Ampex Corporation

Ampex Systems Corporation

Toolz, Ltd.

Robert Bosch Co., Ltd.

George R Varian

Beverley R Gooch

Robert Alden Lewis

Chad Thompson

Nan-Hsiung Yeh

Kurt F Hallamasek

Keith A Kambies

Kuo-Nan Yang

Charles R Olson

Technology is disclosed for measuring distances. A measurement device emits a beam that reflects on the surface of an object. The measurement device determines the distance to the object, based on the time of flight of the beam from transmission to capture by the measurement device. The measurement device derives feedback reference pulses from pulses in the emitted beam and injects them into the device's receive path&#x2014;creating a receive waveform that includes one or more feedback reference pulses and corresponding pulses in the return beam. The device uses the pulses in the waveform to measure time of flight. The measurement device can attenuate the feedback reference pulses to intensities similar or equal to the intensities of the return pulses. The measurement device can include a histogram processor that collects waveform samples at varying comparison thresholds. The device employs the most accurate information at each threshold to create a digitized composite waveform that corresponds to the analog waveform received by the measurement device. In some instances the measurement device can process the digitized waveform&#x2014;removing noise, scaling reference pulses, and removing distortions caused by pulse trailing edges running into subsequent pulses.

Distance measurement device

Constructing a waveform from multiple threshold samples

Technology is disclosed for measuring distances. A measurement device emits a beam that reflects on the surface of an object. The measurement device determines the distance to the object, based on the time of flight of the beam from transmission to capture by the measurement device. The measurement device derives feedback reference pulses from pulses in the emitted beam and injects them into the device's receive path&mdash;creating a receive waveform that includes one or more feedback reference pulses and corresponding pulses in the return beam. The device uses the pulses in the waveform to measure time of flight. The measurement device can attenuate the feedback reference pulses to intensities similar or equal to the intensities of the return pulses. The measurement device can include a histogram processor that collects waveform samples at varying comparison thresholds. The device employs the most accurate information at each threshold to create a digitized composite waveform that corresponds to the analog waveform received by the measurement device. In some instances the measurement device can process the digitized waveform&mdash;removing noise, scaling reference pulses, and removing distortions caused by pulse trailing edges running into subsequent pulses.

Distance measurement device with short distance optics

A method and apparatus is disclosed which minimizes the visual artifacts normally generated when images are compressed for transfer through very narrow band channels such as, for example, the Internet. To this end, the images are pre-filtered and then scaled down prior to compression using a two dimensional spatial impulse filter with good pulse fidelity rather than flat pass bands, rapid cutoff at high frequency and minimal impulse response width. The impulse filter preferably is operated at the 6 db point down about 0.6 to 0.9 of the output image spatial band edge, thereby removing visible aliases in the images while compromising between subjective sharpness and total picture entropy.

Method and apparatus for improving the image quality of transmitted video signals via pre-filtering

A read/write magnetic head includes a step offset formed in the gap of the head which accordingly generates recorded transitions in a recording medium which also contain a step offset in each successively recorded transition along the length of a track. On subsequent playback of the track by the same or similar step gap head, fine transverse mistracking of the head as it follows the track results in a corresponding echo signal being generated along with the main readout signal. The amplitude of the echo signal is indicative of the degree of fine mistracking while the location of the echo signal relative to the main signal is indicative of the direction of mistracking. Fine mistracking correction is provided by circuits which detect the amount and direction of mistracking and supply an error signal to a tracking servo to correct the mistracking.

Step gap head tracking servo

A servomechanism for controlling the position of a magnetic-tape playback head (16) with respect to a track (24) of digital data on a magnetic tape (22) positions the head by reference to an error signal that error-signal-generation circuitry (FIG. 10). generates. Sample-clock signals obtained from simultaneously read azimuth-recorded data tracks clock respective frequency dividers (52 and 54), and a phase detector 56 generates the error signal by comparing the frequency dividers' outputs.

Track-curvature detection using clock phase shift in azimuth recording

An improved magnetic head obviates the need for separate read and write heads in a magnetic storage system by providing a head core having two physical gaps configured to generate a reproduce track width that is narrower than a record track width. The core of the head comprises a tapered center pole disposed between two generally symmetrical main poles to form physical record and reproduce gaps. A magnetically saturable, high permeability element is disposed within the core in a manner that bridges the rear of the record gap.

Two-gap magnetic read/write head

An improved, shielded magnetic core structure is disclosed that is particularly well suited for use in magnetic read and write heads adapted for narrow track, short wavelength magnetic recording systems, and for transformers of high performance, wide band application. The improved magnetic cores use novel field confinement structures to reduce or eliminate leakage magnetic paths which normally do not link the head gap or do not link the transformer windings. This shielding arrangement substantially improves the performance of such devices, as compared to conventional, unshielded heads and transformers. Embodiments involving toroidal cores, thin film heads, and MR heads are disclosed, along with high performance, wide band transformer structures.

Magnetic core with field confinement structure

In an azimuth recording format, the crosstalk of the A channel into the B channel is higher than the crosstalk of the B channel into the A channel because, at the ends of a magnetic recording where the switching contour of constant magnetic field strength is equal to the media magnetization switching field, the switching contour follows a curve. The resulting curvature at the ends of the magnetic recording vary accordingly the angle of azimuth rejection between the B to A azimuth relative to the A to B azimuth at the edges of the track. The use of a record head of a unique design wherein the trailing pole face of the head extends laterally beyond its leading pole face at the over-writing side of the head, removes the curvature at the ends of the transition recordings forming the recorded tracks. In such record heads, the switching contour generated at the trailing pole face of the gap at the over-writing side of the head enters and exits the trailing core generally normal to the pole face and at points thereon which are spaced beyond the corresponding end of the leading core face. Thus, no curvature is generated at the end of the recordings which perform over-writing of the previous adjacent tracks recorded in the media. Thus, the record heads show the same minimized level of crosstalk between the A to B or the B to A azimuth channels.

Azimuth record head for minimizing and equalizing crosstalk between

A transition overshoot of the record current is usual to compensate record head efficiency loss at high frequencies. Recording compatibility is achieved by decreasing the record current overshoot at the digital data signal transitions as the head gap depth decreases due to wear. Additionally, the different gap depth record heads of different head efficiencies require different optimum record current levels to provide maximum signal-to-noise ratio in the reproduced signal. The head gap depth thus is monitored by means of the optimum record current level without actually measuring the gap depth. The desired amount of overshoot is adaptively adjusted to the gap depth during the recording process by tracking the overshoot to the optimum record current level derived by adjusting the record drive level signal. Recording compatibility between different gap depth heads is achieved using the existing normal record current optimization process during recording.

Method and apparatus for automatically adjusting the overshoot of a

A magnetic transducer for reproducing/recording high frequency signals with a magnetic tape medium includes a pair of opposed transducer head halves separated by an insulation gap and bonded together to form a Y-shaped pole structure, each half including a laminated at least partially ferromagnetic core portion bounded on opposite surfaces with outer and inner conductive layers, each of which forms a winding coil portion. Each core section has a leg portion and an angularly disposed arm portion, the distal end of which is capped with a block-shaped ferromagnetic pole tip in magnetic path relation therewith, the two pole tips lying in a common plane transverse to the plane of the gap. The conductive layers, when conductively interconnected, such as by jumpers, form a one or two turn coil for the transducer. The inner conductor is of an inverted generally U-shaped configuration with the bight portion of the two inner conductors passing through, and substantially filling, the openings of the Y-shape on opposite sides of the insulation gap layer beneath the pole pieces. The method of fabricating the magnetic transducer generally comprises the steps of forming at least two generally identical transducer head halves, each having generally one half of a Y-shape, commencing with providing a substrate having a surface shaped to define the core configuration and having a band shaped to define the pole configurations; applying a conductive layer to the surface for providing an outer coil conductor; alternately applying laminated of insulating and magnetic material to form a laminated core section; applying a conductive layer over an insulation layer about the face and side edges of the laminated core section for providing an inner generally U-shaped coil conductor; forming, in the band, a pole piece of magnetic material at the distal end of the arm of the core section; bonding two such transducer head halves in facing relation to form a Y-shaped transducer with the bonding material being insulating and forming the gap between the two pole pieces.

Laminated, high frequency, magnetic transducer and manufacturing method

Input data symbols are written to a synchronization (sync) adder, which appends a pseudo randomly (PN) generated sync bit to generate a sync word. Sync words are sent to a receiver where synchronization is recovered. The receiver re-generates the same PN sequence that was generated at the transmitter. Synchronization recovery apparatus conceptually looks at each bit position to locate the appended PN sequence. When the sync bit position is found, the data stream is assembled into fixed length sync words and the data symbols of the sync words are written into a buffer at an address determined by the position of the sync bit in the PN sequence. Error rates in the data stream of sync words are measurable using a correlator network for reading the bit in the sync bit position of a sync word and for comparing that bit with its expected value in a reconstructed PN sequence to provide a difference value where the difference is a measure of the error rate in the data stream. Stated alternatively, the error rate can be measured by comparing the difference between the received PN sequence, as read from the received data stream, and the reconstructed PN sequence, as generated by the PN generator at the receiver. The error rate measurement does not expressly measure errors in the data symbols but rather uses the known PN sequence that is used for synchronization (recovery) purposes for yet another purpose, i.e. to provide a measure of the channel error rate.

Error rate measusrement using a comparison of received and reconstructed

Input data symbols are written in a write buffer then to a sync adder, which appends a pseudo randomly (PN) generated sync bit to the MSB position of a four-symbol sync word data field, to generate a sync word. Sync words may or may not be randomized and sent to a receiver whereafter synchronization is recovered and perhaps de-randomized symbols are written into particular positions of an ECC block in a read buffer which are derivable from the PN sequence. The ECC block is a data array having multi-bit sync words making up its rows and the bit positions of the sync words making up its columns. Synchronization recovery apparatus conceptually looks at each bit position across a row and in a top-to-bottom direction down each of the columns to locate that column which contains the appended PN sequence. Sync recovery involves the receiver re-generating the same PN sequence that was generated at the transmitter. When the sync bit position is found, the data stream is assembled into fixed length sync words and written into the read buffer. Further, the position of the sync bit in the PN sequence is used to generate an address for writing the ECC codeword in a read buffer. Synchronization recovery circuit passes along to the read buffer both ECC codeword data symbols and sync bit position in the form of a read buffer address. Error rate measurement can be done by comparing a received PN sequence with a reconstructed PN sequence.

Recovering synchronization in a data stream

A magnetic transducer for reproducing/recording high frequency signals with a magnetic tape medium includes a pair of opposed transducer head halves separated by an insulation gap and bonded together to form a Y-shaped pole structure, each half including a laminated at least partially ferromagnetic core portion bounded on opposite surfaces with conductive layers, each of which forms a winding coil portion. Each core section is formed as one-half of a Y-shaped cross-sectional configuration having a leg portion and an angularly disposed arm portion, the distal end of which is capped with a block-shaped ferromagnetic pole tip in magnetic path relation therewith, the two pole tips lying in a common plane transverse to the plane of the gap. The conductive layers on the outer and inner surfaces of the laminated core section form outer and inner conductors which, when conductively interconnected, such as by jumpers, are configured to form a one or two turn coil for the transducer. The inner conductor is of an inverted generally U-shaped configuration with the bight portion of the two inner conductors passing through, and substantially filling, the openings of the Y-shape on opposite sides of the insulation gap layer beneath the pole pieces. The method of fabricating the magnetic transducer generally comprises the steps of forming at least two generally identical transducer head halves, each having generally one half of a Y-shape, commencing with providing a substrate having a surface shaped to define the core configuration and having a band shaped to define the pole configurations; applying a conductive layer to the surface for providing an outer coil conductor; alternately applying laminae of insulating and magnetic material to form a laminated core section; applying a conductive layer over an insulation layer about the face and side edges of the laminated core section for providing an inner generally U-shaped coil conductor; forming, in the band, a pole piece of magnetic material at the distal end of the arm of the core section; bonding two such transducer head halves in facing relation to from a Y-shaped transducer with the bonding material being insulating and forming the gap between the two pole pieces.

Growing community of inventors

Palo Alto, CA, United States of America

George R Varian