CMM micro - How many do I need?

I am setting up a straight run of three towers with 5.8Mhz BH’s to reach a couple of major clients off of the last tower. This is sparcely populated area, and so am thinking of running 900 Mhz AP and 9 dbi horz polerized omnis on tower one and three, with vert pol omni on two, to cover whatever area I can easily.

Question - Do I need to run a CMM micro on each tower? The towers are spaced 16 and 12 miles apart. If I do need to run 3 CMM’s, is there any need to run opposite polarity on the center tower.

I know omni’s are not reccomended by Moto, but if demand is there I can upgrade to sector AP’s later. For now all I want to know is how many if any CMM’s do I need. I do plan to run some type of BAM.

have you done a survey for noise? at which tower is your T-1

Hmmm, my guess is to have the cmm in the middle tower. Any additional equipment on the outside towers could receive sync via timing port right? If they were to connect to the device that is getting the timing from the middle tower/CMM.

haven’t worked with Omnis but I guess you will be using only one at each tower, and then running BH to connect your towers.

As your BH are on 5.7 and AP on 900 they will not cause problem with each other, and as you only have one AP at each site, then you have no inter AP interference issues. However you have will have 2 BH in the middle site, these need to be controlled by a single timing source (unless you want to use 5.7 for one link and 2.4 for the other link).

A common single timing source can be either a CMM micro OR you can get one of the BH to generate sync and then use a timing cable to supply the sync to the other BH and set that to recieve sync via timing port. (BH will be MASTERS).

Hope this helps.

Thank you all for your comments thus far.

I should be more clear on the network design. There will be 3 towers and 3 BHs. The first tower gets fed from a roof top in town that is connected to the grid. I have no plans to offer any service in town. They have good telco and cable service, and yes there is bound to be lots of noise. The towers themselves are going out into the bonnies where the biggest interferrence is rattle snakes. :slight_smile:

So vj, you are saying that the sync pulse gets sent to the other towers (1 & 3) via the backhauls, and the APs pick it off the BH slaves. Is that correct?

Next question then is tower 1. I will need a switch to connect between the 2 backhauls and the AP for tower 1. Any words of advice or caution.

Or am I just being so cheap that I will regret my saved pennies immediately?

Do you have you diagram yet? How are you going to have 3 backhauls?

Sorry for interupting, I have a similar issue and would like to know more about the “timing port” how does this work.

Eweda Maan