OCS & wireless technology

Wireless Options Serial versus Ethernet interfaces Serial-based radios typically replace relatively low-bandwidth RS-232 transmissions A wireless radio (if properly installed) will provide a relatively reliable, low bandwidth connection Serial based industrial hardware/software is generally fault tolerant Ethernet-based radios typically replace high bandwidth 10/100MB transmissions In many situations, a wireless radio will fail to deliver a reliable, high bandwidth connection Much of the software that makes up an ethernet “stack” is many years old - and was written with wired connections in mind. It is often not fault tolerant enough for a wireless environment.

Wireless Options Today, Horner recommends serial based wireless solutions WiFi/802.11. We do not have a WiFi option that we recommend. That doesn’t mean it doesn’t exist - but we haven’t looked for it. 900MHz 1W radio. This is the best solution for most applications in North America. It has the best range and fault tolerance. 2.4GHz 60mW radio. This is currently our lowest cost solution, and the best solution for Europe. Cellular Radio. This is the best option in applications which are highly mobile, remotely located, or in areas of unsuitable terrain. It also provides a convenient messaging service (SMS).

Wireless Basics Wireless systems have several components which must be examined Transmitting Element - provides Power for data sent via RF waves Receiving Device - receives the signal, which must be done with sensitivity & error rejection Environment - will affect RF waves as they pass through, causing interference Antenna - impacts the distribution and focusing of the signals

Wireless Basics Visual vs. RF Line-of-Sight & the Fresnel Zone Visual LOS. The ability to see from one site to another. It requires only a linear path between two points RF LOS. Requires not only Visual LOS, but a football shaped path free of obstacles - called a Fresnel Zone

Wireless Basics Overcoming Obstructions by Raising Antenna Height

Wireless Basics Increasing the RF signal by Increasing Antenna Gain Flashlight Analogy Omnidirectional Directional Omni Directional Yagi

Wireless Basics Summary of Ways to Maximize System Range Use 900MHz Radio Increase Transmitter (TX) Power Regulated by the Government Improve Receiver (RX) Sensitivity Increase Antenna Gain Use appropriate antenna Use short antenna cable Clear the Environment (Fresnel Zone) of Obstructions Physical Obstructions (trees, walls, etc.) RF Interference (wireless LANs, pagers, cell phones, etc.)