Abstract: A pilot tone generator receives optical energy from an optical communication medium carrying a plurality of optical signals. Each optical signal carries data modulated at a unique wavelength and further modulated with a unique identification signal. The identification signal has an amplitude corresponding to an optical power of the associated optical signal. The pilot tone receiver detects each identification signal from the optical energy received and determines its corresponding amplitude. The pilot tone receiver calculates the optical power of each optical signal in the optical energy in response to the amplitude of the associated identification signal.

Abstract: An optical signal having optical energy is received at an optical amplifier. The optical signal may be separated into a low frequency segment and a high frequency segment. The high frequency segment and the low frequency segment may be processed in order to determine a low frequency error signal and a high frequency error signal. The low frequency error signal may be summed with the high frequency error signal in order to generate a total error change associated with the optical amplifier.

Abstract: Methods and apparatus for maintaining a pre-determined ratio of a pilot tone power and a total mean optical power of an optical signal are provided. One apparatus includes an optical source coupled to provide an optical signal in response to a DC bias and an AC bias corresponding to a pilot tone signal. A processor is coupled to compute each of an AC component and a DC component of the optical signal from the same digitally sampled signal. A feedback control is coupled to vary at least one of the DC bias and the AC bias in accordance with a difference between a pre-determined value and a ratio of the AC and DC components.

Abstract: A pilot tone generator receives optical energy from an optical communication medium carrying a plurality of optical signals. Each optical signal carries data modulated at a unique wavelength and further modulated with a unique identification signal. The identification signal has an amplitude corresponding to an optical power of the associated optical signal. The pilot tone receiver detects each identification signal from the optical energy received and determines its corresponding amplitude. The pilot tone receiver calculates the optical power of each optical signal in the optical energy in response to the amplitude of the associated identification signal.

Abstract: Optical energy is provided to an optical amplifier by a first and a second pump laser. The optical energy that is provided is used as a basis for generating a gain associated with the optical amplifier. An error associated with the first pump laser may be identified. One or more parameters associated with the second pump laser may be controlled in response to the error such that the second pump laser increases an optical power output provided to the optical amplifier to compensate for the full or partial failure of the first pump laser. The adjustment in optical power output is used by the optical amplifier to substantially maintain the gain associated with the optical amplifier.

Abstract: Methods and apparatus for maintaining a pre-determined ratio of a pilot tone power and a total mean optical power of an optical signal are provided. One apparatus includes an optical source coupled to provide an optical signal in response to a DC bias and an AC bias corresponding to a pilot tone signal. A processor is coupled to compute each of an AC component and a DC component of the optical signal from the same digitally sampled signal. A feedback control is coupled to vary at least one of the DC bias and the AC bias in accordance with a difference between a pre-determined value and a ratio of the AC and DC components.

Abstract: An optical signal having optical energy is received at an optical amplifier. The optical signal may be separated into a low frequency segment and a high frequency segment. The high frequency segment and the low frequency segment may be processed in order to determine a low frequency error signal and a high frequency error signal. The low frequency error signal may be summed with the high frequency error signal in order to generate a total error change associated with the optical amplifier.

Abstract: A voltage potential at a selected one or more inputs is controlled in order to produce a gain associated with an optical amplifier. One or more characteristics associated with a feedback loop coupled to the optical amplifier may be stored. A signal may be communicated to identify the occurrence of an error associated with the feedback loop. A selected current value may be provided to an element such that the optical amplifier is restored to a state associated with the optical amplifier prior to the failure. The selected current value is based on one or more of the characteristics associated with the feedback loop.

Abstract: Methods and apparatus related to maintaining a pre-determined ratio of a pilot tone power and a total mean optical power of an optical signal are provided. One method includes the steps of detecting the AC and DC components of an optical signal having a pilot tone signal. An amplitude of the pilot tone signal is varied in accordance with a difference between a pre-determined value and a ratio of the AC and DC components. Another method includes the step of generating an optical signal in accordance with a DC bias and an AC bias corresponding to a pilot tone signal. The AC and DC components of the optical signal are detected. At least one of the DC bias and the AC bias is varied in accordance with a difference between a pre-determined value and a ratio of the AC and DC components. An apparatus includes an optical source providing an optical signal in response to a DC bias and an AC bias corresponding to a pilot tone signal.

Abstract: An optical signal having optical energy is received at an optical amplifier. The optical signal may be separated into a low frequency segment and a high frequency segment. The high frequency segment and the low frequency segment may be processed in order to determine a low frequency error signal and a high frequency error signal. The low frequency error signal may be summed with the high frequency error signal in order to generate a total error change associated with the optical amplifier.

Abstract: A pilot tone generator receives optical energy from an optical communication medium carrying a plurality of optical signals. Each optical signal carries data modulated at a unique wavelength and further modulated with a unique identification signal. The identification signal has an amplitude corresponding to an optical power of the associated optical signal. The pilot tone receiver detects each identification signal from the optical energy received and determines its corresponding amplitude. The pilot tone receiver calculates the optical power of each optical signal in the optical energy in response to the amplitude of the associated identification signal.

Abstract: The invention is a system for combining the outputs of two transducers to provide a continuous reading over the combined ranges of the two transducers. The system applies an A.C. signal to the appropriate transducer; the steering for the excitation is controlled by the system microprocessor. The transducers are connected in series mechanically such that the low-range transducer is mechanically stopped before it is overloaded. The outputs of the transducers are connected in parallel and applied to the pre-amp which amplifies the A.C. error signal. The signal from the pre-amp is then applied to the analog-to-digital converter (ADC) for conversion. The ADC converts the pre-amp signal which is then sent to the system microprocessor over a serial link. The system microprocessor then applies the appropriate weighing algorithms to the data and then conveys that information to the parent system.

Abstract: A method of recalibrating an electronic scale is disclosed which causes the scale to indicate accurate weight measurements regardless of variations in the physical and/or environmental conditions under which the scale is operating between a site of origin and a site of installation which tend to adversely effect accurate weight. The method utilizes the removable platter of the scale as a fixed weight of indeterminate amount which is used to calibrate the scale at a site of origin under controlled physical and/or environmental conditions and to recalibrate the scale at a site of installation at which the physical and/or environmental conditions may be different from those that prevailed at the site of origin.

Abstract: Disclosed is a method of recalibrating an electronic scale to maintain accurate weight measurements of a scale regardless of variations in the physical and/or environmental conditions under which the scale is operating between a site of origin and a site of installation which tend to adversely affect accurate weight. Also disclosed is method of obtaining an accurate indication of the weight of an article by an electronic scale at a site of installation regardless of variations in the physical and/or environmental conditions under which the scale is operating between a site of origin and the site of installation which tend to adversely affect accurate weight. Both methods are accomplished by recalibrating the scale to adjust the output of certain electronic control components to compensate for the difference in the physical and/or environmental conditions between the two sites which tend to adversely affect accurate weight indications of the scale.

Abstract: An electronic scale is disclosed having a device for recalibrating the scale from time to time after the scale is moved from the factory to a site of installation in order to adjust the scale for physical and/or environmental operating conditions which are different from those which prevailed at the factory when the scale was originally calibrated after the completion of manufacture and which have an adverse effect on the accuracy of the scale if the scale is not recalibrated under these conditions. The scale is provded with a device which adds a predetermined fixed weight to the load cell of the scale at any desired time or interval of time, and an electronic count indicative of this weight at the site of installation is compared with an electronic count of the same weight taken at the factory and stored in a memory, and the digital readout of the scale is then adjusted by an amount which is the same as the ratio of the original count of the weight and the count thereof taken at the site of installation.

Abstract: A method of changing the sensitivity of a transducer includes applying to the transducer a cyclic excitation signal. The excitation signal has a number of recurring phases of different amplitudes. The transducer's output signal has a like number of recurring phases, each of which corresponds to a phase of the excitation signal. One of the phases of the output signal is selected for data acquisition. Selection of a different phase changes the effective measuring range of the transducer. Preferably, the excitation signal is an a.c. signal, and the output signal is partially demodulated as part of the selection of a phase for data acquisition.

Abstract: A circuit for modulating or demodulating an input potential includes a first operational amplifier for receiving the input potential and a second operational amplifier for outputting an output potential. A resistor network is connected to the operational amplifiers. A switch with a first position and a second position is connected to the resistor network and to at least one of the operational amplifiers. The circuit also includes a mechanism for repeatedly driving the switch between its first position and its second position. When the switch is in its first position, the output potential equals the input potential. When the switch is in its second position, the output potential equals minus one times the input potential.

Abstract: A device for measuring a physical quantity includes a transducer and circuitry for exciting the transducer with an a.c. square wave. The excitation circuitry includes two amplifiers, a switch and a resistor network. The excitation circuitry provides a plus one gain when the switch is in one position and a minus one gain when the switch is in a second position. A similar circuit synchronously demodulates the transducer's output signal. Another similar circuit synchronously demodulates the transducer excitation signal and provides a reference voltage to an analog-to-digital converter (ADC). The ADC converts the demodulated transducer ouptut signal into a binary word. Both demodulated signals are filtered before application to the ADC. An example of the device is a force-measuring device such as a weighing scale incorporating a strain gauge load cell.

Abstract: A vault cartridge having a data storage means for the storage of data therein. The cartridge has a size and a shape which is adapted for insertion within a vault receptacle coupled to a host system. The vault receptacle has a primary portion of a magnetic power coupling means made of a primary core and a primary winding operatively coupled to the core. The vault cartridge further comprises a secondary portion of the core having a secondary winding operatively coupled thereto. The portions of the core within both the cartridge and the receptacle are disposed such that when the cartridge is inserted within the receptacle the two portions of the core are magnetically coupled one to the other. A source of excitation energy applied to the primary winding is magnetically coupled through the core and into the secondary winding of the cartridge. Power conversion means is provided within the cartridge for deriving operating power from the secondary winding.

Abstract: A value printing system is disclosed which provides for storing the indicia to be printed within a secure vault module. The vault module also provides for securely maintaining the system accounting data. Coupled to the vault module is a host module which in turn is coupled to a printer module, whereby the indicia are printed. The vault module and the host module are coupled together by a high speed communications bus which utilizes a memory interchange, or swapping, technique to transfer blocks of data bidirectionally between the vault and the host.