Abstract: A patterned magnetic recording disk, i.e., a disk with discrete magnetically recordable regions that can function as discrete magnetic bits, is formed by ion irradiating a continuous magnetic film of a chemically-ordered alloy having a tetragonal crystalline structure through a patterned non-contact mask. The ions cause disordering in the film and produce regions in the film that have no magnetocrystalline anisotropy. The regions of the film not impacted by the ions retain their chemical ordering and magnetocrystalline anisotropy and thus serve as the discrete magnetic regions that can be recorded as individual magnetic bits. The chemically-ordered alloy is preferably Co (or Fe) and Pt (or Pd) with the c-axis of the tetragonal crystalline film oriented at an angle less than 45 degrees relative to the plane of the film, so that after patterning the discrete magnetic regions can be recorded by horizontal magnetic recording.

Abstract: A new method for making patterned magnetic storage media with magnetic and substantially non-magnetic zones utilizes a selective oxidation processes. Selective oxidation is achieved by subjecting a magnetic layer to an oxygen plasma through voids in a patterned mask. A high resolution patterned mask is made by embossing and reactive ion etch processes. The method is used to fabricate patterned magnetic disks media with alternating magnetic and non-magnetic zones ranging from 10 to 1000 Nanometers in width. Magnetic storage disks produced by this method have high-bit densities, minimal topography and reduced signal noise.

Abstract: An optical disk drive uses an air-bearing slider that supports a solid immersion lens (SIL) with a patterned thin film formed at the focus of the SIL to act as a secondary radiation source. The thin film is patterned to define either an "aperture" or a "scatterer", both of which localize the interaction of the disk drive's incident light beam with the underlying optical disk to create an effectively smaller light spot. In one embodiment the patterned thin film is opaque with a small aperture having a diameter less than the wavelength of the incident light beam. The aperture localizes the transmission of the incident light beam to the area of the aperture and generates an evanescent field that interacts with the optical disk. In a second embodiment, the patterned thin film is metallic and formed as dot that serves as a scatterer. The scatterer acts as an antenna or secondary light source to locally reradiate a portion of the incident light beam to the optical disk.

Abstract: A high density data storage system based on atomic force microscopy uses a tracking servo system based on timing or tracking lines placed on the data storage medium. In a disk drive embodiment with a read-only disk, the timing or tracking lines are formed in sets of triplets with the sets being circumferentially spaced around the disk and interspersed with the surface incongruences that form the machine-readable data features. The data tracks and circumferentially-spaced sets of tracking lines are grouped into radially-spaced bands on the disk. Each set of tracking lines includes at least two lines, one of which is a nonradial line. A separate set of identification (ID) marks associated with each data band are used to initiate a timing gate during which the tracking lines are expected to be detected.

Abstract: An atomic force microscope (AFM) system has a bidirectional actuator to move the AFM tip or stylus in a plane parallel to the surface of the sample to be scanned as well as perpendicularly to the surface of the sample. The actuator is a modified voice coil motor actuator of the type used in compact disc (CD) drives. The stylus is mounted at the end of a support arm that is held in the actuator by a flexure, the flexure permitting movement in the two directions. A set of permanent magnets and two sets of independently controllable electric coils allow the support arm to be moved in the two directions. In a data storage application, a data disk has a series of surface features that represent machine-readable data and the bidirectional actuator is supported by a secondary actuator that moves the primary actuator along a radius of the disk. This allows the bidirectional actuator with the attached stylus to be located to a coarse position within a desired band of data tracks.

Abstract: An atomic force microscope system incorporates a single-crystal silicon cantilever with an integral tip. The cantilever is supported in the AFM system so that it makes an acute angle with the surface of the sample to be scanned. The tip is formed by the convergence of three planes, one of which is one of the two generally parallel planes which define the thickness of the cantilever. The tip lies between the cantilever's two thickness-defining planar surfaces and is thus an in-plane integral tip. The AFM system may have the cantilever surface that converges to the tip oriented to either face the sample or face away from the sample.

Abstract: A satellite communication system for delivering simplex messages to subscribers comprises multiple Message Origination Controllers (MOCs), one or more Message Termination Controllers (MTCs), satellites, and geographically-diverse communication units. Messages destined for particular communication units are transmitted to the one or more MTCs. The one or more MTCs then schedule delivery of the messages to communication units by employing a blocked timing structure for delivery of the messages. The one or more MTCs transmit the scheduled messages to satellites which broadcast the messages to communication units at the scheduled time. Communication units are assigned specific timing blocks during which they monitor radio signals for messages directed to them. During non-assigned timing blocks, communication units remain in a low-power state.

Abstract: In a satellite communication system, communication channels are dynamically assigned in real-time based on actual demand using a regionalized channel assignment and reuse scheme. The tradeoff between system capacity and channel interference:is optimized through the use of interlocking local regions. Satellite communication stations within a radio line-of-sight of each other make up each local region. The communication stations of a local region change as the communication stations move through orbital positions. Channel reuse rules are adapted to system load and demand for services. Each communication station establishes its local region and notifies the other communication stations within its local region whenever it assigns a communication channel to a subscriber unit. Channel assignments within each local region are maintained locally by the defining communication station.

Abstract: A communication system qualifies access to the services it provides to subscriber units based upon the locations of the subscriber units. Subscriber unit location data are routed through a satellite to a gateway where a home subscriber information manager for the subscriber unit resides. This home gateway selects a service control area and corresponding serving gateway to use in establishing calls to and from the subscriber unit. When an area of uncertainty for the subscriber unit's location overlies a boundary between service control areas, additional location data may be obtained to shrink the area of uncertainty. If the area still overlies a boundary, a serving gateway is selected based upon the current serving gateway, the home gateway, and the service control area where the center of the area of uncertainty resides.

Abstract: A network includes a system and a population of subscriber units. System satellites move in low earth orbits and form moving cells on the surface of the earth. A pattern of static areas that covers the service area of the system is defined in a map. The system discovers the static areas for the subscriber units. When an incoming call needs to be directed to a subscriber unit, the subscriber unit's static area is converted into identities of beams that form the cells that coincide with the static area. A ring signal is transmitted in only these cells. Subscriber units monitor area identification signals that identify the static areas coincident with the cells where the signals are transmitted. When the static area known by the system is not among the identified static areas, a subscriber unit engages in re-registration communications.

Abstract: A cellular telecommunication system comprised of low-Earth orbiting satellites featuring allocation of communication channels among users in cells is disclosed. Each subscriber unit is programmed with an embedded class identifier. During periods when it is desirable to limit acquisition of a satellite to some restricted class or set of classes, such as periods of heavy use, the satellite broadcasts a list of inhibited class identifiers allowing only uninhibited classes access to the communication system. The method reduces thrashing by allowing access to users on a hierarchy class basis. The method uses both real time cell loading data and historical cell loading information based on previous experiences and can be programmed to limit access to emergency services in the case of natural disasters.

Abstract: Ongoing communications over radio links between communication stations and subscriber units may be unexpectedly broken. Where the communication stations include low-Earth orbit satellites, communication links are difficult to re-establish because of the timing differential and Doppler-frequency shift associated with the satellite's movement. The communication link is re-established by initially changing the modulation technique in an attempt to re-synchronize the communication station and the subscriber unit. If this fails, the subscriber unit performs an acquisition attempt on another antenna beam of the communication station. If this is not successful, the subscriber may perform an acquisition attempt on antenna beams of another communication station.