Topic: Question for WS90 owners

[mcrossley]

Does the rain rate value increment from zero on the first detection of rain, or a bit later?

[Gyvate]

to be observed closely - as much as I recall, when I see 0.1 mm rainfall, I also see a rain rate
but, as said before, I'd like to verify on the next occasion ...

[Rover1822]

I think, and I may be wrong, that once it has a value that can be above the cut off precision, you will start to see it. I don't know the actual algorithm they are using over an hour, I can imagine several but those would be guesses.

I as well will keep an eye on mine.

Be a question to pose to Ecowitt directly

Edit: I imagine the console would need a few receptions from the WS90 to determine amount over time (rate) , so a single reading, probably not enough to establish a rate.

[mcrossley]

You would think being haptic that it would be able to determine the rate directly rather than the time between tips like a traditional tip sensor.

Anyway, please let me know what you find.

[Rover1822]

Good question, I don't think the WS90 transmits rate. I could be entirely wrong on this, I believe it is  a console thing to work out.
I will do some readings with the SDR next time I have rain to see. But the thing is on rate, the WS90, doesn't have a clock as far as I know, so  rate determination would be based on cpu ticks, which is inaccurate.

[kheller2]

You would think being haptic that it would be able to determine the rate directly rather than the time between tips like a traditional tip sensor.

Anyway, please let me know what you find.

Eh?  “Rate” requires a time delta.  The traditional tipping gauge doesn’t transmit tips, but the amount of water it computed by counting tips over time and then at certain time intervals transmitting that number.   Haptic still has to have a time delta, do some calculation then transmit that number every so many seconds. 

[mcrossley]

I think you are wrong on both counts.

The traditional tipping gauge doesn’t transmit tips

A tipping sensor normally (Davis et al) just sends a tip count, the base station then converts the tip count to a mm/inch value and times the tips to determine rate. The Davis for instance allows you to use different size tippers for metric or imperial units - the transmitter has no knowledge of that.
- Though the sensor could convert each tip to a linear value directly and transmit that - the base station then just determining the rate.
- Of course as the sensors have a degree of computing power they could also determine rate, but we don't currently think (tbc) that is transmitted.

I'm not sure how the Ecowitt haptic sensor works, but I think it is likely it counts rain drops and their size over a time period and converts that to amount in mm/inches. Effectively a drop count in a time period is an intensity or if you like a rate!

But the thing is on rate, the WS90, doesn't have a clock as far as I know, so  rate determination would be based on cpu ticks, which is inaccurate.

Every microprocessor may not have a RTC, but it will have accurate timers - that is how they do time dependent actions like transmitting data etc.

[Rover1822]

Does the rain rate value increment from zero on the first detection of rain, or a bit later?

I've been watching my custom server output (30 sec), and from that, the rate, and daily rain , started their increment from 0 at the same time. Although when viewed on ecowitt, only the rain rate is visible, due to the site only using 2 decimal places (rain rate 0.024, daily rain 0.004 from custom server, so Ecowitt.net shows 0.02 and 0.00). Now is there a possibility of an intervening read as I am using 30 seconds? Sure

[mcrossley]

Great, thanks for that info. It makes my life a bit easier 

[wsNoordbergum]

My WS90 was showing spikes in the rain rate readings of 0.6 mm/h when there was no rain, my WS90 was replaced by Ecowitt under warranty.
Rain rate and amount of rain always started at same time.
I think the rain rate is calculated directly from the piëzo sensor output
More output from piëzo is higher rain rate
When spikes happened the graph was quite linear
The sensor does not wait a period of time to calculate the rain rate as with a traditional seesaw rain counter
But it can also be that the amount of rain is calculated from the rain rate, so sensor->rainrate->rainfall amount instead of sensor->rainfall amount->rainrate-
This would make more sense given the rainfall calibration thresholds
My new WS90 works as it should

[Gyvate]

The sensor does not wait a period of time to calculate the rain rate as with a traditional seesaw rain counter
But it can also be that the amount of rain is calculated from the rain rate, so sensor->rainrate->rainfall amount instead of sensor->rainfall amount->rainrate-
This would make more sense given the rainfall calibration thresholds
My new WS90 works as it should

Is this confirmed by Ecowitt or is this a speculation from your end ?
The way you write it reads as if it were factual.

[wsNoordbergum]

Since the graphs have a 5 min interval on the app there is a possibility that there is a difference in rate/ sum reading
All I see is rain rate and sum going up the same time on graph
And no it is not confirmed by Ecowitt
My apologies for the factual language

I'll try to make a graph in my meteobridge from the data of my WS90 compared to WH40 compared to Davis on a minute interval

See if that gives a clue