Davis VP2 question

[Old Tele man]

OK, I've finally gotten my Davis VP2 assembled and operating, but I have a "newbie" question that I have not (yet) been able to find the answer to: from which data set, inside TEMP & RH or outside TEMP & RH, is the "single" dewpoint temperature (DEW) calculated?
 
Part of my confusion/concern is that the DEW value is displayed "within" the center indoor data box, not in the upper row outside data box. One would 'assume' (I know, I know) it's calculated from the outside data, but it's not discussed in the Davis pamphlets and their telephone help-line isn't open today (weekend).

I plan to operate the new Davis VP2 and the old OSI WMR200 systems "side-by-side" for awhile to collect data simultaneously, BEFORE I finally shut down the OSI outside. Fortunately, there are four 'other' CWOP VP2 stations nearby (closest 0.6 mile, furtherest 3.1 mile), so I will be able to directly compare my results with theirs, both singularly nd collectively averaged.

I'm expecting the %RH data from this VP2 to be more accurate than what the OSI WMR200 provided (!!lousy!!). The WMR200 will be retired to "indoor" use only where I'll use its 10-sensor capabilities to monitor indoor room temperatures for a/c-cooling distribution where %RH values aren't needed. Its sensor temps are fine but its sensor %RH values "suck" everywhere outside 25%-75%RH (that's only 50% range usefulness!), which totally eliminates its practical use as an outside weather system. Thus, IMHO, it is definitely NOT a PROFESSIONAL weather station, regardless of what they claim!
  

[moehoward4]

    Out side temp. and outside R/H are used for dewpoint

[SlowModem]

http://www.wxforum.net/index.php?topic=12193.0

[Old Tele man]

...a direct, simple answer! I love it, Thanks!

[d_l]

Actually the Davis WL software calculates both outside AND inside dew points using the respective temperatures and RHs.

[Old Tele man]

Actually the Davis WL software calculates both outside AND inside dew points using the respective temperatures and RHs.

...ah-ha, I haven't (yet) installed the WeatherLink software onto my WX-computer, so I appreciate the 'forewarned' info.

So, can I guess the s/w treats the two data sets separately, or does it assume the indoor DEW value is simply a rescaling of the outdoor air (constant water content)!?!

[d_l]

AFAIK, the indoor dew point uses only the indoor humidity and temperature as measured by the console or Envoy.  Graphs in WL can show either or both and the Browse summary lists both dew points.

[dalecoy]

A detailed explanation of how the console computes the outdoor dewpoint is contained in http://www.davisnet.com/product_documents/weather/app_notes/AN_28-derived-weather-variables.pdf

That's what is displayed on the console.

I am sure that WeatherLink software treats all of its recorded variables separately. 

[dalecoy]

A detailed explanation of how the console computes the outdoor dewpoint is contained in http://www.davisnet.com/product_documents/weather/app_notes/AN_28-derived-weather-variables.pdf

As far as I can tell, the WeatherLink software does not obtain the outdoor dewpoint from the console/logger. 

It appears that WeatherLink gets (inside and outside) temperature and humidity (and other related parameters) from the logger.  WeatherLink then computes the dewpoint (inside and outside) and stores all of that information. 

That makes a lot of sense.