• RFM69HW
• Moteino or another micro
• 2 Resistors (10ohms)
• Mosfet

• 2 resistors in parallel lying over the RFM69HW crystal acting as heaters
• Mosfet is used to connect the resistors to ground (they are connected to VCC as well) to complete the circuit and heat up the crystal.
• To control the temperature we use PWM to turn the mosfet on and off, the hotter we want the more often we turn the mosfet on.
• The control system uses a PID loop

• Using the PID v1 library on the arduino (using a moteino)
• Measuring temperature with the onboard RFM69HW temperature sensor
• Working well using a setpoint of 20C to test.

• Improve heating efficiency with better insulation
• Tighten the PID loop
• Use an external temperature sensor which maybe more accurate

• https://lowpowerlab.com/forum/index.php/topic,357.0.html

This section is more for documentation.

• 04/01/15 23:04 - AB → AH6,
  • AH6 reporting T-6
  • AB reporting T25

• In this screenshot its possible to appreciate the difference between the frequencies of the nodes, currently AB is only rx'ing 20% of AH6's beacons most likely due to the frequency difference.

• 05/01/15 07:34 - AB → AH6
  • AB = T24
  • AH6 = T1

• Comparing the 2 pictures
  • 1st image frequency difference was 27 pixels
  • 2nd image was 21 pixels