Tracking: Shows the current tracking mode as well as the ability to change the tracking mode. Details on the tracking modes and how they affect power output to the dew strap ports follows. The information is taken from the myDCP4ESP32 documentation, © Robert Brown.
Determining how much power to apply to the Dew Straps
There needs to be a way to calculate how much power to apply to the dew straps based on some value (tracking mode) as well as a range of temperature bands (range) over which the dew strap power is altered.
In general, most dew controllers operate relative to the dew point temperature, and try to maintain the telescope optics temperature at some delta point above the dew point. The myDCP4ESP32 controller has three different methods of maintaining optics temperature which are
- Dew point
Users are advised to spend an evening session monitoring the values, trying various tracking modes and offset values to determine what they feel is best for their equipment setup. Having the flexibility of adjustment provided by the myDCP4ESP32 unit should meet even the most demanding of situations.
Temperature Tracking Algorithms
Power output to a dew controller channel is determined by the tracking mode and the adjusted temperature of channels temperature probe. The output is determined as indicated in the following table.
Power output for a channel is determined by the number of degrees celsius the probe temperature is below ambient temperature. If the probe temperature is 5 degrees below ambient then the power output is set to 50% for the dew strap port.
Power output for a channel is determined by the number of degrees celsius the probe temperature is away from the calculated dew point temperature. As the probe temperature drops towards the dew point power to the dew strap port is increased until it reaches 100% at 1 degree above the dew point.
Power output for a channel is determined by the number of degrees celsius the probe temperature is relative to the midpoint between the ambient temperature and the dew point. If the ambient temperature is 20℃ and the dew point is 2℃ then the midpoint is 11℃, AT-(AT-DP)/2. If the probe temperature is at or above 20℃ then output is 0% but as the probe temperature drops below 17℃ ,AT<3, power is set to 10%. When the probe temperature drops to the midpoint, 11℃, then power is set to 20% until probe temperature drops to 9℃, AT-(((AT-DP)/2)+2) where power is set to 50%. At the dew point, 2℃, and below power is 100%.
Tracking offset is set in the Options tab and affects the algorithms by adjusting them by the offset. For example with Ambient tracking a tracking offset of 3 would adjust the ambient algorithm up 3℃. This would cause output to be 10% at 2℃ above ambient temperature instead of 1℃ below ambient temperature.