Understanding Rain values (including SDR deltas)

[Matthew White]

Hello; firstly it's clear a lot of effort has been put in weewx and all the software around it. eg the SDR import, rtl433. So many thanks to everybody. 

So.... I'm trying to understand the rain/rainTotal and the deltas setting of the SDR import.

The sensor is being reported by RTL as the Bresser5in1, with a rainfall value in mm.  I'm guessing this is total over time? Though it doesn't match to any way shown on the internal display.  

I'm guessing what I need to be sent to Weewx is the delta. but can't seem to work out how to properly configure that.. any pointers welcome...

The sensor map is 

```

[SDR]

    # This section is for the software-defined radio driver.

   

    # The driver to use

    driver = user.sdr

    cmd = "rtl_433 -M utc -F json -f 433.92M -f 868M -H 15"

    [[deltas]]

        rain = rain_mm

    [[sensor_map]]

        windDir = wind_dir.96.Bresser5in1Packet

        windSpeed = wind_speed.96.Bresser5in1Packet

        outTemp = temperature.96.Bresser5in1Packet

        outHumidity = humidity.96.Bresser5in1Packet

        rain_total = rain_total.96.Bresser5in1Packet

        windGust = wind_gust.96.Bresser5in1Packet

        extraTemp1 = temperature.1:11.HidekiTS04Packet

        extraHumid1 = humidity.1:11.HidekiTS04Packet

        extraTemp2 = temperature.2:3.HidekiTS04Packet

        extraHumid2 = humidity.2:3.HidekiTS04Packet

        extraTemp3 = temperature.3:5.HidekiTS04Packet

        extraHumid3 = humidity.3:5.HidekiTS04Packet

```

Currently we're 20m or so under water - which added to out elevation means we're 60m underwater. 

Thanks Matthew

[matthew wall]

On Monday, April 18, 2022 at 3:48:30 AM UTC-4 call...@gmail.com wrote:

The sensor is being reported by RTL as the Bresser5in1, with a rainfall value in mm.  I'm guessing this is total over time? Though it doesn't match to any way shown on the internal display.  

the value rain_mm *should* be the amount of rain that fell within the preceding LOOP interval.  you can verify it by looking at the observation values when you run the weewx-sdr driver (not weewxd!) directly.  see the weewx-sdr readme for instructions about how to run the driver directly.

 

    [[deltas]]

        rain = rain_mm

you want this:

    rain = rain_total

in fact, you do not have to specify any deltas at all, since 'rain = rain_total' is one of the deltas defined in the default SDR configuration.

the 'deltas' section says "for each interval, make the observation on the left the value of the difference of the value of the observation on the right over the interval"

m 

[Andy]

The delta is already set in the sdr.py driver at line 3254. Try removing the delta stanza from your config and restarting. Look at the comments at the start of the sdr.py driver for info on delta.

Andy

[Matthew White]

Ah - I see that makes sense now.. updated and it's now stopped raining!  

Appreciated thanks!

Matthew

[Matthew White]

Thanks Andy.. yes it does explain it in the comments... should have read them properly; which considering software is what I do professionally is a bit embarrassing :-(

Matthew