Hi
i am using Mikrotik RB-411 with Alfa 30dbm Card at both end with 24Dbi grid antenna
both end heights are about 75feet from ground and the area don’t have buildings taller than 40feet LOS is almost clear(as seen from google maps)
distance between both end are about 14km
using Wireless G mode with channel 13 (channel 10-13 are free no one using them)
The problem is at day time the wireless link shows 24Mbps/24Mbps up link/down link speed
but at night it’s 2Mbps/1Mbps(NOT DECREASING AT NIGHT NOW JUST THE DISCONNECT EXTENSIVE DATA LOSS ISSUE IS THERE)
at day SNR is 25 Db and at night it’s about 23-24Db
setup a prtg/ mrtg server and monitor the following thing:
-tx rate
-rx rate
-signal strength
from that, you can see when the signal starting drop and when it’s back to normal…
based on that information, and which day will more frequent having that issue, you can pay a visit for the physical checking…
UPDATE: after observing for 24 hours the problem was clearly due to the error message “Extensive data loss” not only at night but also at days(i have not noticed it previously)
A 1-2 dBm variation in SNR trough the days is well within normal conditions – even 5 would not call for worries. This is just how the atmosphere plays with us – and what is the consequence for you anyway? The fact that the radio rate is adaptive could explain the lower rates at night – simply less traffic, or are you actually experience less throughput at night?
The problem with “Extensive data loss” have been discussed a lot – search the forum for it, and upgrade to latest version.
i changed the protocol to nv2 and the link is stable now but the throughput is only 4Mbps
can any one tell me does the 40mhz channel width really increases the throughput
Change period size to 8 ms and you’ll most likely double the throughput from the default 2ms.
Use parabolic dish antennas, if you can, since grids are more prone to interference. Also, if you can afford for the link to be down, run spectrum scan on each end overnight.
Change period size to 8 ms and you’ll most likely double the throughput from the default 2ms.
will try and post the results
Use parabolic dish antennas, if you can, since grids are more prone to interference. Also, if you can afford for the link to be down, run spectrum scan on each end overnight.
from the picture I can see that your signal levels are -76/-68 dBm. The -76dBm is quite low for reliable link. When I put your params (30dBm TX, 24dBm antenna gain, 14000m distance) into link calculator I get -48dBm of receive level. So if you have antennas connected with short cables (or even via pigtail only) to the radios you have something terribly wrong with the link.
the 30dBm cards looks like an overkill. We have an experience that the RB4xx have troubles with high power cards which cause the box restarts with no obvious reason (maybe the power source module on the board is not able to deliver enough power for the card and the board). And we observe this with DBII cards which should have about 24dBm max TX power. The problem seems to manifest more when you are using low voltage power supply (12V battery backup and so) but we observe it even on 27V.
I woulndn’t expect much support from Mikrotik for ‘non official’ wifi card (Alfa card)
IMHO you should check you devices why there is only -76/-68 (the 8 dBm difference is too much too - if there is no reason for it). Then you should check both RB if there are no unexpected restarts (check uptime, check first lines of the log) related to link disconnects. If you solve the problem with the bad signal then you can lower your TX power (which could eliminate restarts if you have any) or even you can use standard wifi card (made by Mikrotik).
