40kms P2P link netmetal5 with mANT 30 antenna drop signal strength at night,
during day time from rssi hit around -50/-53 but during night time rssi drops to -75/-80
Can anyone give me a reasonable reason regarding this issue
Hi,
actually i don’t know, should be something related to the temperature?
Is this happening every night? Do you use the 20MHz channel?
Antenna aim is good with an rssi of -53 during the day; it seems to be something right in the fresnel zone, or some radio, very near to yours, that work only at night and make a lot of noise.
Just for curiosity (i don’t know if it wall be really useful), have you made a frequency scan during the night?
Does the link pass over lakes or sea? At night there is a lot of refractivity, but i don’t know if it can influence so much (20 or 30 dB) the actual rssi.
Atmospheric Inversion!
Usually it is a layer of warm air trapped between a layer of cold air at ground level and another layer of cold above. If the two end points lie in different layers, the signal can be essentially refracted/reflected. If you have ever had trouble picking up a local radio station on a cool/crisp morning, this is the same cause. This is fairly common over bodies of water, even on fairly short links.