I’ve received first SXT AC gear for testing.
As I realised there are some strange modifications done to manual select MCS data rates.
HOW can I set MCS4 (QAM16) to be max modulation ? as i have some MCS 0-7, 0-8 or 0-9 to choose from.
HOW to limit modulation?
For the 802.11ac you can’t lower the supported data-rates below the MCS7.
So you can choose the max supported data-rate.
Here are the info which 802.11ac MCS represets what:
http://en.wikipedia.org/wiki/IEEE_802.11ac#Data_rates_and_speed
Also you can specify 2 or 3 fields of supported VHT data-rates. First one is for the 1 Spatial-Stream, Second is for the 2 Spatial-Stream and Third for the 3 Spatial-Streams.
Why would you lower the supported MCS to such low MCS as the RouterOS rate-selection will automatically select the best working data-rate?
So its a big disadvantage as QAM16 works most stable under Mikrotik.
I have all around 25+25mhz QAM16 nstreme ptp links they have 225mbps rate with 100%CCQ and ping stable as hell, no problem with tcp etc..
migrating thru different modulation results in 50-70%ccq ,much worse ping jitter.
In result AC as I hoped for stable 360/360 80mhz QAM16 wireless datarates is unavailable…
Can You somehow force driver to not to go higher than QAM16 ?
The 802.11ac standard and the card hardware doesn’t allow such modifications so we can’t do that, sorry.
ok, as I thought. it was looking nice at first glance, now I see that AC is not going to be replacement for PtP radiolink.
two SXT AC in totally quiet environment on the desk right now stability in nv2 is unacceptable 
The first problem is that you are generating the traffic on the SXT board and processing it - that causes a lot of CPU usage and that could cause your problems.
What are the signal levels as it could be too strong signal?
Have you tested both 802.11 and Nv2?
And for Nv2 what what tdma-period size?
Uldis is right, Test like this:
[poweful router] → SXT1 ###### SXT2 —> [powerful router 2]
SXT itself can forward large amount of traffic, but to generate random traffic, you need more powerful machines. or actual data (many torrent users etc)
doesn’t make much difference.
----GE <sxt ac ( ~ ~ ~ ~) sxt AC>—GE—
data rates 650-780 mbps both sides
it’s not stable. but ofcourse it may be desk test issues.
Setting nstreme and frame limit to 1580 so lower than l2 MTU of wireless gives
100% CCQ 866,6Mbps wireles data rate and… max 200mbps HDX of udp btest.
NV2 is behaving as wicked when no upper limit varying 200-450mbps.
but there maybe some interference issues due to desk test.
I’ll try to set it in real environment on monday/tue. As for now lack of modulation
manual choice is biggest dissapoitment of AC for me.
Devices are too close. Lower output power.
please try to check the throughput speed using the Traffic generator:
http://wiki.mikrotik.com/wiki/Manual:Tools/Traffic_Generator
Also please show us your signal and CCQ levels. Just to rule out that devices are too close together or there is some other factor.
Too close. I tested couple days ago UBNT Nanobeam and had same problem. Lowering output power level fixed problem.
I lowered txpowerf to 0, 1 and 3 with all rates fixed. so i got about 60db SNR ccq varyies from 50 to 90%. ohhh if I could set QAM16…
i have similar problem to this one with ccq and stability in this thread http://forum.mikrotik.com/t/sxt-ac-best-settings/79554/23
cannot anyhow make it works stable
ok I got some results. distance 11km, rocketdish and jirous well shielded, clean channel for testing test done over sxt (RB493G-CCR1016)
signal -61/-62 SNR 51 dB
802.11 :
CCq 50-70 / 50-60 %
wireless rate tx/rx 526/351mbps
btest (over sxt) one direction varying 150-250mbps lots of stall
ping avg 12ms max 63ms
nv2:
2 ms frame
ccq 50-70%
wireless rate 270/351
btest 50-150 mbps even more breaks
ping avg 14 max 82 10% loss…
link is UNUSABLE
nstreme:
best fit 3200:
ccq 70-80%
wireles rate 351/520mbps
btest quite stable 160mbps
ping avg 16ms max 27ms 0% loss
So :
1/nv2 is no usable protocol
2/nstreme is no faster than 802.11n 40mhz and nowhere near stability
3/802.11 is nothing we couldn’t achieve on plain ac router.
this was my backup link build on AR9220 with 150mbps troughput with ping stable as hell.
either there is something really wrong with ac under mikrotik yet or there is something wrong with my setup.
Anybody got different / better results?
I think they released it too early and soft is not good yet…
Of my research you can try settings like this, for me allowed to get a bit more stability and speed:
Protocol set on 802.11
Mode: 5GHz-only-AC
Data rates uncheck all under A/G supported and basic, then I put MSC 0-8 two rows under supported VHT and the same under Basic.
I set also distance manually to 1km as it is less than 500m and sometimes it connect with 2km or more in status.
Long preamble.
Thats all so far… maybe ll help you a bit ?
I don’t get it, how do you connect an SXT to rocketdish and jirous?
using soldering iron. it’s quite easy 
to many pigtails
There are Two pigtails to be precise. Each for one chain as usual.