference on the factory floor, including use of licensed frequency bands where possible and restricting use of personal electronics in high-traffic frequency bands such as 2.4 GHz. The NIST/USCAR collaboration began in 2004.