Installation Guide

IBR Installation Guide
Page 26 of 38 Doc # 770-00023.1
Jan. 23, 2015
If a link is not automatically established within ten minutes, then consider the following troubleshooting
suggestions:
 Check to ensure that the partner IBR on the link is operational.
 Change the direction in which the IBR is pointed.
 Change the IBR’s elevation.
 Determine if the link is too long for the environment.
6.9 Pointing & Link Optimization
IBR’s transmit and receive antennas each have a one hundred and twenty degree, 3 dB beam width centered
on the ridge at the top of the radome. Therefore, aligning or pointing an IBR, as discussed below, means
orienting IBR so that the ridge on the radome is facing the desired direction.
6.9.1 Line-of-Sight and Near Line-of-Sight Links.
Horizontal Alignment - Orient each IBR so that its radome is pointed toward the other end of the link.
Because IBR has a relatively wide (120-degree) 3-dB beam width, a few degrees of misalignment is not likely
to have an effect on link performance.
Vertical Alignment – Because IBR has only a fifteen degree 3-dB beam width in the vertical direction, greater
care should be taken in setting the elevation angle so that each IBR is pointing as nearly as possible toward
the other end of the link.
6.9.2 Non-Line-of-Sight Links.
Horizontal Alignment – The process for finding the optimum position for each end of the link depends on
whether it is possible to establish a link by aiming the IBRs at each other, and if there is the possibility of
reflection from a building. The following is a suggested procedure to use if the IBRs do not synchronize after
being aimed towards each other and it is possible to benefit from reflection off a building:
 Start with each IBR in a best-guess orientation toward the other end of the link.
- Keeping the near IBR’s position fixed, rotate the distant IBR hundred and twenty degrees in azimuth.,
and allow one minute for the link to synchronize.
- Rotate the distant IBR another one hundred and twenty degrees, and allow another minute for the
link to synchronize.
- Repeat the process a third time.
 Rotate the distant IBR another one hundred and twenty degrees. At this point, it will be in its original
position.
 Rotate the near IBR one hundred and twenty degrees. Now repeat the steps in (a) above, rotating the
distant IBR through three hundred and sixty degrees in one hundred and twenty degree increments.
When using steps of one hundred and twenty degrees as indicated above, there will be a total of nine possible
combinations of positions for the two IBRs. If the radios are rotated only ninety degrees each step, there will
be a total of sixteen combinations, however, the resulting alignment might be more optimal.
In a situation where the IBRs synchronize when pointed toward each other, and it is not possible to get a
reflection off a building, a more empirical approach might produce a faster result. When a link has been
established, rotate one IBR ninety degrees. If the SNR improves, rotate it another ninety degrees, and
continue in this way until SNR begins to fall, then move back to the previous position. If SNR does not
improve, return the IBR to its original position. Repeat at the other end of the link.
If a link cannot be established, try all sixteen aiming combinations, spending one minute at each combination
to give the link time to synchronize. Do this by locking the near end at 0 degrees azimuth, and then aiming
the far end of the link at 0, 90, 180, and 360 degrees, spending sixty seconds at each position. Next, move the
near end to 90 degrees and repeat at 0, 90, 180, and 360 degrees at the far end. Continue until a link has been
established or all sixteen combinations have been tried.