Abstract: A scrambling system for an audio frequency signal in which an audio signal is divided into blocks, each block being formed of a plurality of frames, the plurality of frames are rearranged on a timebase in a predetermined order at every block so as to be encoded and the encoded signal is re-arranged on the timebase in an original order so as to be decoded, in which there are provided a first signal processing circuit for inserting a redundant portion into a portion between adjoining frames and timebase-compressing the frames in response to the redundant portions upon encoding, a control signal generating circuit for inserting a control signal other than an audio information into the redundant portions, a control signal detecting circuit for detecting the control signal upon decoding and a second signal processing circuit for removing the redundant portions in synchronism with the detected control signal and timebase-expanding the frames in response to the redundant portions.

Abstract: Phoneme recognition uses the silence-phoneme and phoneme-phoneme transition spectral information rather than the phoneme information itself. The transition detector features first and second differences in level for each frequency band.

Abstract: A temperature-compensated crystal oscillator for correcting frequency variations caused by temperature changes by means of a differential amplifier which detects an unbalanced voltage in a bridge circuit including a temperature sensitive element for controlling a capacitance of a variable capacitor. The oscillator includes a circuit element having a temperature characteristic responsive to a temperature characteristic of the variable capacitor. The aforesaid circuit element is positioned in a current sink path of the differential amplifier.

Abstract: A printed circuit including a first conductor formed on an insulating plate as an inductance element, a second conductor formed on the insulating plate as an inductance element which is inductively coupled to the first element, and a common conductor formed on the insulating plate between the first and second elements and mutually inductively coupled to the first and second elements to provide a predetermined desired coefficient of coupling between the first and second elements. A preferred detailed form of the invention additionally includes printed capacitor elements in circuit with the inductance elements to provide an electric band-pass wave filter.

Abstract: A temperature compensated variable oscillator formed of at least two capacitors and a resonator, or vibrator, made of lithium tantalate, in which an inductance element whose inductance value can be varied is connected in series to the vibrator; the capacitance of one of said capacitors is changed linearly in response to temperature variations, and the capacitance of the other capacitor is changed in response to temperature variations, in accordance with a second order relationship between capacitance and temperature, the graphical representation of such relationship being a second degree curve opening upward.

Abstract: A variable band pass filter circuit utilizing first and second ceramic filters including a pair of passive circuits that can be selectively connected between the ceramic filters and wherein the first passive circuit comprises a first capacitor connected between the output of the first ceramic filter and the input of the second ceramic filter and the second passive circuit includes a second capacitor connectable between the output of the first ceramic filter and the input of the second ceramic filter and an inductor connected between the input of the second ceramic filter and a reference point.