Abstract: A speech amplifier circuit increases the maximum perceived loudness at the speaker (412) and reduces distortion at high volume levels without increasing the power consumed by the speech powder amplifier (410). When a low volume is selected by the volume control (414), the microcomputer (418) sets the step attenuator (406) at a correspondingly high attenuation level and the high-pass filter (408) is bypassed. As the volume control (414) is advanced and the speech power amplifier (410) is 12 dB into clipping, the microcomputer (418) activates the high-pass filter (408) and simultaneously steps the gain of the step attenuator (406) by 6 dB.

Abstract: A radar field of interest is divided into cells at a common range but at different angular spacings. The second derivative of the signal intensity of a radar return signal in each range cell is obtained by subtracting the signal intensity in the cell of interest from the signal intensity in the adjacent cell to obtain the first derivative and then subtracting the first derivative thus obtained from the subsequent first derivative. The second derivative is summed with subsequent second derivatives and further summed with the original return signal. The last sum is scaled, raised to an exponential value and again summed with the original return signal. The resultant signals from each range cell are reassembled to form a field of data corresponding to the radar field of interest.