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Oregon Scientific Temperature accuracy

Discussion specific to Oregon Scientific weather stations
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callum91
Posts: 57
Joined: Sat 07 Nov 2009 7:14 pm
Weather Station: WMR88
Operating System: Windows 7
Location: Oundle, Peterborough

Oregon Scientific Temperature accuracy

Post by callum91 » Fri 11 Apr 2014 4:37 pm

Hi

I have decided to run a little test of the accuracy of the temperature sensor/hygrometer. I currently have a WMR88 temperature sensor (Sensor 1) housed in a small wooden radiation screen and I have now added to the radiation screen a small cheap LCD temperature sensor/hygrometer from eBay which also has a Max/Min function and I shall now refer to as Sensor 2.

Observations so far:
  1. Sensor 2 seems to respond more rapidly to temperature changes than Sensor 1 (i.e. when being handled)
  • Sensor 2 consistently reads temperatures 0.6 °C to 1.1 °C lower than Sensor 1 and humidity the same or slightly higher.
  • Sensor 2 temperatures are closer to readings from the local official Met Office site
09/04/14 1200L: Sensor 1 = 14.6 °C Sensor 2 = 13.8 °C
09/04/14 2000L: Sensor 1 = 13.7 °C Sensor 2 = 12.7 °C
10/04/14 0800L: Sensor 1 = 5.6 °C Sensor 2 = 4.7 °C
10/04/14 2100L: Sensor 1 = 11.9 °C Sensor 2 = 11.0 °C
11/04/14 0700L: Sensor 1 = 9.5 °C Sensor 2 = 8.4 °C
11/04/14 1700L: Sensor 1 = 14.9 °C Sensor 2 = 14.1 °C

I know it's only a relatively small difference but it seems strange considering both sensors are in the same screen and about 1 inch apart. Could it be that the cheaper LCD sensor is more accurate?

thegasman
Posts: 23
Joined: Sun 24 Mar 2013 6:42 pm
Weather Station: WMR88
Operating System: Raspbian on Pi2
Location: Ayr, Scotland, United Kingdom
Contact:

Re: Oregon Scientific Temperature accuracy

Post by thegasman » Sun 13 Apr 2014 10:39 am

The only way to find out would be a third sensor and see if it agrees with one of the other two.
As for agreeing with met office, there are so many factors that affect temperatures that you probably would get different readings from one side of your house to the other other, never mind a few miles away.

Martin

callum91
Posts: 57
Joined: Sat 07 Nov 2009 7:14 pm
Weather Station: WMR88
Operating System: Windows 7
Location: Oundle, Peterborough

Re: Oregon Scientific Temperature accuracy

Post by callum91 » Sun 13 Apr 2014 11:53 am

Yes I was thinking the same thing. I need a 3rd sensor of a different kind (maybe a mercury thermometer) or a sensor produced by a different manufacturer.

Thanks,

Callum

Spider-Vice
Posts: 207
Joined: Sat 24 Sep 2011 2:46 pm
Weather Station: PCE FWS-20 (Fine Offset)
Operating System: Windows 10

Re: Oregon Scientific Temperature accuracy

Post by Spider-Vice » Sun 13 Apr 2014 1:36 pm

There are types of sensors that work differently. It's possible your LCD sensor uses the same kind of sensor that is used in vehicles and things like industrial fridges, that need rapid response, and aren't really made to be used in a meteorological environment. It could explain the differences, especially the differences in response.
I'd say that the Oregon sensor is more accurate, also because of the "slowness" it responds with, as to probably measure a more accurate figure, and not a snapshot like the LCD sensor probably does.

jrhilton
Posts: 17
Joined: Thu 31 Jul 2014 4:25 pm
Weather Station: Custom build + old Oregon WMR88
Operating System: Windows 10 / Linux
Location: London

Re: Oregon Scientific Temperature accuracy

Post by jrhilton » Fri 01 Aug 2014 7:24 pm

For what it is worth I have compared my WMR88's wireless thermometer to a calibrated digital thermometer I own and the results were almost identical. Pretty good for a station that only cost £59.99 in my opinion. It was also very close to my old 1-wire system which I have kept running.

The only thing I did notice is it doesn't pick up small quick spikes, which I pesume is because the sensor is inside the pastic case where as my calibrated one has a probe and my 1-wire was simply at the end of the wire with no case. I know some people do mod their sensors to expose the actual sensor more which would probably help.

I have no way to test the humidity sensor though.

I've always said good sensor location and shielding is more important than a sensor being +-0.1 degrees correct for an ammeter observer anyway.

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