7.10 Tests
In the AirLaser IP1000plus firmware three tests are implemented to check the functionality of the optical link.
Laser Alignment Test
The laser Aligment test is only implemented in the four beam model AirLaser IP1000plus/800. The test tells
you whether the local device (the device to which you are logged in) is optimally aligned to the remote site.
For maximum operational reliability, it is important that all four laser meet with nearly the same power the
receiver of the remote site. This ensures that the remote station is located in the center of the laser beam,
which is generated by the four individual lasers. Optimal alignment makes the optical link robust against
slight movements due to thermal influences, heat shimmer and falling leaves or snow.
If the test is started, three lasers are turned off so that only one remains in operation. Now, the received
power is measured by the remote station, which is achieved by one laser. The measurement is repeated for
all four lasers. At the end of the test, which takes about 5 seconds, the measurement result is shown
graphically in web management.
The test is performed using the currently selected laser power reduction, so 0dB or 6dB. During the test, the
link remains in the optical mode, unless the receive power goes below the sensitivity limit of the receiver. The
AirLaser then automatically switches to the backup.
The measured value of each laser is associated with the laser in the image. The view is to the rear of the
unit. From the Link Distance, which is registered on the system site, and the TX-Reduction the Expected RX-
Level is calculated. This is the theoretically maximal possible Receiving Level that can be achieved by one
laser, at the given distance. In practice the achievable value is in some cases significantly lower due to
weather related attenuation of the atmosphere.
The AirLaser can reliably measure the optical receive level up to -36dBm. Lower levels are shown by "---". If
the measured value can not be read from the remote device, this is indicated by "na" in the management.
Small errors in the alignment should not be corrected immediately, but better initially observed. If the error is
at any time of day for several days nearly constant, so the device can be refocused on occasion. However,
the error changes with the time of day and temperature, an alignment should be chosen that brings the
highest possible level of reception in all weather conditions.
If you are not sure if and how you need to change the orientation of your equipment, contact our Customer
Service. We advise you gladly.
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