U.S. Philips Corporation

Onstream, Inc.

Johannes J Kalfs

Abraham Hoogendoorn

Petrus J Van Gerwen

Wilfred A Snijders

Frits A Steenhof

Franciscus A Kneepkens

Theodorus G Martens

Abraham Hoogen-Doorn

Willem A Roos

The invention relates to a comprising a magnetic tape formatted by a write head, and an apparatus comprising a magnetic head unit which is movable on a transverse direction by an actuator. The write head records the magnetic tape with a pattern of servotracks ST101-ST127 which extend in a longitudinal direction. The odd-numbered servotracks contain a first servosignal and the even-numbered servotracks contain a second servosignal Sb which is phase opposition to the first servosignal. The servotracks ST103-ST113 and ST116-ST126 have a typical width W1 and form a group of two bands of N1 servotracks which are separated by a band of N2 servotracks ST114, ST115 having a typical width W2. The magnetic tape is adapted to cooperate with an apparatus comprising eight magnetic write heads. The actuator is controlled in response to the servosignals read by the heads. The center-to-center distance between the magnetic write heads is equal to four times the typical width W1 and, moreover, it holds that:

System for recording and/or reproducing information medium for use in

A system and method for recording and reproducing information includes a magnetic tape, a magnetic-head unit and an actuator. The magnetic tape has servo tracks containing servo signals. The servo signals have been written with a magnetic head, not shown, having a comparatively large gap length. As a result, the servo signals are recorded deep into the magnetic tape. The magnetic-head unit comprises a read head and a write head to inscribe the track, the read head following a bounding line between adjacent servo tracks and in response to the servo signals read from said servo tracks and by the read head. The system in accordance with the invention is characterized in that it comprises control means which determine the sequence in which the information tracks are written, the read head either following a track or between two respective non-overwritten parts of the magnetic tape, or following a track or between two respective overwritten parts of the magnetic tape.

System, apparatus and method for recording and reproducing information

An apparatus for recording an information signal on a record carrier where the record carrier has a first and a second tracking signal of specific frequencies and wavelengths. The tracking signals are recorded in respective first and second tracks which run parallel to each other in their longitudinal direction on the record carrier. The apparatus is provided With a receiver for receiving the information signal, and a converter for converting the information signal into a channel signal. The channel signal includes signal blocks of information with each signal block including a portion of the information signal. A writing head writes the channel signal in a third track on the record carrier. A reading head is adapted to read at least one of the first and second tracking signals from the first and second tracks. A generator generates a control signal from the at least first and second tracking signals read from the record carrier. The apparatus is adapted to record the information signal on the record carrier so that the length of a signal block of the channel signal is equal to an integer multiple of the wavelength of one of the first and second tracking signals.

Recording an information signal on a record carrier provided with

A method and an apparatus are disclosed for recording a binary signal onto a magnetic record carrier. The binary signal is supplied to an input terminal. The apparatus comprise generators for generating at least two write pulses (P.sub.1,P.sub.2) for each bit of the binary signal to be written. More specifically, the generators are adapted to

Magnetic recording method and apparatus which provide at least two write

An apparatus is disclosed for positioning a head relative to a plurality of tracks running parallel to each other in their longitudinal direction on a record carrier. The apparatus comprises a position detection unit for detecting the position of the head in a transverse direction, which has an output for supplying a first and a second position signal when the head is positioned onto each of two tracks. A memory is present for storing the first and second position signals. In a calibration mode of operation, a control signal generator generates a control signal to position the head onto one of the tracks and the memory stores the position signal generated by the position detection means. The control signal generator subsequently generates a second control signal so as to position the head onto the other track. The memory stores the second position signal generated by the position detection means. These position signals are recalled from memory when the apparatus switches from one track to the other, to effect an immediate positioning of the head to the desired track.

Positioning of a head relative to a plurality of tracks

For the clock extraction from n digital signals read from each of n tracks there are provided n phase-locked loops. In order to compensate for speed variations in the speed of transport of the record carrier there is provided an additional frequency control system. This system derives a control signal which is a measure of the speed variations, which control signal is applied to the voltage-controlled oscillators of all the phase-locked loops as a common control signal.

Apparatus for reproducing n digital signals from n adjacent tracks on a

A data processing system comprising a memory receives data in the form of data blocks. Such a data block contains at least one data word and check bits. On the basis of the check bits it is vertified whether the data block contains reliable or unreliable data words. The unreliable data words are not written into the memory but are replaced by an unreliability indicator which is written into the memory at the address reserved for the unreliable dataword in question.

Data processing system in which unreliable words in the memory are

Arrangement for cancelling echo signals in data transmission over a two-wire transmission path. The data signals occurring in the send path are applied to an adjustable signal processing arrangement. From said data signals a synthetic echo signal (e(t)) is derived which is subtracted in a difference producer from the data signal occurring in the receive path. The residual signal (r(t)) is converted into a digital residual signal (r(j)) in an analog-to-digital converter arrangement. An interpolator which increases the sampling rate by a factor L results in the production of a digital control signal (r(i)) from the digital residual signal, for the setting arrangement. The sampling rate of the digital residual signal is M/LT Hz, wherein T is the duration of a data symbol in sec. and M and L represent integers which are relatively prime, L being greater than one.

Arrangement for cancelling echo signals

In the duplex transmission of data signals over two-wire transmission paths the phenomenon of echo-signals is encountered, while simultaneously intersymbol interference occurs between the data symbols themselves. In order to reduce the influence of both the echo signals, and the intersymbol interference, the arrangement comprises a random access memory (16) which produces a correction value (c(i)) at each sampling instant to correct the received data signal. The memory is addressed from registers (13, 14) and a counter (15), the contents of the registers being determined by the data ssymbols transmitted last and the data symbols received last, respectively. A D-A converter (19) converts the correction value into a correction signal (c(t)), which in a difference producer (20) is subtracted from the received data signal. A sampling arrangement (21) samples the corrected received data signal. After D-A conversion (22) and multiplication (17) by a predetermined factor .alpha. each sample furnishes a number by which the correction value is changed to match it to the value of the pulse distortion at the sampling instant.

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Eindhoven, Netherlands

Johannes J Kalfs