12km p2p link - strange problem with signals

RouterOS Wireless Networking
1

Hello there guys,
We established a point to point link over 12km. At the begining everything was fine and the signal strenght was about -70.
We managed to deliver 35mbits 1 way. And suudenly after a few rainy days (after 4 months of no problems and a lot rain too) the link looked like this

signal-strength: -85dBm
tx-signal-strength: -85dBm
noise-floor: -96dBm
signal-to-noise: 11dB
tx-ccq: 58%
rx-ccq: 60%
p-throughput: 19567
overall-tx-ccq: 58%
authenticated-clients: 1
wds-link: no
nstreme: yes
polling: yes
csma-disabled: no
framing-mode: none
routeros-version: “3.22”

Really poor performance. We decided that the rain coused the problems so we checked our antennas, cables and so on…
Nothing strange, but signals are still bad.
We tried to move the antennas to the left or right to align them better but no luck either.
Can you give me a hint of what caused the problem…i will explain below what is the equipment for both sides.


AP:
RB411AH, R5H, PoE 24v (10 meters UTP Cable)

Station:
RB333, R52H, PoE 18v (90 meters+ UTP Cable) - is it possible to be a problem with the voltage : [admin@MikroTik]
/system health> print
fan-mode: manual
use-fan: main
active-fan: main
voltage: 15.7


Frequency - 5250 (5ghz-turbo) - no interference


I will be verry thankful for any help.
Thanks in advance.

2

Replace the radio cards.

3

Any reason to think its from da cards?
Any reason to become damaged?

I really want to know why anything happened before buying stuff :slight_smile:

4

Could have blown the diversity chip.

Cards are cheap. I try to have an entire spare AP with antennas when I have a problem before I send anyone up the tower.

5

Try to open the Routerboard and put you finger on the R5h card heatsink.
See it’s warm or hot, if it very hot mean the card was spoiled.

Beside this, for temporary solution, try to change you operation mode to 5Ghz but not 5G-turbo.
-85dbm for the link is consider very bad.

6

Ah the famouse R52h

Bin it!

Sounds like diversity chip blown as already suggested.

However for the time being and to keep network up and running… Reduce bandwidth to 5Mhz and it should last another 2 years.

See my previous posts re bandwidth/noise.

Make sure N type connectors are of MICROWAVE GRADE and no cheap import. In commercial radio we would use Gold or silver plated.

Microwaves travel through the skin of materials (metals) and do not travel deep inside.

This is of course the complete opposite at the other end of the radio spectrum, say Medium Waves or even DC, whereby the current travels inside the material.

The higher the frequency, the closer the wave travels to the surface.
Hence the use of Gold or Silver platings in microwave cavity equipment.

PS… 2 different metals brought together and throw a little corrosion in with the mixture, add some RF and you have made yourself a potential semiconductor diode.
Pass through that some good old fashion radio signals and you have more radio signals all over the place at differing frequencies, adding to noise.

Its called the “diode effect” and is more common than you might think on radio tower structures.