Hi, I have been using MIKROTIK here in Senegal for several years. This time I would like to try a 54Km 5Ghz link with two SXT 5HPnD
BUT as its rather far, I was thinking to fix the unit facing a 2.4mt prime focus dish as to enhance the RX and TX...
Any opinions out there ...
The First link will be up on a high building here in DAKAR (around 89mt) and the other on a hill top (101mt) on the top of a 60mt pylon..
We have LOS as we receive an MMDS signal at this point coming from the same building, but the MMDS TX is 12.5w and in the 2.5 - 2.7 GHZ range ...

I asked a similar question in another thread and received the answer "it is too far". You mentioned that you want to use an external antenna; I think under these circumstances an external antenna would be required, the more gain the better. I would also suggest either running the path on "RadioMobile" software with the real numbers. Over a path of this distance height above average terrain and tower or structure height are going to be critical because of curvature of the earth. Make sure that your fresnel zones are clear, most microwave path anomalies occur as a result of fresnel zone issues. On this band you only have 1 watt to play with, that makes your antenna a very important component as far as how you achieve an EIRP that will either make or break the path. Don't forget that you need a few extra db at both ends for fade margin and weather conditions. I know that it really rains there. I wish you the best of luck

I'm personally familiar with that specific site on the hill of Dakar as I have been there and I'm familiar with the MMDS transmission site in Dakar. I've visited both sites a couple of years ago.

A link is possible to achieve but would require very solid and big dishes. You're at the edge of what's possible there.
It depends on how much speed you need and how much loss is acceptable during rain.

I did the calculations for microwave equipment during my visit to Dakar. One of the challenges is the water in between. The fresnel zone touches the water and can produce unwanted reflections which get into the way. The lower frequency you use, the bigger the fresnel zone is, the more effect it has. On the other hand, the higher the frequency is, the smaller the dishes, the more expensive the commercial solutions and the more difficult to reach distances and the more affect the rain can have.

So its a question on how much spectrum you can use and finding the optimal frequency.
I have seen 60cm dishes with 41km and 40Mbit in service with a RSSI of -69.


PS: say hi to Sidy

Hi,
I already have an MMDS reception point on the hill (2.5-2.7) the 130 tv stations are treated and passed into a 13Ghz link going to Mbour and Thies. This is up and working and two 500w MMDS TX either side are currently furnishing the two towns with an MBR of +38.
Now the challenge is to link Mbour, Thies and Dakar with Intranet and Internet. For Mbour and Kisanne (Where the hill is) Its up and working with a 28Mbs connection with 2 x SXT 5HPnd's on bridge mode with WDS and 802.11.
Now I would like to link Dakar (Kébé) and Kisanne, with again two SXT 5HPnd.
Using the calculator its seems possible, BUT at 8Km from Kisanne there are two hills which might affect the frennel. Thats why I asked if pointing the SXT's to a 1.2Mt dish would give us more gain , OR does the SXT have an mmx connector inside so that we can connect an external 30db parabolic (which i already have) ?????

Any suggestions ...
David

PS Sidy is with EXCAF I'm with DELTANET !!

It has be done with (at my point) 2 x Routerboard RB750UP router 32MB 5-ethernet (Level4), 2 x RouterBoard RB411AH 64MB 1-LAN 1-miniPCI (RouterOS L4) and 2 x DBii F50NPRO on them and as AP I used the RouterBoard RB912UAG-5HPnD 30dbm Gig-eth (RouterOS L4) with 2 x hipro-tech 6GHz RF splitters on it.
Second client to AP, was over the sea.
Dishes were used 4 x 60cm ARC DA5830SD1 5GHz 30dBi Dual-Pol Dish Antenna (1 for one client, 2 for AP and 1 for the other client).
ALL of them were "MANUAL Locked" at 39Mbps.
Frequency used was 5780MHz.
Good thing is that with "manual dropping" the signal for testing/fading reasons over the sea, the result was to STILL stayed LOCKED at 39Mbps at EVEN at -83dB. signal strength.

Configuration used:
A spot (client bridge - 13.2Km far from AP): RB750UP - RB411AH - DBii F50NPRO - ARC DA5830SD1
B spot MAIN AP (station bridge): RB750UP - RB912UAG-5HPnD - 2 x hipro-tech 6GHz RF splitters - 2 x ARC DA5830SD1
C spot (client bridge 47.6Km far from AP): RB750UP - RB411AH - DBii F50NPRO - ARC DA5830SD1

Some photos of the config:

...............................with 2 x hipro-tech 6GHz RF splitters on it.

How much actual loss in using these RF splitters?

...............................with 2 x hipro-tech 6GHz RF splitters on it.

How much actual loss in using these RF splitters?

It's 0,2dB at 5GHz and 0.23dB at 6GHz

Hello everybody, 54 km with Sxt, it is definitely impossible to me, anyway i tried to ask in other thread some similar long range links: 22,43 and 30 km but we would like to get 100 Mbit/sec tcp speed in one direction.I have got RB 411 GL it is a powerful device with 680 Mhz CPU and 64 MB Ram, and i thought DBii cards with 28-30 dBi Rocket Dish Ubiquiti antenna but for 30 km need 32-34 dBi i think,if the line of sight is good and the Freshnel zone is clear is it possible to achieve this speed?What do you think?

100Mbit/s TCP speed I don't think that will be that easy.
You will need AT LEAST a HIGH POWER device PLUS at least 1m dish with ~33dBd gain at ~40km distance.

The first link is 22,43 km, and i heard about the Dbii F50N-PRO card is very good card, 20 dBm tx-power for 40 Mhz at MCS7 and the receiver sensitivity is -77dBm,but we should achive at least -65 dBm signal strenght with 28-30 dBi dual chain Rocket dish, but i am afraid that it is won't be enough, we need around -55-60 dBm signal strenght with 100% CCQ,anyway the 411 GL is capable of 100 Mbit/sec speed, i tested with FTP server ,but on 22 km completely different

On a 23km link with the DBii's and the ARC 30dBd dishes, I've got -62dB/-61dB signal strengths and "manually locked" at 180Mbpps with 100%/100% CCQ at 40MHz bandwidth.
So I think that's easy enough.

EXAMPLE:
Take a look at this link with the RB411AH and the DBiis on them and with the 30dBd ARC dishes at 25km distance

Nice, and what is the tcp speed of this link?

This is not TCP but it is OK with us.

Nice performance, we are planning to start an WISP, so not impossible to achive the 100 Mbit/sec, anyway i counted with Rocket Dish 32-34 dBi and Dbii cards around -52 dBm signal strenght on 22.43 km, but this is just theory

IF you align all OK, I guess that you'll get ~ -57 to -59dB signal with the Rocket Dish 32-34.

Yes need to align perfectly, i know, here is another one interesting thread:

http://forum.mikrotik.com/viewtopic.php?f=7&t=60932

I would like to ask a question here:
To get a good signal I have tried and used an mmds feeder head (2.5-2.5Ghz) on the focal point of a 2.4mt focal point dish. This is given me a 37dbmv signal coming out of a 32db down convertor on tv signals (600-860Mhz) Its up and working at 55Km from the 12.5W mmds site.
I was thinking of pointing an STX 5Ghz unit to a 1.2mt dish (as if it was a head) and trying it for a 54km 5ghz link.
This would probable inhance the gain of the sxt 16db system, or am I wrong ... ????

I am not an expert, but 54 km for Sxt devices is definitely too much, check that link that i put here, that is 46 km link with Ubnt 34 Rocket Dish and Dbii cards and RB 433AH, i know the equipments are very expensive, but we are planning similar links for 22 and 30 km links

but we are planning similar links for 22 and 30 km links

I have the SXT up and working on a 28Km link without any problem. We didn't even bother to align them properly as it was just a test, but we do have them on 802.11 with WDS at 28Megs.
As it was just for a PtP link to update some equipment via a PC we only needed 1Meg .......
For the 54Km we are trying this coming week ''Just for the fun'' and I will try to point them to two 1.2Mt sat dishes if we do not get a signal.. I'm about 70% sure it will work. Using the Mikrotik calculator it says it can ... wait and see .....


David

We need 100 Mbit/sec tcp speed in one direction,it is impossible with sxt, that's why need at least 28 dBi dual chain antenna, and powerful routerboard with mini pci, anyway the 28-30 dBi Rocket dish is only 64cm, and the 32-34 dBi is 97,2 cm

Hi,
I already have an MMDS reception point on the hill (2.5-2.7) the 130 tv stations are treated and passed into a 13Ghz link going to Mbour and Thies. This is up and working and two 500w MMDS TX either side are currently furnishing the two towns with an MBR of +38.
Now the challenge is to link Mbour, Thies and Dakar with Intranet and Internet. For Mbour and Kisanne (Where the hill is) Its up and working with a 28Mbs connection with 2 x SXT 5HPnd's on bridge mode with WDS and 802.11.
Now I would like to link Dakar (Kébé) and Kisanne, with again two SXT 5HPnd.
Using the calculator its seems possible, BUT at 8Km from Kisanne there are two hills which might affect the frennel. Thats why I asked if pointing the SXT's to a 1.2Mt dish would give us more gain , OR does the SXT have an mmx connector inside so that we can connect an external 30db parabolic (which i already have) ?????

Any suggestions ...
David

PS Sidy is with EXCAF I'm with DELTANET !!

David, contact me offline andreas@fink.org. I have some good ideas for you folks.