Abstract: A method and an apparatus for detecting a defect of a magnetic tape which is loaded in a dictating machine for recording and reproducing dictations. In the event of initialization, the tape is automatically transported in a fast forward mode for a predetermined period of time and, then, a counter is loaded with an initial value. Thereafter, the tape is rewound while, at the same time, the counter counts reel rotation detection pulses. The tape is decided to be defective when the count of the counter at beginning of tape does not lie in a predetermined range, and free from defects when the count lies in the predetermined range. In an operation mode after the initialization, presence/absence of the pulses is detected.

Abstract: In an apparatus for automatically supplying and selectively reproducing a plurality of cassettes, the error rate for each cassette and for each reproduction is automatically generated and stored in a separate area of a memory and, when the error rate exceeds a threshold rate, the deteriorating cassettes are automatically dubbed onto blank cassettes to ensure that deterioration of each tape or other record medium never exceeds a predetermined amount. In addition, the operator may independently cause any cassette to be dubbed when he deems the image produced therefrom to be too highly degraded regardless of the error rate of the signal recorded therein.

Abstract: A method and circuit arrangements for detecting and evaluating dropouts or drop-ins on recording media, comprising reading and modifying the recorded digital signals, the size and type of fault being evaluated on the basis of fixed threshold levels. In the case of a dropout, for example, the fault is weighted by determining the differential of the envelope of the read signal. In the case of a drop-in, other noise signals are left out of consideration by nonlinear emphasis of the drop-in and appropriate choice of the threshold value. A circuit combination enables both dropouts and drop-ins to be detected and evaluated.

Abstract: A completely automated apparatus for disk certification which has a very high volume production per unit area of square footage required. Volumes of 108 million disks per year require only 1200 square feet of facility, about 3% of the space required for the prior art certification systems. The apparatus uses standard unmodified disk drives and is completely integrated with a conveyor and pickup system for automatic loading and unloading of diskettes. A method of sequencing operations on a disk is disclosed whereby all tracks of disk are written to provide a first test signal. Then all tracks are read after all tracks are written to provide a first read signal. Calculations are performed on the first read signal to obtain a calculated signal and the calculated signal is compared with a known standard.

Abstract: A system for evaluating a recording system is disclosed, which includes a monostable multivibrator (MMV) for receiving the recovered data stream from the disc drive. The time constant of the MMV is controlled by a second, matched MMV which receives a fixed frequency input. By applying the output of this matched MMV to another input of the MMV receiving the recovered data, the time constant of the first multivibrator may be adjusted with the delay being a function of the period of the input frequency to the second multivibrator.

Abstract: A light beam is made to impinge upon a light reflecting section of a magnetic head provided with a magnetic layer having the light reflecting section on the surface. A change in characteristics of the light beam reflected by the light reflecting section, which is caused by the Kerr effect in accordance with a change in internal magnetization of the magnetic layer, is detected photoelectrically. Magnetic characteristics of the magnetic head are measured on the basis of the detected change in characteristics of the reflected light beam.

Abstract: A method and circuit arrangements for detecting and evaluating dropouts or drop-ins on recording media, comprising reading and modifying the recorded digital signals, the size and type of fault being evaluated on the basis of fixed threshold levels. In the case of a dropout, for example, the fault is weighted by determining the differential of the envelope of the read signal. In the case of a drop-in, other noise signals are left out of consideration by nonlinear emphasis of the drop-in and appropriate choice of the threshold value. A circuit combination enables both dropouts and drop-ins to be detected and evaluated.

Abstract: A glide head is used to test a rigid magnetic disk surface for projecting asperities. Using a two rail head with the read/write transducer mounted at the rear of the rail at the side of the head toward which the head is being radially advanced and skewing the head so that the trailing edge of the head approaches each track before the leading edge as the head is advanced, it is possible to write a pattern from a known position relative an event or asperity identified by a mechanical transducer associated with the head to the index location. Using a developer, it is then possible to readily identify the asperity during microscopic examination of the disk surface.

Abstract: A novel tape testing apparatus of the type which senses errors, stops the tape, and causes the error to be moved to an error-correction or an error-inspection station. The apparatus of the invention is characterized by means to rapidly try to remove the error by additional passes through an error removal station and then, if necessary bring the error-bearing portion of the tape precisely under an inspection station by a precise distance-metering process.

Abstract: A magnetic storage indicator (40) is disclosed for use on a recording tape processing apparatus, such as a cassette winder (10). Magnetic storage indicator (40) comprises a recording head (50) and a downstream playback head (51). Signals received at the playback head (51) are transmitted to a pre-amplifier (60), an equalization circuit (70) and a record amplifier (80) and then back to the recording head (50) where the amplified signal is recorded onto the moving tape. If the oxide layer is on the side of the tape in contact with the record head (50) and the playback head (51) a feedback loop is completed, causing the circuit to oscillate. This condition is transmitted to a light emitting diode (48) indicating that the tape is properly wound.

Abstract: A read-write head is provided with a plurality of piezoelectric transducers which produce signals related to its movement as it flies over an adjacently rotating recording disk. By filtering these signals to determine their spectral components in low, medium and high ranges, hard contacts between the head and disk, disk wear or roughness and head movement can be determined.

Abstract: A method and apparatus for automatic high speed inspection of information recorded on magnetic video tape to determine if the original recording has been altered by erasure or over-recording has been added to in a previously unrecorded portion of the tape. To facilitate the inspection, a low frequency signal is added to the audio track of the tape at the time the original recording is made. Inspection consists of sensing the tape's video control track and the audio track containing the added low frequency signal while rewinding the tape at high speed. During rewind, sensing means positioned on the backside or non-oxide coated surface of the tape receives signals from both the video control track and audio track. The detected signals are processed by an error detection circuit where they are analyzed to determine the tape speed, control track pulse amplitude, audio signal amplitude, control track pulse pattern, and low frequency audio signal pattern.

Abstract: A process for authenticating recording media which are to be safeguarded against falsification and which possess discrete regions of an exchange-anisotropic magnetic material, by comparison of the polarity of a residual magnetization which is left over, because of the exchange anisotropy of the magnetic material, from a predetermined initial magnetization after exposure of the material to a specific temperature cycle and, subsequently, to a magnetic AC field which decreases to zero, with the polarity of a residual magnetization formed in the same way from an opposite initial magnetization, and an apparatus for carrying out the said process.

Abstract: The magnetic intensity in a succession of strips (12) in an article (10) is measured by producing relative motion between the article (10) and a magnetic sensing head (23) to produce a succession of first voltage waveforms. Each such waveform has a shape substantially characterized by the positions of the poles (13 and 14) in a respective strip (12). Each incremental portion of the shape has an amplitude proportional to the magnetic intensity sensed along the surface of the strip (12) and to the instantaneous speed of the relative motion between the sensing head (23) and such surface. By coupling a generator (31) to the article (10), a second voltage waveform is produced having a shape for each strip, wherein each incremental portion has an amplitude proportional to an instantaneous speed equivalent to the speed producing the first voltage waveform for the respective strip (12).

Abstract: The unit for testing a plurality of tracks of a high-speed recorder in parallel comprises an emission subassembly for the transmission of data to the recorder to be tested and a test subassembly. The emission subassembly mainly comprises a generator for producing a pseudo-random or ramp-function sequence of binary numbers consisting of a plurality of binary elements in parallel. The test subassembly comprises a data storage device for storing the data reproduced by the tested recorder, a second generator programmed in the same manner as the first, a device for comparing the reproduced sequence with the emitted sequence and an error analysis device which delivers a measurement of the error rate and serves to locate the detected errors.

Abstract: A system for testing magnetic tape comprising a pair of magnetic head assemblies positioned at a fixed length along the path of magnetic recording tape. A read-out signal of the first magnetic head is delayed by a delay circuit by time t=l/V, where l is the length between the first magnetic head and the second magnetic head, and V is the tape feeding speed. A logical AND circuit and a logical exclusive-OR circuit are provided for receiving the output of the delay circuit and the read-out signal of the second magnetic head. When the AND circuit provides an output signal, it is recognized that both the first and second magnetic heads have sensed a permanent defect. When the exclusive-OR circuit provides an output signal, it is recognized that either the first magnetic head or second magnetic head has sensed a temporary defect. Accordingly, both a permanent defect and a temporary defect are detected by running magnetic tape only once in a predetermined direction.

Abstract: The invention relates to a method of contact-free, almost continuous measurement and monitoring of the width, thickness and position of magnetic tracks on moving film strips within wide limits of the speed. The track width and track position of the magnetic tracks are measured optically and the magnetically acting track cross section is measured electromagnetically via the track volume. The measured values are together recorded, evaluated and displayed and/or used for recontrolling the casting arrangement for emitting warning signals or for stopping the coating machine.

Abstract: Process and apparatus for detecting and evaluating defects in memory-retaining characteristics of magnetic tape, said process and apparatus providing means for sensing an initial error in a first track of the tape and then relating the initial error to all other errors which are sensed in other tracks of the tape within a preselected segment of tape the start of which coincides with the location of the initial error. Each of the other sensed errors within the segment defined by the initial error defines its own error evaluation segment over which it is evaluated. Thus, depending upon the error content of the tape, a plurality of overlapping error evaluation segments may be defined. Each error sensed on the tape is processed and categorized as either a one-, two- or three-track error depending upon the number of other track errors sensed within its segment. The apparatus includes means for counting and reporting the number of each type of error sensed on the tape.

Abstract: A method and apparatus for measuring the electroacoustic properties of magnetic tapes by means of recorded test signals of varying frequency and amplitude, wherein measured values of the reproduced signals which depend on the biassing current and correspond to predetermined parameters are obtained; for each of the relevant values of the biassing current the amplitude of the test signal to the recorded is varied until the predetermined value of the reproduced signal is attained, and the measured value of the reproduced signal obtained in this way is registered, an amplitude-modulated test signal is recorded and, by means of a test programming unit and upon the attainment of a parameter value which controls this programming unit, the relevant measured value of the reproduced signal to be determined is transmitted to an intermediate storage device for further evaluation and the biassing current is varied in order to determine the next value to be measured.

Abstract: A multi-track magnetic recording head is used to record data in human readable form on a magnetic track on a record medium. A viewer, having a viewing window containing microencapsulated ferromagnetic particles, is used to read the data. When the viewing window is placed in operative proximity with the magnetic track, an image corresponding to the data on the track is formed on the viewing window to enable a user of the record medium to read the data thereon. The image on the viewing window is erased after reading by providing relative movement between the viewing window and a magnetic field.