Proxim Wireless U58-45 User Manual Modified page regarding RF exposure warning

Proxim Wireless Corporation Modified page regarding RF exposure warning

Contents

Modified page regarding RF exposure warning

INSTALLATION AND MAINTENANCE MANUALTsunami FAMILYFAST ETHERNET WIRELESS BRIDGES December, 1999PAGE 3-18 SECTION 3: INSTALLATION & ADJUSTMENTS3.10 Antenna Installation & AlignmentThe antenna installation consists of permanently mounting the antenna outdoors on a tower,building roof, or other location that provides line-of-sight path clearance to the far-end location. Ingeneral, antennas smaller than 2 feet diameter are not recommended for urban areas due to theirwider beamwidths, which results in higher interference susceptibility.Antennas should be ordered with a suitable mounting kit specific to the site requirements. Forexample, specifying round or angle tower leg adapters, or a roof tripod as necessary.The antenna must be very rigidly mounted, with adequate room for azimuth and elevationadjustment from the rear.The antenna polarization must be the same at both ends of the link, either vertical or horizontal.In general, antenna mountings require a support pipe to which upper and lower support bracketsare attached with “U” bolts. The antenna and optional elevation and azimuth adjustment rods arethen mounted onto the support brackets. The whole structure must be adequately grounded forlightning protection. The antenna system must always be installed according to the manufacturer’sinstructions.Unless special test equipment is available, two operating Tsunami terminals are required to alignthe antennas. Alternatively, a CW generator may be used to transmit a signal toward the endunder alignment.The antenna is coarse aligned using visual sighting and then fine aligned using the receive signallevel (RSL) voltage of the Tsunami.The RSL voltage reading can still be used to peak antennaseven if the radios have not synchronized, however far-end RSLcannot be measured from the near-end terminal until radiosare synchronized.To coarse align the antenna, first set it for flat elevation (no up or down tilt) using a spirit level.Then point it at a heading marker obtained using a compass back-bearing from an adjacentlocation, (ideally, 100 feet or more away from the antenna).If a heading marker cannot be set sufficiently far away (for example when on a city building roof orlooking through a window) then a rough azimuth setting can be obtained by sighting along theantenna feed.INSTALLER CAUTION: Antennas used for this device must be fix-mountedon permanent outdoor structures to provide 5 feet or more separation fromall persons during device operation to comply with FCC RF exposurerequirements. Installers should contact manufacturer for applicable gain andtype restrictions to ensure compliance.
INSTALLATION AND MAINTENANCE MANUALTsunami FAMILYFAST ETHERNET WIRELESS BRIDGES December, 1999PAGE 3-19 SECTION 3: INSTALLATION & ADJUSTMENTSIt should be verified that both antennas are on the samepolarization by using the manufacturer’s instructions. Otherwisethe RSL will be approximately 25 to 30 dB below the calculatedlevel.Most antennas will also need fine alignment obtained using an operating link because it is veryimportant to maximize the receive RF signal level at each end of the radio link.Read Section 3.7 before applying DC power to the Tsunami radio.Once the coarse alignment has been set-up at both ends, then the link can be powered and somelevel of reliable communication established. The voltage at the Tsunami front panel RSL test pointshould be measured with a DVM to determine the relative receive RF signal level.For the fine alignment, adjusting first the azimuth and then the elevation of the local antenna willmaximize the RSL voltage. Then, the far antenna is aligned in the same way, using the RSLvoltage of its local Tsunami radio.When aligning antennas it may be convenient to run two wires from the RSL and ground testpoints to the antenna so that the voltmeter reading is directly visible to the technicians aligning theantenna. Also, a cellular telephone or two-way radio may be useful for coordinating alignmentactivities between both ends of the link. Once the radios are coarse aligned and synchronized, thebuilt-in orderwire phone service can also be used to coordinate alignment between both ends ofthe link.An orderwire telephone will provide end-to-end voicecommunications once radios are synchronized. Synchronizationusually can be accomplished by coarse alignment only. Aftersynchronization, the orderwire phones can be used to communicatebetween radio sites for antenna fine alignment. The phoneinterconnect cable can be extended to the antenna when desired.The larger the antenna size, the more critical alignment becomes: for example, with a 2 foot dish,the antenna can be moved ±3 degrees off the correct heading before the receive signal leveldrops by 3 dB. This compares with a 6-foot dish which may only be moved ±1 degree for thesame degradation.The graph shown in Figure 3-6 shows the typical variation of RSL voltage as the receive signallevel is increased from threshold to a higher level. There is some variation between Tsunamireceivers, but an approximate estimate of the potential RSL value may be made using this figure.

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