Abstract: A digital camera has a half mirror that splits the optical path from a taking lens to the image-sensing device and an optical viewfinder that offers the light reflected from the half mirror as a visible image. Inside the optical viewfinder, a photometric device is disposed. The amount of light measured by the photometric device is used for exposure control in ambient-light shooting and for automatic light adjustment in flash shooting.

Abstract: A video display apparatus includes a display device, resolution conversion unit, and display position setting unit. The resolution conversion unit converts the resolution of an input video signal into that of the display device. The display position setting unit sets the display position of a first video signal in each field to be displayed on the display device on the basis of the temporal relationship between a time from generation of a vertical sync signal to input of the first video signal and the generation timing of a horizontal sync signal.

Abstract: A system and method that processes video to extract a keyframe-based adequate visual representation. The method utilizes a hierarchical processing technique. The first stage in the hierarchy extracts a chromatic difference metric from a pair of video frames. An initial set of frames is chosen based on the chromatic metric and a threshold. A structural difference measurement is extracted from this initial set of frames. A second threshold is used to select key frames from the initial set. The first and second thresholds are user selectable. The output of this process is the visual representation. The method is extensible to any number of metrics and any number of levels.

Abstract: A digital data transmission apparatus which can suitably route and transmit to a desired apparatus two types digital data, that is, digital data of a serial digital interface (SDI) format and a serial digital data interface (SDDI) format having a partially common format to the SDI format even if they are mixed, the digital data transmission apparatus having a first routing apparatus (20, 20A) having a first signal supplying means (102) for supplying the data of a first transmission packet of the SDI format; a second signal supplying means (104) for supplying data of a second transmission packet of the SDDI format having a common control data portion to that of the SDI format and having the same data length; a first input terminal receiving the data of the first transmission packet; and a second input terminal receiving the data of the second transmission packet and outputs the first input data supplied to the first input terminal from the first output terminal and outputs the second data supplied to the secon

Abstract: Disclosed is a liquid crystal display (LCD) with black matrixes of low reflectivity capable of reducing the reflection of back light. The black matrix of the disclosed LCD includes a photoshield layer formed on the back surface of a front substrate, and at least one internal photo-interference layer formed over the photoshield layer. The internal photo-interference layer has a refraction index different from that of the photoshield layer. The internal photo-interference layer has a double-layer structure consisting of a chromium nitride layer and a chromium oxide layer.

Abstract: A receptacle assembly that receives a back light assembly and a display unit of a liquid crystal display device is disclosed. The receptacle assembly for receiving the back light assembly comprises a first receptacle module and a second receptacle module engaged with the rear surface of the first receptacle module to support the first receptacle module. The first receptacle module and the second receptacle module are formed of plastic and metal respectively. Therefore, the distortion that can be generated by the exterior impact and the vibration and the deflection due to the heat can be prevented. Further, the productivity is improved by simplifying the engaging structure of the receptacle assembly, and the size stability is improved.

Abstract: A fluorescent lamp 6 emits illumination light (primary light), which is deflected by means of a light guide plate 4 to be converted into a light flux having an enlarged cross section. A liquid crystal display panel 3 is supplied with the light flux via a prism sheet (light control sheet) 12. The prism sheet 12 or an alternative light control sheet to be employed is capable of rotating polarization involved by the light toward a direction of light transmission axis of a polarization plate 14. An effective light input to the liquid crystal display panel 3 is achieved by light transmission through the polarization plate 14 at a high transmission rate. The liquid crystal display panel 3 controls polarization state of the inputted light and, according to the state, causes the light to pass through another polarization plate (analyser) 15. Emission occurs, under intensity control depending on positions, via the polarization plate (analyzer) 15, to provide an image.

Abstract: Cholesteric liquid crystal films using varying pitch helix structures aligned perpendicular to the surface of the film for broadband reflection and transmission of circularly polarized light distort the light at large viewing angles of incidence due to the elliptical cross section of the CLC helix with the light at large incident angles. By using compensating films of an infrared cholesteric liquid crystal to rotate the major axis of the elliptical light to ±45 degrees and a homeotropic film having elongated molecules with the long axis perpendicular to the surface of the film to convert the elliptically adjusted light from the IR CLC film to circularly polarized light, the distortions at large angles can be eliminated. The compensated light will be circularly polarized for large angles of incidence over a broad band.

Abstract: The electrical asymmetry in certain electro-optic display device structures employing orientation layers, evidenced as an internal DC voltage, is reduced or eliminated by inserting a barrier layer between the orienting layers and adjacent electrode layers, thereby reducing or eliminating a DC offset which leads to flicker in a display image when such devices are driven with an AC waveform.

Abstract: A method is disclosed for controlling a pretilt angle direction for a liquid crystal cell comprising the steps of first setting the magnitude of pretilt angle and a plurality of pretilt angle directions in an alignment layer. This first step is achieved by irradiating linearly the alignment layer with polarized or unpolarized UV light. One of the plurality of pretilt angle directions is then selected by exposing the alignment layer to UV light a second time.

Abstract: A liquid crystal display device according to the present invention includes a first substrate; a second substrate; a liquid crystal layer interposed between the first substrate and the second substrate; and a sealing member formed of a sealing material for confining the liquid crystal layer between the first substrate and the second substrate, the sealing member defining a sealing portion. The first substrate includes a plurality of gate signal lines, a plurality of source signal lines, a plurality of switching devices disposed in the vicinity of intersections of the plurality of gate signal lines and the plurality of source signal lines, a plurality of pixel electrodes respectively connected to the plurality of source signal lines through the plurality of switching devices, and an interlayer insulating layer provided below the plurality of pixel electrodes and covering the plurality of switching devices, the plurality of gate signal lines and the plurality of source signal lines.

Abstract: A liquid crystal display apparatus in which an arrangement possibly susceptible to degradation in display quality by a miss shot of a laser used for turning a-Si to p-Si is avoided and a narrow frame can be attained, is provided. A gate interconnection for a plurality of transistors in a driving circuit area is arranged along a folded line having two lines extending in two different directions and a bent portion when viewed two-dimensionally, and channel regions of the driving transistors are arranged along the two lines, such that the channel regions do not overlap the bent portion, when viewed two-dimensionally.

Abstract: A moving picture signal is encoded by motion-compensated prediction using motion vectors for each motion-compensated block of the moving picture signal. The motion vectors are arranged into motion vector groups for each predetermined number of motion vectors. A code table is selected among a plurality of code tables for each motion vector group for encoding the motion vectors. Code table selection information is then output. The motion vectors is encoded by variable-length coding using the selected code table in accordance with the code table selection information. The code table selection information, the encoded motion vectors and an encoded predictive error signal are then multiplexed. A moving picture bit stream encoded as above is decoded. The moving picture bit stream is demultiplexed into the motion vectors, the code table selection information and the encoded predictive error signal.

Abstract: The presentation support system comprises a projector that displays presentation images utilized in a presentation, a presentation support device that produces support information for supporting the presentation according to the progress status of the presentation, and a support information display device that displays the support information. The projector is equipped with a support controller that supplies the support information display device with the support information supplied from the presentation support device.

Abstract: Apertures for use in an illuminating apparatus for forming patterns in a semiconductor wafer and illuminating apparatus including such apertures are provided. The aperture includes a shielding area and a non-circular transparent area within the shielding area. The transparent area has a ratio of a short axis to a long axis (R=short axis/long axis) that exceeds 0 and is smaller than 1 (0<R<1), the short axis being substantially perpendicular to the long axis. The transparent area may have an elliptical shape with an eccentricity (e) that exceeds 0 and is smaller than 1 (0<e<1). The transparent area may be positioned within the shielding area to define two thin portions of the shielding area and two thick portions of the shielding area with the long axis linking the thin portions of the shielding area and the short axis linking the thick portions of the shielding area.

Abstract: A tetraalkylammonium hydroxide (TAAH) solution recovered from a development waste through separation therefrom of impurities such as photoresist is mixed with a surface-active substance to have the surface tension thereof adjusted to a desired one, and then reused as a rejuvenated developer. Thus, the surface-active effect (wetting properties) of the rejuvenated developer recovered from the development waste is properly adjusted and controlled, whereby fine photoresist patterns can be stably and effectively developed. Usable surface-active substances include surfactants, and dissolved photoresist contained in the development waste or a photoresist-containing solution such as a photoresist-containing treated solution derived therefrom.

Abstract: An analog detection system for determining a ring-down rate or decay rate 1/&tgr; of an exponentially decaying ring-down beam issuing from a lifetime or ring-down cavity during a ring-down phase. Alternatively, the analog detection system determines a build-up rate of an exponentially growing beam issuing from the cavity during a ring-up phase. The analog system can be employed in continuous wave cavity ring-down spectroscopy (CW CRDS) and pulsed CRDS (P CRDS) arrangements utilizing any type of ring-down cavity including ring-cavities and linear cavities.

Abstract: There are disclosed an image transformation apparatus for performing a transformation processing for outputting a color image by an image output device such as a color printer. The image transformation apparatus has an image receiving section for receiving an image represented by digital data, an image sort discrimination section for discriminating whether the image received by said image receiving section is a halftone dot image or a multiple gradation image, an image transformation section for applying a conversion processing for the multiple gradation image to the halftone dot image when it is decided by said image sort discrimination section that the image received by said image receiving section is the multiple gradation image, and a driver section for outputting an image discriminated as the halftone dot image by said image sort discrimination section and an image converted into the halftone dot image by said image transformation section to an image output device for outputting a visual image.

Abstract: To provide a system in which a configuration is simple and a switching of an optical line can be performed at a high speed. A protection unit for performing optical line protection by using K1-K2 information inserted into a payload is provided for each physical interface. The protection unit includes a filter for separating a payload of user data and a payload including K1-K2 information according to a control signal in a received payload, a selector for switching user data to be transmitted or K1-K2 information to be transmitted after adding a control signal of a value corresponding thereto, and a control unit for controlling an output buffer to a switch block and creating K1-K2 information to be transmitted and communicating with a physical interface card of another system on the basis of K1-K2 information.

Abstract: The synchronous digital communications system according to the invention serves to transmit electric signals optically. The electric signals to be transmitted are converted from electrical to optical form (E/O1, E/O2, E/On) and then transmitted using wavelength division multiplexing (WDM) or dense wavelength division multiplexing (DWDM). A synchronization manager and a connection manager are provided. The synchronization manager is adapted to configure dedicated optical synchronization links. The connection manager is adapted to configure switched optical communication links from a pool of wavelengths, taking account of the dedicated synchronization links only. This has the advantage that independently of the switched communication links, synchronization is constantly ensured throughout the system. Each network element (NE1, NE2, NE3) has at least one interface unit that is reserved for synchronization and that continuously receives signals at the wavelength (&lgr;1) reserved for synchronization.

Abstract: An optical communication system is provided which is capable of easily calibrating a difference in outputs of each of wavelength-multiplexed optical signals.

Abstract: Light in the visible spectrum is modulated using an array of modulation elements, and control circuitry connected to the array for controlling each of the modulation elements independently, each of the modulation elements having a surface which is caused to exhibit a predetermined impedance characteristic to particular frequencies of light. The amplitude of light delivered by each of the modulation elements is controlled independently by pulse code modulation. Each modulation element has a deformable portion held under tensile stress, and the control circuitry controls the deformation of the deformable portion. Each deformable element has a deformation mechanism and an optical portion, the deformation mechanism and the optical portion independently imparting to the element respectively a controlled deformation characteristic and a controlled modulation characteristic. The deformable modulation element may be a non-metal.

Abstract: A light collecting optical system wherein the position where light is collected is scanned in the optical axis direction by using a wavefront converting element capable of changing power without using a mechanical device, and aberration occurring during the scanning is canceled by using the wavefront converting element to minimize the degradation of light collecting performance due to the scanning in the optical axis direction.

Abstract: A microscope having a mirror for deflecting light from an illumination light source in a direction of an objective lens and illuminating a specimen via a condenser lens disposed above the mirror includes a stage support which is mounted on the upper surface of a base portion to permanently hold a stage, on which a specimen is placed, with respect to the optical axis direction of the objective lens, a condenser body mounted on the upper surface of the base portion, a condenser lens holding member for holding the condenser body, an elevating mechanism for vertically moving the condenser lens holding member, and a focusing mechanism for moving the objective lens in the optical axis direction.

Abstract: An optical apparatus minimizes autofluorescence and stray light as well as leakage of excitation light and efficiently utilizes illuminating light from a fluorescence illumination optical system to allow observation of a bright fluorescence image. An observation apparatus has an objective, an observation optical system unit including a variable magnification optical system, and an imaging optical system unit including an imaging lens and an eyepiece. A fluorescence illumination apparatus, which is provided separately, is removably attached to the observation apparatus. The fluorescence illumination apparatus has a light source, a collector lens unit, and a reflecting member placed between the objective and the observation optical system unit at a position displaced from the optical axis of the objective to make light from the light source incident on the objective. An excitation filter is provided between the light source and the reflecting member.

Abstract: The optical pickup includes a two-wavelength laser diode having two light sources that emit a laser beam for the DVD and a laser beam for the CD, a light-receiving member, and a beam splitter. The beam splitter is provided with a wavelength-separating layer composed of a first and a second interfaces and an optical thin plate between the interfaces, having a specific refractive index n2. The first and second interfaces each have a first and a second wavelength selecting films coated thereon, which reflect or permeate the laser beams each by the specific rates, bring the optical axes of the laser beams after having reflected on the first and second interfaces into coincidence, permit the laser beams to go out of the beam splitter, and make the return beams from the optical disks permeate through the wavelength-separating layer to guide them toward the light-receiving member.

Abstract: The object of the present invention is to provide a zoom lens system being extremely reduced size such as a standard single focal length lens, having very few number of lens elements, being ultimately reduced cost, having a zoom ratio about 2.2, and also having high optical performance without using any aspherical surface. The zoom lens system has, in order from an object side, a first lens group G1 having a negative refractive power and a second lens group G2 having a positive refractive power, and performs zooming by changing an air space between the first lens group G1 and the second lens group G2. The first lens group comprises, in order from the object side, a negative lens group Ln consisting of one or two negative lens elements and a positive lens L12 having a convex surface facing to the object side. All surfaces consisting of the first lens group G1 are spherical or plane surfaces. Predetermined conditional expressions are satisfied.

Abstract: An auxiliary imaging lens is attachable to the main part of zoom lens on the object side; and is configured such that, when capturing an image for a screen having an aspect ratio of 4:3, an effective imaging area having such a size that the screen having an aspect ratio of 4:3 in a case without using the auxiliary imaging lens is just held therein can be secured, and a focal length yielding a field of view area substantially on a par with a field of view area obtained when capturing an image for a screen having an aspect ratio of 16:9 can be set.

Abstract: A lens comprises a single lens, both surfaces of the lens is a meniscus-shaped and aspheric lens, and side surface side thereof is a convex surface, and, when a refractive index of the lens is represented by n, a central thickness thereof is represented by t, a radius of curvature of a concave face thereof is represented by r1, the radius of curvature of the convex face thereof is represented by r2, and a focal length thereof is represented by f, the lens satisfies the following equations: 1 - 0.2 <   ⁢ ( n - 1 r1 ) / f < 0 , 0.08 <   ⁢ ( 1 - n r2 ) / f < 0.1 , and 0.35 <   ⁢ t f < 0.55 .

Abstract: A finder optical system for a single lens reflex camera is provided with a photographing optical system, a beam splitter for splitting light passed through the photographing optical system. First light deflected by the beam splitter forms a primary image at a position downstream from the beam splitter. Second light passed through the beam splitter is incident on a CCD. A relaying optical system is arranged on an optical path of the light deflected by the optical element to relay the primary image to form a secondary image. A reflection surface is arranged between the relaying optical system and an eyepiece optical system The reflection surface deflects light, which is directed from the relaying optical system, toward the eyepiece optical system, to proceed in a direction parallel with an optical axis of the photographing optical system. The secondary image is formed between the reflection surface and the eyepiece optical system.

Abstract: In a door mirror assembly for a vehicle, a case is supported at a door mirror stay provided at a vehicle door and mounted to a door mirror visor, whereby the door mirror visor is disposed above the door mirror stay. An overlap portion provided at the case and an overlap portion provided at an opening of the door mirror visor are overlapped one above the other and mounted, and a gap between the opening of the door mirror visor and the lower part of the case is thus stopped. Therefore, generation of wind noises caused by wind entering through the gap between the opening of the door mirror visor and the lower part of the case while a vehicle is in motion can be prevented.

Abstract: This invention comprises a head 3 for reading information from a disk storage medium 2, an actuator 5 for moving the head 3, and a control circuit 8 for calculating a control signal from the position signal, that was read by the head, using an eccentricity observer 21. The control circuit 8 selects a first eccentricity estimation gain during seek control and selects a second eccentricity estimation gain during following control. This makes it possible to perform seek control that is not affected by the eccentricity error.

Abstract: In a high-density flexible disk drive, a color of at least a surface of a cover (22) (in addition, a color of at least a surface of an eject button (30)) is different from that of at least a surface of a body of a front panel (20). A user can visually distinguish the high-density flexible disk drive from a normal-density dedicated flexible disk drive in which a color of a surface of a cover is identical with that of a surface of a body of a front panel. Thus, a large-capacity flexible disk can be correctly inserted into the high-density flexible disk drive without being erroneously inserted into the normal-density dedicated flexible disk drive.

Abstract: In the sliding surface of a magnetic head to a magnetic tape, the center of a magnetic gap G is offset to the center CL of a core width so that the overwrite edge Ga of the magnetic gap G approaches the center CL of the core width. As a result, the data track left to a magnetic tape by overwrite is recorded with the portion of a magnetic head which is located at the center of cores and in good touch with the magnetic tape, whereby the recorded pattern of the data track is stable and the variation of a reproduced output can be suppressed.

Abstract: Electrical protection device for a railroad vehicle, including electrical energy consuming units 6, 7 and electrical power supply means 1 to 5, electrical energy being supplied on at least two liner electrically separated from the ground formed by the vehicle as a whole, in particular its chassis and the electrically conductive parts connected to it. The electrical protection device includes detector means 50 for detecting a short circuit alternating current flowing from one of the two power supply lines to ground, to detect any short circuit between the other power supply line and ground.

Abstract: A solid electrolytic capacitor includes an anode element made of a valve action metal, a dielectric oxide film formed on a surface of the anode element, a solid electrolytic layer formed on a surface of the dielectric oxide film, and a cathode layer formed on a surface of the solid electrolytic layer. The solid electrolytic layer has an iron concentration not greater than 100 ppm. Alternatively or in combination therewith, a weight fraction of residues in the solid electrolytic layer is smaller than 5 wt %. The polymerization residue is an oxidizing agent and a monomer that is produced when such solid electrolytic layer is formed.

Abstract: The invention relates to the provision of a cooling effect on electrical or electronic components which are within a housing and which in combination form electrical apparatus. Conventional cooling means such as fans can be too noisy for many forms of electrical apparatus and in accordance with the present invention there is provided a heat dissipation formation which is provided with an inlet and outlet connected by a passage within the housing. The formation can be formed to encourage the flow of air through the same and can be formed to pass close to or in contact with components which need to be cooled. The flow of air allows heat to be transferred to the same and the heated air flows out of the housing thereby cooling the components in the same.

Abstract: A housing for an electrical device has a plurality of housing parts, including a first housing part adapted to carry an electronic component and having a mounting surface with a crease, and a second housing part arranged on the mounting surface and formed so that it at least sealingly engages in the crease of the first housing part, so as to enhance a heat withdrawal from the electronic components.

Abstract: An illuminator includes a light source, and a light guide panel for guiding light from the light source to outside. The light guide panel is formed with a transparent electrode. The light source is an LED chip having an electrode held in direct electrical contact with the transparent electrode.

Abstract: A toy simulates an illuminated overhead moon with a long-legged spacecraft under it. The toy includes a lighting apparatus secured to a balloon by string under tension. The lighting apparatus, located wholly outside the balloon, illuminates the inside of the balloon so the balloon appears to glow. The lighting apparatus has at least three arms extending from a body having a locking fastener. The locking fastener is attached by string under tension to the neck of the balloon. Each arm terminates in a window for contacting the skin of the balloon and for transmitting light through the skin to the interior of the balloon. In a preferred embodiment, the lighting apparatus is of sufficiently low weight that the toy floats in air.

Abstract: A vehicular indicator lamp that provides an observer with a novel visual impression even when the point of observation is moved either horizontally or vertically while ensuring clarity of the lamp. A reflective surface of a reflector is divided in an orthogonal grid into a plurality of segments, each of which is allocated a reflective element. The reflective surface is formed as a two-dimensional wavy surface in which concave surface reflective elements and convex surface reflective elements are alternatingly repeated in each of two directions. As a result, in the case where the reflective surface of the lamp is viewed from the front, when the point of observation is moved horizontally or vertically, the brightness pattern of the reflective surface changes dynamically to accompany the movement of the point of observation, causing the observer to perceive a strong glittering sensation.

Abstract: To read data stored on a memory cell transistor with a floating gate, a flash memory uses: a single-gate reference transistor; a differential sense amplifier; and a gate voltage generator for generating a gate voltage for the reference transistor. The gate voltage generator includes: a dummy cell transistor, which has the same structure as the memory cell transistor and has been turned ON; a current mirror for creating a current proportional to a drain current of the dummy cell transistor; an NMOS transistor for generating a gate voltage for the reference transistor in accordance with the current created by the current mirror; and a voltage hold circuit for holding the gate voltage generated. Even if temperature or fabricating process conditions have changed, this construction ensures accurate and high-speed read operation.

Abstract: A memory device is described, which includes a sense amplifier circuit that is composed of a reference voltage generator, a differential amplifier, and a sensing voltage generator, and a sense amplifier controller that controls an operation of the sense amplifier circuit. The reference voltage generator is enabled depending upon control of the sense amplifier controller before the sensing voltage generator is enabled. As a result, a reference voltage from the reference voltage generator is set to required voltage level, earlier than that from the sensing voltage generator.

Abstract: A non-volatile semiconductor memory includes a memory cell array having a plurality of electrically-rewritable non-volatile memory cells. The memory cell array is provided with an initially-setting data area, programmed in which is initially-setting data for deciding memory operation requirements. The non-volatile semiconductor memory also includes an initial-set data latch. The initially-setting data of the memory cell array is read out and transferred to the data latch in an initially-setting operation.

Abstract: This invention provides a nonvolatile semiconductor memory device capable of avoiding complicatedness of algorithm for normal write operation and a write operation prior to erasing in a memory system in which the distribution of threshold of cells after erasing is adjusted. This nonvolatile semiconductor memory device generates check bits as error correction code according to a check bit generating matrix so formed that in both the normal write operation and the write operation prior to erasing, the factors of “1” of respective rows satisfy the quantity absolutely necessary for generating check bits and the quantity of the factors of “1” is an odd number.

Abstract: A voltage-level shifter has a first and a second power supply terminal to which a first and a second potential are supplied, respectively, the second potential being lower than the first potential; a first input terminal to which a first input signal is supplied, the first input signal having a high and a low level according to the first and the second potentials; a second input terminal to which a second input signal is supplied, the second input signal being an inverted signal of the first input signal.

Abstract: A memory device includes a memory array, a plurality of external lines, a command buffer, and control logic. The plurality of external lines is adapted for receiving an external command. The command buffer is adapted to store at least one command buffer entry. The control logic is coupled to the plurality of external lines and the command buffer. The control logic is adapted to access the memory array based on one of the command buffer entry and the external command. A method for providing commands to a memory device is provided. The memory device includes a command buffer, control logic and a memory array. The method includes reading a first buffered command from the command buffer. The first buffered command is provided to the control logic. The memory array is accessed based on the first buffered command.

Abstract: A dynamic random access memory solves long-existing tight pitch layout problems using a multiple-dimensional bit line structure. Improvement in decoder design further reduces total area of this memory. A novel memory access procedure provides the capability to make internal memory refresh completely invisible to external users. By use of such memory architecture, higher performance DRAM can be realized without degrading memory density. The requirements for system support are also simplified significantly.

Abstract: A dynamic memory requires refreshing to retain data in its memory cells. This may cause access to the dynamic memory for purposes other than refreshing (external access) and access to it for refreshing to compete with each other, resulting in a performance deterioration. According to this invention, a pipelined dynamic memory (PDRAM) is used, and the pipeline frequency (CLK) of the pipelined dynamic memory is made higher than the frequency (CLK1) of external access, and access required for refreshing is made to an unoccupied slot (a timing when any external access request is never issued) in the pipeline of the pipelined dynamic memory. This makes refreshing of the internal dynamic memory an internal operation, which eliminates the need to take refreshing into consideration at the time external access is made, leading to improvement in operating ease and speed.

Abstract: A method of locating a submarine cable includes the steps of transmitting a toning signal along the submarine cable, the toning signal being a superposition of a first signal waveform to be detected and at least a second signal waveform such that the second signal waveform interferes with the first signal waveform to limit the peak to peak amplitude of the toning signal for transmission. Preferably, the toning signal is a square wave. The method provides a way of offsetting the loss of transmission distance due to the use of state of the art optical repeaters. Pre-emphasis of high frequency harmonics in the toning signal enables a detectable toning signal to propagate still further.