Re: [weewx-user] Re: UV index

[Damjan Hajsek]

I will do that and post results here

Dne sreda, 18. april 2018 15.22.25 UTC+2 je oseba Greg Troxel napisala:
>
> Damjan Hajsek > writes: 
>
> > So we can't do nothing to make UV index show right value, because with 
> > calibrating I can not get real data? 
>
> This can probably be solved, but "calibration" is very likely not the 
> approach. 
>
> Let me try to summarize what we know. 
>
>   Your station seems to show reasonable UV values on the console. 
>
>   Your station reports some encoded values that a weewx driver reads. 
>
>   Currently, the bits for UV are extracted in some straightforward way 
>   and assumed to be the UV index.  This is leading to values that are 
>   not even close to correct. 
>
>   "Calibration", in weewx and generally, is a mechanism that makes small 
>   changes to values to make them closer to the correct values. 
>   Calibration is by definition a very minor change, like subtracting 0.7 
>   hPa of pressure, or adding 0.5 C of temperature.  Or perhaps 2 C, but 
>   not 20 C.  Calibration as a concept depends on having a close-to-right 
>   value with a simple relationship, so that "V = R + c" holds fairly 
>   closely for readings R, and calibration value c, and true value V. 
>
>   So far, we have no reason to believe that attempting something like 
>   calibration above with the values being read by weewx for your station 
>   will give reasonably correct answers. 
>
> And then making assumptions: 
>
>   Probably, the way the weather station sends UV index to the computer 
>   is not just an integer in a field.  We don't understand how that is 
>   done yet. 
>
> So the path forward is, more or less: 
>
>   1) Ensure (assume, and retry if not, because absent the manufacturer 
>   documenting it, and documenting it correctly, we have to assume) that 
>   the UV field really is the UV field. 
>
>   2) Ensure that the path from bits in the UV field to the number that is 
>   recorded is straightforward and reversible. 
>
>   3) Keep records of pairs of displayed UV value and 
>   reported/recorded-in-weewx UV values.  A simple chart with two columns 
>   would be fine (but I might add date/time in case it is useful). 
>
>   4) Put this chart in a spreadsheet or csv format 
>
>   5) Make a scatter plot of console vs weewx values, where each point is 
> an 
>   observation pair, with console on x axis and weewx-read value on y 
>   axis. 
>
>   6) Figure out if there is a clear relationship and what it is.  Try to 
>   come up with a formula, especially one that we can explain after we 
>   create it how it works. 
>
>   Change the driver to use the formula. 
>
> I am guessing these steps seem too complicated, but I expect others can 
> help. 
>
> So I would suggest that you do steps 3 and 4, for at least several days 
> and preferably a week, at night, and at various points during the day, 
> both sunny and cloudy days, and post a link to the spreadsheet, or 
> preferably mail csv format to the list. 
>
> Without steps 3 and 4, then I don't see a way to make progress. 
>
> Greg 
>
> 
>

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Re: [weewx-user] Re: UV index

[Greg Troxel]

Damjan Hajsek  writes:

> So we can't do nothing to make UV index show right value, because with 
> calibrating I can not get real data?

This can probably be solved, but "calibration" is very likely not the
approach.

Let me try to summarize what we know.

  Your station seems to show reasonable UV values on the console.

  Your station reports some encoded values that a weewx driver reads.

  Currently, the bits for UV are extracted in some straightforward way
  and assumed to be the UV index.  This is leading to values that are
  not even close to correct.

  "Calibration", in weewx and generally, is a mechanism that makes small
  changes to values to make them closer to the correct values.
  Calibration is by definition a very minor change, like subtracting 0.7
  hPa of pressure, or adding 0.5 C of temperature.  Or perhaps 2 C, but
  not 20 C.  Calibration as a concept depends on having a close-to-right
  value with a simple relationship, so that "V = R + c" holds fairly
  closely for readings R, and calibration value c, and true value V.

  So far, we have no reason to believe that attempting something like
  calibration above with the values being read by weewx for your station
  will give reasonably correct answers.

And then making assumptions:

  Probably, the way the weather station sends UV index to the computer
  is not just an integer in a field.  We don't understand how that is
  done yet.

So the path forward is, more or less:

  1) Ensure (assume, and retry if not, because absent the manufacturer
  documenting it, and documenting it correctly, we have to assume) that
  the UV field really is the UV field.

  2) Ensure that the path from bits in the UV field to the number that is
  recorded is straightforward and reversible.

  3) Keep records of pairs of displayed UV value and
  reported/recorded-in-weewx UV values.  A simple chart with two columns
  would be fine (but I might add date/time in case it is useful).

  4) Put this chart in a spreadsheet or csv format

  5) Make a scatter plot of console vs weewx values, where each point is an
  observation pair, with console on x axis and weewx-read value on y
  axis.

  6) Figure out if there is a clear relationship and what it is.  Try to
  come up with a formula, especially one that we can explain after we
  create it how it works.

  Change the driver to use the formula.

I am guessing these steps seem too complicated, but I expect others can
help.

So I would suggest that you do steps 3 and 4, for at least several days
and preferably a week, at night, and at various points during the day,
both sunny and cloudy days, and post a link to the spreadsheet, or
preferably mail csv format to the list.

Without steps 3 and 4, then I don't see a way to make progress.

Greg



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Re: [weewx-user] Re: UV index

[Damjan Hajsek]

my altitude is 296m and here is firmware 
https://ambientweather.wikispaces.com/ws1002-wifi

I will ask company to give me exact data about sensors, when I get it I 
will post it here.



Dne sobota, 14. april 2018 20.50.25 UTC+2 je oseba mwall napisala:
>
>
>
> On Saturday, April 14, 2018 at 2:11:29 PM UTC-4, Damjan Hajsek wrote:
>>
>>
>> 
>> Ok I checked in manuals. Is this enough, if not I will contact company 
>> which makes this seather station to send me exctly which sensors are build 
>> in.
>>>
>>>
>>>
> that looks like luminosity ("light sensor") and uv ("UV sensor")
>
> so your radiation adjustment is probably ok (are you at a fairly high 
> altitude?)
>
> i have no idea what the uv would read.
>
> i think you are correct to do this in the StdCalibrate.  if we had 
> definitive specifications for the hardware, and we had definitive 
> specifications for the wu protocol, and we had definitive specifications 
> for how the station emits data for wu, and we had definitive specifications 
> for how those values vary from one firmware version to another, then i 
> might be able to encode the conversions in the interceptor driver.
>
> in lieu of that, use StdCalibrate.
>
> m
>

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Re: [weewx-user] Re: UV index

[mwall]

On Saturday, April 14, 2018 at 2:11:29 PM UTC-4, Damjan Hajsek wrote:
>
>
> 
> Ok I checked in manuals. Is this enough, if not I will contact company 
> which makes this seather station to send me exctly which sensors are build 
> in.
>>
>>
>>
that looks like luminosity ("light sensor") and uv ("UV sensor")

so your radiation adjustment is probably ok (are you at a fairly high 
altitude?)

i have no idea what the uv would read.

i think you are correct to do this in the StdCalibrate.  if we had 
definitive specifications for the hardware, and we had definitive 
specifications for the wu protocol, and we had definitive specifications 
for how the station emits data for wu, and we had definitive specifications 
for how those values vary from one firmware version to another, then i 
might be able to encode the conversions in the interceptor driver.

in lieu of that, use StdCalibrate.

m

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Re: [weewx-user] Re: UV index

[Damjan Hajsek]

Ok I checked in manuals. Is this enough, if not I will contact company 
which makes this seather station to send me exctly which sensors are build 
in.



Dne sobota, 14. april 2018 18.02.32 UTC+2 je oseba mwall napisala:
>
> On Saturday, April 14, 2018 at 4:53:18 AM UTC-4, Damjan Hajsek wrote:
>>
>> No UV and radiation are not the same value.
>>
>
> UV, radiation, and illuminance are three different things.  some stations 
> measure illuminance, then convert to radiation.  some measure radiation. 
>  measuring uv requires a different sensor.
>
> there are conversion factors to go between illuminance and radiation, but 
> those are gross approximations.
>
> uv index is arbitrary.  davis hardware uses a 0-16 integer scale. 
>  rainwise uses something else.  ukmet uses something else.
>
>  
>
>> radiation = radiation * 0.731
>>
>
> your hardware might be reporting luminance, not radiation.
>
> check the hardware specs to see exactly what kinds of sensors it has. 
>  does it have just illuminance, then it is fabricating a UV index and a 
> radiation value?  or does it actually measure UV?
>
> once you know exactly what the hardware is capable of doing, then we can 
> see how that maps to the packets that the interceptor driver is receiving 
> from it.
>
>

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Re: [weewx-user] Re: UV index

[mwall]

On Saturday, April 14, 2018 at 4:53:18 AM UTC-4, Damjan Hajsek wrote:
>
> No UV and radiation are not the same value.
>

UV, radiation, and illuminance are three different things.  some stations 
measure illuminance, then convert to radiation.  some measure radiation. 
 measuring uv requires a different sensor.

there are conversion factors to go between illuminance and radiation, but 
those are gross approximations.

uv index is arbitrary.  davis hardware uses a 0-16 integer scale.  rainwise 
uses something else.  ukmet uses something else.

 

> radiation = radiation * 0.731
>

your hardware might be reporting luminance, not radiation.

check the hardware specs to see exactly what kinds of sensors it has.  does 
it have just illuminance, then it is fabricating a UV index and a radiation 
value?  or does it actually measure UV?

once you know exactly what the hardware is capable of doing, then we can 
see how that maps to the packets that the interceptor driver is receiving 
from it.

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Re: [weewx-user] Re: UV index

[gjr80]

If you are using StdCalibrate to fix radiation and UV by such large factors 
there is clearly something not right with the driver. As Greg said a few 
posts back the driver should be decoding the raw UV/radiation data and 
returning proper values, clearly it is not. I suggest you go back to the 
fourth post in this thread and provide Matthew with a debug=1 log output 
(you have provided the LOOP and REC data requested but you actually 
provided a wee_debug report not 'log output with debug=1', they are 
different - you need to set debug=1 in weewx.conf then restart weewx and 
post the log output, I would say for 10 minutes or so). 

There is little else that we can do for you until the driver is fixed.

Gary

On Saturday, 14 April 2018 18:53:18 UTC+10, Damjan Hajsek wrote:
>
> No UV and radiation are not the same value.
> UV values are in bold because I made it bold to see it better.
> Yes I am soure my station report the same value as it is on console I 
> checked that many times.
> Here is my calibration section.
>
> [[Corrections]]
> 
> # For each type, an arbitrary calibration expression can be given. 
> # It should be in the units defined in the StdConvert section.
> # Example:
> # foo = foo + 0.2
> radiation = radiation * 0.731
> rainRate = rainRate * 0.1
> #barometer = barometer * 10.0025
> pressure = pressure * 1.0035
>   UV = UV * 0.003
> #windSpeed = windSpeed * 4.5
>
> Dne sobota, 14. april 2018 09.44.14 UTC+2 je oseba Andrew Milner napisala:
>>
>> If you do not have your calibration statement are you saying that UV and 
>> radiation are the same value??
>>
>> What is your calibration??  You just said it is very high.
>>
>> Why are some UV values in bold print in the loop and rec packets??
>>
>> Are you sure that your weather station actually outputs the same index 
>> value which you see on the weather station console??  So far all the 
>> evidence seems to imply that it does not provide the UV index in the same 
>> form that you see it on the console.
>>
>>
>>
>> On Saturday, 14 April 2018 10:10:39 UTC+3, Damjan Hajsek wrote:
>>
>>> Yes I hope we can solve that, because I use now verry high factor for 
>>> calibration to see aproximatelly the same result as on console.
>>>
>>> Dne sobota, 14. april 2018 02.35.05 UTC+2 je oseba gjr80 napisala:

 Unlikely to be anything to do with units, UV and radiation use the same 
 units irrespective of the unit system in use. From the loop/archive data 
 last shown I would hazard a guess that the driver is (now) doing its thing 
 correctly and presenting weeWX with credible UV and radiation values. If 
 these values correspond with what is displayed on the console then I don't 
 think there is any issue with the driver. In that case perhaps we need 
 some 
 elaboration on 'weewx doesn't read it right'.

 Gary

 On Saturday, 14 April 2018 10:13:24 UTC+10, Andrew Milner wrote:
>
> Damjan
>
> I do not think you are telling us everything which you are 
> doing/changing!!  When you first posted to this thread the loop records 
> were in US units, and UV values appeared to be very high.  Your latest 
> posting has loop records in metric, and UV values appear to be more like 
> UV 
> index values.
>
> So, do you still have a problem?  If you have been changing your 
> database units then your database could well contsin a mixture of 
> imperial 
> and metric values - with very unpredictable results.
>
>
>
> On Saturday, 14 April 2018 02:49:33 UTC+3, Greg Troxel wrote:
>
>> Andrew Milner  writes: 
>>
>> > matthew has already said tha weewx does not calculate uv index - it 
>> merely 
>> > uses the data provided by the station 
>>
>> But if there is some hardware that provides bits in a UV field, then 
>> a 
>> driver for that hardware should be translating the bits into an index 
>> value according to the encoding used.  I don't think we should be 
>> using 
>> calibration notions as a substitute for a well-understood 
>> representation.  But maybe I'm missing something here. 
>>
>

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Re: [weewx-user] Re: UV index

[Damjan Hajsek]

No UV and radiation are not the same value.
UV values are in bold because I made it bold to see it better.
Yes I am soure my station report the same value as it is on console I 
checked that many times.
Here is my calibration section.

[[Corrections]]

# For each type, an arbitrary calibration expression can be given. 
# It should be in the units defined in the StdConvert section.
# Example:
# foo = foo + 0.2
radiation = radiation * 0.731
rainRate = rainRate * 0.1
#barometer = barometer * 10.0025
pressure = pressure * 1.0035
  UV = UV * 0.003
#windSpeed = windSpeed * 4.5

Dne sobota, 14. april 2018 09.44.14 UTC+2 je oseba Andrew Milner napisala:
>
> If you do not have your calibration statement are you saying that UV and 
> radiation are the same value??
>
> What is your calibration??  You just said it is very high.
>
> Why are some UV values in bold print in the loop and rec packets??
>
> Are you sure that your weather station actually outputs the same index 
> value which you see on the weather station console??  So far all the 
> evidence seems to imply that it does not provide the UV index in the same 
> form that you see it on the console.
>
>
>
> On Saturday, 14 April 2018 10:10:39 UTC+3, Damjan Hajsek wrote:
>
>> Yes I hope we can solve that, because I use now verry high factor for 
>> calibration to see aproximatelly the same result as on console.
>>
>> Dne sobota, 14. april 2018 02.35.05 UTC+2 je oseba gjr80 napisala:
>>>
>>> Unlikely to be anything to do with units, UV and radiation use the same 
>>> units irrespective of the unit system in use. From the loop/archive data 
>>> last shown I would hazard a guess that the driver is (now) doing its thing 
>>> correctly and presenting weeWX with credible UV and radiation values. If 
>>> these values correspond with what is displayed on the console then I don't 
>>> think there is any issue with the driver. In that case perhaps we need some 
>>> elaboration on 'weewx doesn't read it right'.
>>>
>>> Gary
>>>
>>> On Saturday, 14 April 2018 10:13:24 UTC+10, Andrew Milner wrote:

 Damjan

 I do not think you are telling us everything which you are 
 doing/changing!!  When you first posted to this thread the loop records 
 were in US units, and UV values appeared to be very high.  Your latest 
 posting has loop records in metric, and UV values appear to be more like 
 UV 
 index values.

 So, do you still have a problem?  If you have been changing your 
 database units then your database could well contsin a mixture of imperial 
 and metric values - with very unpredictable results.



 On Saturday, 14 April 2018 02:49:33 UTC+3, Greg Troxel wrote:

> Andrew Milner  writes: 
>
> > matthew has already said tha weewx does not calculate uv index - it 
> merely 
> > uses the data provided by the station 
>
> But if there is some hardware that provides bits in a UV field, then a 
> driver for that hardware should be translating the bits into an index 
> value according to the encoding used.  I don't think we should be 
> using 
> calibration notions as a substitute for a well-understood 
> representation.  But maybe I'm missing something here. 
>


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Re: [weewx-user] Re: UV index

[Andrew Milner]

If you do not have your calibration statement are you saying that UV and 
radiation are the same value??

What is your calibration??  You just said it is very high.

Why are some UV values in bold print in the loop and rec packets??

Are you sure that your weather station actually outputs the same index 
value which you see on the weather station console??  So far all the 
evidence seems to imply that it does not provide the UV index in the same 
form that you see it on the console.



On Saturday, 14 April 2018 10:10:39 UTC+3, Damjan Hajsek wrote:

> Yes I hope we can solve that, because I use now verry high factor for 
> calibration to see aproximatelly the same result as on console.
>
> Dne sobota, 14. april 2018 02.35.05 UTC+2 je oseba gjr80 napisala:
>>
>> Unlikely to be anything to do with units, UV and radiation use the same 
>> units irrespective of the unit system in use. From the loop/archive data 
>> last shown I would hazard a guess that the driver is (now) doing its thing 
>> correctly and presenting weeWX with credible UV and radiation values. If 
>> these values correspond with what is displayed on the console then I don't 
>> think there is any issue with the driver. In that case perhaps we need some 
>> elaboration on 'weewx doesn't read it right'.
>>
>> Gary
>>
>> On Saturday, 14 April 2018 10:13:24 UTC+10, Andrew Milner wrote:
>>>
>>> Damjan
>>>
>>> I do not think you are telling us everything which you are 
>>> doing/changing!!  When you first posted to this thread the loop records 
>>> were in US units, and UV values appeared to be very high.  Your latest 
>>> posting has loop records in metric, and UV values appear to be more like UV 
>>> index values.
>>>
>>> So, do you still have a problem?  If you have been changing your 
>>> database units then your database could well contsin a mixture of imperial 
>>> and metric values - with very unpredictable results.
>>>
>>>
>>>
>>> On Saturday, 14 April 2018 02:49:33 UTC+3, Greg Troxel wrote:
>>>
 Andrew Milner  writes: 

 > matthew has already said tha weewx does not calculate uv index - it 
 merely 
 > uses the data provided by the station 

 But if there is some hardware that provides bits in a UV field, then a 
 driver for that hardware should be translating the bits into an index 
 value according to the encoding used.  I don't think we should be using 
 calibration notions as a substitute for a well-understood 
 representation.  But maybe I'm missing something here. 

>>>

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Re: [weewx-user] Re: UV index

[Damjan Hajsek]

Yes I hope we can solve that, because I use now verry high factor for 
calibration to see aproximatelly the same result as on console.

Dne sobota, 14. april 2018 02.35.05 UTC+2 je oseba gjr80 napisala:
>
> Unlikely to be anything to do with units, UV and radiation use the same 
> units irrespective of the unit system in use. From the loop/archive data 
> last shown I would hazard a guess that the driver is (now) doing its thing 
> correctly and presenting weeWX with credible UV and radiation values. If 
> these values correspond with what is displayed on the console then I don't 
> think there is any issue with the driver. In that case perhaps we need some 
> elaboration on 'weewx doesn't read it right'.
>
> Gary
>
> On Saturday, 14 April 2018 10:13:24 UTC+10, Andrew Milner wrote:
>>
>> Damjan
>>
>> I do not think you are telling us everything which you are 
>> doing/changing!!  When you first posted to this thread the loop records 
>> were in US units, and UV values appeared to be very high.  Your latest 
>> posting has loop records in metric, and UV values appear to be more like UV 
>> index values.
>>
>> So, do you still have a problem?  If you have been changing your database 
>> units then your database could well contsin a mixture of imperial and 
>> metric values - with very unpredictable results.
>>
>>
>>
>> On Saturday, 14 April 2018 02:49:33 UTC+3, Greg Troxel wrote:
>>
>>> Andrew Milner  writes: 
>>>
>>> > matthew has already said tha weewx does not calculate uv index - it 
>>> merely 
>>> > uses the data provided by the station 
>>>
>>> But if there is some hardware that provides bits in a UV field, then a 
>>> driver for that hardware should be translating the bits into an index 
>>> value according to the encoding used.  I don't think we should be using 
>>> calibration notions as a substitute for a well-understood 
>>> representation.  But maybe I'm missing something here. 
>>>
>>

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Re: [weewx-user] Re: UV index

[Damjan Hajsek]

Hi
Yes I changed units because I am from europe and units should be all in 
metric system and I did that because I noticed that wind on console shows 
10km/h and in weewx that was abot 5 times less, like 2 km/h. So I still 
didn resolve that too.
And problem with UV still persist, I solved it for now with calibration. I 
have deleted database after that and started all over again, because weewx 
even didn't work.
So now it is like fresh installation.

Dne sobota, 14. april 2018 02.13.24 UTC+2 je oseba Andrew Milner napisala:
>
> Damjan
>
> I do not think you are telling us everything which you are 
> doing/changing!!  When you first posted to this thread the loop records 
> were in US units, and UV values appeared to be very high.  Your latest 
> posting has loop records in metric, and UV values appear to be more like UV 
> index values.
>
> So, do you still have a problem?  If you have been changing your database 
> units then your database could well contsin a mixture of imperial and 
> metric values - with very unpredictable results.
>
>
>
> On Saturday, 14 April 2018 02:49:33 UTC+3, Greg Troxel wrote:
>
>> Andrew Milner  writes: 
>>
>> > matthew has already said tha weewx does not calculate uv index - it 
>> merely 
>> > uses the data provided by the station 
>>
>> But if there is some hardware that provides bits in a UV field, then a 
>> driver for that hardware should be translating the bits into an index 
>> value according to the encoding used.  I don't think we should be using 
>> calibration notions as a substitute for a well-understood 
>> representation.  But maybe I'm missing something here. 
>>
>

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Re: [weewx-user] Re: UV index

[gjr80]

Unlikely to be anything to do with units, UV and radiation use the same 
units irrespective of the unit system in use. From the loop/archive data 
last shown I would hazard a guess that the driver is (now) doing its thing 
correctly and presenting weeWX with credible UV and radiation values. If 
these values correspond with what is displayed on the console then I don't 
think there is any issue with the driver. In that case perhaps we need some 
elaboration on 'weewx doesn't read it right'.

Gary

On Saturday, 14 April 2018 10:13:24 UTC+10, Andrew Milner wrote:
>
> Damjan
>
> I do not think you are telling us everything which you are 
> doing/changing!!  When you first posted to this thread the loop records 
> were in US units, and UV values appeared to be very high.  Your latest 
> posting has loop records in metric, and UV values appear to be more like UV 
> index values.
>
> So, do you still have a problem?  If you have been changing your database 
> units then your database could well contsin a mixture of imperial and 
> metric values - with very unpredictable results.
>
>
>
> On Saturday, 14 April 2018 02:49:33 UTC+3, Greg Troxel wrote:
>
>> Andrew Milner  writes: 
>>
>> > matthew has already said tha weewx does not calculate uv index - it 
>> merely 
>> > uses the data provided by the station 
>>
>> But if there is some hardware that provides bits in a UV field, then a 
>> driver for that hardware should be translating the bits into an index 
>> value according to the encoding used.  I don't think we should be using 
>> calibration notions as a substitute for a well-understood 
>> representation.  But maybe I'm missing something here. 
>>
>

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Re: [weewx-user] Re: UV index

[Andrew Milner]

Damjan

I do not think you are telling us everything which you are 
doing/changing!!  When you first posted to this thread the loop records 
were in US units, and UV values appeared to be very high.  Your latest 
posting has loop records in metric, and UV values appear to be more like UV 
index values.

So, do you still have a problem?  If you have been changing your database 
units then your database could well contsin a mixture of imperial and 
metric values - with very unpredictable results.



On Saturday, 14 April 2018 02:49:33 UTC+3, Greg Troxel wrote:

> Andrew Milner > writes: 
>
> > matthew has already said tha weewx does not calculate uv index - it 
> merely 
> > uses the data provided by the station 
>
> But if there is some hardware that provides bits in a UV field, then a 
> driver for that hardware should be translating the bits into an index 
> value according to the encoding used.  I don't think we should be using 
> calibration notions as a substitute for a well-understood 
> representation.  But maybe I'm missing something here. 
>

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Re: [weewx-user] Re: UV index

[Greg Troxel]

Andrew Milner  writes:

> matthew has already said tha weewx does not calculate uv index - it merely 
> uses the data provided by the station

But if there is some hardware that provides bits in a UV field, then a
driver for that hardware should be translating the bits into an index
value according to the encoding used.  I don't think we should be using
calibration notions as a substitute for a well-understood
representation.  But maybe I'm missing something here.

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Re: [weewx-user] Re: UV index

[Damjan Hajsek]

I have this weather station
https://www.ambientweather.com/amws1000wifi.html
I will try to make more loop packages and see what station send.

Dne sreda, 11. april 2018 18.42.13 UTC+2 je oseba Greg Troxel napisala:
>
>
> I did misunderstand, sort of.  I think you are in a situation where 
> either 
>
>   your station is behaving strangely 
>
>   the interceptor driver fo fine offset station does not have support 
>   for decoding UV index, and is just reporting byte values until that's 
>   figured out 
>
>   something else :-) 
>
> So I would recommend recording displayed values vs LOOP packet values, 
> and creating a scatter plot.  I also recommend reading the driver source 
> code to see what it thinks it is doing now.  With any luck the 
> relationship will be clear and reliable, and you can contribute 
> new/improved support to the driver. 
>

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Re: [weewx-user] Re: UV index

[Andrew Milner]

matthew has already said tha weewx does not calculate uv index - it merely 
uses the data provided by the station


On Wednesday, 11 April 2018 19:42:13 UTC+3, Greg Troxel wrote:

>
> I did misunderstand, sort of.  I think you are in a situation where 
> either 
>
>   your station is behaving strangely 
>
>   the interceptor driver fo fine offset station does not have support 
>   for decoding UV index, and is just reporting byte values until that's 
>   figured out 
>
>   something else :-) 
>
> So I would recommend recording displayed values vs LOOP packet values, 
> and creating a scatter plot.  I also recommend reading the driver source 
> code to see what it thinks it is doing now.  With any luck the 
> relationship will be clear and reliable, and you can contribute 
> new/improved support to the driver. 
>

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Re: [weewx-user] Re: UV index

[Greg Troxel]

I did misunderstand, sort of.  I think you are in a situation where
either

  your station is behaving strangely

  the interceptor driver fo fine offset station does not have support
  for decoding UV index, and is just reporting byte values until that's
  figured out

  something else :-)

So I would recommend recording displayed values vs LOOP packet values,
and creating a scatter plot.  I also recommend reading the driver source
code to see what it thinks it is doing now.  With any luck the
relationship will be clear and reliable, and you can contribute
new/improved support to the driver.

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Re: [weewx-user] Re: UV index

[Andrew Milner]

correction - from the loop data you provided it appears your weather
station is not outputting a UV Index in the UV field, but is instead
outputting some numerical value which you need to try and convert into an
index - which may or may not be possible.  Without knowing more examples of
console UV index value compared to UV loop data output by station we cannot
really offer any more input!!  It is not however a weewx configuration
issue as such, since your station does not appear to be outputting the UV
index itself!!



On 11 April 2018 at 16:20, Damjan Hajsek  wrote:

> Maybe we didn't understand right.
> Station show real value of UV index on my terminal at home.
> But not on my web page by weewx. So it is settings in weewx
>
> Dne sreda, 11. april 2018 15.08.09 UTC+2 je oseba Greg Troxel napisala:
>>
>> Damjan Hajsek  writes:
>>
>> > Anyone know what to use in
>> > [StdCalibrate]
>> >
>> > [[Corrections]]
>> >
>> > to correct UV index? Because now at night it is UV = 15
>>
>> (I don't have any actual experience here, either with weewx calibration
>> or with UV sensors that ever show 15.)
>>
>> Typically, "calibration" involves minor adjustments to a sensor that is
>> basically working ok, like adding 0.7 hPA to pressure.  There is an
>> underlying assumption that the sensor has the right slope but just a
>> small offset.
>>
>> A UV sensor that reports a UV index of 15 at night sounds so seriously
>> off that it seems more likely that something is catastrophically wrong
>> which cannot reasonably be resolved with calibration.  I have not
>> checked calibration on my UV sensor, but it reliably shows 0 at night
>> and patterns that appear to corrrelate well with sunny vs not and sun
>> angle.  I would not be shocked if it reads 3.8 when it should read 4.0;
>> I would have to be far more thorough to figure that out, vs eyeballing
>> graphs and not being suspicious.
>>
>> I would recommend looking at all other ways of observing the sensor
>> value (console?), and see if there are any setup errors.
>>
>> Finally, I would log the data without calibration for a while, and graph
>> that in a scatter plot against UV data from some nearby station that you
>> believe is working ok.  If that turns out to be a line with slope 1 and
>> offset 15, then subtracting 15 is good strategy.  But until you know
>> that such a relationship holds, the assumption that there is a single
>> linear offset seems unwarranted.
>>
>> Greg
>>
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Re: [weewx-user] Re: UV index

[Damjan Hajsek]

Maybe we didn't understand right.
Station show real value of UV index on my terminal at home.
But not on my web page by weewx. So it is settings in weewx

Dne sreda, 11. april 2018 15.08.09 UTC+2 je oseba Greg Troxel napisala:
>
> Damjan Hajsek > writes: 
>
> > Anyone know what to use in 
> > [StdCalibrate] 
> > 
> > [[Corrections]] 
> > 
> > to correct UV index? Because now at night it is UV = 15 
>
> (I don't have any actual experience here, either with weewx calibration 
> or with UV sensors that ever show 15.) 
>
> Typically, "calibration" involves minor adjustments to a sensor that is 
> basically working ok, like adding 0.7 hPA to pressure.  There is an 
> underlying assumption that the sensor has the right slope but just a 
> small offset. 
>
> A UV sensor that reports a UV index of 15 at night sounds so seriously 
> off that it seems more likely that something is catastrophically wrong 
> which cannot reasonably be resolved with calibration.  I have not 
> checked calibration on my UV sensor, but it reliably shows 0 at night 
> and patterns that appear to corrrelate well with sunny vs not and sun 
> angle.  I would not be shocked if it reads 3.8 when it should read 4.0; 
> I would have to be far more thorough to figure that out, vs eyeballing 
> graphs and not being suspicious. 
>
> I would recommend looking at all other ways of observing the sensor 
> value (console?), and see if there are any setup errors. 
>
> Finally, I would log the data without calibration for a while, and graph 
> that in a scatter plot against UV data from some nearby station that you 
> believe is working ok.  If that turns out to be a line with slope 1 and 
> offset 15, then subtracting 15 is good strategy.  But until you know 
> that such a relationship holds, the assumption that there is a single 
> linear offset seems unwarranted. 
>
> Greg 
>

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Re: [weewx-user] Re: UV index

[Greg Troxel]

Damjan Hajsek  writes:

> Anyone know what to use in
> [StdCalibrate]
> 
> [[Corrections]]
>
> to correct UV index? Because now at night it is UV = 15

(I don't have any actual experience here, either with weewx calibration
or with UV sensors that ever show 15.)

Typically, "calibration" involves minor adjustments to a sensor that is
basically working ok, like adding 0.7 hPA to pressure.  There is an
underlying assumption that the sensor has the right slope but just a
small offset.

A UV sensor that reports a UV index of 15 at night sounds so seriously
off that it seems more likely that something is catastrophically wrong
which cannot reasonably be resolved with calibration.  I have not
checked calibration on my UV sensor, but it reliably shows 0 at night
and patterns that appear to corrrelate well with sunny vs not and sun
angle.  I would not be shocked if it reads 3.8 when it should read 4.0;
I would have to be far more thorough to figure that out, vs eyeballing
graphs and not being suspicious.

I would recommend looking at all other ways of observing the sensor
value (console?), and see if there are any setup errors.

Finally, I would log the data without calibration for a while, and graph
that in a scatter plot against UV data from some nearby station that you
believe is working ok.  If that turns out to be a line with slope 1 and
offset 15, then subtracting 15 is good strategy.  But until you know
that such a relationship holds, the assumption that there is a single
linear offset seems unwarranted.

Greg

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