# Errata for Building Wireless Community Networks

The errata list is a list of errors and their corrections that were found after the product was released. If the error was corrected in a later version or reprint the date of the correction will be displayed in the column titled "Date Corrected".

The following errata were submitted by our customers and approved as valid errors by the author or editor.

Color Key: Serious Technical Mistake Minor Technical Mistake Language or formatting error Typo Question Note Update

Version Location Description Submitted By Date Submitted Date Corrected
Printed
Page 77

In section 6.2.3 of Rob Flickinger's book, he calculates the total system gain as below: "Next, add up all of your gains (radios + antennas + amplifiers) and subtract your losses (cable length, connectors, lightning arrestors, and miscellaneous other losses). Let's assume you are using Orinoco Silver cards (15dBm), no amplifiers, with a 12dBi sector on one side, and a 15dBi yagi on the other. We'll assume you're using one meter of LMR-400 and a lightning arrestor on each side, allowing 0.25dB loss for each connector, and 1dB for each pigtail. Since all of the units are in dB, we can use simple addition and subtraction: radio - pigtail - arrestor - connector - cable - connector + antenna Site A: 15 - 1 - 1.25 - 0.25 - 0.22 - 0.25 + 12 = 24.03 Site B: 15 - 1 - 1.25 - 0.25 - 0.22 - 0.25 + 15 = 27.03 A + B = 51.06 total gain " It is incorrect to add in the radio transmit power twice. If you are calculating total path gain, then the power gain figure of the receiving radio is immaterial. The correct calculation is below: radio - pigtail - arrestor - connector - cable - connector + antenna Site A: 15 - 1 - 1.25 - 0.25 - 0.22 - 0.25 + 12 = 24.03 - pigtail - arrestor - connector - cable - connector + antenna Site B: - 1 - 1.25 - 0.25 - 0.22 - 0.25 + 15 = 12.03 A + B = 36.06 total gain

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