900mhz range question

I have two grain elevators

one at 165’ the other at 145’

The AP is on the 165’ attached to a 9dBi HPOL omni.

Would it be possible to link the two at 17 miles with an integrated SM?


They are both above the tree line.

3856’15.64" N 7553’20.55" W Elevation 65’ Location of 145’


38"56’23.43" N 7534’1.80" W Elevation 49’ Location 165’


-OR-

145’ to 278’ (278’ has APC with 9dBi HPOL Omni) at 25 miles.

38
40’04.55" N 7535’01.19" W Elevation 20’ Location 278’

38
56’15.64" N 75*53’20.55" W Elevation 65’ Location of 145’[/img]

You “could” with the right antenna, but it’s not a good idea.

The AP being a multi-point device divides it’s time across all the child SM’s. The traffic from the remote tower will suck up quite a bit of bandwidth on the main tower and affect all the users on the main tower.

Also, the link is only going to run at 1X so your available BW from the remote tower to the main tower will be pretty limited. It really depends on what your subscribers will tolerate.

You would be better served by putting together a MikroTik link, or step up to an OFDM BH solution.

Actually I have a t1 to each tower. Just looking for a better way than VPN tunnels to connect both towers for management purposes.


The 900 integrated SM has a 10dBi antenna. Will this be enough gain to make the link?

And… how much throughput will I lose by extending the range setting to 18 miles?

i honestly don’t think you’ll have a problem and i’m even wondering why you wouldn’t achieve 2x…as long as you’re 2db or more above the noise floor i think you’ll be good for 2x…

we have a watertower and a communications tower 19.71 miles apart that can see each other - we never intended them to. they link at about -81. i’m not even sure if they’re aimed at one another

I could live with -81 as a managment link. Gonna give it a try this week and will post results.