Ambient WS2902 and Ventus W830 seems to be the same weather station.
Yes, they are all made by Fine Offset. Along with many other reseller brands.
According to both manuals, the update interval is 16 seconds.
- Is this the update interval both on the screen and on server, and are they updated simultaneously?
The sensors update the console every 14 seconds. The console then updates the screen every 16 seconds and it uploads to WU every 16 seconds. It uploads to other services at different intervals that are much longer. Depending on brand/firmware; WOW 5 minutes, Ambientweather.net 1 minute, Ecowitt.net 1 minute, WeatherCloud 10 minutes, and Customized server upload is however many seconds you want (but the sensors are still only reporting every 14 seconds). PWSweather via Ambientweather.net is 1 minute and PWSweather via Customized server upload is 1 or more minutes (I recommend 5 minutes for PWSweather).
I don't know if the screen and WU update/upload are at the exact 16 second mark simultaneously. Maybe, maybe not. Doesn't really matter because WU does its own thing and is unreliable and inconsistent. Just watch any WU station and you'll realize this.
16 second update interval is not very frequent when looking at wind speed and direction.
- Are wind speed and direction sampled faster, but average/max gust reported every 16 seconds?
I cannot fin the sample rate of the wind speed/direction, so hope someone can advise.
Even though the screen only updates every 16 seconds the sensors are constantly working. It isn't like it only wakes up every 16 seconds to take a measurement. At every 14 seconds the data that the sensor sends is the average wind speed for that 14 sec interval and the max is the gust. The direction is the average of that 14 second interval.
If you want better than this then buy a Davis Vantage Pro 2.
