Hi One advantage of doing all the compensation off of a single sensor is that *if* there are cross effects and *if* you can characterize them, you can correct them out. Put another way, if the pressure reading changes by 0.01% per C, having a reasonable idea of the temperature of the sensor lets you take care of that.
Things like sensor drift and sensor hysteresis … that’s not quite so easy to take care of. The only hope there is that they are small enough to be neglected. The same issue with hysteresis is actually a big limit on humidity compensation of some devices. They adsorb water vapor at a very different rate than they desorb. Modeling that can be really messy. Bob > On May 19, 2016, at 1:49 AM, Attila Kinali <att...@kinali.ch> wrote: > > On Thu, 19 May 2016 06:33:38 +0200 > "Björn Gabrielsson" <b...@lysator.liu.se> wrote: > > >> What are time-nuts using for monitoring the environment? > > The Sensirion SHT21 has become the gold standard silicon based > humidity sensor over the past years. Even though it's quite old > (IIRC close to 10 years) it has performance metrics that still > rival modern sensors. Its rather "large" package with the 1mm > pitch makes it one of the easier to solder sensors as well. > It's only drawback is its relatively large price of €6 > > As for barometric sensors, the ones by Measurment Specialities > are quite good. The MS5607-02BA03 for example does a resolution > of 2.4Pa with a long term stability of 100Pa/a. > There is also the MS5611-01BA03 which offers 1.2Pa resolution, > but also doubles the price and I am not so sure whether that > tiny bit more resolution is more than just noise. > > A little advice: If you want to measure pressure with high precision, > you should think about temperature stabilizing the sensor. > > The same is true for humidity, but does not work as well, as temperature > stabilization (aka heating) changes the relative humidity and thus > the measurement value depends quite a bit on how the air around the > sensor flows. > > Also, provide good and low noise power to the sensors. These are > precision instruments with high resolution ADCs. To work properly > they need a clean power source. > >> I have been playing a little with the Bosch BME280 - doing air pressure, >> temp and relative humidity in a small form factor. Easy to interface to >> Raspberry Pi or Arduino. > > The only Bosch sensor i've ever used was a BMA250 acceleration sensor. > It worked reasonably well, but i've never evaluated it for precision > or accuracy. But at least it looks like Bosch does not exagerate > in their datasheets. > > > Attila Kinali > -- > Reading can seriously damage your ignorance. > -- unknown > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.