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Ten Commandments of Wireless Communications | WP-33-REV0-0109-1/6 © 2009 by B&B Electronics Mfg. Co., Inc.

10 Commandments of Wireless Communication - 59059 The Ten Commandments of Wireless Communications

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10 Steps to Assure Wireless Success

1.Thou shall know thy dBm and recall thy high school logarithms.

Radio Frequency (RF) power is measured in milli Watts (mW) or, more usefully, in a logarithmic scale of decibels (dB), or decibels referenced to 1 mW of power (dBm). Since RF power attenuates as a logarithmic function, the dBm scale is most useful. Here are some examples of how these scales relate:

1mW = 0dBm A 2-fold increase in power yields 3dBm of signal. 2mW = 3dBm A 10-fold increase in power yields 10dBm of signal. 4mW = 6dBm A 100-fold increase in power yields 20dBm of signal. 10mW = 10dBm 100mW = 20dBm 1W = 30dBm

2.Covet not high frequencies - as the lower the frequency, the more forgiveth the laws of physics and propagation.

Industrial applications typically operate in “license free” frequency bands, also referred to as ISM (Industrial, Scientific and Medical). The frequencies and power of these bands varies from country to country. The most common frequencies encountered are:

2.4 GHz – nearly worldwide 915 MHz band – North America, South America, some other countries 868 MHz band – Europe

As frequency rises, available bandwidth typically rises, but distance and ability to overcome obstacles is reduced. For any given distance, a 2.4 GHz installation will have roughly 8.5 dB of additional path loss when compared to 900 MHz. However, lower frequencies require larger antennas to achieve the same gain.

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