Wireless USB for the factory

Vision systems and industrial I/O may benefit from a recently developed wireless scheme for connecting peripherals to computers. The first generation of wireless USB interfacing is likely to take the format depicted here. The wireless USB connection is between a wireless hub and dongles plugged into USB-certified devices such as cameras, mice, PDAs, or display terminals. Belkin Corp. recently developed hub/dongle connections for the Cable-free USB format. An alternative approach comes from Gefen Inc., which makes small sender/receiver units that fit in an ordinary USB port to provide a Cable-free USB connection. Billed as the world's first UWB image-transfer board, this device from FotoNation, San Francisco, permits wireless transfer of photos at 200-Mbit/sec rates between cameras and PCs. It follows the PTP-IP (picture transfer protocol IP) standard and implements WiMedia-style Wireless USB through use of a UWB chip from Wisair Corp. The difference between direct sequence and OFDM transmission techniques can be illustrated by time and frequency domain plots like these devised by authors at Intel Corp. Direct-sequence transmissions use super-short pulses at differing frequencies. The resulting bandwidth is quite wide. OFDM, sometimes referred to as multiband UWB, uses several carriers at different frequencies and initiated at different times. The resulting frequency domain plot consists of frequency bands with minimal overlap. January's Consumer Electronics Show marked the first public demonstration of wireless USB equipment. USB, for Universal Serial Bus, is the standard used for connecting computers to mice, scanners, digital cameras, printers, and so forth. The wireless version of USB eliminates the cord between the computer and the peripheral by substituting a radio link. The use of RF on wireless USB lets the peripheral sit as far as 30 ft away, though the highest transmission speeds come if the separation is only 10 ft or less. And the peripheral needn't be