OK, let's do the maths... Assume the default rain window (rain_period) of 900 seconds (15 minutes). WeeWX will calculate loop rainRate as sum of loop rainfall over the last 900 seconds * 3600/900.
First rain event is loop packet at 08:40:27 where 0.11811023622 fell. Previous rainRate was 0.0 so we know no rain fell in the previous 15 minutes. weeWX would calculate rainRate as 0.11811023622*3600/900 = 0.472440945. Log indicates 0.472440944882. Loop packets from 08:40:28 to 08:51:15 inclusive have no recorded rainfall so rainRate remains at 0.11811023622*3600/900 = 0.472440945. Log indicates 0.472440944882 in each loop packet. Loop packet 08:51:40 has a rain event that includes 0.11811023622 rainfall. weeWX would calculate rainRate as (0.11811023622+0.11811023622)*3600/900 = 0.94488189. Log indicates 0.944881889764. No further loop rainfall occurs so loop rainRate remains 0.944881889764 for the rest of the screen capture. Had the screen capture continued and no further rainfall occurred I would expect loop rainRate would decay to 0.472440944882 in the first loop packet after 08:55:27. rainRate would drop to 0.0 in the first loop packet after 09:06:40. rainRate in archive records works a little differently, in particular when software record generation is used (it's not clear what is being used in this case but I expect it will be software record generation). When software record generation is used the archive record rainRate is taken as the average of the loop rainRate values seen during the archive period. In this case the first archive record at 08:40:00 had seen no rain and rainRate = 0. The screen capture indicates 0.0 The 08:42:00 archive record would have seen loop packets at 08:40:15, 08:40:27 and 08:40:28 with respective rainRate values of 0, 0.472440944882 and 0.472440944882. The average of these is (2*0.472440944882)/3 = 0.31496063. The screen capture indicates 0.31496063. The 08:44:00 archive record will have seen the loop rainRate value of 0.472440944882 seven times. The average being 0.472440944882. The screen capture indicates 0.472440944882. The 08:46:00 archive record saw loop rainRate of 0.472440944882 three times so the resulting average is 0.472440944882. The 08:48:00 archive record saw loop rainRate of 0.472440944882 four times so the resulting average is 0.472440944882. The 08:50:00 archive record saw loop rainRate of 0.472440944882 once so the resulting average is 0.472440944882. These values agree with the screen capture. The 08:52:00 archive record saw loop rainRate of 0.472440944882 three times and 0.944881889764 once so the resulting average is 0.590551181102. The screen capture indicates 0.590551181102. The 08:54:00 archive record saw loop rainRate of 0.944881889764 three times so the resulting average is 0.944881889764. The screen capture indicates 0.944881889764. So the upshot is given the rain values in the loop packets weeWX is calculating loop and archive rainRate exactly as it should. Where I believe the error lies is in the loop rain values as mentioned by the OP in post #3. If we look at the first rain event the rain_total jumps from 63.0 to 63.3 yet rain is recorded as 0.11811023622; we would have expected 0.3 ie the simple difference between success rain_total values. Also, if we multiply 0.11811023622 by 2.54 we get 0.3. So clearly we have a cm to inches conversion occurring somewhere that is not needed. My quick look at the SDR driver did not reveal anything, probably needs Matthew's eye! Gary On Tuesday, 27 November 2018 01:49:13 UTC+10, Andrew Milner wrote: > > I cant get anything like the given rainrates for the period of the log > > A longer log extract is definitely needed!! > > > > On Monday, 26 November 2018 10:39:48 UTC+2, gjr80 wrote: >> >> Hi, >> >> What makes you say the rainRate is wrong? By default weeWX calculates >> rainRate over a 15 minute sliding window, your screen capture covers >> approximately 16 minutes with at least two rain events so seeing a non-zero >> rain rate in all packets/records after the first rain event is expected. >> You can change the window size by setting the rain_period config option in >> weewx.cnf: >> >> [StdWXCalculate] >> .... >> [[Calculations]] >> .... >> rain_period = xxx >> .... >> >> Where xxx is the rain_period to be used in seconds. You will need to >> restart WeeWX or do a config reload for the new setting to take effect. >> >> Gary >> >> -- You received this message because you are subscribed to the Google Groups "weewx-user" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
