Abstract: An aircraft recorder system is provided in which a vibration sensor including at least one of a micro-electromechanical systems (MEMS) microphone and a MEMS accelerometer. The system further includes a cockpit voice recorder (CVR) and an active microphone. The active microphone and the vibration sensor each output signals to a signal processor including a subtractor configured to output, to the CVR, a signal that is a result of a subtraction of the signal from the vibration sensor from the signal from the active microphone.

Abstract: Various systems may benefit from appropriate thermal protection. For example, various flight recorder systems may benefit from thermal isolation of a flight recorder memory core. A system can include a memory core of a flight recorder. The system can also include an inner chamber housing the memory core. The system can further include an outer chamber housing the inner chamber with a vacuum between the inner chamber and the outer chamber. The system can additionally include a signal path from avionics equipment to the memory core through the outer chamber and the inner chamber. The system can also include a power path for the memory core through the outer chamber and the inner chamber.

Abstract: Various systems may benefit from appropriate thermal protection. For example, various flight recorder systems may benefit from thermal isolation of a flight recorder memory core. A system can include a memory core of a flight recorder. The system can also include an inner chamber housing the memory core. The system can further include an outer chamber housing the inner chamber with a vacuum between the inner chamber and the outer chamber. The system can additionally include a signal path from avionics equipment to the memory core through the outer chamber and the inner chamber. The system can also include a power path for the memory core through the outer chamber and the inner chamber.

Abstract: Various systems may benefit from appropriate thermal protection. For example, various flight recorder systems may benefit from thermal isolation of a flight recorder memory core. A system can include a memory core of a flight recorder. The system can also include an inner chamber housing the memory core. The system can further include an outer chamber housing the inner chamber with a vacuum between the inner chamber and the outer chamber. The system can additionally include a signal path from avionics equipment to the memory core through the outer chamber and the inner chamber. The system can also include a power path for the memory core through the outer chamber and the inner chamber.

Abstract: Various systems may benefit from appropriate thermal protection. For example, various flight recorder systems may benefit from a vacuum protected flight recorder memory. A system can include a memory core of a flight recorder. The system can also include an inner chamber housing the memory core. The system can further include an outer chamber housing the inner chamber with a vacuum between the inner chamber and the outer chamber. The system can additionally include a signal path from avionics equipment to the memory core through the outer chamber and the inner chamber. The system can also include a power path for the memory core through the outer chamber and the inner chamber.

Abstract: Various systems may benefit from appropriate thermal protection. For example, various flight recorder systems may benefit from thermal isolation of a flight recorder memory core. A system can include a memory core of a flight recorder. The system can also include an inner chamber housing the memory core. The system can further include an outer chamber housing the inner chamber with a vacuum between the inner chamber and the outer chamber. The system can additionally include a signal path from avionics equipment to the memory core through the outer chamber and the inner chamber. The system can also include a power path for the memory core through the outer chamber and the inner chamber.

Abstract: Various systems may benefit from appropriate thermal protection. For example, various flight recorder systems may benefit from a vacuum protected flight recorder memory. A system can include a memory core of a flight recorder. The system can also include an inner chamber housing the memory core. The system can further include an outer chamber housing the inner chamber with a vacuum between the inner chamber and the outer chamber. The system can additionally include a signal path from avionics equipment to the memory core through the outer chamber and the inner chamber. The system can also include a power path for the memory core through the outer chamber and the inner chamber.

Abstract: Various communication systems may benefit from the appropriate suppression of unnecessary transmissions. For example, certain position reporting systems may benefit from suppressing transmission of data from position reporting beacons using geographic location. A method can include determining a current position of a vehicle. The method can also include comparing the current position of the vehicle to a position-reporting mask. The method can further include reporting the position of the vehicle conditionally based on the comparison to the mask.

Abstract: Various systems may benefit from appropriate triggers to action. For example, various deployable safety devices, such as emergency locator transmitters and flight recorders, may benefit from a multiple input release mechanism. A method can include identifying the presence of at least one crash indicator. The method can also include performing an analysis of aircraft distress based on aircraft parameters other than the at least one crash indicator to provide an analysis result of aircraft distress. The method can further include triggering the release of a safety device contingent upon the presence of the at least one crash indicator being accompanied by a positive result of aircraft distress.

Abstract: A system and method for storing data in a linked list memory architecture maintains several key list parameters. When data to be stored is received, a memory manager determines the list in which the data belongs and retrieves several of the parameters. The parameters retrieved indicate the address of the current location at which the received data is to be stored and the address of the next location that is to be linked to the current list. The memory manager writes the data to the current location pointed to by the first address and writes the second address into a pointer field in that current location. Because the address of the next location in the list is determined before data is written to the current location, this next address can be written in the same cycle in which the data is written.

Abstract: A packet processor uses service priority and loss priority to designate a class of service for packet data. The service priority is used to determine the priority by which packets are routed out of the packet processor. The loss priority is used to determine which packets, if any, are discarded when buffer fullness exceeds a predetermined threshold. When a packet is received, the fullness of the packet buffer and/or a queue within the buffer is checked to determine whether a threshold is received. A decision is made whether to discard the packet based on the loss priority and the buffer fullness. A buffer manager, examines the fullness of each queue within the buffer and determines which class of packets to read out of the buffer.

Abstract: A computer bus for transferring data among a plurality of modules coupled thereto, and having flexible, distributed bus arbitration. A plurality of data lines is operable to transfer bits of data among modules attached to the bus. A single arbitration line is coupled to each module, and is used to indicate whether the bus is available for the next bus cycle. A bus packet clock, called a BUP clock, is used to divide the bus into cycle periods called BUP time slots. An access time clock further divides these BUP time slots into time access slots. The BUP time slot is the unit of time for which a module will be granted access to the bus. The BUP time slot is selected so that modules will be granted access to the bus for a length of time defined by a packet length. Each module on the bus is provided with arbitration circuitry for determining whether that module will be granted access to the bus for the next BUP time slot.

Abstract: A high-speed floating point conversion apparatus and method are disclosed, with special reference to selectable conversion of "source" IEEE format numbers to any of the "destination" IBM, DEC, or SEL formats. In the preferred embodiment, the exponent is input to a shift control block. The exponent is converted to a different base, resulting in a remainder. The remainder of the exponent base conversion is input to the shift position control input of a shift register (preferably a barrel shifter) which has received the fraction (or mantissa) of the original floating point number. The fraction is shifted an amount necessary to compensate for the exponent's base conversion. The shift position control bits are available after a very short period of time, so that the shifting process of the barrel shifter is also completed quickly. The exponent and shifted fraction (or mantissa) are then input to format conversion units which format the data bitwise as necessary for a particular output format.

Abstract: A frequency-hopping datalink and providing communication between a base station, relay unit and multiple remote units utilizes time-division multiplexing and transmits information signals containing information relevant to the next frequencies of transmission. Signals from the base station are transmitted on a first frequency to a relay unit which retransmits the signals on a second frequency to a group of remote units. The information signal from the base station contains information concerning the frequencies of the next transmission and the time slot allotted for the remote units to respond. The remote units respond back at the first frequency which is received by the relay unit and rebroadcast to the base station at the second frequency.

Abstract: A frequency and phase demodulating circuit provides direct frequency demodulation utilizing only addition, subtraction and multiplication steps. Division of signals is avoided, as is the need for a look-up table of trigonometric values corresponding to the results of such division. By maintaining a substantially constant input amplitude to a quadrature sampler, a number of approximations may be made without introduction of error. Compensation for actual signal variation, as well as for first order errors due to the approximation process of the invention, results in accurate frequency evaluation and avoids the necessity for differentiating an initial phase determination.

Abstract: An adaptive differential phase shift keyed (PSK) signal demodulator which optimally tracks changes in the symbol rate of the signal. An input signal is delayed by one symbol period by passing the signal through a charge coupled device (CCD) clocked by pulses phase locked to the symbol rate (F.sub.br) by a phase locked loop, the phase locked loop also outputting clock pulses at the symbol rate to strobe a symbol decision circuit. The CCD has L stages and is clocked at a rate L.multidot.F.sub.br. As the phase locked loop tracks changes in the symbol rate, the clock pulses are varied in rate so that the CCD delay is adaptively optimized for a given symbol rate. Digital tuning is provided by an adjustable divider circuit coupling the voltage controlled oscillator of the phase locked loop to the CCD, so that by digitally selecting the division ratio the demodulator is tuned to a different symbol rate.

Abstract: The disclosure is applicable for use in a logging-while-drilling apparatus for obtaining subsurface measurements during drilling in a fluid-filled borehole. Acoustic carrier waves are generated downhole in the borehole fluid and are PSK modulated in accordance with digital data representative of downhole measurements. The PSK modulation is obtained by momentarily unidirectionally either decreasing or increasing the frequency of the acoustic carrier signal until either a desired phase lag (for a decrease in frequency) or phase lead (for an increase in frequency) is imparted to the acoustic carrier signal. An uphole receiving subsystem includes transducers for converting the modulated acoustic carrier waves to electronic signals and circuitry for demodulating the electronic signals to recover the measurement information taken downhole. In accordance with an important feature of the invention, a filter is provided for selectively filtering the electronic signals before the demodulation thereof.

Abstract: The disclosure is applicable for use in a logging-while-drilling apparatus for obtaining subsurface measurements during drilling in a fluid-filled borehole. Acoustic carrier waves are generated downhole in the borehole fluid and are PSK modulated in accordance with digital data representative of the measurements. The PSK modulation is obtained by momentarily unidirectionally either decreasing or increasing the frequency of the acoustic carrier signal until either a desired phase lag (for a decrease in frequency) or phase lead (for an increase in frequency) is imparted to the acoustic carrier signal. An uphole receiving subsystem includes transducers for converting the modulated acoustic carrier waves to electronic signals and circuitry for demodulating the electronic signals to recover the measurement information taken downhole.

Abstract: The disclosure relates to an apparatus for receiving a carrier signal modulated with digital symbols, the symbol rate being related to the carrier frequency, such as by a submultiple or a ratio of integers. The invention is an adaptive carrier-aided symbol tracking loop in which signals derived from a symbol-coherent carrier maintain and aid symbol synchronization during periods of no symbol transitions. The invention is particularly applicable to systems wherein the received modulated carrier signal has been transmitted over a noisy transmission path, such as in a logging-while-drilling system. In accordance with the invention there is provided a phase-locked loop which includes a voltage controlled oscillator and an error signal generator for controlling the oscillator. In response to the carrier, a first signal is generated at substantially the symbol rate and, in response to symbol transitions, a second signal is generated which has a phase that depends upon symbol transitions.

Abstract: A video system having a transmitter in which a composite signal is formed by combining digital information with scanlines of an analog video signal generated by a line scanning device, and a receiver in which the digital information is recovered. The digital information is combined with the analog video signal at predetermined locations along scanlines of the video signal, and these predetermined locations are varied in order to prevent visible deterioration of the video image. In the video receiver, the digital information is recovered by examining the composite signal at the predetermined locations to extract the digital information. Each bit of digital information to be conveyed is represented by a first pseudo-random digital pulse sequence (or its complement, depending on whether the data bit is 1 or 0) which is superimposed on a selected scanline of the analog video signal to form the composite signal.