We have a 10mb BH that is 20 Miles away. I have noticed that during the day the link runs at -68, but during the night it runs as high as -79/-80. This is a 5.7 Frequency, do you think that this may be due to a “usage load” or something at night that causes the link to degrade like this?
Have you performed a spectrum analysis when this occurs to see if there is a source of interference coming online each evening.
10-12 dB is a huge swing which is why I ask about a potential interferer.
Does this happen every night? Did it start at one particular time or has it always been this way?
jmoore,
I have noticed something similar at a particular site. The thing is, I’m shooting through a MASSIVE thicket of trees. Also, this area (Southeast Texas) is extremely humid. My theory is that the additional mositure on and in the trees at night is absorbing my RF. I also see something similar happen when it rains…any site shooting through trees has problems.
I’m not sure what can be done about this particular issue, since it’s dependent on nature. If it is interference from another RF source, you might try adjusting your tranmission/receive frequency.
Hope this helps.
In fact, i can see the opposite of that: i have a 15 mile link, what usually has 900-950RSSI daytime (about -70dB signal) but at night (usually from 18h to 6h) it’s about 1100-1200. It’s not connection with heavy rain at least in this area. I have clear LOS (I can see the 25th meter and above of the 50m building where master is located)
jmoore wrote: We have a 10mb BH that is 20 Miles away. I have noticed that during the day the link runs at -68, but during the night it runs as high as -79/-80. This is a 5.7 Frequency, do you think that this may be due to a "usage load" or something at night that causes the link to degrade like this?
Might be tropospheric ducting causing you a problem. Ducting happens when a layer of air which is at a different humitidy and/or temperature is sandwiched between other layers. A "duct" is thereby formed. When ducting is happening you can frequently hear stations which are very far away and not hear stations which are very close.
Fog IS a ducting phenomena. You can sometimes see the layer as you drive at night. Typically it will be at a certain altitude above ground and as you drive you will sometimes rise above it and sometimes be below it while at other times you will be in the fog. When conditions are right certain frequencies will not be able to pass thru the "duct" to go above it or below it . Antennnas which are in the duct may not be able to talk to antenna which are not in the duct.
Our network is "maritime over land" meaning that we work the Three Rivers portion of Virginia. The coverage area is approximately 50% covered by salt water rivers and marshes and the Chesapeak Bay. Last Thursday between 0200 and 0400 half the SM in our network re-registered about 20 times while the rest of them just kept running fine.
This is most common at UHF but still problematic at 5.7 GHz. Our network is a 900 MHz Advantage network.
Here is a usefull link.
http://home.cogeco.ca/~dxinfo/tropo.html