For base station antenna at window of first floor and rover at near ground level, the radio path go through wall of many homes with mildly wet external wall.
Any idea how radio is affected by going through wet wall?
For place that is mildly raining for 180 days per year, meaning road and residential home building wall are kind of mildly wet continuously for many days in a row, how would radio range be affected on 868/915 MHz? Many thanks
From my own observation, living in an area prone to flooding and heavy rain/winds/storms, I haven’t noticed a drop in RSSI or any extra noise during extreme wet periods or storms. I’m on 915MHz. I also have repeaters 1000m above sea level on tops of mountains that can be clouded over with thick fog all day. Surrounding nodes at a lower elevation don’t see a difference in signal strength than if it was fine and sunny. I was surprised by this. I can regularly see a repeater 50km away, with good reliability – regardless of the weather.
Many thanks. Sorry for my non-precise question. I edited it.
My query is for radio wave going through mildly wet wall of residential home. If wall is fully conductive, like metal, radio wave is blocked. Wet wall is ‘a bit conductive’.
For signal going through air in rain, storm and cloud (not wet wall), I do not know the exact difference between 868/915 and 1575MHz. May not be too different. 1575MHz is GPS which is designed to be reliable in storm, rain and bad weather, where human life depend on it.
Again seems something to test.
My own limited testing, rain didnt seem to affect the range. Been doing most of my range tests while walking dog, so havent gone out in rain very much!
… The base station in a attic, with tile roof, so would of been rain on the tiles.
Could just have two fixed base-stations, in same location, and just leave them running long term. Even the periodic NodeInfo packets (eg set to once an hour) could be used to test signal strength.
… look at rangetest.csv from each device, and correlate with weather recordings.
(although frustratingly rangetest.csv only includes SNR not RSSI)
What range is SNR reading? Does it roof at says 20 dB and not go higher even if signal is stronger than a certain limit?
For a strong signal SNR might be circa 12dB, not seen much higher than that.
Reception will be at the failure point when the reported SNR is close to the specified limit for the spreading factor -7.5dB for SF7 to -20dB for SF12.
Just looked at a rangetest.csv, see between about -23db and 7.5db.
That 7.5db was when both devices in same room (line of sight!)
… probably could get slightly higher with better antenna. (sender was a baseplane monopole with 2m coax, rs was a small helical that comes with heltec v3. ) - default LongFast.
I have found that weather conditions can affect reception at the outer limits of my range.
While I have not found rain to be a measurable factor I have found heavy dense fog can be.
I have a node on a mountain top that can see 30 miles. When the mountain is fogged in/ dense overcast for me in the valley, I will not see heartbeats from the most distant nodes.
Conversely, in weather conditions I can not identify, generally at night I can some times pick up nodes 50 miles out or more. The weather factors affecting range are more complicated than just whether it is raining or not.
Physical obstructions play a vastly more significant roll than does weather. Moving a node from my attic to the roof top, made of 1 inch thick concrete tiles more than doubled my range!
Can’t say tested in Fog.
Wonder if the longer range periods where something akin to
what is the difference/change between the roof antenna mount position (antenna take signal from ‘free air outside’) and when antenna was inside attic (outside signal has to pass through ‘something’ before reaching antenna)?
Just concrete tiles or some attic has insulation material with aluminium foil that is quite blocking for radio wave.
HF band, below 30MHz and below Maximum_usable_frequency, can reflect between earth and ionsphere. I am not sure if ducting occure at 868/915 MHz.
Ducting may occure at 868/915 mhz but very very rare mostly in the 2 meter area of the freq band it also will happen in the 10 meter band (Hf) area but mostly 800,900 mhz band will cut right through the Ion layers of earth …