Subscriber Discussion

Wireless Application 1000' Through Obstructions

UI
Undisclosed Integrator #1
Feb 23, 2017

Looking to add a couple remote cameras to a site about 1000' away.  There are some obstructions like trees and a couple 2 story buildings.  It's in a town house community so no direct line of site.  We've used Ubiquiti sucessfully in short (100-200') hops many times even shooting through a tree or two.  We have radios running for years without any issues.  I don't know if they will work in this application though?  Any suggestions? 

UI
Undisclosed Integrator #2
Feb 23, 2017

It may be a case where you have to buy and try.  We've had some success with UBNT's 900mhz radios when there's obstruction.  The downside is they cost about twice as much as 2.4/5g's and they ave limited bandwidth in comparison.  If only 2 cameras that shouldn't be a problem, if they can get through the obstructions.  I assume you have power at the camera end.  

 

Another option is to see if there's a bounce point halfway that could see both ends and get power and mount another radio with an omni there to repeat.

(1)
JH
Jay Hobdy
Feb 24, 2017
IPVMU Certified

I second the 900mhz. We have gone through some pretty thick trees, one site had a 40 or 50 foot thick tree line.

Doubt they are going to go through a building though. Maybe use the roof as a hop, or look to go around

(1)
DP
Donald Peters
Feb 24, 2017
IPVMU Certified

While 900 MHz will communicate through some trees, it's highly congested in most areas and will provide very limited bandwidth.  I have yet to find a product capable of transmitting through a building.

UI
Undisclosed Integrator #3
Feb 26, 2017

Ive used the engenuis ENH700EXT with an external parabolic antenna for a similar application that you subscribe with decent success. Typical speed was like 11MBPS.

This was to manage cameras at an HOA gate, using the presidents home internet in the rear of the community. But were upgrading the gate call box to a voip one, and Im having comcast install a landline internet for that.

Avatar
Jon Dillabaugh
Feb 26, 2017
Pro Focus LLC

Why not try some Ubiquiti Mesh Pro APs? There has to be a midpoint or two that you could use in the middle. 

(1)
(1)
U
Undisclosed #4
Feb 26, 2017
IPVMU Certified

A passive reflector can be made from two directional antennae, directly connected coax to coax, with each one angled at one endpoint.

The lost gain is considerable, but probably better than going thru two buildings.

(1)
JH
John Honovich
Feb 27, 2017
IPVM

The lost gain is considerable

Any sense of how considerable? 3dB? 10dB? More?

DP
Donald Peters
Feb 27, 2017
IPVMU Certified

It really depends on the antennas used, free path loss to the first antenna and from the distal radio.  It's possible to make this work but I suspect you could burn a ton of time doing so.  Adding two radios at the relay point would likely provide a more stable solution.  

U
Undisclosed #4
Feb 27, 2017
IPVMU Certified

Probably a lot more.  So much depends on the distance between the transmitter and reflector and how narrowly the signal can be delivered to the reflector. Because of inverse power law losses.

Here's a somewhat random calculation (unverified) found on a blog:

If the distance to the hilltop (or obstructing building) is less than 0.75 mile AND the total PTP distance is less than 1.5 miles, it may be possible to place a passive repeater on the hilltop to acheive the NLOS link. The Transmit EIRP should be at least +48 dBm (24 dBm into a 24 dBi antenna), the passive repeater should consist of 2 each 36" (24 dBi) back-to-back dish antennas connected together with less than 1 dB feedline loss, and the Receive antenna should be a 36" (24 dBi) dish. The 2 antennas on each end of the transmit link should both be vertical polarization, and the 2 antennas on each end of the receive link should be horizontal polarization (or vice-versa). This is to prevent interference between the 2 links. Both links need to be aligned and clear of ANY obstructions or reflections for this to work.

Here is the math for a 1.5 mile path with passive repeater at .75 mile:

+48 dBm EIRP - 102 dB path loss(.75 mile) + 24 dBi receive antenna gain - 1 dB cable and connector loss + 24 dBi transmit antenna gain - 102 dB path loss(.75 mile) + 24 dBi receive antenna gain = -85 dBm received signal (without receive amplification).

Depending upon the data rate, receiver preamp gain, receive cable loss and receiver sensitivity, this should work at some level. (e.g. Cisco Aironet 340 AP requires -84 dBm for 11 MBps and -87 dBm for 5.5 MBps) As this example does not give any fade margin, the distances need to be less or the antenna gains need to be higher to produce a reliable link in all weather conditions. 

As Donald says it might or might not work, and it might take a while to even know that.

New discussion

Ask questions and get answers to your physical security questions from IPVM team members and fellow subscribers.

Newest discussions