Wind data HTTP (Ecowitt) vs. Ecowitt GW1000
Posted: Sat 08 Jan 2022 12:33 am
It's winter: light snow at -26°C, not much incentive to go outside. Rummaging through my spare parts bin I find an unused Raspberry Pi and an Ecowitt GW1000 gateway. Whoa, why don't I create a backup CumulusMX system? Ready ... set ... go
Here is what I did:
• Clone (!) the SD card of my main system
• Edit the Cumulus.ini file so the backup system doesn't upload to my website(s)
• Update the IP/MAC address of the second GW1000 in the Cumulus.ini file
• Change the port address for the web interface to 8888
After booting up the second Pi and logging into the interface, I changed the station type from "HTTP (Ecowitt)" to "Ecowitt GW1000". (It's winter, I've got nothing better to do ...) After running the two systems for a few days I noticed some differences in the monthly log files, namely the wind values. This Excel table highlights the differences (I have deleted the rows with matching values).
OK, right now it's not very windy, but still it's interesting to see that the HTTP values for windspeed and windgust are always higher than the GW1000 values. I'm not really concerned about the differences in the windbearing, that's maybe for another day. But what's the reason for the windspeed/gust differences? Is it that I use two different GW1000 gateways?? To find out, I change the IP address of the backup system to the same one used in the main system and let it run for a few hours:
Again the HTTP values are higher than the ones reported by the GW1000 protocol. Is this another case of Segal's law, or maybe the two protocolls don't provide the same data precision (integer, floating) ... or ... or am I missing something?
Here is what I did:
• Clone (!) the SD card of my main system
• Edit the Cumulus.ini file so the backup system doesn't upload to my website(s)
• Update the IP/MAC address of the second GW1000 in the Cumulus.ini file
• Change the port address for the web interface to 8888
After booting up the second Pi and logging into the interface, I changed the station type from "HTTP (Ecowitt)" to "Ecowitt GW1000". (It's winter, I've got nothing better to do ...) After running the two systems for a few days I noticed some differences in the monthly log files, namely the wind values. This Excel table highlights the differences (I have deleted the rows with matching values).
OK, right now it's not very windy, but still it's interesting to see that the HTTP values for windspeed and windgust are always higher than the GW1000 values. I'm not really concerned about the differences in the windbearing, that's maybe for another day. But what's the reason for the windspeed/gust differences? Is it that I use two different GW1000 gateways?? To find out, I change the IP address of the backup system to the same one used in the main system and let it run for a few hours:
Again the HTTP values are higher than the ones reported by the GW1000 protocol. Is this another case of Segal's law, or maybe the two protocolls don't provide the same data precision (integer, floating) ... or ... or am I missing something?