Batboard

Yes, I know, bad idea. But we're stuck with it.

This is a 2.2 mile link. Installed a 4940AP and 4940SM, both connectorized. Antennas were not included in the quote nor purchased for the job. We used a pair of 13dbi antennas, not enough signal strength so I put a dish on the SM. Connection is made, but RSSI is low. Spectrum analysis shows approximately -75dbm signal. I tried a higher gain panel on the AP, still have a weak RSSI but spectrum reading is higher than the last. I have an overall signal gain of ~50 db. Both antennas are vertically polarized. The throughput is 3.5Mb from the AP, 2.75Mb from the SM, where the trees are near. A throughput test shows a lot of frame loss so VOIP will not be possible, and that is the customer's need.

Has anyone here tried rotating the polarity of one end of the link? The dish on the SM is the older style made for use with backhauls and can be rotated axially nearly 180º. The panel antenna on the AP can be rotated in 45º increments.

dag wrote:Yes, I know, bad idea. But we're stuck with it.

This is a 2.2 mile link. Installed a 4940AP and 4940SM, both connectorized. Antennas were not included in the quote nor purchased for the job. We used a pair of 13dbi antennas, not enough signal strength so I put a dish on the SM. Connection is made, but RSSI is low. Spectrum analysis shows approximately -75dbm signal. I tried a higher gain panel on the AP, still have a weak RSSI but spectrum reading is higher than the last. I have an overall signal gain of ~50 db. Both antennas are vertically polarized. The throughput is 3.5Mb from the AP, 2.75Mb from the SM, where the trees are near. A throughput test shows a lot of frame loss so VOIP will not be possible, and that is the customer's need.

Has anyone here tried rotating the polarity of one end of the link? The dish on the SM is the older style made for use with backhauls and can be rotated axially nearly 180º. The panel antenna on the AP can be rotated in 45º increments.

Trying to cross polarize the path will cause you to loose about an additional 30 db. Don't think that is what you want to do.

A chain saw will make many paths get better in a very short time.

Jim

This is where OFDM really shines. A short hop through trees and no hard obstructions will be no big deal for a PTP300 or better link. Upgrade the customer to one of the PTP products (or whatever Cambium is calling them). I have done a few of them. It is possible, but not without OFDM.