Abstract: A system is provided for extending the playing time of standardized video cassettes. The system utilizes a rotating head drum having mounted thereon a first set of video heads displaced 180.degree. with respect to each other, a second set of video heads displaced by a certain amount from 180.degree. with respect to each other, a rotating winding of a transformer, and relays to interconnect the heads of either the first or second set of heads with the rotating winding as the head drum rotates. The relays are controlled by stationary coils and logic to respond to the setting of switches to enable the system to operate at normal tape speed via the first set of heads or reduced tape speed via the second set of heads without requiring any change in the speed of rotation of the head drum.

Abstract: An apparatus for reconnoitering terrain from a moving aircraft is provided. The apparatus comprises a mirror arrangement perpendicular to the object plane of the terrain under observation and means for the stepwise tilting of the mirror about an axis perpendicular to the terrain. The apparatus further includes a television camera having an optic axis directed at the mirror and inclined at an angle with respect to the terrain. Means interconnect the camera and tilting means to activate the camera only when the mirror is stopped in a position.

Abstract: A helical scan recording and playback apparatus wherein magnetic video tape forms a helix about the peripheral surfaces of two coaxial drums which define an annular gap for magnetic heads which orbit in a chamber between the drums and engage inclined tracks at the inner side of the helix. The heads are mounted on a disk which is rotatable on a sleeve surrounding with clearance a shaft for the drums and having an internal protuberance which is tiltable with respect to the periphery of the shaft by a rod extending through an opening in the flange of one of the drums. The inclination of the plane of orbital movement of the heads relative to the central symmetry plane of the gap is changed when the speed of lengthwise movement of tape during playback deviates from the speed of lengthwise movement of tape during recording.

Abstract: Received signal is filtered by a filter tuned to a predetermined harmonic the modulation frequency lying outside of the modulation region of the received signal. Such harmonic results from modulation distortion due to multipath reception. Output of filter is irregularly occurring pulse sequence which is converted to a constant signal which in turn energizes an indicator.

Abstract: An apparatus is provided for recording on videotape to insure the absence phase error between different sequences in the assembling mode. The apparatus includes a reference pulse source and circuitry to apply reference pulses from the source to a first recording of the tape through a fixed transducer head for recording and playback. The reference pulses also control the speed of the motor driving the tape through a servo mechanism. A tachometer-generator is operatively connected to the motor to produce a train of pulses related to the motor speed at a frequency comprising a fixed integer multiple of the frequency of the reference pulses. The output of the tachometer is fed to a counter which divides the tachometer pulses by the fixed integer so that the output of the counter represents a train of pulses, the frequency of which is equal to that of the reference pulses.