Abstract: An audio signal processing device extracts a first series of frequency components from a first input signal with a high signal-to-noise ratio and a second series of frequency components from a second signal with a low signal-to-noise ratio. A middle-amplitude slice of each of the first series is extracted by limiting the amplitude of each to a lower threshold level, subtracting the result from the signal before limiting, and limiting the amplitude of this difference to an upper threshold level. The gain of each middle-amplitude slice is controlled in response to noise from a second input signal. Each result of controlling the gain is added to a corresponding frequency component extracted from the second input signal. Each frequency component of the second input signal is amplitude-limited and the result subtracted from a corresponding result of adding.

Abstract: A circuit for detecting a specified color in a color image signal operates on first, second and third primary color signals from a color camera. A complementary color, resulting from additive mixing of two primary colors, is detected by taking the sum and differences of the signal representing the two primary colors. The third primary signal is subtracted from the sum signal to produce a vector sum signal and the difference signal is rectified. The signal which indicates the presence of a complementary color is generated by subtracting the rectified signal from the vector sum signal and comparing it to a fixed reference level. A primary color is detected by subtracting the sum signal from the third primary signal to produce the vector sum signal. Fine adjustment of the target color is obtained by amplifying the two primary color signals differentially to maintain a constant sum of the two primary color signals.

Abstract: An equalizing circuit is disclosed, in which a received signal is divided into high frequency components in different bands and a low frequency component; after having subjecting the high frequency components to a predetermined signal processing, they are amplitude-modulated, based on amplitudes thereof; and amplitude modulated signals thus obtained and the low frequency component are combined to obtain a synthesized signal. By effecting such a equalizing processing, it is possible to make the reproduced image quality of a video signal more distinct and to make an audio signal, whose band is restricted, have richer sound quality.

Abstract: In a DA converting circuit using a PAM circuit and low pass filters, an analogue signal of high quality can be obtained by removing ringing due to the cut-off frequency of the filters. A PAM signal outputted by the PAM circuit is switched on and off by a plurality of electronic switches arranged in parallel. Further outputs thereof are combined by an adding circuit through a plurality of LPFs to obtain a synthesized analogue signal. The inputs and the outputs of the LPFs described above are turned on and off by a plurality of electronic switches linked with each other. The different switches are driven by pulses produced from a clock signal, corresponding to a sampling frequency for the PAM circuit.

Abstract: In a ghost detector, synchronous detection is performed on a received video signal to provide a detected signal which is then converted to a band-limited signal having a predetermined bandwidth, a scanning synchronous component signal is extracted from the detected signal to provide a switching control signal for a ghost component detecting period on the basis of the synchronous component signal, and the band-limited signal is switched in response to the switching control signal so as to provide a switching signal.

Abstract: A low frequency compensating circuit for audio signals is disclosed, which comprises frequency component separating means for separating an audio signal coming from a predetermined audio signal source into a low frequency component signal under a predetermined frequency and a high frequency component signal over the predetermined frequency to output separately the low frequency component signal and the high frequency component signal; variable delaying means for delaying the low frequency component signal so that delay time increases with increasing frequency; fixed delaying means for delaying the high frequency component signal by a fixed delay time, which is almost equal to the delay time set for the predetermined frequency by the variable delaying means; and synthesizing means for combining delayed signals outputted by the two delaying means. In this way, clearness and crispness are obtained for the low frequency region and at the same time sound doesn't become unnatural for the high frequency region.

Abstract: An FM stereo receiving device according to the present invention has an object to be able to demodulate a stereo signal in a state close to a monaural reception, in which a pilot signal is extracted from an FM-demodulated output; a subcarrier signal is formed, based on this pilot signal; IF signals are switched intermittently by this subcarrier signal; and intermittent IF signals are IF-detected to obtain intermittent signals of base-band signals.These intermittent signals are switched by means of two switches, based on a subcarrier signal. Low frequency components of each output audio signal are extracted to obtain left and right signals EL and ER through a de-emphasis circuit.Owing to this device, it is possible to enlarge a reception region for an FM stereo broadcast with a high sensitivity.

Abstract: In a device for inverting the scanning direction of NTSC signals, signals for every line are converted into digital signals to be stored, which are read out inversely in time. The digital signals thus read out are transformed into a pulse train (sampling signals) having a clock frequency of 4fsc by means of a D/A converter, from which the brightness component is separated by means of a low pass filter. A pulse train of 4fsc of color modulated wave is obtained by forming the difference between the brightness component and the output of the D/A converter. The color modulated wave is obtained through a band pass filter, whose central frequency is fs, after having inverted alternately the pulses in this pulse train in the polarity.

Abstract: In a device for inverting the scanning direction of NTSC signals, signals for every line are converted into digital signals to be stored, which are read out inversely in time. The digital signals thus read out are transformed into a pulse train (sampling signals) having a clock frequency of 4fsc by means of a D/A converter, from which the brightness component is separated by means of a low pass filter. A pulse train of 4fsc of color modulated wave is obtained by forming the difference between the brightness component and the output of the D/A converter. The color modulated wave is obtained through a band pass filter, whose central frequency is fs, after having inverted alternately the pulses in this pulse train in the polarity.

Abstract: In an FM stereo receiving device according to the present invention, a received first FM-modulated wave is demodulated by means of an FM-demodulator, from the demodulated output of which a subcarrier signal is produced, further a monaural signal is extracted by means of an LPF, and the monaural signal is again FM-modulated by means of a voltage controlled oscillator to obtain a second FM-modulated wave. Then a difference frequency component wave is produced by a multiplication operator and an LPF, starting from the first FM-modulated wave and the second FM-modulated wave and the FM-modulated wave and the difference frequency component wave are switched over with the subcarrier signal by means of a switch circuit. In this way signals of a right ear side component and a left ear side component are obtained and a stereo signal is obtained by FM-demodulating both the signals by means of the FM-demodulator.

Abstract: A magnetic recording reproduction device is disclosed, in which the rotation axis of the motor is disposed substantially parallelly to the base plate and the diameter of the drum holding rotary heads is reduced to a half of that utilized heretofore, owing to a construction of the tape driving system, by which the tape is wound around the drum after having been bent approximately by 90.degree. and twisted approximately by 90.degree..

Abstract: An analog-to-digital conversion system for converting an analog signal to a digital signal for recording is configured to detect a low level period of the analog signal, amplify a low noise in the analog signal in the detected period by a predetermined multiplying ratio or by an amount corresponding to the signal amplitude, and subtract from the converted digital signal a number of bits corresponding to the amplification degree in the same period after analog-to-digital conversion, so as to reduce the influence of a noise entering in the analog signal before analog-to-digital conversion.