2012 Temperature Tests
Contents
Initial Temperature Tests
Platinum Temperature Probe Test 1
Two experiments have been carried out to see whether the platinum sensor is working. Figure 1 shows the results of the first test. In this test, the probe was placed in a small peltier cooled fridge until ~hour 5. Using a physorg thermocouple the fridge temperature was approximately 1.3 degrees C. The probe was then removed at around hour 5 and placed in a freezer which was set at a temperature of around -18. The expected value of the probe was over 65535 and thus beyond the range of the 16-bit value. It was concerning to see values lying within the probes range. It can also be seen from this image, that the probe is inverting the temperature measurements.
The probe was continuously run until the battery flattened at around hour 13. A 2200mAH Lipo battery was used.
Platinum Temperature Probe Test 2
In this test, several different things were performed.
- The probe was encapsulated in a water tight box enclosure with a silica gel desiccant
- The code was modified to cycle the radio module on and off every 5 seconds and take and transmit 10 samples
- The radio was still on when the measurements were taken.
- The MCU was still on when the measurements were taken.
- The radio was powered on for over 2seconds before the measurements were taken.
- Two measurements were taken: a 12bit single ADC sample and a 16bit 16x Oversampled reading.
In this test we think that the radio being on influences the temperature measurement. We also believe that the 16x oversampled value gives a better estimation of the temperature value.
Platinum Temperature Probe Test 3
test with whole probe sleeping and waking while in a cooled bath of antifreeze starting at around -10C. Bath measured with an accurate thermometer manually.
