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Freqman
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Need help with 8km PTP

Tue Jun 15, 2010 10:07 pm

2x RB800's
4x xr5
2ft Radio Waves 28db
3ft Radio Waves 30db
90% of distance is over water
No LOS issues

CCQ looks great ~90/~95 until I start sending traffic then they CCQ goes south. See attached image with 3Mb of traffic.
I adjusted power until the strengths were in the mid 50's with the same results.
I upgraded one side to the 3ft dish with the same results
These are dual polarity feed horns so I tried 2 different XR5's, 2 different Pigtails and LMR on the Vertical with the same results. SNR in the High 50's and throughput stinks.

Open to all suggestions.
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Letni
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Re: Need help with 8km PTP

Wed Jun 16, 2010 3:30 am

Change frequency. Change Channel Size. Limiting Rates. Enable NStreame (Does wonders for us.) I know the recommendation is the leave power at default but you will probably want to lower it.
What RouterOS version are you using?

-Louis
 
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tgrand
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Re: Need help with 8km PTP

Wed Jun 16, 2010 5:50 am

Yes lower the TX-Power at each end by approximately 20 db.
Aim for around -60db in each direction.
 
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colebert
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Re: Need help with 8km PTP

Wed Jun 16, 2010 6:06 am

definitely, definitely lower power levels.

mid-50s will be just fine
 
Freqman
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Re: Need help with 8km PTP

Wed Jun 16, 2010 8:56 pm

Change frequency. Change Channel Size. Limiting Rates. Enable NStreame (Does wonders for us.) I know the recommendation is the leave power at default but you will probably want to lower it.
What RouterOS version are you using?

-Louis
Tried Turbo.
Tried Nstreme
As indicated in my first post I dropped the power to get the signal in the mid 50's.
tried limmiting rates to 48/48 and it would get there but drop as soon as I put traffic through it.

All produce the same results only about 4Mbps through
any other ideas?
 
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colebert
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Re: Need help with 8km PTP

Wed Jun 16, 2010 9:06 pm

lock to a SINGLE RATE rather than leaving them all selected.

it's also not clear to me what ROS version you are using. latest build (4.10?) or 3.x?

You probably won't want to hear this but, in my experience (and some others on this board) using two XR5 in the same RB causes all sorts of problems. When I tried two XR5 per RB600 board I had all kinds of CCQ issues. The moment I split the radios up into separate enclosures and routerboards my CCQ was solid on all links.
 
Freqman
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Re: Need help with 8km PTP

Wed Jun 16, 2010 9:43 pm

I am using 4.5 on rb800
I only using 1 XR5's at a time in the box the other 1 is disabled when testing.
I just tried "locking in" several of the data rates at a time and through put is still bad.
Can someone confirm my thinking that if you can get up to a -35 signal higher gain dishes are not needed, the problem is elsewhere?
 
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JP_Wireless
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Re: Need help with 8km PTP

Wed Jun 16, 2010 9:53 pm

lock to a SINGLE RATE rather than leaving them all selected.

it's also not clear to me what ROS version you are using. latest build (4.10?) or 3.x?

You probably won't want to hear this but, in my experience (and some others on this board) using two XR5 in the same RB causes all sorts of problems. When I tried two XR5 per RB600 board I had all kinds of CCQ issues. The moment I split the radios up into separate enclosures and routerboards my CCQ was solid on all links.
Try the above but i think it is easy and cheaper to change the cards to R52 (65mwatt) ie 17dbm max leaving it at default and you will get over 12meg bothways simultanously acroos 20km though mine is with 2ft solid dish antena. I have use this senario for real time dual nstreme ie sending and receiving diffrent and was able to carry 4meg/4meg both ways for a gsm operator without loss! So i think either of this suggestion will work perfectly.

8km link over water is too short to have data carriage problem! I only have this proble when i did 48km terrestial link, but at 30dbm with 4ft dish antenna, it works but have to engage only one interface at a time.
 
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Re: Need help with 8km PTP

Wed Jun 16, 2010 10:04 pm

Sorry, the senario i printed in my last post was based on 5GHz and not 2.4. If you are using 2.4GHz, You are likely suffering from interference from the water waves looking at your rx/tx rate under statistic and you poor ccq with its corresponding poor thourough put! 2.4 may not be good over active water. Higher frequency may be better. (Stand to be corrected)

thanks.
 
Freqman
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Re: Need help with 8km PTP

Wed Jun 16, 2010 10:26 pm

Sorry, the senario i printed in my last post was based on 5GHz and not 2.4. If you are using 2.4GHz, You are likely suffering from interference from the water waves looking at your rx/tx rate under statistic and you poor ccq with its corresponding poor thourough put! 2.4 may not be good over active water. Higher frequency may be better. (Stand to be corrected)

thanks.
This is XR5-5ghz.... anyone one else have thoughts? Also looking for confirmation that if you have a -35 signal at default power settings it is a waste of time to upgrade to bigger dish.

Thanks
Freqman
 
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Re: Need help with 8km PTP

Wed Jun 16, 2010 11:13 pm

This is XR5-5ghz.... anyone one else have thoughts? Also looking for confirmation that if you have a -35 signal at default power settings it is a waste of time to upgrade to bigger dish.
Thanks
Freqman
YES! It is a waste of time upgrading to bigger dish and nobody is asking you to go for bigger dish from all the post above!

Let's has a look at the config 1st! are you using bridge mode or routing?

If using bridge, is wds running bcos station wds must go with wds eabled for that interface, check the config line by line and you may find something is wrong.

If all is correct by your standard, reset the radios and do a simple bridge configuration and run the test, if it works, go ahead to do other configuration one after the other.

But if a simple config gives you the same result, you have to go by another choise of card as i suggested ealier.
 
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Letni
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Re: Need help with 8km PTP

Wed Jun 16, 2010 11:26 pm

You could try pointing the dishes up toward the sky more so you are shooting over the tops of each other. Enough where you are minimizing how much is reflecting off the ground/water.

Still have not told us what version of RouterOS you are using.

-Louis
 
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colebert
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Re: Need help with 8km PTP

Thu Jun 17, 2010 12:08 am

He's using 4.5. Probably should upgrade to 4.10.

Are you keeping nstreme on? (Nstreme=On, Polling=On, CSMA=disabled)

Put your card at 17db for all rates. (Set your data rates to 36mbps ONLY)

I do not recommend you change antennas... just push less power through them.

You want 50s or 60s for power. If you still get bad CCQ then experiment with using less power (10db) to see if this helps.

I do not have first-hand experience with water links but I'm pretty sure they sometimes have problems like this.

Does your power level fluctuate greatly when you try to pass traffic? If so you might have a bad card.
 
Freqman
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Re: Need help with 8km PTP

Thu Jun 17, 2010 3:02 pm

He's using 4.5. Probably should upgrade to 4.10.

Are you keeping nstreme on? (Nstreme=On, Polling=On, CSMA=disabled)

Put your card at 17db for all rates. (Set your data rates to 36mbps ONLY)

I do not recommend you change antennas... just push less power through them.

You want 50s or 60s for power. If you still get bad CCQ then experiment with using less power (10db) to see if this helps.

I do not have first-hand experience with water links but I'm pretty sure they sometimes have problems like this.

Does your power level fluctuate greatly when you try to pass traffic? If so you might have a bad card.
Thanks for all the help. I am keeping Nstreme off for now, we have about 30 ptp links and have not had to use nstreme to get good throughput.

Steps I will take-

1. Upgrade to newest firmware
Test

2. lower power to get -60
test

3. lock in 36mbps
test

4. Lower the power alot.

5. Reset, start over and try without WDS

Thanks again for the help will let everyone know.

Freqman
 
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tgrand
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Re: Need help with 8km PTP

Thu Jun 17, 2010 8:09 pm

On a side note regarding multiple radio cards in a single enclosure:

RF signals bounce around within an enclosure, these reflections can also cause gain within the enclosure.
Good practice in these scenarios is to line the inner surfaces of the enclose with microwave absorbing materials.

The drawback to this, however, is that it converts the microwave energy into heat energy, and a cooling mechanism should then be implimented.
 
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JP_Wireless
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Re: Need help with 8km PTP

Fri Jun 18, 2010 7:28 pm

On a side note regarding multiple radio cards in a single enclosure:

RF signals bounce around within an enclosure, these reflections can also cause gain within the enclosure.
Good practice in these scenarios is to line the inner surfaces of the enclose with microwave absorbing materials.

The drawback to this, however, is that it converts the microwave energy into heat energy, and a cooling mechanism should then be implimented.
I don't really agree with these since RF signal are also composed of 0's and 1' just like other electronics pulse signal, It will be transported via the pigtail out of the box to the antenna b4 it is let loose. Ur assumption is cool if pigtail is not used or if it is leaking and this will deplete the signal at the other end.
 
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Re: Need help with 8km PTP

Fri Jun 18, 2010 8:36 pm

How high off the ground (and water) are the antennas?

Does tide affect this body of water?

Do you have enough height for 100% fresnel zone clearance?

It sounds like the radio waves are getting deformed either by reflection off the water or by an obstruction.

Make sure you are running horizontal polarity at both ends. You might have to go higher with the antennas.

Try locking the radios down to a much lower modulation like 18Mbps or 6Mbps. Fewer bytes per wave should improve your CCQ.

Good luck,

Tom

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