Abstract: A signal strength that is associated with a first wireless communications channel is detected. Electromagnetic energy is transmitted over the first wireless communications channel in response to the signal strength being sufficiently weak. A determination is made whether a handoff should be made to a second wireless communications channel having a signal that is weaker than a signal of the first wireless communications channel. Related systems and methods are described.

Abstract: Provided is a satellite ground control system and method based on a communication satellite. The system includes: a communication satellite link means for monitoring and controlling a system device and transmitting remote measurement data and a process result to the central control station; an interface for analyzing the command, transmitting the command to a processing means and transmitting remote measurement data and a process result to the communication satellite link means; a satellite operating means for receiving a command from the interface, transforming the command into a remote command and transmitting remote measurement data to the interface; and a control satellite link means for transmitting the received remote command, receiving the remote measurement data, transmitting the remote measurement data to the satellite operating means, and transmitting a process result of monitor and control of a corresponding system device to the interface.

Abstract: An aircraft wireless data communication system includes an aircraft computer/server in communication with a plurality of aircraft systems. Access to the aircraft systems via the computer/server is available in real-time via wireless communication with a ground-based computer system. The ground-based computer system includes a computer that can be accessed from one or more networks of computers. Each authorized computer user on an airline, manufacturer, or supplier network has remote real-time access to the aircraft computer/server. Properly authorized remote users can: perform comparisons between the aircraft actual configuration identity and an aircraft authorized configuration identity; perform system diagnostic testing; view system status and parameters; collaborate with users from local and remote organizations using real-time aircraft data; and upload and download software and data to and from aircraft systems.

Abstract: A system for providing real-time television broadcasts to aircraft 4 via satellite 2 is described. The broadcast signal 11 is transmitted to the aircraft 4 together with a communications signal 10, forming part of an existing communications network air interface. The system separates the communications signal 10 from the broadcast signal 11 and enables the real-time broadcast to be displayed on-board the aircraft.

Abstract: A method and apparatus for mitigating communications interference between satellite communications systems in different orbits is disclosed. The method comprises the steps of evaluating a geometrical relationship between a second ground station and the satellites in the second satellite constellation, and directing communications between the second ground station and the second satellite according to the evaluated geometrical relationship. In one embodiment communications are handed over from a first satellite to another satellite when the first satellite is no longer at the highest elevation angle of visible satellites. In another embodiment, handover occurs when the first satellite drops below a minimum elevation angle.

Abstract: Chronologically synchronizing a unique positing signal generated by a positioning-unit device at a known location with a reference positioning signal generated by a reference transmitter at a known geometric distance. The positioning-unit device receives and interprets a reference positioning signal. It then generates and transmits a unique positioning signal, wherein the unique positioning signal is aligned with a frequency steerable clock. The positioning-unit device then receives the unique positioning signal. The positioning-unit device then adjusts the frequency of the frequency steerable clock by an amount derived from a measured frequency difference. The positioning-unit device then determines a reference positioning signal propagation delay between the reference transmitter and the positioning-unit device. At this stage, a time difference is measured between the received reference positioning signal and the received unique positioning signal.

Abstract: A communication system, method, computer program product, and apparatus include common equipment shared between multiple independently administered networks. The common equipment is reconfigurable and expandable and provides changed communication capacity and functions when additional elements are added or reconfigured. Configurable features include, for example, communication bandwidth, Quality of Service, and a number of communication satellites included in the communication system. The common equipment includes expandable elements including, for example, a single hub modem chassis that can expand to communicate with more than one communication satellite and a protocol processor that can share a protocol processing task with another protocol processors.

Abstract: A low earth orbit (LEO) satellite data uplink is provided. In one embodiment, a method of providing a data uplink to a LEO satellite includes determining position information using a LEO signal received from the LEO satellite, a first ranging signal received from a first ranging source, and a second ranging signal received from a second ranging source. The method also includes determining a timing advance parameter using a local clock reference and a LEO satellite clock reference. The method further includes preparing a data uplink signal comprising uplink data to be broadcast to the LEO satellite. In addition, the method includes synchronizing the data uplink signal with the LEO satellite using the timing advance parameter. The method also includes broadcasting the data uplink signal to the LEO satellite.

Abstract: The present invention provides a method for determining an authorization status of a satellite broadcast service for a mobile vehicle. A call center receives a request for the authorization status of the satellite broadcast service for the mobile vehicle. The call center sends a request signal to the mobile vehicle. The call center then receives an authorization status signal from the mobile vehicle. The call center then sends the authorization status to the satellite broadcast service.

Abstract: Provided is a method and system for transmitting MPEG frames between a DOCSIS based satellite modem termination system (SMTS) and a corresponding satellite modem (SM) system. The method includes identifying at least one data stream requiring transmission between the SMTS and the SM, the data stream including one or more MPEG frames. Next, the MPEG frames are organized within SMTS data queues based upon predetermined parameters and then transmitted based upon their organization within the data queues.

Abstract: A satellite communications system is described for increasing capacity through spectrum reuse by multiple satellites. The system includes a constellation of satellites traveling in a geosynchronous orbit, where the geosynchronous orbit defines a satellite track. The satellite track of the constellation overlaps a geostationary orbital location occupied by a legacy satellite traveling in a geostationary orbit. To prevent interference between the co-located constellation and legacy satellite, each of the constellation satellites operates in a silent mode when traveling within an interference beam width of a ground terminal in communication with the legacy satellite. Once outside of the interference beam width, the constellation satellites return to an active mode of operation.

Abstract: A partial mesh link channel is established within a satellite communication system by allocating return link channel resources to the partial mesh link channel.

Abstract: A communication system, method, computer program product, and apparatus include common equipment shared between multiple independently administered networks. The common equipment is reconfigurable and expandable and provides changed communication capacity and functions when additional elements are added or reconfigured. Configurable features include, for example, communication bandwidth, Quality of Service, and a number of communication satellites included in the communication system. The common equipment includes expandable elements including, for example, a single hub modem chassis that can expand to communicate with more than one communication satellite and a protocol processor that can share a protocol processing task with another protocol processors.

Abstract: In an LNB 10, a power supply circuit 12 has pre-regulators PRa and PRb provided one for each of power supply paths respectively from ports 13a and 13b, a bypass portion BP that, when the potential difference between the output terminals of the pre-regulators PRa and PRb is greater than a predetermined threshold value, short-circuits together those output terminals, and main regulators REG1 and REG2 provided in the stage following the bypass portion BP to generate, from the output voltages Va? and Vb? of the pre-regulators PRa and PRb, drive voltages VA and VB for the internal circuits A and B. With this circuit configuration, simple though it is, even if there are instantaneous variations in the voltages fed from a plurality of receivers connected, no variations appear in the currents respectively extracted therefrom.

Abstract: A system and method for communicating between ground stations and mobile satellites effectively eliminates the need for transferring information from one ground station to another. Communication between a ground station and a mobile satellite is accomplished via an intermediate network of geosynchronous control satellites. The mobile satellite is positioned within a three-dimensional cellular grid formed by the network of geosynchronous satellites. This system is particularly applicable to a terrestrial network communicatively coupled to the geosynchronous network via one or more ground stations. The terrestrial network of ground stations no longer needs to perform expensive, time-consuming and manual synchronization and hand-off procedures.

Abstract: Systems and methods for handling a transition of a roaming mobile user device (i.e., a roaming client) from one access point (AP) to a target AP, referred to herein as soft inter-AP handoff. This technique involves a second mobile user device that is already connected with the target AP, called a roaming coordinator, assisting in handoff coordination between the APs. This coordination includes assisting the roaming client in establishing a client-to-client connection to relay data traffic during the handoff, while the roaming client establishes a connection with the target AP using traditional techniques. Soft inter-AP handoff allows a faster hand-off between APs than traditional techniques, and may reduce jitter in communications with the roaming device during the transition.

Abstract: A communication system has a plurality of ground stations and a plurality of satellites located in a first orbit with respect to the earth. The satellites generate a plurality of beams corresponding to a respective plurality of cell. The plurality of beams has widths that vary relative to position in the orbit to maintain a cell size of the plurality of cells. A plurality of user terminals within the cells receives communication signals from the satellite.

Abstract: A method and apparatus for transmitting messages between a communicator and a central monitoring station using a wireless control channel, bypassing voice channels comprising, receiving a message at a communicator the message comprising application specific data, encoding the message along with a call origination trigger in a call origination control message to invoke forwarding of the encoded message and the encoded call origination trigger by a serving system upon detecting the call origination trigger. Transmitting the call origination control message to the serving system over the wireless control channel. The serving system detects the call origination trigger, and forwards the call origination trigger and the encoded message over a communications channel to a central monitoring station in response to detecting the call origination trigger. The central station decodes the encoded message to retrieve the application specific data.

Abstract: Methods and apparatus for detecting local maximums in a two-dimensional data set. Apparatus is provided for detecting a local maximum in a two-dimensional data set, where a stream of data elements represents the data set. The apparatus includes first detection logic that receives the data stream and operates to detect a first data element that represents a peak in a first dimension of the data set. The apparatus also includes second detection logic that receives the data stream and operates to detect a second data element that represents a peak in a second dimension of the data set, wherein a local maximum is detected if the first and second data elements are the same element.

Abstract: A wireless communications system, and a corresponding method, for use with an aircraft, includes airborne pico cell base stations mounted on the aircraft, the base stations capable of communication with wireless devices used by subscribers on the aircraft via using switching/transaction processing equipment located optionally on the aircraft or in the ground network with one or more ground-based networks. The system includes aircraft location equipment, in communication with the base stations, that determine the aircraft's location, including latitude, longitude, altitude, and other relevant data. Finally, the system includes a wireless communications enable/disable module that receives the aircraft's location and enables and disables wireless communications through the base stations based on the aircraft's location.

Abstract: An electronic volume device of an invention includes a common volume I/O 371 for receiving an i-th common volume level Dcom[i] (i=1 to N) on a common scale of N steps, a volume converter 373 for converting the Dcom[i] into a j-th unique volume level Dvol[j] on a unique scale of n steps; and a volume controller 372 for controlling an electronic volume based on the unique volume. The volume converter 373 includes a volume memory for storing an offset between the Dcom[i] and the Dvol [j] and a volume controller that controls at least one of the Dvol[j] and the offset such that the received Dcom agrees with the sum of the Dvol[j] and the offset and controls the Dvol[j] on a higher priority than the offset.

Abstract: A hybrid cellular telephonic and satellite radio broadcast system for enabling a wireless mobile computer to rapidly and effectively access information from the Web. The combination of a mobile wireless receiving computer, with wireless cellular telecommunication associated with the receiving computer for transmitting a request for data from the receiving computer to the Web, an implementation for accessing the requested data from the Web, a satellite transponder, wireless communication for transmitting said accessed requested data to the satellite transponder, an implementation on the satellite transponder for broadcasting the accessed requested data and apparatus in the mobile wireless receiving computer for receiving the broadcast data.

Abstract: A system for providing mobile interactive satellite services includes a satellite operable to communicate with mobile units, a terrestrial base transceiver station operable to communicate with mobile units, and a ground station in communication with the satellite and the terrestrial base transceiver station to provide mobile interactive satellite services. The mobile interactive satellite services include a multicast component and an interactive component such that the ground station provides both the multicast component and the interactive component using the satellite, with the terrestrial base transceiver station used to provide an ancillary terrestrial component. A device for communicating with a mobile interactive satellite service system includes an antenna, a transceiver coupled to the antenna and operable to communicate with a mobile interactive satellite service system, a user input device, an output device, a processor unit, and a network interface.

Abstract: Provided are an automatic operation system for automating satellite control operation, a method thereof, and an automatic satellite ground control system using the same. The object of the present research is to provide an automatic operation system that can reduce operation manpower and cost by automatically operating an entire satellite ground control system, which requires a plurality of operators to be properly operated, all the times, a method thereof, and an automatic satellite ground control system using the same. The satellite ground control system of the present research includes: a mission timeline receiving unit, an operation procedure editing unit, an operation procedure analyzing and code transforming unit, an operation procedure executing unit, a subsystem process state monitoring unit, and an access managing unit for providing interface with each of the subsystems.

Abstract: A data transfer method via a packet oriented channel and a continuous channel in parallel between a mobile station and a base station, where the transfer via the continuous channel is interrupted whereby at least one transfer gap is formed.

Abstract: A satellite communications system includes a satellite that is configured to wirelessly communicate with radioterminals in a satellite coverage area over a satellite frequency band, and an ancillary terrestrial component that is configured to wirelessly communicate with radioterminals in the satellite coverage area over at least some of the satellite frequency band, to thereby terrestrially reuse at least some of the satellite frequency band. Wireless communications with a radioterminal are handed over from the ancillary terrestrial component to the satellite if the radioterminal transmit power exceeds a threshold, and a received satellite signal quality exceeds a threshold, even though the radioterminal is able to wirelessly communicate with the ancillary terrestrial component.

Abstract: A system for communications on an extraterrestrial body may include a space-based component and an ancillary extraterrestrial component on the extraterrestrial body. The space-based component may be configured to provide wireless communications with a plurality of radioterminals located on the extraterrestrial body over a satellite frequency band wherein the space-based component includes at least one satellite orbiting the extraterrestrial body. The ancillary extraterrestrial component may be configured to provide wireless communications with the plurality of radioterminals located on the extraterrestrial body. Moreover, the ancillary extraterrestrial component may reuse at least one satellite frequency of the satellite frequency band, and the space-based component and the ancillary extraterrestrial component may be configured to relay communications therebetween. Related methods are also discussed.

Abstract: A satellite system includes a plurality of orbit slots having a first orbital and a second orbital slot. A first satellite occupies a first orbital slot and generates a first set of uniform beams. A second satellite located in a second orbital slot generates a second set of uniform beams. A tiling pattern on the face of the Earth has a plurality of cells, with each of the cells having a defined frequency for communication. The first set of beams and the second set of beams are generated according to parameters to avoid interference between them. The parameters may include satellite orbit separations, beam size, multiplicity of band reuse, and ground station received beamwidth.

Abstract: A satellite communications system (10) includes a hub (14), a satellite (32), and any number of remote terminals (16). Each remote terminal (16) includes a remote receiver (38), a monitor (40), and a network access controller (42). Each remote receiver (38) is configured to receive and down convert the system's entire spectrum of interest from which channels are accessed by the remote terminals (16). The monitors (40) independently perform FFT processes over this entire spectrum, but at a low frequency resolution which is no higher than needed to distinguish channels. Based on these spectral analyses, uplink/inbound channels are independently selected by the network access controllers (42) at each remote terminal (16). Remote terminals (16) immediately transmit data to the hub (14) as soon as they select an uplink/inbound channel.

Abstract: A communication system employing optical fibers and a high data rate satellite is utilized to provide high-speed Internet access to various geographic regions. In one aspect, a first teleport station is located geographically separated from a first user. The first teleport station is connected through a network access point to the Internet. The second user communicates through a satellite to the first teleport station to access the Internet. The teleport station and the network access point use a long haul optical fiber.

Abstract: A method, apparatus for providing at least near continuous broadcast services to one or more terrestrial receiver stations is disclosed. The system comprises a plurality of satellites, each satellite in an inclined, elliptical geosynchronous orbit, each satellite providing a portion of the at least near continuous broadcast service to the terrestrial receiver. In one embodiment, the system also comprises a receiver station having an legacy antenna modified so as to include a sensitivity pattern substantially matched to the track of the apparent position of the satellites actively broadcasting information to the receiver stations. The present invention is also embodied in a method for receiving at least near continuous broadcast service from at least one of a plurality of satellites at a time, each satellite in an inclined, elliptical, geosynchronous orbit.

Abstract: A communication system has a high altitude communication device that has an antenna for directing beams to a fixed cell pattern with a polarity of cells. A specific pattern of cells having the same communication resource is provided. Preferably, cells having the same resource are separated. The antenna is shaped to suppress interference with locations having the same resource. The areas not having the same resource are not suppressed to allow the system to have maximum capacity and allow a smaller antenna aperture.

Abstract: A radio signal relay device such as satellite is used to cover several relatively small geographical regions with relatively narrow beams as well as a relatively large geographical region with a single beam. This relatively wide beam permits legacy equipment to be used. A transmitting device in a beam transmits a signal to the relay device, which in turn retransmits the signal to a receiving device. The transmitting devices, relay device, and receiving devices synchronize communication by using a particular mode of communication which includes a band of carrier frequencies and a protocol. In addition to communicating like mode signals from a transmitter to a receiver, the relay device may be used in a dual mode communication system to translate signals from the one mode to another. A translator may direct a transmitter to modulate a signal on a different carrier frequency, convert one protocol into another protocol, or both.

Abstract: A method and apparatus for processing a data signal for transmission to a remote device transmits at least two synchronized copies of the data signal, in optical form, in different directions. To that end, the data signal first is synchronized to a clock signal to produce a composite signal. The composite signal then is converted to an optical signal, which is referred to as an “outgoing signal.” A plurality of copies of the outgoing signal then are transmitted. At least two copies of the outgoing signal are transmitted in different directions.

Abstract: An aircraft communications system includes a wireless local area network (LAN) access point positioned within the aircraft that receives and transmits wireless communications to and from at least one portable wireless communications device. A control panel is operatively connected to the wireless LAN access point and positioned within the flight deck of the aircraft. A communications transceiver is operative with the control panel and wireless LAN access point and operative for receiving and transmitting a communications signal between the wireless LAN access point and a ground-based transceiver. Communications between the portable wireless communications device and ground-based transceiver can be controlled from the flight deck using the control panel in one non-limiting example.

Abstract: A communication system has a stratospheric platform with a payload controller and a phased array antenna having a plurality of main array elements for generating a plurality of communication beams and a plurality of auxiliary elements for canceling interference between the communication beam. A gateway station communicates with the stratospheric platform. The gateway station scales the plurality of elements to form a reconfigurable plurality of beams. The gateway station communicates an embedded control signal to the stratospheric platform to communicate a scaling of elements to form the communication beams and the auxiliary element output. The auxiliary element output is used to provide interference canceling.

Abstract: Shortcomings in conventional Very High Frequency (VHF) Digital Link Mode 3 (VDL-3) communication techniques for implementing air/ground (A/G) diversity site group (DSG) communication are identified and resolved. Beacon schedules are used to coordinate the use of VDL-3 TDMA management slots. Limited autonomy local address management techniques are used to distribute blocks of unique addresses to the ground stations (GS's) of a DSG from a common base of local addresses maintained at a control site, thus assuring that the respective ground stations assign a unique local identifier to each aircraft supported by the DSG. Aircraft supported by a DSG are polled to obtain time of arrival (TOA) and signal quality information used to: intelligently select the transmit ground station and the receive ground station used for communication between an specific aircraft and the control site; and, intelligently manage contiguous communication handoffs of aircraft from one ground station to another ground station of the DSG.

Abstract: A communication system for a mobile platform satellite service (MPSS) system includes a receiver subsystem (RS) and a transmitter subsystem (TS). A satellite transponder is in communication with the RS and the TS of the mobile platform. A satellite service ground station includes a transmitter subsystem (TS) and a receiver subsystem (RS). A communication link is established between the MPSS system and the ground station, via the satellite transponder. The communications link includes fixed satellite service (FSS) data superimposed on MPSS data in the same frequency band to thereby maximize both satellite transponder utilization and interference budget usage.

Abstract: A sender of a message can transmit a message to an unspecified user merely by specifying a condition of space without specifying a recipient of the message, using an information processing terminal transmitting a message not with a user address to specify a user but with an area address (a condition of space) to specify an area within an electric wave reachable range of a radio base station; and a server converting the area address to a user address which specifies a PHS terminal currently located in the area represented by said area address and transmitting the message with a converted address to a switching equipment.

Abstract: A method for controlling data transmission rate in order to save waste of resources due to Non-Line Of Sight (NLOS) region when a mobile terminal passes through the NLOS region in an interactive satellite communication system is disclosed. The method includes the steps of setting at least one threshold; at a Network Control Center (NCC) adjusting allocated resources based on the Constant Resources Allocation (CRA) after detecting whether Satellite Access Control is lost or not; compensating transmission delay by reallocating if the mobile terminal returns from the NLOS region within a first threshold duration, wherein the mobile terminal maintains the fine sync state during the first threshold duration; and deallocating all resources allocated based on the CRA if the mobile terminal does not return from the NLOS region within the first threshold duration.

Abstract: Interference between satellite radioterminal communications systems may be reduced by transmitting and receiving satellite uplink frequencies in a Time Division Duplex (TDD) mode by a wireless base station in a first sector thereof, while simultaneously refraining from transmitting and receiving satellite uplink frequencies in the TDD mode by the wireless base station in a second sector thereof that points to a low elevation angle satellite. Satellite uplink frequencies may be transmitted and received in the TDD mode by a satellite that communicates with radioterminals in the second sector.

Abstract: A demand assignment method for a communication network including a hub and a plurality of user nodes includes adding a demand field to each data burst from a user node. Further, the method includes transmitting a first and second frame with first and second burst time plans from the hub to each user node, and transmitting a first and second respective data burst and demand field from each of the user nodes to the hub according to the first and second control information. The first data burst from each user node arrives simultaneously at the hub, and the second data burst from each user node arrives simultaneously at the hub. Further, the second data burst from each user node arrives immediately following the arrival of the first data burst from each user node.

Abstract: A communication network control method for a communication network including a hub and a plurality of user nodes includes adjusting system parameters to maximize communication data rate and minimize bit error rate given current conditions of the wireless channel, current loading of the network, and user constraints. In particular, the method includes transmitting a first and second frame with first and second control information from the hub to each user node, and transmitting a first and second respective data burst from each of the user nodes to the hub according to the first and second control information. The first data burst from each user node arrives simultaneously at the hub, and the second data burst from each user node arrives simultaneously at the hub. Further, the second data burst from each user node arrives immediately following the arrival of the first data burst from each user node.

Abstract: A method and system for processing communications based on altitude is provided. When a network receives a request to connect a communication to or from a mobile station, the network will determine the mobile station's current altitude. The network can make this determination by acquiring a GPS reading of the mobile station's current location, which can include an indication of altitude as well as latitude and longitude. Based at least in part on the altitude, the network can then decide whether to allow the requested communication to proceed. For instance, if the altitude is greater than a predetermined threshold level, then the network may preclude the communication. A network can also take into consideration other factors in addition to the altitude of a mobile station, such as the latitude and longitude coordinates of the mobile station, in deciding whether to allow a requested communication to proceed.

Abstract: A mobile wireless communications system including a plurality of individual transponding nodes of various types, all in communication with a central processing hub. A local user signal is processed by the central processing hub and radiated through multiple paths to a plurality of the plurality of individual transponding platforms simultaneously. The signal is then re-radiated by each of the plurality of the plurality of individual transponding platforms to a mobile terminal that receives the re-radiated signal from the plurality of the plurality of individual transponding platforms coherently and in phase. The number of transponders and codes used to transmit each user signal can be readily adapted to user requirements. Additionally, each user is assigned a profit value by the central processing hub depending upon certain user characteristics. The assigned user profit value allows the total system utility/profitability to be maximized.

Abstract: A system and method for switching between transmission modes provides more efficient use of available bandwidth. A content delivery system determines, based upon a predetermined limit, whether to broadcast content to a plurality of mobile platforms or unicast the data content via a point-to-point communication link. Acknowledgment signals from the mobile platforms are used to determine if the predetermined limit has been exceeded. A specific number or percentage defines the predetermined limit within a specified time period. The number of acknowledgment signals received is compared to the limit to determine if an exceedance condition has occurred.

Abstract: A communication system has a plurality of ground stations for communicating communication signal to a plurality of satellites located in an inclined elliptical sub-geosynchronous orbit with respect to the earth. The plurality of satellites operate in a service area in a synchronized manner to provide continuous coverage to the service area. The satellites generate a plurality of beams with variable beamwidths to obtain a substantially uniform cell size covering the service area. A user terminal within the service area receives communication signals from the satellite.

Abstract: A system that provides information to a second passenger vehicle, to create an information network between the second passenger vehicle and an information source, the system including a first transmitter/receiver unit disposed on a first passenger vehicle and adapted to receive an information signal that includes the information from the information source, and to transmit the information signal, a receiver located on the second passenger vehicle, the receiver being adapted to receive the information signal, and adapted to provide at least some of the information for access by a passenger associated with the second passenger vehicle, and a second transmitter/receiver unit that receives the information signal and transmits the information signal, to provide the information signal between the first transmitter/receiver unit and the receiver.

Abstract: A two-way satellite communication system is disclosed. A transceiver transmit signals over a return channel to a satellite and receives signals over a downlink channel from the satellite. A hub communicates with the transceiver over the return channel, wherein the hub provides connectivity between the transceiver and a packet switched network.

Abstract: A process for synchronizing data between a remotely located device, such as a personal digital assistant, Internet-enabled phone, handheld computer, laptop or desktop computer, and a central computer system. The data may be related to offline applications running on the device.