Showing papers on "Transmission delay published in 1971"

Effects of transmission delay on conversational behavior on echo-free telephone circuits

Abstract: The present study sought to determine the effects of echo-free transmission delays of 600 ms and 1200 ms on conversational behavior when subjects were unaware that delay was present. Sixteen pairs of male subjects conversed 10 minutes each over an echo-free telephone circuit with zero delay and 10 minutes each with 600 ms round-trip delay; a second group of 16 pairs conversed 10 minutes each on zero delay and 1200 ms round-trip delay. Subjects noticed nothing unusual about the circuit, but the delay caused a statistically significant increase in frequency of confusions and in amount of both double talking (simultaneous speech from both speakers) and mutual silence. Analysis by means of an on-off pattern generating model revealed that subjects seem to make some adjustments in their speaking behavior; they tend to wait longer for responses and keep talking longer when interrupted. The two delay values of 600 ms and 1200 ms produced virtually identical effects in the measures made here. All of the subjects in the study were inexperienced with delay circuits; this experiment does not address itself to the possibility that experienced subjects might react differently to the delay. Further work will investigate the effects of training subjects to notice delay.

Extensions of packet communication technology to a hand held personal terminal

Abstract: Electronic communications technology has developed historically almost completely within what might be called the circuit switching domain. Not until the last decade has the other basic mode of communication, packet switching, become competitive. Thus, as a technology, packet communication has only begun to be explored. Circuit switching can be defined in the broad sense as the technique of establishing a complete path between two parties for as long as they wish to communicate, whereas packet switching is where the communication is broken up into small messages or packets, attaching to each packet of information its source and destination and sending each of these packets off independently and asynchronously to find its way to the destination. In circuit switching all conflicts and allocations of resources must be made before the circuit can be established thereby permitting the traffic to flow with no conflicts. In packet switching there is no dedication of resources and conflict resolution occurs during the actual flow perhaps resulting in somewhat uneven delays being encountered by the traffic. Clearly, without the speed and capability of modern computers, circuit switching represented a cheaper and more effective way to handle communications. For radio frequency assignment and telephone exchanges the resource allocation decisions could be made infrequently enough that manual techniques were originally sufficient. Also, since voice was the main information being communicated, the traffic statistics were sufficiently compatible with this approach to make it quite economic for the period. Packet switching of a kind, the telegram, persisted throughout this period but due to the high cost of switching and the limited demand for fast message traffic never attracted much attention.

The control of congestion in packet switching networks

Abstract: Any communication network has a limit to the traffic it can carry. If there is more than a certain traffic demand, some of the traffic must be rejected. Both the nature of the limitation and the reaction of the network to excess demand depend on the design of the network. The network in a condition where it must reject traffic is called 'congested'.

Automatic equalization method and apparatus

Abstract: This invention relates to a method of and an apparatus for providing equalization to frequency dependent delay and amplitude distortions in a transmission line. The apparatus includes an adjustable equalizer having a plurality of delay networks, an amplifier, a peak-to-average difference detector, and a control logic for selectively switching the delay networks and amplifier into and out of the path for the incoming signal. Adjustment of the equalizer to a given transmission line is carried out under the control of the control logic and in response to peak-toaverage difference signals supplied by the detector. To that end, a train of test pulses is transmitted to the equalizer via the transmission line, and the delay networks and amplifier are selectively switched into and out of the signal path in timed synchronism with successive ones of those pulses, thereby providing different combinations of phase and/or amplitude compensation for such pulses. The peak-to-average difference detector responds to the compensated pulses to identify the particular delay network or delay network/amplifier combination that best compensates for the distortion introduced by the transmission line, and the control logic locks that combination into the signal path. In the case where the equalizer is used in an FM transmission system, it is interposed between the transmission line and the FM demodulator so that the equalization takes place prior to the recovery of the demodulated baseband signal.

Delay compensation in multiplex transmission systems

Abstract: A time assignment speech interpolation system is disclosed utilizing time-shared common control processing circuits. Speech signals from a plurality of trunks are interpolated on a lesser plurality of transmission channels by connecting trunks only during active periods. In order to accommodate transmission channels of varying delay times (e.g., cable and satellite channels), receiving terminal switching operations are delayed for a time corresponding to the transmission delay of the corresponding channel. This is implemented by common control digital delay time-out for each new connection.

Variable delay line utilizing one part reflection type amplifier

Abstract: A microwave delay line includes a first path of negligible delay time, a second path providing a predetermined delay time determined by a delay line section terminated by a one port reflection type amplifier, and a control for selectively feeding a microwave signal over one of the paths. A signal can be held in the delay line section of the second path to thereby impart a desired delay to that signal.

Transmission-delay control of radio links in a mutually synchronised p.c.m. network

Abstract: In a mutually synchronised p.c.m. network, the relatively fast transmission-delay variations of radio links may restrict the use of such links. To overcome this problem, a method is proposed in which the delay is automatically compensated using an inherent facility of a typical hybrid-modulated radio link.