long distance backhaul

After reading all the posts related to long distance backhaul with canopy, I have some questions.

All my proposed links are between 100-150 km. We have been using motorola canopy successfully for the last few years and have been pretty impressed with it.

We are trying to link 140 km with BH20 and we had done a test shot with BH10 and it was successful. Now we would like to do it with BH20 and then we plan to upgrade later as our traffic increases to BH30/60/150.

Q.1. How much fade margin we would need for 140 km for BH20 to work flawlessly? Since rx sensitivity @20mbps is -79, would a signal of -59 be ok?

Q.2. How good are the OFDM radios BH30/60/150/300 in withstanding lightening. We have had no problems with BH10 BH20, AP or SM in lightening. Since we would be needing connectorized OFDM radios, are they as good as BH10/20 in lightening prone zone.

Q.3. Can 100 mbps throughput be achieved by 150mbps radios through a distance of 150 km. If yes, what would I need. The antenna size, fade margin required for those QAM modulations, etc.

Any help is highly appreciated

ken

Some things to keep in mind;

First you are at the edge of where the standard canopy BH10 and BH20’s can run with a reflector, distance wise. Yes it should be OK at -59, but I would be leaning more towards using an integrated BH 30 or BH 60, as they can handle interence a little easier and they have a stronger radio inside of them.

That brings up another thing; if you get any interference running with your link or accross this link, it will more than likely go down.

Are you using standard canopy backhauls for this test or are you using the connectorized cylone canopy backhauls?

As for the BH 150/300 units remember that the channels are twice the size on the spectrum, so you need more room for that. As for lighting protection on the units, follow the grounding guides. I have seen AP’s, backhaul’s and SM’s get hit by lightning and cause damage to the equipment that they were hooked up to.

I was using standard backhaul, not the connectorized. I plan to use BH10/20 in the initial phase and will upgrade to Bh30/60/150/300 as the traffic grows

its been many days and I have not had a reply. I would really appreciate if somebody with very long distance gave their feedback.

Just speaking for myself, there are no flawless long distant connections.

We have a 20 mile hop, pwr level of -52 noise floor is at -77. Three times a year for no reason it quits for about 2 hours in the evening for a week. Then works great.

I would look for ways to shorten the hop. or go fiber.

What you are asking for is a solution to a problem that we do not have enough information to solve.

This is not a formal mechanism for support. I would suggest that you call mot tech support and see what they can help you figure out.

If they cannot determine the solution, you might consider hiring consultant to do an analysis of the RF spectrum, terrain, and other aspects of this link.

I am available and I can refer to a couple of others.

I thought a standard 5.7 BH had a linit of 56km (35miles)? Or am I wrong?

oops

I thought they had limitation at 35 miles, until I got them registered and passing traffic at 55 miles. The next test I did was with 88 miles and it registered and passed traffic.

It depends on the noise floor… if you have a clean environment you can get away with it…

also remember that not all radios are calibrated the same… you may have got luck with a more powerful pair then the standard…

In 10M modulation your C/N requirements are only 3 db in 20BH they would be 10db.

For the distance you are proposing I would definately go with the 30/60M connecterised, if you can give me the GPS co-ordinates of the 2 locations, height of the tower your locating on, and your minimum bandwidth requirements I can run some link budgets to tell you what size(gain) antennas you will require to get that link.

Also remember at that distance the curvature of the earth will come into play and you will need to be on top of a hill somewhere.

Just remember that the 150/300meg channels are double the width of the 30/60meg units. You will probably have some RF issues.

Also what type of terrain are you shooting over, and how tall are your towers? Curvature of the earth itself requires over well over 300 feet at that range.

In order to get that type of shoot working properly there needs to be no RF interferance at all on either end.

If you still want to try this I would use a connectorized version.