Installing and aligning BH's with Reflector Dishes

OK, so this may seem like a stupid question, but are there any tricks and hints anyone can offer in aligning 2 BH’s which will be using the Canopy reflector dishes? It is my first time doing this.

Using the dishes, my beam is narrowed down to 6 degrees, so if I got one person at each tower trying to point these to each other (9.2 miles apart) it seems to me like the window is pretty small. I can’t imagine that both people could be moving the dishes around trying to “lock onto” each other. So what is the best way to approach this? Does one side just try and eyeball it the best they can, and then the other side tries to register, and then just go back and forth doing minor adjustment to each side to get the best signal?

Also on a related note, I am confused by Motorola’s model numbers. Are the 5400BHRFDD and the 5700BHRFDD and the BP27RD all the same thing? In our case specifically, will we be able to use the same Canopy dishes that we used for our 5.7 SM’s with our 5.4 BH’s? My distributor says yes, but it is confusing.

Thank you.

In my experiences…

Assuming this is on flat ground, aim your antennas visually using field glasses. Get it spot on to the other end, it does not matter much if you are 100% aimed at the dish itself. Be sure to adjust the elevation such that you factor in that canopy reflectors normally look like they are pointing “down” more than up. This is outlined in the user manuals.

Once both ends are aimed this way, you should be able to turn on the radios (having pre-programmed them for frequency and color code and IP address) and be good to aim one end. What I do is set the far end to master set the pair for 2-level modulation, and look at the near end set as the slave (the one you are at) and adjust it until the values are acceptable. Values should be what you calculate in terms of fade margins in terms of dB levels and jitter values. Roll to the far end. Set this end to slave now and the other end to master and adjust again so that values are acceptable. You may or may not even wind up adjusting it much. Run link evaluations to ensure that the link is good. You should be looking at something like 100/100 in 2-level. Anything lower than 90/90 in 2-level means you won’t be able to run 4-level reliably. Your jitter should be in the neighborhood of 1-4.

Once your values are good, set the link to run 4-level modulation and let it cook. Run link tests again, ensuring they are greater than 40-50% up/down (Off the top of my head I think these are acceptable values for 4-level modulation tests). Jitter should be 1-9, maybe spikes to 10 (not the greatest but it would work).

I never have had issues eyeballing it first (with or without field glasses) and following my method.

Exactly what phreak said, plus…

I highly recommend using tone at both ends. Start with visual alignment, and then on the slave use tone to listen for the master, all it takes is a whiff to get going in the right direction.

Once your end is aimed - get it as good as you can, switch master/slave roles and repeat. You will probably find that’s it’s good at that point.

A 10 mile with good LOS should be rock solid with 27" dishes at each end. You should expect to see -65 or better, 80% up/down, and Jitter of 7 in 2X mode.

I have an eyeball that does tone alignment…

hahaha :lol:

Thanks everyone. I think I may run a test alignment across a big parking lot or something with some tripods. One of our towers is very hard to get to depending on the weather, so I need to try and get this at first try. We have often had to snowshoe up there (about a 3 hr hike each way) when there has been too much snow for snowmobiling up there.

If I do not post anything here in the next couple of weeks, send air rescue to Grey Head peak in Telluride, CO. I’ll have food and water with me for a couple of days… :wink:

Thanks again.