01 / Calm
Lower-risk conditions
Heating begins below approximately 3.0 °C spread and reaches full demand around 0.5 °C.
Lab Build / 01
Automatic Optical Dew-Control System.
A field-validated embedded controller that turns environmental conditions into automatic, proportional heating at telescope optics.
Build Architecture
Environmental signal becomes physical action.
EDS supplies current observing conditions. Device-local logic evaluates dew risk, regulates demand, and applies heat through an embedded power stage at the telescope.
Environment-responsive control path / Current prototype- 01 / Environmental State EDS observing telemetry Temperature, dew point, humidity, and data freshness
- 02 / Device Decision Dew spread and control state Profile, hysteresis, and input validity
- 03 / Heater Demand 0% Off or 50–100% active Continuous proportional automatic demand
- 04 / Electrical Actuation ESP32 PWM and power stage Logic-level command translated into heater power
- 05 / Optical Protection Heat applied at the telescope Physical response around the optical assembly
Why It Exists
Dew is an environmental problem with an optical consequence.
Astrophotography sessions operate close to changing ambient conditions. As the air temperature approaches the dew point, exposed optical surfaces can collect moisture and lose contrast or become unusable for the session.
A fixed heater setting treats every night as the same night. This build instead connects current environmental observations to device-local regulation. It heats only when the selected risk profile calls for it and changes output as the temperature-to-dew-point spread changes.
The result is not simply a PWM controller. It is a complete path from environmental sensing to a bounded decision, electrical actuation, local operator feedback, and field hardware at the telescope.
- Input
- EDS observing conditions
- Decision
- Dew spread / profile / data state
- Output
- Off or proportional heater demand
- Interfaces
- OLED / Web / ASCOM Alpaca
Automatic Regulation
An explicit Off state. A continuous active range.
Auto separates the decision to heat from the amount of heat. When no heat is required, output is exactly zero. Once active, demand is continuously mapped across the effective 50–100% range of the reference heater. Its stock Low, Medium, and High positions correspond approximately to 50%, 75%, and 100%; this controller regulates between those reference points.
No heating required
0%
Explicit Off
Active Auto heating
50–100%
Continuously proportional
Observing Profiles
Profiles change when heating begins and how quickly the full-power region is reached. They are not three fixed heater levels.
02 / Crisp
Balanced response
Heating begins below approximately 5.0 °C spread and reaches full demand around 1.0 °C.
03 / Paranoid
Earlier protection
Heating begins below approximately 7.0 °C spread and reaches full demand around 2.0 °C.
Control Boundaries
More than an on/off threshold.
The control policy includes explicit operating states and data-quality boundaries so an automatic decision cannot silently outlive its input.
Explicit Off
No-heat decisions bypass ramping and command zero output directly.
Proportional control
Active demand changes continuously rather than selecting Low, Medium, or High steps.
Stable transitions
Hysteresis and bounded ramping prevent rapid switching and abrupt active-domain changes.
Expired-data Off
Freshness is tracked with the observation. Expired EDS data exits Auto and commands Off.
Manual override
The operator can leave Auto, select a direct heater output, or command Off at any time.
Physical Build
Embedded control carried through to field hardware.
The prototype combines low-voltage logic, a separately powered heater path, local status, and telescope-side integration. The ESP32 commands the load; it does not supply heater current directly.
ESP32
Runs control policy, network services, local feedback, and observatory integration.
PWM power stage
Translates logic-level demand into controlled power for the heater strap.
OLED status
Shows operating state, output, network condition, and EDS availability at the device.
Telescope heater
Applies the regulated thermal output around the optical assembly during observing.
Software & Interoperability
One embedded device. Several control surfaces.
The firmware keeps automatic policy, manual operation, device feedback, and observatory interoperability in one bounded controller.
-
01 / Firmware
Off, Manual, and Auto modes
Device-local control with profile selection, smoothing, freshness handling, and safe boot.
-
02 / Local
OLED status and dark-sky display
Immediate device state without requiring the observatory computer.
-
03 / Browser
Device-hosted web control
Mode, output, environmental state, and display settings on the trusted local network.
-
04 / Observatory
ASCOM Alpaca / N.I.N.A.
Network discovery and interoperable control from the imaging workflow.
-
05 / Environment
EDS observing input
Current conditions and data age fetched from EDS and validated by the controller.
EDS Integration
Environmental intelligence into physical response.
The projects remain separate. EDS publishes environmental observations; this external build decides how to regulate its heater and owns the electrical actuation at the telescope.
Observe and publish
Current environmental state and freshness are made available over the network.
Decide and regulate
The embedded controller turns dew spread and profile into bounded heater demand.
Act at the optics
The power stage applies the requested thermal response at the telescope.
Field State
A working prototype tested in an observing setup.
The controller has moved beyond bench logic into outdoor astrophotography use, where network availability, display brightness, cabling, heater response, and observatory software all become part of the engineering problem.
Current status
Field-validated prototype
Operational build / Iteration continues
Field validation confirms that the architecture can operate as one integrated build. It is not a claim of universal heater compatibility, certified safety, or guaranteed dew prevention.
The current implementation is purpose-built around a reference heater, an ESP32 controller, EDS observing data, and a trusted observatory network.
Collaboration
Embedded control, observatory integration, and field prototypes.
MDNT is open to focused technical discussion around environmental automation, embedded controls, ASCOM Alpaca interoperability, and field-tested cyber-physical builds.
- Environmental device-control patterns
- Embedded firmware and power-stage integration
- ASCOM Alpaca interoperability
- Observatory field testing
PGP contact details are available on the MDNT contact section.