So a few months ago we purchased an 11 GHz PTP820S 2+0 link. We
recently installed it, and it appears to be working fine, aside from a
little bit of frame loss that we are investigating. While looking
into this frame loss issue, I stumbled across something that concerns
me. On Cambium's support forum there is a post that states that when
dealing with 2+0 links both radios must be in the same sub-band.
There is no explanation of why this is the case. In our situation,
the radios are in separate sub-bands. When we did the frequency
coordination, the only two 80 MHz channels available were in different
sub-bands. I passed those channels along to our vendor who worked
with Cambium to get a BOM. At no point did anyone say that this was a
problem. So now, fast forward a few months, and I stumble across this
post, and now I'm wondering what the implications will be. Both links
are up and running. Signal on both is right where it should be (-39
on one, -40 on the other). Both are running at maximum modulation.
There are no defective blocks shown on the radio interfaces. There is
no indication that this sub-band mismatch is causing any issues, aside
from possibly this frame loss thing. However, if I mute the radios on
one link, the frame loss persists, so I don't think it's related.
In case it matters, the two links are oppositely polarized. On one
side we've got a 2 foot dish with an OMT combining the radios. On the
other side, we've got an 8 foot dual-pol dish.
So I'm wondering if anyone knows why Cambium says that you can't use
radios from different sub-bands. Are we in for trouble at some point?
Craig
- [AFMUG] PTP820S 2+0 configuration Craig Baird
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