Abstract: Systems and methods for detecting or predicting a seismic event. The methods comprise, by a system: receiving at least one communication signal using a carrier recovery component with a fixed location remote from a source of the at least one communication signal; determining at least one of (i) phase deviations of the at least one communication signal over time and (ii) differential propagation delays over two paths which the at least one communication signal traveled; performing operations to detect patterns in at least one of the phase deviations and differential propagation delays that indicate an occurrence of seismic activity with level(s) of confidence; and using the level(s) of confidence to detect or predict the seismic event.

Abstract: An optical monitoring circuit includes a photoelectric device such as a photo-detector that produces a signal in response to incident light thereon corresponding to a characteristic of the incident light such as intensity, or wavelength. A light source is disposed within the circuit for emitting a beam of light, a portion of which is to be incident upon the photoelectric device. The photoelectric device when reversed biased provides an output electrical signal from which the intensity of light from the light source impinging thereon can be determined. The photoelectric device when forward biased provides an output signal from which the temperature of the photoelectric device can be determined. A method and circuit are disclosed for calibrating out the unwanted effect of light from the light source affecting accuracy of the determined temperature derived from the output signal when the photoelectric device is forward biased.

Abstract: The invention relates to a method for the estimation of chromatic dispersion in multichannel optical network spans during active operation. The invention further discloses a chromatic dispersion monitor for real time monitoring of accumulated dispersion in individual channels. The method effectively estimates accumulated chromatic dispersion by obtaining a contour map of the eye diagram correlating more than three points for measuring at least two parameters to known dispersion. This can provide accurate BER indication before failure occurs and provide indication of the sign of dispersion for faster correction.

Abstract: An optical monitoring circuit includes a photoelectric device such as a photo-detector that produces a signal in response to incident light thereon corresponding to a characteristic of the incident light such as intensity, or wavelength. A light source is disposed within the circuit for emitting a beam of light, a portion of which is to be incident upon the photoelectric device. The photoelectric device when reversed biased provides an output electrical signal from which the intensity of light from the light source impinging thereon can be determined. The photoelectric device when forward biased provides an output signal from which the temperature of the photoelectric device can be determined. A method and circuit are disclosed for calibrating out the unwanted effect of light from the light source affecting accuracy of the determined temperature derived from the output signal when the photoelectric device is forward biased.

Abstract: The invention relates to a method for the estimation of chromatic dispersion in multichannel optical network spans during active operation. The invention further discloses a chromatic dispersion monitor for real time monitoring of accumulated dispersion in individual channels. The method effectively estimates accumulated chromatic dispersion by obtaining a contour map of the eye diagram correlating more than three points for measuring at least two parameters to known dispersion. This can provide accurate BER indication before failure occurs and provide indication of the sign of dispersion for faster correction.

Abstract: Disclosed is a circuit for and method of testing a facsimile transceiver to determine whether it is operating properly. The method employed utilizes a document having a test pattern on a first portion thereof which is placed adjacent the read head of the transceiver. The reading means of the transceiver is energized and the test pattern is scanned. The output of the reading means, when the transceiver is being diagnosed, is directed to a digital memory and stored. Subsequently, the output of this memory is connected to the transmitter section and from there to the receiver section of the transceiver which is then energized to display the contents of the memory on a second portion of the document. In the preferred embodiment of the invention, the test pattern is located on a portion of a document which does not encompass the entire circumference of a rotating drum.

Abstract: A facsimile method and apparatus wherein the white level is set during prescanning in one direction from a first extremity to a second extremity of a document. Scanning then proceeds with the white level set in a second direction from the second extremity to the first extremity. The white level is set using variable gain amplifier means comprising a digital-to-analog converter and gain control means comprising a digital register which stores a binary word representing the whitest level sensed during prescanning in the first direction.

Abstract: Disclosed herein is a facsimile apparatus with an improved sheet transport means including a transport path and a feeder in the path for moving sheets along it to a scanner. A sensor is situated in the path for sensing the length of the sheets being fed to the scanner. The sensor is utilized for detecting the length of the document such that it may be removed from the scanner by engaging the trailing edge of the sheet.

Abstract: The scanning drum of a facsimile receiver carries a longitudinally extending stripe such that portions of the stripe at opposite extremities of a document carried by the drum are exposed. The width of the stripe at the exposed portion adjacent the leading edge of the document is sensed by an optical sensing head and stored in memory prior to transmitting dark/light variations in the document. The scanning of the document continues until the optical scanning head is juxtaposed to the exposed portion of the drum adjacent the trailing edge of the document. At this time, the width of the stripe is again detected and compared with the width in memory so as to verify that the scanning of the document is complete. The facsimile transmission is then terminated.