Comparing sensor readings side by side & the beauty of choice - Printable Version
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Comparing sensor readings side by side & the beauty of choice - hvalentim - 12-03-2015
Today I placed one SHT15 and one DHT22 side by side, let them settle a while and then measured values read over 10 minutes in 2 second intervals and did some averages.
Under my room particular circumstances, results show the SHT reporting a difference compared to the DHT of approximately +3.8% in Humidity and +1,9% in temperature.
I understand many of you have done similar exercises, probably in a more reliable/detailed way and over more extended periods of time. Short of benchmarking the different chips under a controlled environment and against a perfectly accurate instrument, which is not easy, this is nevertheless an interesting exercise.
So, does anyone have more such comparisons to share? Perhaps even from running stations?
In the end, having the ability to compare, make up our own mind and hand-pick stuff is the beauty that makes a system such as WeatherDuino effectively far more powerful and interesting that any other pre-built weather station.
DHT22
Avg. Temp. (ºC): 14,95
Avg. Hum. (%): 62,27
STD Temp: 0,049924883
STD Hum.: 0,212347547
SHT15
Avg. Temp. (ºC): 15,24
Avg. Hum. (%): 64,63
STD Temp.: 0,06831321
STD Hum.: 0,272655715
DHT22 Values - SHT15 Values
Avg. Temp. (ºC): -0,29
Avg. Hum. (%): -2,36
RE: Comparing sensor readings side by side & the beauty of choice - hamix - 01-07-2015
I use SHT11 (out) and DHT22 (in) and I tested these sensors under same conditions. (All three sensors are on my desk.)
Results are:
Inside temperature sensor: 24.2°C, 50.2 %H (DHT22)
Outside temperature sensor: 24.0 °C, 56.7 %H (SHT11)
Case temperature sensor: 26.3°C (TMP36)
There is an offset options for inside temperature sensor at Config_RX.h file but there is not for other sensors. I think that the differences are not negligible.
Any advice/hint would be appreciated.
RE: Comparing sensor readings side by side & the beauty of choice - werk_ag - 01-07-2015
hamix,
The readings from the TMP36 are intended to be merely indicative of the temperature inside the TX unit box. The way we deal with the readings from this sensor may lead to some imprecisions. Don't compare it with more precise sensors.
Regarding the two other sensors, trust in the readings of the SHT11.
According to my experience, the DHT22 is a good sensor but somewhat inaccurate in RH readings, also not suitable to be used outside for long time, specially in places with constant high RH levels.