Showing papers on "Telephony published in 1969"
TL;DR: In a small-cell mobile telephone system, each channel may be used simultaneously in cells spaced sufficiently apart to limit cochannel interference.
Abstract: In a small-cell mobile telephone system, each channel may be used simultaneously in cells spaced sufficiently apart to limit cochannel interference. The extent of the interference depends upon the distance between cochannel cells, the number of land stations per cell, and the receiver capture ratio. The quantitative relationships among these parameters are derived for various cell configurations.
29 citations
TL;DR: Computer interconnections allowing half-duplex data communications have been analyzed using a single-server dualqueue model and storage usage for message queuing at each computer and associated message delays are considered.
Abstract: Computer interconnections allowing half-duplex data communications have been analyzed using a single-server dualqueue model. Storage usage for message queuing at each computer and associated message delays are considered as functions of communications parameters.
6 citations
01 Jun 1969
TL;DR: The principles on which the new types of echo suppressor have been designed are described, but the performance achieved is limited by the present condition of telephone networks; if return losses could be increased, the design could be suitably modified to take advantage of these.
Abstract: The paper describes the principles on which the new types of echo suppressor have been designed. The performance achieved, particularly as regards mutilation, is limited by the present condition of telephone networks; if return losses could be increased, the designcould be suitably modified to take advantage of these. The methods used for theoretical analysis of the behaviour of echo suppressors in telephone connections could be applied to the study of other voice-operated devices used in telephony. Much of the basic statistical information on speech waveforms is also of wider application
5 citations
TL;DR: The long-term plan for a telephone administration should be to introduce an integrated digital network in which only a minimum number of conversions and reconversions is required: ideally only one per connection.
Abstract: The basic processes of transmission and switching are cheaper for multiplex digital signals than for their voice-frequency equivalents, and introduce little or no impairment of the message. Conversion between analogue and digital signals introduces much of the cost and almost all of the impairment in a p.c.m. communication system. The long-term plan for a telephone administration should therefore be to introduce an integrated digital network in which only a minimum number of conversions and reconversions is required: ideally only one per connection. Transmission between exchanges should use multiplex p.c.m. and switching of concentrated traffic should be digital (either analogue or electromechanical). A planned transition from present practices towards a digital network is possible, because the partial use of p.c.m. is technically and economically beneficial provided that the applications be carefully chosen. Junction transmission, trunk transmission, tandem switching, group selection in terminal exchanges and integration over limited areas are considered. A digital network whose main traffic is telephony can also carry other messages such as telegraph and data.
4 citations
TL;DR: In this article, the authors describe the essential features of a digital store developed at the Bell Telephone Laboratories, which is part of a computer-like control system that will be used in telephone switching applications.
Abstract: This paper describes the essential features of a digital store developed at the Bell Telephone Laboratories. It is part of a computer-like control system that will be used in telephone switching applications. The paper covers the memory device (Piggyback Twistor), read and write techniques, circuits for driving and sensing, the broad system, and finally maintenance philosophy and a cost analysis.
3 citations
TL;DR: The No.1 Electronic Switching Systems (ESS) use stored program control to perform the telephone switching function as mentioned in this paper, however, to include new features in an operational office via program changes, without affecting service, is a unique task.
Abstract: The No.1 Electronic Switching Systems (ESS) use stored program control to perform the telephone switching function. Central processor units, including memory, are duplicated for reliability. New features are generally provided by program changes only and their inclusion in a precutover office poses no new problems. However, to include new features in an operational office via program changes, without affecting service, is a unique task. This task was faced in the development of a new route control feature for the AUTOVON network.
3 citations
Patent•
18 Mar 1969
TL;DR: A MICROWAVE RADIO RELAY system is described in this paper, where the authors show that the ERRONEOUS INSERTION of TELEPHONY SIGNALS in a SPARE Radio Channel can not be caused by FAULTY SWITCHING.
Abstract: A MICROWAVE RADIO RELAY SYSTEM IS PROVIDED IN ACCORDANCE WITH THE TEACHINGS OF THE PRESENT INVENTION WHEREIN THE TRANSMISSION QUALITY OF TELEVISION SIGNALS BEING TRANSMITTED IN A SPARE RADIO CHANNEL IS MAINTAINED AND THE DISTORTION THEREOF DUE TO THE ERRONEOUS INSERTION OF TELEPHONY SIGNALS THEREIN IS COMPLETELY AVOIDED. IN ONE EMBODIMENT OF THE PRESENT INVENTION A MICROWAVE RADIO RELAY SYSTEM INCLUDING FIRST AND SECOND BASEBAND TERMINAL STATIONS AND AT LEAST ONE LEAK-INSERTION STATION IS PROVIDED WITH AT LEAST ONE TELEVISION SIGNAL TRANSMITTING RADIO CHANNEL, AT LEAST ONE TELEPHONY SIGNAL TRANSMITTING RADIO CHANNEL AND AT LEAST ONE SPARE RADIO CHANNEL CAPABLE OF REPLACING EITHER OF SAID TRANSMITTING RADIO CHANNELS UPON THE DETECTION OF A FAILURE THEREIN. EACH OF SAID RADIO CHANNELS IS DIRECTED FOR TRANSMISSION IN ONE DIRECTION AND IN ADDITION, AT LEAST ONE TELEPHONY SIGNAL RADIO CHANNEL AND AT LEAST ONE SPARE RADIO CHANNEL IS PROVIDED FOR OPPOSITELY DIRECTED TRANSMISSION. THE LEAK-INSERTION STATION IS PROVIDED WITH BRANCHING OUT AND INSERTION CAPABILITIES FOR TELEPHONY SIGNALS IN EITHER TRANSMISSION DIRECTION, HOWEVER, THE INSERTION AND BRANCHING OUT OF TELEPHONY SIGNALS BEING TRANSMITTED IN SAID ONE DIRECTION IS ACCOMPLISHED ONLY IN CONJUNCTION WITH THE RADIO CHANNELS DIRECTED FOR TRANSMISSION IN THE OPPOSITE DIRECTION. THUS, TELEPHONY SIGNALS FOR INSERTION ARE NEVER INTRODUCED DIRECTLY INTO RADIO CHANNELS DIRECTED IT SAID ONE DIRECTION BUT ARE ONLY INSERTED AT A POINT WHERE TELEPHONY SIGNALS ARE NORMALLY PROVIDED THEREFOR. ACCORDINGLY, THE ERRONEOUS INSERTION OF TELEPHONY SIGNAL IN A SPARE RADIO CHANNEL TRANSMITTING TELEVISION SIGNALS CANNOT BE CAUSED BY FAULTY SWITCHING.
3 citations
TL;DR: A survey in Santiago, Chile as mentioned in this paper showed a total unsatisfied demand for residential telephone connections which is four times as large as the waiting list, due to nonownership of homes and excessive delay in providing new lines.
Abstract: A survey in Santiago, Chile, shows a total unsatisfied demand for residential telephone connections which is four times as large as the waiting list. Factors hiding the demand include nonownership of homes and excessive delay in providing new lines.
3 citations
TL;DR: In this article, a description of equipment providing acoustical transmission over ordinary telephone lines and utilizing standard telephone handsets is presented, including a discussion of the more pertinent parameters which determine the final design of the equipment.
Abstract: A description of equipment providing acoustical transmission over ordinary telephone lines and utilizing standard telephone handsets is presented. Included is a discussion of the more pertinent parameters which determine the final design of the equipment. Among them are proper orientation of the granular carbon transmitter, maximum line bit rates, and tolerable total harmonic distortion. The frequency and transient response of all acoustical transducers employed in the equipment are presented. The results of local and cross-country tests are summarized; also included is a summary of the actual operational experience over a period of two years from large numbers of units in use over the entire country.
2 citations
TL;DR: In this paper, a self-contained digital-computer program for power line-power line crossings has been presented, and a comparison of the computer results with experimental measurements is provided.
Abstract: Previous work on power-line-produced telephone interference has dealt with the case of a single equivalent power conductor. This paper presents the theory applicable to a multiconductor power line excited by general, linear networks. A self-contained digital-computer program employing these techniques has been written. It rigorously handles the important case of actual communication line-power line crossings. A comparison of the computer results with experimental measurements is provided.
2 citations
TL;DR: The Dendenkosha (NTT) electronic switching system for experiment DEX-I system was designed as the experimental space division unit to study the program control technique, and has the ferreed switch network and the central control of 4-μs memory cycle time.
Abstract: After 10 years research on the electronic switching system, Nippon Telephone and Telegraph (NTT) decided to develop the electronic switching system with stored program control in 1964. The Dendenkosha (NTT) electronic switching system for experiment DEX-I system was designed as the experimental space division unit to study the program control technique, and has the ferreed switch network and the central control of 4-μs memory cycle time. Another test system, the DEX-T1 system was also designed to apply the PCM technique to switching network. Lines are concentrated by the ferreed switch network controlled from the remote parent office and are switched through the pulse code modulation (PCM) switching network at the parent office. Both systems were installed in the Electrical Communication Laboratory, NTT, and tests were completed in 1967. From these experiments the DEX-2 system for the field trial was designed. Small crossbar switches and miniature relays were adopted to make the system smaller, and high-speed logical elements were used to improve the call-processing capability and simplicity of the central control, and the magnetic drum was introduced for the economy of memories. This system occupies only one-third of the space of the existing switching system and has a capability of about 30 000 lines.
TL;DR: A new maritime mobile radio telephone system adopted by Nippon Telegraph and Telephone Public Corporation (NTT) and the satellite repeater arrangement, adopted to reduce service-dead areas, is described.
Abstract: A new maritime mobile radio telephone system adopted by Nippon Telegraph and Telephone Public Corporation (NTT), is described. An outline of the technical features of the entire system and the satellite repeater arrangement, adopted to reduce service-dead areas, is given.
TL;DR: The 10-C telephone switching system comprises modular multistage link switching networks composed of reed crosspoint matrices, controlled by a stored-program controlled central processor system, mainly composed of integrated circuit logic and ferrite memory features.
Abstract: The 10-C telephone switching system comprises modular multistage link switching networks composed of reed crosspoint matrices, controlled by a stored-program controlled central processor system. In addition to the advantages inherent in the use of sealed contacts, such as high transmission quality, low noise, long life, etc., the following useful system features are obtained: high switching speed, high crosspoint efficiency, optimum match between network and central control, efficient path search and marking procedures, easy extensibility, and integrated quasi-electronic plug-in mounting techniques. The 10-C central processor system is mainly composed of integrated circuit logic and ferrite memory features: high speed, simplicity, compact construction, and high intrinsic reliability. Common storage in extensible randomaccess ferrite memory is provided for program instructions, and translation and parameter tables, as well as variable call data. The duplicate processors working in the load-sharing mode are complemented with a program-reload and automatic recovery system. The first exchange of this type was handed over to the Belgian administration in 1967 and integrated in the Antwerp area automatic telephone network.
TL;DR: In this paper, a study of a high channel density 450-MHz communication system employing 6 groups of 10 channels each in a 300-kHz band was made for air-ground telephone service by single sideband.
Abstract: Directed toward FCC Docket 16073 on air-ground telephone service by single sideband, a study has been made of a high channel density 450-MHz communication system employing 6 groups of 10 channels each in a 300-kHz band. To accomplish necessary tolerance to out-of-band transmitter radiation, all mobile stations need automatic power output control. Other important system features, such as privacy and first come, first serve from queue when all busy, result from the use of a common data channel. With the accomplishment of the necessary equipment and logical techniques, a communication system of much greater frequency utilization appears technically and economically feasible.
TL;DR: A fully transistorized low-cost visual communication system has been constructed for the high-speed transmission of still two-level pictures (black and white) over the unmodified existing telephone networks, which reduces the transmission times of ordinary facsimile by a factor of from 10:1 to 20:1, still producing readable pictures with a signal-to-noise ratio of 20 dB.
Abstract: A fully transistorized low-cost visual communication system has been constructed for the high-speed transmission of still two-level pictures (black and white) over the unmodified existing telephone networks. It reduces the transmission times of ordinary facsimile by a factor of from 10:1 to 20:1, still producing readable pictures with a signal-to-noise ratio of 20 dB. The case of short-distance communication (private telephone exchanges) and some other possibilities of particular application are also discussed. Experimental results are shown, recorded under various operating conditions.
TL;DR: In this paper, the power distribution system serving the Bell Telephone Laboratories, Holmdel, N. J., is described with emphasis on reliability achieved with dual public utility feeders, and with primary and secondary selective load center design.
Abstract: The power distribution system serving the Bell Telephone Laboratories, Holmdel, N. J., is described. Operation of the system is discussed with emphasis on reliability achieved with dual public utility feeders, and with primary and secondary selective load center design.
Journal Article•
TL;DR: This presentation explains the development of types of codes used in telecommunications, and some of the factors that go into designing a good code.
Abstract: PULSE CODE MODULATION IS VERY USEFUL FOR TELEPHONY, BUT THERE ARE MANY WAYS TO IMPLEMENT THE PROCESS. FACTORS ABOUT WHICH SYSTEMS CAN AND DO DIFFER ARE SAMPLING RATE (THE ONLY FACTOR UPON WHICH THE WORLD IS AGREED: 8000/SEC), NUMBER OF CHANNELS CODED ON A SINGLE LINE, LENGTH OF A BINARY WORD, COMPANDING LAW, NUMBER OF TIME SLOTS AND CHANNELS PER FRAME, FRAMING AND SIGNALLING, AND TRANSMISSION CODES. THE COMPANDING LAW IS THE BIGGEST STUMBLING BLOCK. INTERNATIONAL GROUPS ARE TRYING TO AGREE ON APPROPRIATE STANDARDS, BUT ARE HAVING A DIFFICULT TIME COOPERATING. /BPR/
Patent•
01 May 1969
TL;DR: A ringing selector for an interconnection system includes a slipping counter 11 having a number of stages S0-S10 each associated with a telephone extension and connected through an output transistor TR1-TR10.
Abstract: 1,248,813. Counters. TELRAD TELECOMMUNICATION & ELECTRONIC INDUSTRIES Ltd. 25 April, 1969 [15 May, 1968], No. 21239/69. Heading G4A. [Also in Divisions H3-H5] A ringing selector for an interconnection system includes a slipping counter 11 having a number of stages S0-S10 each associated with a telephone extension and connected thereto through an output transistor TR1-TR10. The input to the counter includes the telephone dial contacts 1 and an additional series-connected switch 2/2 which is operated to seize the device so that the dial impulses cause the counter output to be stepped the required amount. When the dial returns to normal the respective output transistor is enabled to apply a calling signal to the required extension. In operation cradle switch 2/1 and additional switch 2/2 are closed which causes transistor 7 to bring up relay 10 after capacitor 8 has charged up. The contacts of relay 10 prepare counter 11 and prepare the circuit associated with transistor 19. Dialling pulses are transmitted and the output of counter 11 steps until the base of the required output transistor TR1-TR10 is marked. When the dial returns to the rest position capacitor 15 is charged up until transistor 19 conducts to apply an operating potential to the emitters of transistors TR1-TR10 so that the marked transistor conducts and sounds an audible alarm at the respective telephone extension. After a time delay capacitor 8 discharges causing relay 10 to drop out and the device to reset to its initial state. The device is stated to be completely independent of the speech path circuitry.
TL;DR: A computer-oriented classification technique to search for representative classes of impulse waveforms has been developed and classes of impulses have been found experimentally in representative samples of actual noise from telephone channels.
Abstract: The impulse noise that occurs on telephone channels affects the performance of data transmission systems more than it affects voice communications. As a step in constructing a more meaningful model of a telephone channel for use in data transmission studies, a computer-oriented classification technique to search for representative classes of impulse waveforms has been developed. Classes of impulses have been found experimentally in representative samples of actual noise from telephone channels. Results concerning these classes and the impulses in these classes are presented.
TL;DR: In this article, a means for locating the pole and zero frequencies of the equalizer network is described, as well as the use of a frequency response slide rule for rapidly verifying the results.
Abstract: The telephone exchange cable plant may be a mixture of several gauges in a particular run. Predicting its electrical behavior precisely when only one gauge is involved is difficult at best. Gauge mixtures and the lack of accurate records preclude the computational course in the practical case. A method is given for the graphical analysis of cable attenuation obtained from measurements. A means for locating the pole and zero frequencies of the equalizer network is described, as is the use of a frequency response slide rule for rapidly verifying the results. In addition, it is shown that the use of a time-sharing computer can be helpful in specifying components and in the general administration of equalizer projects when large numbers are involved.