The tipping bucket must be ut in a linear fashion as the only thing which can 
be wrong is the bucket size itself, assuming it is lubricated and moving 
freely. Have you ecperimented with dripping water into the gauge and measuring 
the number if tips for a fixed quantity of water? It must be a linear 
relationship as near as dammit.

Sent from my Windows 10 phone

From: TheChoctlab
Sent: 19 September 2017 08:49
To: weewx-user
Subject: Re: [weewx-user] Re: Rain gauge errors

Got it.  Thank you.

On Monday, September 18, 2017 at 10:48:05 PM UTC-7, Andrew Milner wrote:
A single addition would work for the daily total in the daily rain table, but 
not fir the individual archive records in the archive table.  
 
Sent from my Windows 10 phone
 
From: TheChoctlab
Sent: 19 September 2017 08:44
To: weewx-user
Subject: [weewx-user] Re: Rain gauge errors
 
After re-reading your post, the following occurred to me:

UPDATE archive SET rain = rain + yy WHERE dateTime > xxxxxxxxx;

yy being the difference between the tipping bucket and manual gauges.



On Monday, September 18, 2017 at 8:47:22 PM UTC-7, Andrew Milner wrote:
I forgot to add
1. Take a copy of the database before manipulating/updating values
2. If you 'correct' the readings MAKE A NOTE OF THE DATE TO WHICH YOU DID THE 
UPDATE and then on subsequent manipulations it would be
 
UPDATE archive SET rain = rain * 2 WHERE dateTime > xxxxxxxxx;

On Tuesday, 19 September 2017 06:43:46 UTC+3, Andrew Milner wrote:
Depends what you mean by 'manipulate'!!
 
If you have a formula that would convert VP2 reading to match manual reading 
then the formula could be put into the calibration section of weewx.
 
If you want to change existing readings already in the database then you can 
use SQLite to issue sql statements direcly
eg to double all rain readings before epochdate xxxxxxxxx would be something 
like:
 
UPDATE archive SET rain = rain * 2 WHERE dateTime < xxxxxxxxx;

On Tuesday, 19 September 2017 06:02:13 UTC+3, TheChoctlab wrote:
My VP2 rain gauge, not unlike other tipping bucket gauges, is often inaccurate. 
I have a Stratus RG202 manual gauge to compare it to.

I understand that I will need to manipulate weewx.sdb to reflect the readings 
from the manual gauge.  But, I am not sure what exactly to manipulate.


Guidance please.
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