Abstract: Improved dispersion compensating circuits for optical transmission systems are disclosed. According to the improved method, there is provided a compensation circuit comprising a varactor diode network. The network is preferably inserted between a source of laser modulating signal and the laser. A low-pass filter or all pass filter constructs the network. The network preferably includes an inductor or inductors and a combined circuit, which includes varactors. The network preferably provides an amplitude dependent delay of the modulating signal applied to the laser or to the optical receiver as post dispersion correction circuitry. In a first embodiment, a fixed capacitor is in series with a varactor and connected to a DC bias through inductor. Additional embodiments, using multiple varactors in different circuit configurations, with particular advantages for various applications identified.

Abstract: A conditioned air delivery system is provided for parked aircraft. The system can accommodate elevated thermal loads while maintaining operation, albeit with reduced flow rates or slightly elevated temperatures. When temperature set points are not reached or cannot be maintained, a second compressor of a refrigeration unit is operated in parallel with a first compressor. When refrigerant pressure becomes excessive, a second fan is operated that is associated with a condenser of the system. Still higher pressures, indicative of higher thermal loads, can cause the system to shut down operation of one of the compressors, reducing the overall cooling capacity of the system, while maintaining the supply of refrigerated air to the aircraft. The airflow may be reduced to maintain an air temperature at or near the desired temperature. Coordination of several parallel and redundant refrigeration units may be provided with a single blower and coordinated control.

Abstract: This anti clipping circuit is for a laser transmitter used to transmit sub-carrier multiplexed signals for CATV applications. The circuit design is based on actual clipping measurements showing the specific time and duration of the clipping events is random. The individual clipping pulses interval is fixed, every 4 us. A PHEMT peak detection circuit is used in conjunction with a missing pulse detector/timer to catch all the clipping events. Thus the laser bias current is adjusted automatically at the specific time of the clipping event and for the duration of all the clipping pulses in the event. The controlled increase and decrease of the lasers bias current is DC coupled back into the normal DC bias path via a diode. This gives the anti clipping circuit noise isolation when there are no clipping events and avoids laser clipping during the laser current recovery time as when using an AC coupling scheme.

Abstract: A method is provided for determining the integrity of a domain defined in a network. The method includes processes and systems to facilitate the discovery a conceptual ring topology of the domain in the network, and the determination of the integrity of the domain based on the conceptual ring topology that was discovered.

Abstract: A method is provided for using an uncooled laser package having pre-established performance specifications that include a pre-established optical power level. The package is to be used at a second set of performance specifications that include a second optical power level greater than the preestablished optical power level. The method begins by applying a bias level to a laser diode in the uncooled laser package that optimizes distortion and causes the laser package to generate the second optical power level. The bias level is greater than a pre-established bias level specified to generate the pre-established optical power level. Next, the uncooled laser package is heated or cooled to maintain a substantially constant laser diode temperature.

Abstract: A process for masking one or more predetermined portions of a surface of a card, for example a hologram, a signature area, or an area to be later personalized, to prevent a printed transfer media from being coated onto the predetermined surface portion as the transfer media is coated onto the remaining surface of the card. As a result of masking the predetermined surface portion, the predetermined surface portion is not covered by the transfer media.

Abstract: An in-line distortion generator for coupling in-line with a non-linear device (NLD) produces an output signal of useful amplitude, but with low composite triple beat and cross modulation distortions. The distortion generator comprises an instant controlled non-linear attenuator which utilizes the non-linear current flowing through a pair of diodes to provide the proper amount of signal attenuation over the entire frequency bandwidth. The distortion generator circuitry is always matched to the NLD, thereby ensuring a frequency response that is predictable and predefined. The distortion generator may also include a temperature compensation circuit to ensure consistent operation throughout a wide temperature range.

Abstract: A method is provided for using an uncooled laser package having pre-established performance specifications that include a pre-established optical power level. The package is to be used at a second set of performance specifications that include a second optical power level greater than the preestablished optical power level. The method begins by applying a bias level to a laser diode in the uncooled laser package that optimizes distortion and causes the laser package to generate the second optical power level. The bias level is greater than a pre-established bias level specified to generate the pre-established optical power level. Next, the uncooled laser package is heated or cooled to maintain a substantially constant laser diode temperature.

Abstract: A method is provided for maintaining the temperature of a laser diode located in a laser package. The method begins by monitoring a photocurrent generated by a photodiode that collects light from a back-facet of the laser diode located in the laser package while maintaining a constant bias level to the laser diode. Next, the laser diode is heated or cooled to maintain a substantially constant photocurrent, thereby maintaining the temperature of the laser diode at a substantially constant value. The laser package may be an uncooled laser package such as a coaxial can laser package.

Abstract: An in-line distortion generator for coupling in-line with a non-linear device (NLD) produces an output signal of useful amplitude, but with low composite triple beat and cross modulation distortions. The distortion generator comprises an instant controlled non-linear attenuator which utilizes the non-linear current flowing through a pair of diodes to provide the proper amount of signal attenuation over the entire frequency bandwidth. The distortion generator circuitry is always matched to the NLD, thereby ensuring a frequency response that is predictable and predefined. The distortion generator may also include a temperature compensation circuit to ensure consistent operation throughout a wide temperature range.

Abstract: An SQL program executor and an SOL compiler both include options for avoiding recompilations of execution plans whenever the runtime object and the compile time object referenced by an execution plan meet predefined schema similarity criteria. Thus, recompilation is sometimes avoided even though the compile time object has been altered or the run time object is not the same object as the compile time object. To enable late binding, schema information is stored in each execution plan for each object to be accessed by the execution plan. The stored schema information is a subset of the full object schema, and includes information about all the aspects of the objects to be accessed which must remain unchanged in order for the execution plan to be operable. While executing a compiled program, the SQL executor avoids recompilations of execution plans whenever the runtime object and the compile time object referenced by an execution plan meet predefined schema similarity criteria.

Abstract: An arrangement for heating the passenger area of a vehicle. To increase the heating efficiency without requiring the use of more fuel, disposed upstream of the exhaust gas heat exchanger is a catalytic converter that particularly during idling and in a partial load range provides additional thermal energy via secondary combustion of unburned hydrocarbons. To regulate the heat flow that is transferred to the warm water circuit, an exhaust gas diverter is provided that can be controlled by thermal-lug switches in such a way that when heat is required, it can divert the exhaust gas through the exhaust gas heat exchanger or, when too much heat is being supplied from the cooling water and the exhaust gas, the exhaust gas is conveyed directly to the atmosphere via the muffler.