LightPointe AireLink 60, Инструкция по установке и эксплуатации

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AireLink

60 Installation and User Manual Rev. D System Installation
Page 78
Figure 5-17: Simple illustration of the alignment process
Note:
For longer distances between the antennas the side lobes might not be
visible due to the much lower signal power contained in a side lobe when
compared to the main lobe.
16. When aligning the system it is important to take a look at the Receive Signal Strength using
either a voltmeter attached to the alignment voltage connector located at the side of the radio
housing, or using the LightPointe BLE Tool and Observe the RSSI value shown in the radio
submenu. The RSSI chart in Fig. 5-18 shows the RSSI signal voltage as a function of the
deployment distance under ideal and clear weather conditions. Therefore, and when the system
is installed under non-clear weather conditions, the values can be lower during the actual
installation process. 60 GHz systems are also impacted by oxygen absorption (see Fig. 2-2) and
these values can vary several dB between sea level installations and installations at higher
altitudes. The RSSI values are different for the low band and the high band radio and the values
vary slightly and within a few percent from one radio system to another due to manufacturing
tolerances. However, the chart provides a very good indication of expected RSSI values as a
function of deployment distance. The overall goal of the alignment process is to align the system
as close as possible to the RSSI value provided in the RSSI chart. The RSSI voltage reading in
Volt corresponds to the RF RSSI signal reading in dBm. In other words, and with the correct
polarity chosen, a system that is not aligned at all will show a negative voltage reading close
to –0.80 Volt and this translates into a -80 dBm power reading. This signal level is far too low
to establish a data connection. During the alignment process the voltage reading will increase,
meaning “less negative” voltages or higher RF RSSI reading in dBm will be recorded. The goal
is to align the system at its best possible and highest RSSI reading (e.g. increase the voltage
reading. When using the
Lightpointe BLE Tool , the RSSI reading is given in dBm directly.