Abstract: A low voltage driver tolerant of high voltage and suitable for driving a processor and a memory device. A first protection NFET is coupled to the drains of a series-coupled PFET and NFET forming the basic driver components. Another protection NFET is connected in series to the first NFET. This second protection NFET requires approximately 1 volt for turn on, such that a resultant 3 volts appear at the output of the complete driver assembly. When the output driver is not enabled and 5 volt inputs are being applied from the memory circuit, the two NFET protection transistors block the 5 volts from reaching the processor output driver.

Abstract: A system and method for providing sound in a computer are disclosed. An audio module for controlling digitized sound I/O is included in a media stream controller. The media stream controller may also coordinate graphics and video which allows multiple media subsystems to be supported from a single bus device. A software application may initiate sound data transfer by sending a conventional DMA mode command to the media stream controller. The media stream controller activates an audio interrupt service routine which processes the request without using a conventional DMA controller. Digital sound data is transferred across a local bus using high speed burst mode block transfer commands and is buffered by the media stream controller in a display memory. Concurrently, the media stream controller may output sound data from the display memory to a sound output device using a double buffering method.

Abstract: An apparatus and a method are provided to obtain oscillations from a crystal at a particular frequency by introducing real and imaginary components of voltage to the crystal. The imaginary component of voltage is different from the real component of voltage by a particular phase angle such as 90.degree.. The voltage introduced to the crystal is processed to produce a first current having characteristics corresponding to such voltage and to produce a second current having characteristics related to the imaginary component of such voltage. The first and second currents are combined to produce a first current corresponding to the real component of the voltage introduced to the crystal. This current is shifted through a phase angle of 90.degree. to produce a second current corresponding to the imaginary component of the voltage introduced to the crystal. The first current is converted to a first voltage which is regulated to provide a particular gain.

Abstract: A system for processing a stream of data and automatically selecting a portion or all of the data stream for block writing to a memory. The memory is capable of storing data in response to a block write command and a normal write command. The system contains a first data register and a second data register having the same data width. The first data register accepts data from the data stream in accordance with the its data width. Data stored in the first data register is transferred to the second data register. The first data register is then loaded with a portion of the data stream which is contiguous to the data stored in the first data register prior to the transferring. The data in the first and the second data registers is then compared. If the data in the first and the second registers is the same, then the content of a data counter is increased by one. When the content of the data counter exceeds a predetermined value, the system executes a block write command.

Abstract: A CPU introduces software commands to a first limited capacity memory (e.g. FIFO), on an integrated circuit chip. Data (e.g. graphics) from a first portion of a second memory (off chip) is processed in accordance with such commands. A second portion (e.g. FIFO) of the second memory may also store commands normally passing from the CPU through the first memory. When the first memory becomes full, the commands may pass from the CPU through the second portion of the second memory (which may have a storage capacity considerably greater than that of the first memory) and then through the first memory. The commands may continue to flow in this auxiliary path until the second portion of the second memory becomes empty. A third memory of a limited capacity on the chip may pass the commands from the CPU to the first memory in the normal operation or to the second portion of the second memory when the first memory becomes full. The CPU may also pass commands to other peripheral equipment while a ready line is high.

Abstract: An improved frame structure for use in mobile communications systems utilizing slotted protocols is provided. According to the present invention, consecutive slots in a frame are assigned to each mobile unit so that the mobile unit transmits to a base station during the first slot and receives a transmission from the base station during the second slot. This frame structure, permits the mobile unit to monitor various frequencies for a longer and more continuous period of time. It is important for the mobile unit to have enough time to monitor frequencies while it is not transmitting or receiving so that base station handoff and interference avoidance handoff techniques can be performed by the mobile communications system. Furthermore, according to the frame structure provided by the present invention, the mobile units can be designed with a standard frequency synthesizer.

Abstract: The present invention provides methods for combining antenna diversity and gain control in a communications system using a single chain of receiver electronics. A number of input parameters related to various characteristics of a received signal are used to determine the quality of the received signal. The antenna diversity and gain control procedures are enabled or disabled based on the signal quality. The antenna diversity procedure estimates the signal level of the non-operational antenna using an infinite impulse response digital filter. The gain control procedure selects one of three gain paths based on the received signal strength.

Abstract: A variable speed playback system exploits multiple-period similarities within a residual signal, and includes multiple-period template matching which may be applied to alter the excitation periodical structure, and thereby increase or decrease the rate of speech playback. Embodiments of the present invention enable accurate fast or slow speech playback for store and forward applications without changing the pitch period of the speech. A correlated multiple-period similarity measure is determined for an excitation signal within a compressor/expander. The multiple-period similarity enables overlap-and-add expansion or compression by a rational ratio. Energy variations at the onset and offset portions of the speech may be weighted by energy-based adaptive weight windows.

Abstract: A conventional CELP speech codec synthesizes a pitch interval in a sound by synthesizing a scaled innovation signal--typically, a random signal--and adding it to a scaled pitch signal derived from the synthesized speech of the previous pitch interval. This invention continues this practice when it is advantageous, but, at the onset of the sound or whenever else needed, replaces the scaled innovation signal with a scaled spike signal. This is done since a spike is sometimes more useful than an innovation signal is, innovation signals being by definition crafted to instead represent differences between adjacent pitch intervals within a sound rather than at the onset of a sound.

Abstract: The present invention provides methods for combining antenna diversity and gain control in a communications system using a single chain of receiver electronics. A number of input parameters related to various characteristics of a received signal are used to determine the quality of the received signal. The antenna diversity and gain control procedures are enabled or disabled based on the signal quality. The antenna diversity procedure estimates the signal level of the non-operational antenna using an infinite impulse response digital filter. The gain control procedure selects one of three gain paths based on the received signal strength.

Abstract: The present invention provides methods for combining antenna diversity and gain control in a communications system using a single chain of receiver electronics. A number of input parameters related to various characteristics of a received signal are used to determine the quality of the received signal. The antenna diversity and gain control procedures are enabled or disabled based on the signal quality. The antenna diversity procedure estimates the signal level of the non-operational antenna using an infinite impulse response digital filter. The gain control procedure selects one of three gain paths based on the received signal strength.

Abstract: A cost-effective anti-howling system and method enables fast detection of the presence of true double talk, and substantially eliminates undesirable howling attributable to sudden changes in the acoustic echo path between a speakerphone microphone and loudspeaker during speakerphone conversations. Speakerphone embodiments include a delay-compensated and normalized cross-product calculation performed by a system processor having at least two memory buffers. One buffer is associated with the loudspeaker signal and the other buffer is associated with the microphone signal. The delay-compensated cross-product of the microphone voice signal input and the loudspeaker voice signal output is determined and normalized by energy estimates of the two signals to reduce the calculation error made by variance in the signal level.

Abstract: An extended memory mapping and selecting scheme for a microprocessor structured with multiple internal address lines. The internal address lines are coupled to external memory devices via a dual port RAM which enables the addresses of the external memories to be mapped and translated into the internal address lines for access by the microprocessor. The memory addressing capability is effectively enhanced by allowing the limited number of internal address lines to address larger external memories having a greater number of address locations.

Abstract: A loop gain processing scheme for a speakerphone arrangement determines system loop gain according to two echo feedback paths within the speakerphone system. Gain values for each half-loop are calculated separately to ensure that both the local and far end telephone or speakerphone system are stable. A first half-loop includes gain contributions from a feedback path extending from a local speakerphone microphone to a hybrid line interface, which couples the speakerphone to the telephone network line, and subsequently to a local loudspeaker. A second half-loop defines a feedback path from a line receive channel to a transmit channel. Gain contributions are input into a system controller which determines gain values for each of the half-loops to accurately set the proper gain switching mode.

Abstract: A hybrid focal plane array (FPA) structure including a soft, localized, and thick epoxy for supporting the FPA on a cooling device. The hybrid FPA arrangement includes a crystalline optical substrate with a layer of an optically sensitive material disposed on one surface of the substrate. The optically sensitive side of the substrate layer is coupled to a MUX chip via an interconnection scheme. The layered configuration of the detector, the optically-sensitive material, interconnection network, and the MUX is mounted to a platform or dewar cold plate with a pliable, thick epoxy which is locally deposited onto the platform to effectively form a raised mounting cushion which supports the MUX and reduces deleterious effects resulting form a close coupling of the FPA to the mounting platform.

Abstract: A direct connect antenna includes a passive patch-type antenna mounted to a radio, wherein the need for and use of a coaxial cable extension arrangement is eliminated. Thus, the characteristic impedances of the load and source can be better matched, resulting in lower reflection and distributed losses. The antenna is formed with guide slots for alignment and simple snap-on connection of the antenna to the radio to prevent coaxial connector mismatch and damage. The radio may be directly affixed and electrically coupled to a PCMCIA compliant interface card which is insertable into a host computer. Accordingly, radio signals received by the direct connect antenna and radio arrangement are processed through the PC card and the computer.

Abstract: A focal plane array (FPA) mounted in an imbalanced configuration including several layers of materials with differing thermal expansion coefficients (TECs), moduli of elasticity, and thicknesses to maintain surface planarity and improve the reliability of the FPA during thermal cycling and excursions. An optical substrate is coupled to a multiplexer through an array of indium bumps. The typical TEC mismatch between the optical substrate and the multiplexer is eliminated by forcing the multiplexer to exhibit an effective TEC equal to that of the optical substrate by particularly selecting the types of materials used and the thicknesses of the individual layers of the composite structure. Consequently, undesirable deflections and distortion of the multiplexer and the indium bumps are minimized, thereby substantially improving FPA reliability.

Abstract: A navigation and guidance system which directs a user toward a desired destination. Position and steering information are integrated into a single display to allow the user to immediately determine whether the correct course is being traveled, and to inform the use of any directional changes which may be necessary to be directed toward the desired destination waypoint. The user's position and course are determined by a navigation system and indicated on the display as a directional pointing icon, such as a line or arrow. The destination is displayed as a point. The user's Point of Closest Approach (PCA) can then be calculated according to current position, course, and the position of the desired destination. As the use's course gets closer to the bearing of the destination waypoint the PCA indicator can correspondingly shift with the user's movements. By superimposing the PCA over the destination waypoint, the user may precisely steer his or her craft to the desired destination.

Abstract: A hybrid focal plane array (FPA) structure including a Balanced Composite Structure (BCS) in which several layers of materials having differing thermal expansion coefficients stabilize the FPA during cryogenic cooling. An optical substrate with a layer of an optically sensitive material detects impinging radiation. The optically sensitive material is coupled to a multiplexer (MUX) substrate via interconnection bumps. The MUX is bonded to a layer of a material having a high TEC. A rigid core layer is sandwiched between the MUX and a balancing layer formed of a material having similar mechanical and geometrical characteristics to the MUX substrate. The three-layer BCS consisting of the MUX, the rigid core layer and the balancing layer is designed to have an effective TEC matching that of the optical substrate. The bumps and the optically sensitive material are thus protected from undesirable stresses generated during thermal excursions, thereby resulting in substantially improved FPA reliability.

Abstract: A method for using a value of range rate observed by a receiver, such as a GPS receiver, to determine the coordinates of points on the surface of the earth from which this value of range rate would be observed. These coordinates are given in an earth-centered, earth-fixed (ECEF) coordinate system, and they form a locus of points of equal range rate. The coordinates of these points provide general estimates of the location of the receiver. By calculating multiple loci of points which intersect each other, a more precise determination of the location of the receiver may be made.