Abstract: Briefly, in accordance with one embodiment of the invention, a circuit comprises: a sigma-delta modulator including an input signal port, an output signal port, and a signal path. The signal path includes a feedforward signal path and a feedback signal path. The signal path is adapted to be coupled to a dither signal and the circuit is adapted to adjust the dither signal substantially in accordance with a signal applied to the input signal port. In accordance with another embodiment of the invention, a method of improving the stability of a sigma-delta modulator, the modulator employing dither, comprises the steps of: applying a signal to the input port of the sigma-delta modulator; applying a dither signal to the signal path of the sigma-delta modulator; and adjusting the dither signal applied substantially in accordance with the signal applied to the input port.

Abstract: An optical device 201, having one or more input waveguides 25 coupled to one side of a slab waveguide 20 and an array of output waveguides 26 coupled to an other side of the slab waveguide, is improved by including a transition region 22 immediately adjacent to the slab that operates to reduce insertion loss between the waveguide array 26 and the slab waveguide. The transition region includes a number of silica paths (a.sub.I . . . a.sub.n) that intersect the waveguide array. The silica paths have widths W(a.sub.n) that progressively decrease as they become further away from the slab waveguide. The silica paths are parallel to each other and perpendicular to the waveguide array. Disclosed embodiments include an M.times.N star coupler, a Dense Waveguide Division Multiplexer, and a 1.times.N power splitter. In each of these embodiments, insertion loss is substantially reduced over similar devices not employing such a transition region.

Abstract: Applicants have discovered methods for making, treating and using diamonds which substantially enhance their capability for low voltage emission. Specifically, applicants have discovered that defect-rich diamonds--diamonds grown or treated to increase the concentration of defects--have enhanced properties of low voltage emission. Defect-rich diamonds are characterized in Raman spectroscopy by a diamond peak at 1332 cm.sup.-1 broadened by a full width at half maximum .DELTA.K in the range 5-15 cm.sup.-1 (and preferably 7-11 cm.sup.-1). Such defect-rich diamonds can emit electron current densities of 0.1 mA/mm.sup.2 or more at a low applied field of 25 V/.mu.m or less. Particularly advantageous structures use such diamonds in an array of islands or particles each less than 10 .mu.m in diameter at fields of 15 V/.mu.m or less.

Abstract: The present invention is an embedded random access memory device especially adapted for use with digital processors having a pipelined data architecture. In accordance with one embodiment of the present invention a write access cycle performed at a memory location within the memory device is phase shifted by one phase of a clock cycle relative an access cycle of a read operation. This is advantageous in that the integrity of data which traditionally would have been presented late in the write access cycle can still be maintained, since the entire write cycle is now shifted one phase later. A precharge signal which follows the write access is correspondingly shifted by one phase of a clock cycle. A wait state is inserted between the write access cycle and a read access cycle which directly follows in the same memory bank of the memory device. The wait state eliminates conflicts between the access cycle and the precharge cycle.

Abstract: An Electrically Erasable Programmable Read Only Memory (EEPROM) provides backup and initialization data for random access memory (RAM) in a control unit. In order to update the EEPROM with new releases of a program and data, the EEPROM is divided into two segments, each with a separately controllable write enable voltage. Advantageously, this allows a new release to be written into one segment of a single EEPROM without erasing the other segment until the newly written segment has been verified.

Abstract: A tunable laser whose lasing frequency can be changed by varying the absorbance of absorber layers that are preceding a standing wave of the laser cavity. Changes in the absorbance of the layers are accomplished by varying the strength of the absorber layers through application of voltage to the layers.

Abstract: A composite distribution cable for connection to a customer's premises has a fiber optic cable, twisted voice band pairs, copper power cables, and a coaxial cable within a common sheath. Water blocking members within the cable fill the voids between the conducting members and the sheath upon contact with water or other liquid.

Abstract: One communications device (called the "impersonating" device) can selectively impersonate another communications device (called the "impersonated" device) by arranging the impersonating device to take over and/or use the same network identification number (typically stored in an identification number memory and used to control selection of incoming calls to which the device responds) normally associated with the impersonated device. As a result of impersonation, there is a hand-off between the devices, with the impersonated device becoming dormant and the impersonating device becoming active, such that calls normally received by the impersonated device are received by the impersonating device, and such that calls originating in the impersonating device get the identical network treatment as would be accorded to calls originated by the impersonated device, all of this without any need to adjust or update profiles stored in a network database.

Abstract: A single sideband modulator circuit for modulating an optical signal with an RF signal to provide a frequency shift to the optical signal. The modulator circuit utilizes a dual path modulator having an electrical terminal and two optical terminals. An RF signal is provided to the electrical terminal and an optical signal is provided to each optical terminal so that the optical signal input to one terminal travels in the direction of the RF signal to produce an output optical signal having a carrier band and a single sideband, and the optical signal input to the other optical terminal travels in the opposite direction of the RF signal to produce an output having only a carrier band. A coupler adds the resulting optical output signals so that the carrier bands are cancelled, leaving only the sideband.

Abstract: Briefly, in accordance with one embodiment of the invention, a device for use in a magnetic recording read channel adapted to be coupled to a magneto-resistive (MR) read head comprises: an integrated circuit adapted so as to introduce a controllable amount of second-order nonlinearity into the magnetic recording read channel signal path to at least partially offset nonlinearity associated with use of the MR read head. Briefly, in accordance with another embodiment of the invention, a method of reducing nonlinear signal effects in a magnetic recording read channel signal path associated with use of a magneto-resistive (MR) read head comprises the step of: introducing into the read channel signal path a scalable square of the read channel signal.

Abstract: In large multi-tiered hierarchical alarm systems for high capacity telecommunications transmission systems, it is important to notify the maintenance craft of only the highest alarm, and to notify only when the alarm has been validated by persisting for a sufficiently long time. Advantageously, this is accomplished by timing alarms and freezing the timing when a higher level alarm is detected. If the higher level alarm is no longer present, timing on the lower level frozen alarm signal continues until there is a timeout. A timed out alarm is reported to the maintenance craft.

Abstract: An apparatus is provided for adding a dither signal to an optical carrier modulated with an information signal. The apparatus includes a dithering element having an input and an output in series with an optical carrier modulated with an information signal. A differential element having an inverting input, a non-inverting input, and an output is coupled to the input of the dithering element. A signal generator, which is provided for producing a desired dither signal to be added to the modulated optical carrier, is coupled to the non-inverting input of the differential element. A feedback element produces a signal related to the output of the dithering element and couples the signal related to the output of the dithering element to the inverting input of the differential element.

Abstract: Each column in the memory array of transistors of a programmable read only memory (ROM) can be programmed in either a conventional mode or an inverted mode. In the conventional mode, each transistor is either programmed (i.e., connected to the corresponding bit line) or unprogrammed (i.e., left unconnected to the corresponding bit line). In this way, the programming mode can be selected, independently for each column, to limit the maximum number of transistors that can be programmed in any given column to one half of the total number of transistors in the column. As such, the total capacitance along a bit line is reduced and the access time is therefore also reduced, resulting in a faster ROM. The information as to which columns are encoded using which programming modes is contained in a component of the ROM. That programming-mode information is accessed when reading data out of the memory array to determine whether or not to invert the data for the various columns.

Abstract: A method identifies and models the distortion in a document using a two-dimensional nonlinear filter. The two-dimensional nonlinear filter is then used to improve the performance of optical character recognition systems in recognizing characters in documents that have been degraded, as for example by repeated photocopy reproductions or by fax transmission.

Abstract: A method and apparatus for coding an image comprising (at least) two regions (e.g., a facial region and a background region) which are to be coded with different quantization error parameters (e.g., quantizer step sizes), wherein the respective quantization error parameters are determined with use of a feed-forward rate control technique. Initial quantization error parameters are assigned to each region, and the overall bit rate which would result for the coding of the given frame is computed based on these assigned quantization error parameters. The computed bit rate is compared to a given bit rate constraint which may, for example, represent a limitation of a transmission channel. Based on the result of this comparison, one or both of the assigned quantization error parameters are adjusted, thereby resulting in different quantization error parameters for the two regions.

Abstract: A system for monitoring the integrity of electrical connections includes a transformer with its primary coupled across a dual split contact arrangement and the secondary coupled to both an energy source and a monitoring circuit. When the contact condition is made the secondary impedance reaches a given value which results in a low output indicated by the monitoring circuit. The energy source is preferably a radio frequency oscillator driving the transformer secondary, which is also connected to a monitoring circuit. Preferably, the output from a current reference circuit, coupled to the secondary of the transformer, is coupled to the energy source circuit and the monitoring circuit so as to produce a given output in the monitoring circuit when the contact condition is made.

Abstract: A highly efficient, low delay pitch parameter derivation and quantization permits overall delay which is a fraction of prior coding delays for equivalent speech quality at low bitrates. In distinguishing between pitch period information for voiced and non-voiced frames of input signals, non-voiced frames are assigned a non-zero "bias" value, while voiced frames have associated with them generated pitch information based on an analysis of signals in a present frame and comparison with signals relating to the pitch in a prior frame. Transitions from non-voiced to voiced input frames are efficiently accomplished using a non-uniform quantization method based on an analysis of a sequence of frames. Typical uses include low delay, low-bitrate coders such as Code Excited Linear Prediction (CELP).

Abstract: The invention provides a telephone station having a voice announce device. The telephone station includes user interface devices and a telephone station controller coupled to the user interface devices. The telephone station controller selects one of the user interface devices to announce a call from a remote caller based on a state of the telephone station. If the telephone station is in a NOT-BUSY state, the telephone station controller outputs a voice print corresponding to the remote caller to a speaker of the user interface devices to announce the call. If the telephone station is in a BUSY state, the telephone station controller outputs a voice print corresponding to the remote caller to a personal interface device of the user interface devices to announce the call. If the telephone station is in a SPEAKER state, the telephone station controller outputs displayable data to a display device of the user interface devices to announce the call.

Abstract: A system and associated method for determining if a channel signal carried by a discrete wavelength channel is properly centered for that wavelength channel. A signal generator is provided that superimposes a secondary signal over the original signal in a signal channel. Tone detectors are provided at a point after the superimposition of the secondary signal. The tone detectors detect the superimposed tone signal at wavelengths that are longer and/or shorter than the wavelength assigned to the wavelength channel. By measuring the degree of balance between wavelengths longer than the wavelength assigned to the wavelength channel and the wavelengths shorter than the wavelength assigned to the wavelength channel, it can be determined if the original signal is centered for that wavelength channel. If a predetermined degree of balance is not obtained, the original signal for the wavelength channel can be corrected or can be recognized as being non-compliant.

Abstract: Forgeries are detected by curve fitting the signature in question. The length of the curve fitted signature and the length of the signature in question are compared. If the signature in question is a traced or copied forgery, it will tend to have a significant amount of jitter which results in a significantly longer length than the curved fitted signature.