Power conserving adaptive control system for generating signal in portable medical devices

A method for adjusting power emitted by a light emitting device used for medical applications, comprising the steps of:

• determining a characteristic of a signal associated with a physiological parameter measured using light produced by the light emitting device,
• generating a control signal representing the characteristic of the signal, and
• providing the control signal to a power unit coupled to the light emitting device and providing power to the light emitting device and adjusting the power provided to the light emitting device in accordance with the control signal.

In a device for monitoring a patient parameter including a signal source for emitting a monitoring signal and a sensor for receiving a modulated signal representing the emitted monitoring signal modulated by the parameter, a method for controlling a signal characteristic of the emitted monitoring signal, comprising the steps of:

• measuring received signal characteristics of the modulated signal,
• evaluating the received signal characteristics of the modulated signal with respect to required signal characteristics of the modulated signal for generating the parameter output,
• controlling an emitted signal characteristic of the emitted monitoring signal so that the received modulated signal possesses the required signal characteristics.

The emitted monitoring signal controller of claim- 17 for controlling a signal characteristic of the emitted monitoring signal, further comprising the steps of:

• decreasing the emitted signal power level when the received signal characteristics of the modulated signal exceed the required signal characteristics for generation of the parameter output, and
• increasing the emitted signal power level when the received signal characteristics of the modulated signal are lower than the required signal characteristics for generation of the parameter output.