摘要:
In an electronic telephone a speech network for connecting a transmitter and receiver to a line powered telephone line which utilizes a bridge configuration that is so arranged that the network will function on very low d-c line voltages, thereby enabling the set to be connected in multi-party applications with a conventional hybrid transformer set on long loop applications.
摘要:
Fraudulent toll telephone calls are detected by the recognition of extraneous supervisory signals which are generated in the originating office in response to a perpetrator placing such a call. The invention provides a means of detecting a second proceed-to-send signal received at the originating office and of recording in memory means the identities of the calling and called parties. Timing means for achieving the detection is connected to the automatic message accounting trunk circuit of the originating office and, upon detection, an MF receiver is also connected thereto for a predetermined interval of time.
摘要:
The chromatic pulse dispersion of a light beam in an optical fibre can be equalized by dispersing the light beam into a spectrum, detecting different portions of the spectrum and producing signals related to each portion, applying different time delays to the signals and then combining the signals to provide an output. The spectrum can be divided into discrete portions having a range of wavelengths, with optical delay lines, optical filters, and multiple section photodetectors used. The spectrum can be formed on one surface of a PIN diode, having the I layer of a thickness which varies along the length, giving in effect division of the spectrum into an infinite number of portions.
摘要:
A pair of interchangeable memories is provided, one of which receives a PCM frame while simultaneously transmitting one, while the other of which, containing the previous frame, outputs the channel bits for parallel processing. Each simultaneous conference is assigned a temporary storage location in which the associated channels are accumulated to yield the total conference signal. Subsequently, each channel is subtracted from its conference total to produce the final conference signal. The final conference signals replace the unprocessed frame in the memory where, at the end of the current frame, it is interchanged with the other memory. And so on.
摘要:
A light emitting diode structure has one or more convex lens formations formed on the surface through which the light issues to provide larger incident angles and reduce internal reflection. Conveniently the structure comprises a multi-layer epitaxially grown structure, and the lens or lenses may be formed integral with the outer surface.
摘要:
A method of jacketing an electric cable having a corrugated metal sheath, in which the sheath is cleaned, a coating of thermosetting, castable polyurethane is applied to fill the troughs in the corrugations, a fabric is wrapped onto the coated sheath and coated with the same polyurethane, and thermoplastic polyurethane is extruded onto the cable to form a jacket. The coatings of the polyurethane serve as an adhesive for bonding the jacket to the metal sheath. A cable produced by this method comprises a layer of fabric circumscribing the corrugated metal sheath and a jacket of thermoplastic polyurethane overlying the sheath, the fabric being embedded in a layer of thermosetting, castable polyurethane bonding the jacket to the sheath.
摘要:
For a reversed bias double heterostructure diodes, particularly GaAs diodes, electroabsorption can be obtained with reverse bias and light emission can be obtained with forward bias. However bulk absorption is large at wavelengths close to the band edge, where light emission occurs. Thus light emission through a modulator at zero bias is low. By providing for the light emulsion to be at a larger wavelength than that corresponding to the band edge high modulation efficiencies can be obtained. This is achieved by suitably doping the emitter differently as compared with the modulator so that light emission occurs at wavelengths greater than that at the fundamental energy gap.
摘要:
A photodiode detector comprises a substrate on which a plurality of detector sections are formed, in series. Reverse bias is applied to the separate sections, the bias more negative for each section from the input end. The absorption bandwidth for each section can vary and the bandwidth of a section can be variable.
摘要:
A telephone having an interchangeable dial face insert, the insert of transparent material having a shape which fits over an aperture in the dial face of the housing. There is a protrusion on one edge of the insert which enters a slot in the periphery of the aperture in the dial face, and a resilient clip on the periphery of the aperture in the dial face, at a position opposite the slot, the clip engaging over the edge of the insert. A further insert, having information and/or cosmetic patterns thereon, can be positioned beneath the transparent insert.