Canopy & Smoke

We have a backHaul Links where The link goes down in night hours.

In morning hours the link performs with Above 90 % eff. & RSSI & Jitter > 850-950 & 2-7 respectively.

After 7-00 PM the downlink eff. goes down to 40-50 % & also Slave loses the connectivity.

The link distance is 16 km.The Master does not have Reflector , where as the slave does have the same.

What we have found is that there are chimneys which emit lot of smoke due to coal fired boilers in night hours till morning 8-00 am .

Can the smoke result in such issue.As depending on wind conditions it can become very tricky to position the backhauls…?will putting reflectors help…?

Reflectors will definitely help.

matrixsup wrote:

Can the smoke result in such issue.As depending on wind conditions it can become very tricky to position the backhauls..?will putting reflectors help..?

Probably temperature inversion

The Smoking Chimney is just 100 mtrs & LOS passes through it.

We would be rasing height as well put the reflector to ensure long terms solution.


I may be way off here but the smoke could be a problem. Is it actually smoke or just steam? If the smoke is from coal buring boilers. Are the boilers 100% efficient? Do they burn 100% of the coal? Could small particles of coal be in the smoke that could attenuate the RF? Coal is carbon based right?

Reflectors will definitly help.


I am not sure about 100 % efficiency…But when it sends exhausts…it just creates a column of black non-opaque column of some height.

We put the reflectors , still occasional registration does take place.

The frequency of outage has reduced to less than 2 to 10

We have started to face this problem very frequently at night…We see 50/100 sessions/registrations & re-registrations…

In Morning the link works @ 100 %

An cluses ,we r on 7.0.7.

We’re a WISP in Central California and have seen a 2-3 dBm degradation in signal quality since the 300+ wildfires started. It has been three weeks so far of consistently thick, smokey skies along the mountain ranges and customers with weaker signals have been loosing connection frequently. Customers who have not had any connection issues have a 2-3 dBm weaker signal.

Visibility most days is only about 5-8 miles (due to smoke) and the majority of our customers are 10-15 miles out. Has anyone else experienced a change in signal quality which may be due to this kind of smoke scenario?

The coal smoke will definitely cause a problem, especially at night as the air cools and the density of the smoke increases.

Your 90% efficiency is low for a backhaul link in my opinion - 100% both ways is my standard. Canopy requires 3dB above the noise floor for a 1X link, and 10dB for a 2X link. If you add a reflector at the master end you are effectively raising your system gain by ~18dB which will give you the margin you need.

The internal antenna in Canopy is 60 degrees. The wide pattern is creating significant diffraction as the signal passes through the small particles of cabon and soot in the smoke ( The reflector will narrow the beamwidth to 8 degrees reducing the diffraction through the smoke.