Abstract: A respiration monitor that indicates respiration or loss of respiration by detecting carbon dioxide in expired air in an endotracheal tube comprises a tubular member adapted to receive respired air from an endotracheal tube and having diametrically opposed planar windows substantially transparent to infrared radiation; an infrared analyzer comprising a source means for producing an unmodulated beam of infrared radiation passing through the planar windows and respired air, and a solid state detector means to receive infrared radiation after passage through said windows and respired air and to generate an output signal in response to the presence of CO.sub.2 in respired air, means for detecting the time between signals generated by said detector, and alarm means responsive to a predetermined delay between said signals.

Abstract: An AM broadcast transmitter uses a PWM modulator that requires a pulse width filter. It has been found that the filter load varies over the modulation cycle resulting in distortion. To overcome this problem, a varying voltage is applied to an RF driver stage during portions of the modulation cycle.

Abstract: An audio waveform is modified before being applied to a typical FM stereo generator having a low-pass filter which normally produces ringing in response to a clipped signal by pre-emphasizing the audio and reducing the level of that pre-emphasized audio when reaching the maximum allowable modulating signal level. This pre-emphasized audio level is reduced by an amount determined by the ringing in the low-pass filter in the stereo generator to follow.

Abstract: An audio processor for an FM stereo system including a peak clipping circuit to prevent overmodulation further includes means responsive to the audio signal before and after the clipping means for detecting the amount of energy lost due to peak clipping and gain control means for reducing the amplitude level of the clipped audio signal in proportion to the peak energy lost to prevent overmodulation due to the shifting of the entire signal level which is associated with any asymmetry of the clipped signal.