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Many digital systems, such as PCM systems, data processing and data transmission systems, use twisted ring counters. Most of these twisted ring counters are subject to multimoding. This paper develops tools and methods for predicting all possible modes in twisted ring counters, and derives a general solution for suppressing the wrong modes. Suppression is accomplished by adding a few circuit connections from the output of certain stages to the input of another stage. The paper derives the number of necessary connection lines and their connection points for the various types of counters.

A theoretical analysis is presented in which the phase pertubations of the sounding signal due to ionospheric propagation are interpreted into a ‘phase-error’ rate. An indication of how this may be used to assess the likely error rate associated with an information channel using that frequency is also given. The paper describes how the sounding technique will be used to control the time at which to change frequency, the best standby frequency and the degree of redundancy required to protect the information. The paper is a sequel to that presented by the authors at the IEE conference on signal-processing methods for radio-telephony, London, May 1970.

In data transmission systems used to transmit numerical information over considerable distances for control or indication purposes, the information is sent as a serial train of digits to conserve bandwidth, each digit having two possible states. The paper describes a system for the transmission of such information using the Dekatron tube in a number of roles. These tubes enable the functioning of the timing system to be monitored so that faults may be quickly and easily located by visual observations of the behaviour of the glow discharges.

Two laboratory computers have been interconnected through an addressed-block data transmission system (ring) as described by J. R. Pierce and implemented by W. J. Kropfl. This paper gives an idea of the equipment, programming, and protocols of communication through that system.

This paper describes methods for the reduction of jitter in transmission chains with regenerative repeaters. These methods are based on the application of pattern transformations to the output signals of successive repeaters. As a result, the coherent accumulation of jitter from signal dependent jitter sources is prevented. Instead, the jitter accumulates on a power basis. It is shown that in this way a significant reduction of jitter is obtained. This result is demonstrated by both theoretical data and measurements on an experimental transmission chain which correspond fairly closely. Furthermore, the realization of the pattern transformations by simple coding techniques is presented in detail.

The paper deals with the methods employed for the transmission of data which have been used in the Fighting Services up to the present day. An historical review is made of the main types of instruments used over the last 40 years, particularly for Naval purposes. The development of the present types of data transmission-in particular the magslip-is dealt with more fully, and references are made to parallel developments in this and other countries. Various applications are described, giving the methods of application and limitations of use of the various types of element. A number of photographs showing typical magslip elements are included, and an abbreviated list of types of magslips and some performance figures are given in an Appendix.

This paper deals with two aspects of the investigations of mobile data transmission. The first aspect shows the equipment for measuring and recording of parameters that influence the transmission. The second aspect shows the development of an analog simulation of the data transmission with the possibility of adjusting significant parameters independently. Finally the applicability of the model is verified by comparison between simulation and actual transmission.