Abstract: A synthesizer circuit with spur compensation utilizes fractional division in the synthesizer loop. The fractional divider includes means for compensating the spurs when the fractional numerator N=0. The synthesizer includes means for selecting a reference divisor R such that a non zero value of fractional numerator is produced and such that the generated spurs fall below the side band noise limits of the synthesizer's voltage controlled oscillator.

Abstract: The novel polyester of the present invention is melt processable and is capable of forming an anisotropic melt phase. The polyester includes a relatively low concentration of 6-oxy-2-naphthoyl moiety. Other key moieties are 4-oxybenzoyl moiety, terephthaloyl moiety, 1,4-dioxyphenylene moiety, and 4,4'-dioxybiphenyl moiety. The presence of the 1,4-dioxyphenylene moiety in the specified concentration in combination with the other moieties surprisingly has been found to be capable of advantageously lowering the melting temperature of the resulting polyester while making possible the substantial maintenance of a highly attractive heat deflection temperature in molded articles formed from the same. Fibers which exhibit a relatively high modulus also may be formed.

Abstract: A frequency synthesizer (10) for providing a modulated output signal (fo) includes a reference frequency signal (fr) and a voltage controlled oscillator (14). For dividing the frequency of the output signal from the voltage controlled oscillator (14) by a divisor, a programmable divider (16) is coupled to the output of the voltage controlled oscillator (14). To produce a phase-locked loop in which the frequency of the output signal from the voltage controlled oscillator (14) is equal to the frequency of the reference frequency (fr) signal multiplied by the divisor, a phase detector (12 ) having a first input coupled to the reference frequency signal (fr), a second input coupled to the output of the programmable divider (16), and an output coupled to the input of the voltage controlled oscillator (14) is also provided. A first integrator (24) for integrating a modulating signal provides an integrated signal and a first control signal.

Abstract: A phase locked loop (100) with a sample and hold phase detector (106) with adjustable gain. A switching circuit adjusts the slew rate of the phase detector by either introducing additional ramp capacitance (122) in the phase detector or by increasing the current for charging the ramp capacitor (116).

Abstract: A frequency synthesizer for providing a modulated output signal includes a phase comparator, a loop filter, and a voltage controlled oscillator (VCO). The phase comparator receives a reference input signal and a signal related to the VCO output, and generates a control current. A modulation circuit receives a modulation signal and provides both a modulation current and a modulation voltage. The modulation current is summed with the control current at one input of the loop filter, while the modulation voltage is applied to a second input of the loop filter. The VCO is controlled by the output of the loop filter to produce the modulated output signal.

Abstract: A method for supporting metalloporphyrins on polybenzimidazole articles is disclosed herein. Microporous polybenzimidazole articles are treated with a strong base to produce an anionized polybenzimidazole article. A metalloporphyrin salt is dissolved in a solvent and is mixed with the anionized polybenzimidazole article to produce a microporous polybenzimidazole metalloporphyrin complex. This compound can be used in the selective oxidation of alkanes, olefins and aromatic compounds and is quite useful in the separation of oxygen from a gas stream. An alternative method of forming this complex by mixing directly the polybenzimidazole particulate with a weak metalloporphyrin salt without the use of a strong base results in lower percentages of substitution then does the principal method.

Abstract: A road marker having a stiff but resilient body including a cavity formed therein to receive a suitable adhesive material for securing the marker to the road surface, and adaptable for the inclusion of one or more apertures in said body to receive one or more hermetically sealed lens and retro-reflector elements prior to adhesion of the road marker to the roadway. The body of the road marker is formed with a continuous edge portion and a frusto-conical central portion configured so as to limit contact between vehicle tires and the outer lens surface which may be disposed therein, thereby limiting abrasion and extending the useful life of the road marker. The body of the road marker also includes an aperture to receive a nail in order to facilitate installation of the road marker on the road surface.

Abstract: A variable capacitance circuit includes a varactor having an anode side and a cathode side. A first variable bias voltage is applied to one of the sides and one of a plurality of voltages is applied as a second bias voltage to the other side for controlling the capacitance of the varactor. A voltage multiplier circuit connected to a voltage divider network is used for supplying the plurality of voltages. A decoder is responsive to input signals for selecting and applying one of the multiple voltage outputs. The variable capacitance circuit is used in a voltage controlled oscillator of a frequency synthesizer for providing extended frequency range.

Abstract: A frequency synthesizer is provided including a reference frequency generator coupled to one input of a phase detector. The output of the phase detector is coupled via a pair of alternatingly connected filters through a voltage controlled oscillator and a divider circuit to the remaining input of the phase detector to form a phase locked loop. The first filter of the pair is designated for operation on a main channel frequency while the remaining filter is designated for operation on a priority channel frequency. The capacitive elements of each respective filter remain fully charged up for operation on their respective frequencies and thus when such filters are alternately switched between to change frequency from the main channel to the priority channel, the capacitive elements need not be charged to new levels to accommodate such frequency change.

Abstract: This invention provides a process for photochemical epoxidation of olefins with molecular oxygen in a liquid phase with irradiation in the presence of a combination of 1,2-diketone photosensitizers.Propylene can be converted to propylene oxide by reaction with molecular oxygen in an ortho-dichlorobenzene reaction medium in the presence of 2,3-butanedione and 1-phenyl-1,2-propanedione photosensitizers, at a space time yield rate of at least 15 grams per liter hour.