Text version of the page

Ten Commandments of Wireless Communications | WP-33-REV0-0109-6/6 © 2009 by B&B Electronics Mfg. Co., Inc.

10 Commandments of Wireless Communication - 59059 9.Cable loss

Those high frequencies you are piping to your antennas don’t propagate particularly well through cable and connectors. Use high quality RF cable between the antenna connector and your antenna and ensure that all connectors are high quality and carefully installed. Factor in a 0.2 dB loss per coaxial connector in addition to the cable attenuation itself. Typical attenuation figures for two popular cable types are listed below.

WHITE PAPER

Loss per 10 feet (3 meters) of cable length Frequency RG-58U LMR-400 900 MHz 1.6 dB 0.4 dB 2.4 GHz 2.8 dB 0.7 dB

While long cable runs to an antenna create signal loss, the benefit of elevating the antenna another 25 feet (7.6 m) can more than compensate for those lost dB.

10.Thou shalt recognize the issues of latency and packetization before thou issueth purchase orders.

Before you lift a finger towards the perfect wireless installation, think about the impact of wireless communications on your application. Acceptable bit error rates are many orders of magnitude higher than wired communications. Most radios quietly handle error detection and retries for you - at the expense of throughput and variable latencies.Software must be well designed and communication protocols must be tolerant of variable latencies. Not every protocol can tolerate simply replacing wires with radios. Protocols sensitive to inter-byte delays may require special attention or specific protocol support from the radio. Do your homework up front to confirm that your software won’t choke, that the intended radio is friendly towards your protocol, and that your application software can handle it as well.

International Headquarters: Ottawa, IL USA 815-433-5100 www.bb-elec.com European Headquarters: Oranmore Co. Galway Ireland, +353 91 792444 www.bb-europe.com
B&B ELECTRONICS