Abstract: An arrangement for cooling an electronic assembly includes a circuit board, an enclosure member and at least one electromechanical actuator. The circuit board has a first surface, a second surface, and at least a first heat-generating element secured to the first surface. The circuit board further comprises at least one aperture extending between the first surface and the second surface. The enclosure member is secured to the circuit board so as to form a fluid tight barrier of a compartment defined at least in part by the enclosure member. The compartment includes a first subcompartment defined at least in part by the first surface and the enclosure member and a second subcompartment defined at least in part by the second surface and the enclosure member. The at least one electromechanical actuator is secured within the fluid type barrier and is operable to generate a flow movement in the direction of the at least one aperture when liquid is disposed in the fluid tight barrier.

Abstract: Control data is communicated utilizing a multi-frame format that consists of individual frames each having a number of rows and columns. As each row is received from a transmitting unit, the data and position of the row within a frame is verified by use of a checksum and is immediately utilized by the receiving unit. This reduces the amount of storage that must be provided by the receiving unit for the reception of control information to that of a single row. In addition to verifying the row identification, the identity of each frame within the multi-frame is also verified before an individual row is utilized. In a first embodiment, the operation of generating the checksum is seeded with the current row number. In a second embodiment, the operation of generating the checksum is seeded with the result of an Exclusive OR operation of the current row number and frame number.

Abstract: An arrangement for cooling an electronic assembly includes a circuit board and an enclosure member. The circuit board has a first surface, a second surface, and at least a first electronic component or other heat-generating element secured to the first surface. The enclosure member is secured to said circuit board so as to form a fluid tight barrier of a compartment defined at least in part by said enclosure member. Such compartment includes a first subcompartment defined at least in part by said first surface and said enclosure member and a second subcompartment defined at least in part by said second surface and said enclosure member. The circuit board further includes at least one aperture extending between the first surface and the second surface such that the first subcompartment is in fluid communication with the second subcompartment.

Abstract: An arrangement for electromagnetically shielding a circuit carrying substrate includes first and second shielding members and a plurality of elastically deformable shielding connectors. The first shielding member has first and second dimensions exceeding first and second dimensions defined by the circuit and is disposed on a first side of the circuit. The second shielding member also has first and second dimensions exceeding first and second dimensions defined by the circuit and is disposed on a second side of the circuit. The first and second shielding members define at least one slot therebetween. Each of the plurality of shielding connectors is both plastically deformable and electrically conductive, and furthermore extends between the first shielding member and the second shielding member. The plurality of shielding connectors are disposed within and throughout said slot and spaced apart by a distance that is less than one-fourth the wavelength of an effective operating frequency of the circuit.

Abstract: An arrangement for enclosing a fluid includes a circuit board and an enclosure member. The circuit board includes an electronic component secured thereto. The enclosure member is secured to the circuit board such that the enclosure member and the circuit board cooperate so as to create a fluid tight barrier of a compartment defined by the circuit board and the enclosure member.

Abstract: An arrangement for cooling an electronic assembly includes a circuit board having a primary circuit board portion and a secondary circuit board portion integrally secured to the primary circuit board portion. The arrangement also includes an enclosure member secured to the circuit board so as to create a fluid tight barrier of a compartment defined at least in part by the enclosure member. The arrangement further includes a first electronic component secured to the primary circuit board portion such that the first electronic component is located within the compartment. The arrangement also includes a second electronic component secured to the secondary circuit board portion such that the second electronic component is located outside of the compartment. The arrangement also includes a liquid disposed within the compartment such that the liquid is in a heat exchange relationship with the first electronic component.

Abstract: Synchronizing local timing units to a central timing unit to determine the difference in timing between external links and the local timing units so as to synchronize the centralized timing unit to the external links. This difference in timing is then transmitted to the central timing unit, which utilizes this information to adjust the timing of the central timing unit. The adjustment to the central timing unit brings it into synchronization with the selected external link. The local timing units are synchronized to the central timing unit via multiple timing paths set up through switching units within the network. Each switching unit switches one bit of data for each group of data being received on each of the external links. In addition, information received by each of the external links designating the accuracy of the external link is transmitted to the central timing unit so that the central timing unit can select the external link having the highest accuracy.

Abstract: A switching network having a plurality of independent switching groups with each switching group capable of switching one bit of each group of data from external data links through a telecommunication switching system and port units interfacing the data links directly control which of the switching groups will be active. This allows extra switching groups to be utilized as replacement switching groups should a switching group actively switching a bit of the incoming data be disabled. This increases the overall reliability of the telecommunication switching system since a failure of a port unit will only effect the external data link that is connected to that unit. In addition, this eliminates complicated and centralized control for the switching units which would be needed to inform the switching units which units should be active and the bit a given switching unit should be communicating.

Abstract: A switching network having a plurality of independent switching units with each switching unit switching one bit of each group of data from external data links through a telecommunication switching system. The plurality of switching units is greater than the number of bits that must be switched which increases reliability. This allows the extra switching units to be utilized as replacement switching units should a switching unit actively switching a bit of the incoming data be disabled. The switching units provide full broadcast switching of data from any individual external link to any number of the other external links. A plurality of port units terminate the external links, and a plurality of control paths are provide from a central controller to each of the port units. Each of the switching units communicated one of the control paths. For control, each port unit determines a set of control information that is identical from a majority of the control paths.

Abstract: Synchronizing a local timing unit to a central timing unit in a first switching system to determine the difference in timing between a connected external link and the local timing unit. This timing difference is then transmitted to the central timing unit which utilizes this information to adjust a frequency synthesizer that outputs the frequency of the external link to a second switching system. The local timing units are synchronized to the central timing unit via multiple timing paths set up through switching units within a switching network of the first switching system. The timing difference transmitted from the local timing unit is transmitted over a plurality of control paths through the switching units. Each switching unit switches one bit of data for each group of data being received on each of the external links connected to the first switching system. Any of the external links connected to the first switching system can be utilized to provide timing information for the second switching system.

Abstract: Establishing a plurality of timing paths through a switching network that has a plurality of independent switching units with each switching unit switching one bit of each group of data from a given external data link through the switching network. Each switching unit establishes a path to each of a plurality of port timing units where each port timing unit controls a set of port units. Further, each port timing unit is responsive to timing information received on the plurality of timing paths to utilize the timing information to provide timing to its set of port units. Each port timing unit comprises timing difference detectors with each timing difference detector determining a difference in timing between an individual one of the plurality of timing paths and timing generated by the timing unit. Each of the port timing units is responsive to the difference in timing for adjusting the timing of the port timing unit to agree with the timing of the central timing unit.

Abstract: An apparatus and method are disclosed for use in detecting and localizing electrostatically susceptible areas of electronic systems. An exemplary apparatus includes: (1) an ESD gun for providing a source of electric current; (2) a wire coil for generating a magnetic field; and (3) a shielded transmission line, such as a coaxial transmission line ("coax"), for receiving current from the gun. The center conductor of the coax is coupled at one end to the gun and at the other end to one end of the wire coil. The other end of the wire coil is coupled to ground. The current flowing through the wire coil creates a magnetic field, which is bi-directional and orthogonal to the plane of the coil. The magnetic field causes errors in the operation of the system under test when the coil is placed in close proximity with ESD susceptible system components. As such, components that are ESD susceptible can be easily detected and localized.

Abstract: Duplicated optical detectors detect the removal of a printed circuit board and are also used as indicators to indicate conditions on the printed circuit board. The detectors comprise a controller, two pairs of light emitting diodes (LEDs), and two light pipes mounted through and secured to a latch handle attached to the printed circuit board. Each light pipe extends over a pair of LEDs in the closed position of the latch handle. One LED of each pair is utilized as a transmitter, and the other LED of the pair is utilized as a light sensor. In the closed position of the latch handle, light is communicated from the transmitter via the light pipe to the light sensor and through the latch handle to the back of the printed circuit board. For purposes of detecting the removal of the board, as the board is being removed, the latch handle pivots away from the board moving the light pipes from the closed position that is over the LEDs.

Abstract: Simplifying measurement equipment so that any two frequency sources can be accurately and quantitatively compared to each other. With this simplified measurement equipment, calibration can be performed on an oscillator using an external reference signal, while the oscillator is being used in an active system. By simplifying the measurement equipment, the equipment can be built into a time base unit allowing recalibration to be performed at relatively short time intervals. A frequency difference detector based on ring counters and an existing controller in a telecommunication switching system compare an accurate external reference against an oscillator of the time base unit for calibration in the field. Within the telecommunication switching system, a highly accurate external reference signal is normally available from an interconnected telecommunication network.

Abstract: A phase-lock loop (FIG. 1) is initialized at power-up by an oscillator (14) control signal (28) that has previously been stored by a processor (20) in a non-volatile memory (27). The stored control signal is generated by the phase-lock loop's controller (12) in response to receipt of a calibrated reference input signal, as part of manufacturing of the phase-lock loop and occasionally thereafter during normal operation. Being stored in non-volatile memory, the control signal is not lost upon removal of power from the phase-lock loop. The stored control signal is then used to control the oscillator instead of the controller's output upon power-up and until the later one of (a) receipt by the phase-lock loop of a valid reference signal and (b) receipt of a directive for the controller to take over control of the oscillator.

Abstract: Solving the aging problem of crystal oscillators by doing field recalibration. The solution is to utilize an accurate external reference signal to determine when the frequency of the digital temperature compensated crystal oscillator (DTCXO) has drifted from the reference signal in excess of a specification. When this occurs, the DTCXO has used its internal compensation values to correct its output hence the difference between the external reference signal and the frequency of the DTCXO in excess of the specification is due to aging. A new compensation value for the present temperature is calculated using the reference signal. Using the well known fact that the temperature aging uniformly shifts the frequency over the temperature range, a controller utilizes the difference between the new compensation value and the stored compensation value for the present temperature to shift the entire set of compensation values to compensate for the aging effect.

Abstract: Cross coupling framing signals between two timing subsystems to adjust the phase relationship between the timing subsystems. In a standby timing system, framing signal of the standby timing system is used to start a counter, and framing signal of the active timing subsystem is used to stop the counter. The delay due to drivers, receivers and interconnecting cables is made to be an integer number of counts (nominal count) of the counter. Any difference between the contents of the counter and the nominal count represents the difference in phase between the standby timing subsystem and the active timing subsystem. The standby timing subsystem is adjusted to eliminate this phase difference by eliminating the difference between the nominal count and the contents of the counter.

Abstract: Visual indication of an operational condition on a printed circuit board by utilizing a pair of LEDs for each operational indication and by utilizing each LED of a pair to verify that the other LED can emit light greater than a predefined level. In addition, if an error condition is determined to exist in a pair of LEDs, a central processor is notified of this fact to allow the error condition to be remedied. Further, if a failure is detected in the pair, both LEDs are utilized to indicate an operational condition on the printed circuit board. This increases the probability that the LED pair will be able to indicate the operational condition.

Abstract: In an optical differential signal transmission system, both the optical signal and its complement are transmitted via a single optical fiber, by using wavelength-division multiplexing. In a multipoint transmission system, tri-stateable differential optical signal transmitters and receivers capable of discerning tri-state differential optical signals are used, to allow a plurality of signal sources to share the same optical signal transmission path on a time-division multiplexed basis.