Northrop Grumman Systems Corporation

Michael J Trainor

Warren E Guthrie

Scott Alan Stratmoen

Louis R DiFrancisco

Stuart John Collar

Walter Jerry Pohribnij

Kris Rausch

Robert J Sutowski

A radio modem is disclosed that includes a radio receiver for receiving radio signals comprising data frequency multiplexed onto a carrier signal having a carrier frequency. An oscillator generates a reference frequency for an FM discriminator, which is connected to the antenna and to the for demodulating said data from said radio signals using said reference frequency. A microprocessor has an input connected to the output of the FM discriminator. The microprocessor also has an output. The microprocessor is programmed to sample the signal voltage output by the FM discriminator, average the signal voltage samples, and compare the average to a preset voltage. The microprocessor is programmed so that if the average differs from the preset voltage, the microprocessor generates an error signal at the microprocessor output. The oscillator is coupled to the microprocessor output so that the error signal adjusts the frequency of the oscillator.

Micro-controller based frequency calibration

A method for generating a random time interval suited for use in defining re-transmission time intervals so as to avoid communication contention utilizes at least one external seed and a plurality of linear maximal sequences. According to one embodiment, a first seed is provided and a first linear maximal sequence is initialized therewith. A second seed is generated via cooperation of the first linear maximal sequence and the external signal. At least one second linear maximal sequence is initialized with the second seed. A new time interval is started when the second linear maximal sequence sequences to a predetermined value.

Random time interval generator

A balanced battery charger maintains a balanced charge upon a plurality of battery cells which are connected in series with one another. The balanced battery changer has a monitoring circuit for determining when an imbalance between the charge upon the battery cells occurs and a charging/discharging circuit for selectively charging and discharging at least a selected one of the battery cells so as to generally balance the charge upon the battery cells. Balancing the charge upon the battery cells substantially enhances the life thereof.

Balanced battery charger

Improved electronic circuitry incorporated into a tag attached to a user worn wrist strap of a static electrical discharge dissipation system. The electronic circuitry monitors the electrical connection of the wrist strap from the user to ground and tests the functionality of the tag. The electronic circuitry comprises an oscillator, a signal transmitter, a discharge resistor and a discharge resistor check circuit for monitoring the accuracy of the discharge resistor. The electronic circuitry also comprises a skin resistance check circuit for monitoring the electrical connection of the wrist strap to the user, and a ground fault detect circuit for monitoring the electrical connection of the wrist strap to ground. The electronic circuitry further comprises a testing circuit for checking the frequency of the oscillator, monitoring the spectrum of a signal transmitted by the signal transmitter, checking the functionality of the ground fault detect circuit, checking low and high limits of the discharge resistor, and checking the functionality of the skin resistance check circuit.

Wrist strap test mode circuitry

A method is disclosed for controlling operation of a battery powered modem to implement power conservation by adaptive modem sleep. The method comprises detecting the presence of a periodic network timing signal and detecting transition of the modem processor to a processing ready condition, wherein received RF signals can be processed. A processor ready signal is generated in response to detection of the processing ready condition and compared in time to occurrence of the network timing signal. A sleep error signal is generated which represents the interval between occurrence of the network timing signal and the processor ready signal. A modem is then directed into a sleep mode for periods of time sufficient to reduce the sleep error signal to be within a predetermined error budget.

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Palatine, IL, United States of America

Michael J Trainor