Showing papers on "Keying published in 1986"

Mode errors: a user-centered analysis and some preventative measures using keying-contingent sound

Abstract: It is often claimed that the user interfaces of advanced integrated systems are mode-free. However, if one applies the user-centred analysis developed in this paper, it is clear that almost any system of realistic complexity will have modes of some kind. By using this analysis it is also possible to identify the situations in which modes are likely to give rise to errors and those where they will not. Various measures for preventing mode errors are suggested. One of these is to signal mode by generating sounds which are contingent on the users' actions. Experimental work presented shows that this mode-dependent keying-contingent sound can be an effective way of making users aware of mode changes. Mode errors were reduced to a third of the number observed with a control group.

Office automation systems

Abstract: An improvement in an office automation system for composing and printing text such that when the presence of an operator is required at the printer, the operator can instruct the system to delay the printing action and wait for a command to start printing. The start command may be generated by the printer itself, when a certain required action has been performed, or by the operator, by means of keying in a code at the control panel of the printer. A display at the control panel of the printer may show a message related to the cause of the delay.

Coherent Optical Receivers: Performance Analysis And Laser Linewidth Requirements

Abstract: The performance of coherent optical receivers is affected by the phase noise of the laser transmitter and the laser local oscillator and by the shot noise due to the detectors employed in the receiver. In this paper, the performance of coherent optical receivers is discussed, taking into account both noise sources. Further, the maximum permissible laser linewidth AP for coherent optical communications systems is reported. Both heterodyne and homodyne systems are considered. It is shown that the value of AP depends on the system bit rate Rb and on the modulation/demodulation technique employed: for heterodyne receivers with noncoherent postdetection processing [used in conjunction with amplitude-shift keying (ASK) or frequency-shift keying (FSK) modulation formats], Av_0.09 Rb; for heterodyne receivers with coherent postdetection processing [used in conjunction with the phase-shift keying (PSK) modulation format], Av< 2.26 X 10-3 Rb; and for PSK homodyne receivers, Av 3.1 X 10-4Rb. This paper presents the main results only; details of the mathematics involved have been published elsewhere. The purpose is to give a user a set of simple laser linewidth requirements without forcing him to analyze the research results scattered among several publications.

Frame Synchronization for Direct-Detection Optical Communication Systems

Abstract: The problem of locating a periodically inserted frame synchronization pattern in random data is considered for a directdetection optical communication channel. Both pulse-position modulation and on-off keying with known symbol synchronization are considered. The high signal-to-noise ratio approximation of the maximum likelihood decision rule is derived for each of these cases. Analytical bounds and simulation results on synchronization probability show that the high SNR ML rule has a performance approaching that of the optimum ML rule over a wide range of signal-to-noise ratios. This decision rule also provides a substantial performance improvement over the correlator rule with virtually no additional implementation complexity.

Video superimposition system with chroma keying

Abstract: A graphic decoder circuit for a compact disk player has a color signal generator (6) called a color look-up table (CLUT), which outputs RGB video signals stored in parts addressed by color code signals. The color code signals are simultaneously supplied to a decoder circuit (10), which in turn outputs switching signals (Ys) for superimposition only when specific color signals designated by switching means (11) are inputted. Thus, graphic information from the compact disk player formed by arbitrary colors can be superimposed on pictures obtained from a television receiver or the like.

A duplex infra-red system for in-building communications

Abstract: This paper discusses the application of optical links using indirect scatter to in-building portable communications. The design considerations for such systems are described, and the reasons for selecting a time division multiplexed approach with ON-OFF keying. Both analytical and experimental determination of the path loss for indirect scatter channels are discussed, and it is shown that about 85 dB of path loss can be expected for practical devices in representative office environments. A means for improving S/N in a pulsed system which is average power limited is described. An experimental system based on the above considerations was constructed consisting of a fixed base unit (and range extension repeaters), having essentially hemispheric field of view, and a portable unit having a radial transmitter and hemispheric receiver fields of view. The operation, construction, and performance of the prototype system is discussed.

Frequency-noise cancellation in semiconductor lasers by nonlinear heterodyne detection

Abstract: The bit-error-rate (BER) performance of conventional noncoherent, heterodyne frequency-shift-keyed (FSK) optical communications systems can be surpassed by the use of a differential FSK modulation format and nonlinear postdetection processing at the receiver. A BER floor exists for conventional frequency-shift keying because of the frequency noise of the transmitter and local oscillator. The use of differential frequency-shift keying with nonlinear postdetection processing suppresses this BER floor for the semiconductor laser system considered here.

Differential phase shift keying demodulator

Abstract: A demodulator delays a signal modulated by differential phase shift keying, compares the delayed modulated signal with a modulated signal which is not delayed, and samples the result of comparison a plurality of times for the delay time.

Differential phase shift keying demodulator

Abstract: A differential phase shift keying demodulator for demodulating a signal modulated by differential phase shift keying is arranged to compare the modulated signal with a delayed modulated signal at different points of time within a period required for transmitting one bit of data.

Coherent lightwave transmission experiments using amplitude and phase modulation at 400-Mbit/s and 1-Gbit/s data rates

Abstract: Coherent lightwave heterodyne receiver sensitivities and system performance were studied for amplitude shift keying (ASK) and differential phase shift keying at bit rates of 400 Mbit/s and 1 Gbit/s. The receiver used in these experiments employed a new balanced mixer design1 which is highly efficient in its use of local oscillator (LO) power. Sensitivities are the best reported at these bit rates, and error rates as low as 10−10 were obtained.

Costas loop self-homodyne experiment for a diode laser receiver

Abstract: An optical Costas loop self-homodyne experiment with semiconductor lasers at 0.82 μm is reported. Phase synchronisation and signal demodulation for suppressed-carrier phase-shift keying modulation at 40 Mbit/s are demonstrated.

Board game with changeable playing pieces

Abstract: A board game apparatus for use in playing a game between two players includes a game board having an alternating pattern of light and dark squares, a first set of game pieces which is light in color, and a second set of game pieces which is dark in color. First keying devices are attached to the light squares of the game board and second keying devices are attached to the dark squares. The first keying devices affect the appearance of the first set of game pieces but not the second set of game pieces, and said second keying devices affect the appearance of the second set of game pieces but not the first set of game pieces. A game piece of one of the sets becomes a game piece of the other set when the piece is turned over.

Method for the analogous or digital coding of information for use in angle and pulse modulation processes

Abstract: During the coding and transmission of analog or digital information, it is important to transmit this information reliably and economically, that is to say with narrow bandwidth. So that the transmission paths are better utilised, multi-value coding and/or pulse-modulation methods have therefore been developed. The multi- value coding could only be used reliably and with supportable expenditure up to 16 QAM (quadrature amplitude modulation) or up to 16 PSK (phase-shift keying modulation). In the case of the invention, the reliability of transmission is increased and the expenditure is reduced by changing the phase in the code-changing current in such a manner that an uninterrupted sequence of positive and negative halfwaves is produced (Figure 17a,b, 18a,b) and/or that transmission occurs on the basis of angle (Figure 28) or pulse modulation in a narrow-band manner or only with a code-changing current of one frequency, the code states being defined by the amplitude magnitude and/or phase steps.

Surface acoustic wave device for differential phase shift keying convolving

Abstract: A differential phase shift keying convolver having a plurality of tracks includes at least one track where an opposite phase convolution output is produced. Each track includes two output gates spaced at the center for differential phase shift keying demodulation. Among these output gates, some gates selected in accordance with the phase relationship between convolution outputs are connected to provide sum and/or difference outputs of the convolution signals. The opposite phase convolution outputs can be produced by arranging at least one of the input transducers in a step-like configuration, by using multistrip couplers, or by providing a metal film in a selected position of the traveling path of surface acoustic waves for application of a control voltage.

Process and arrangement for regulating the keying ratio of at least one electrical signal

Abstract: A process and apparatus for use in digital length or angle measuring systems for regulating the keying ratio of at least one periodic electrical signal A signal is produced, proportional to the desired keying ratio, and compared with the periodic electrical signal A momentary difference signal is generated from the comparison If the frequency of the periodic electrical signal is within a selectable frequency range, the momentary difference signal is applied to a correction circuit, which is circuited parallel to a storage unit The correction circuit supplies a correction signal, based on the momentary difference signal, to a sum amplifier The sum amplifier is operative to superpose the correction signal on the periodic electrical signal, thereby regulating the keying ratio of the periodic electrical signal The storage unit is operative to store a signal proportional to the difference signal If the frequency of the periodic electrical signal is outside the selectable frequency, the correction signal is derived from the contents of the storage unit

Threshold performance of M-ary noncoherent frequency-shift keying in non-Gaussian noise

Abstract: An expression for the error probability of M-ary noncoherent frequency-shift keying (NCFSK) for locally optimum threshold detection in non-Gaussian noise, frequently encountered in practice, is derived, which demonstrates that a significant improvement in performance can be achieved when M is greater than two.

Steady picture developing method

Abstract: PURPOSE:To make input operation efficient by storing a repeating procedure for a picture to be used steadily in a control table of a terminal equipment for repeatedly displaying a command for the display of a menu on a screen and starting the repeating procedure by a keying operation. CONSTITUTION:A control table 11 storing the repeating procedure of a picture to be used steadily is arranged in the terminal equipment 1 having a processing part 13 so that the procedure of registeration addressig of the table 11 can be started by a function key on a keying device 12. Thus, a required picture can be automatically displayed only by depressing the function key once.

Automatic checking device of keyboard

Abstract: PURPOSE:To check a keyboard without manual operations by determining automatically the positioning of keys on the keyboard and detecting the position of keys, etc. CONSTITUTION:A keying device 13 where one or plural rows of keying units 11-11 and a key detecting unit 12 preceding keying units are set to a carrier 10 which runs in one direction at the upper side of a keyboard 7 set to a checking device 1 is provided. A pallet 5 is carried in by a chain conveyor 4, and a connector 14 in the side of the checking device 1 is inserted to or removed from a connector box 6 automatically, and the carrier 10 and keying units 11-11 are controlled to check the keyboard with the position of the first key 24a, which is detected by the key detecting unit 12, as the origin.

Improvements in or relating to keying of video signals

Abstract: A keying apparatus for providing colour separation overlay of foreground and background video signals derives a keying signal by non-additive mixing from the foreground signal (4, 7), Keying means (9, 10, 11, 18, 19, 20) are controlled by the keying signal Bv and select between the foreground signal Rf, Gf, Bf and a combination of the background signal Rb, Gb, Bb and the luminance signal Y of the foreground signal. By making use of the foreground luminance signal to modulate the luminance of the background signal when the background colour portions of the video signal is being received, transparency and, optionally, shadow effects are obtained in a relatively simple circuit arrangement requiring little user adjustment for setting up video effects. Also, by making use of the foreground luminance signal to modulate the luminance of the background signal, relatively little noise is introduced into the background signal.

Modified AM sound broadcasting system

Abstract: The invention relates to a modified AM sound broadcasting system for the additional simultaneous transmission of discrete information by means of phase modulation, by means of which, in addition to the usual sound information, other uncorrelated additional information can be transmitted such as, for example, data, commands, information, signals and so forth. The aim of the invention of creating a transparent data channel with increased data rate and increased protection against interference requires soft phase-shift keying with a suitable pulse shape. This object is achieved by means of a special pulse shaper and phase modulator at the transmitter end and by means of suitably matched time constants and cut-off frequencies of at least three low-pass filters of the phase demodulator at the receiver end. A further development further increases the stability of the AM sound reception in the sense of an AFC.

Kana character keyboard

Abstract: PURPOSE:To input KANA (Japanese syllabary) characters at a high speed by generating precise coordinates between keying potentials of character keys determined by the positions of the character keys and keying speeds of fingers and the appearance frequencies of KANA characters. CONSTITUTION:A character array when the use frequencies Poj of KANA characters (j) of Japanese are arranged in decreasing order and a key array when keying potentials HK determined by the keying speed of fingers keying keys K and the distance from a home key to keys (k) are arranged in decreasing orders, are made to correspond to each other one to one. Now, Pojs are arranged in decreasing order, and at the same time, keying potentials HK of the keys K are arranged in decreasing order. In this case, the value of a Q keying speed coefficient decreases alternately for the right and left hands except one position, so the order of the hands (h) as to HK arrayed in the decreasing order is nearly right and left alternation order. For the purpose, the array of Poj and the array of HK are made to correspond to each other and a character (j) in the array Pxj is assigned to a key (k) in the array of HK, so that two connecting characters of Japanese are inputted by nearly left-hand alternate keying.

Input controlling system

Abstract: PURPOSE:To improve speed and certainty of inputting by making the mode setting of a keyboard from a program made to perform processing, and making the keying data of the keyboard information processing input under a set mode. CONSTITUTION:A keyboard control firmware 40 starts controlling action responding to an application program 20, and then sent to a keyboard 30 from a host 10 by the program 20. Responding to mode switching command COM that instructs keying scan system, the firmware 40 determines whether the keying scan system on the keyboard is an N key roll over system or an N key lockout system, and scans the state of keying of the keyboard 30 as a keyboard of keying scan system selected by the firmware 40.

Control system for information input transmission

Abstract: PURPOSE:To attain the rational and smooth jobs and furthermore to prevent crimes by adding the functions of an operator key and a job controller key respectively. CONSTITUTION:The areas 4 and 5 of a keyboard 3 are defined as the positions for insertion of a controller key for a job controller and an operator key respectively. When either one of both keys is set off, no designation (by a cursor) is displayed on an information output screen 1 for an input position after a module is read out. Thus the keyboard 3 is locked and accepts no keying of the input information. Therefore the input of information is impossible. The input information is valid only when both the operator key and the controller key are turned on.

Relative frequency-shift keying

Abstract: This invention is a description of a digital communication system which employs two carrier signals and precise 'a priori' information at the transmitter shown in Figure 1, to improve the signal-to-noise performance of the receiver. The two carrier signals are shifted in frequency by the digital information to be transmitted and can be demodulated down to very low values of signal-to-noise ratio at the receiver shown in Figure 2. The improved performance is obtained by using sum and difference signals at the final detector. The digital information is extracted as the difference signal while the sum signal is used to reduce the received noise by means of a high gain negative feedback loop. The receiver is able to exploit the use of both frequency and phase information in the received signals and the relative frequency-shift technique employed bears some resemblance to the Special Theory of Relativity.

Controlling method of multi-operating system

Abstract: PURPOSE:To allow the 2nd operating system (OS) to end the OS itself by requesting the end of a task from an I/O control part to the 1st OS when keying is applied from a console to the I/O control part in a specific sequence. CONSTITUTION:When keying from the console to the 1st OS1 is requested and the keying the console is executed, whether the inputted key is an ESC or not discriminated. If the key is other than the ESC, the code is returned to the keying request source to end the processing. When the inputted key is the ESC, the succeeding keying request is applied to the OS1. After keying from the console, whether the key is a BS or not is discriminated, and if the key is other than the BS, the initially inputted ESC code is returned to the requesting source. In case of the BS, a task end request is applied to the OS1 and the execution of the OS2 ends because the input control part operates as a part of the OS2.