A New Measuring Set for Message Circuit Noise

The 1962 sample survey of message circuit noise and loss on Bell System toll connections is described and discussed in this article. The result» are presented in terms of the distribution of noise levels on toll calls as established in the present system, the distribution of end-office to end-office losses on these calls, and the dist1'ibution of airline distances between end-offices, It is shown that the noise distribution referred to the eubscriber:« set has a mean of 19,7 dbrnc with a standard deviation of 7.8 db, that the mean of the distribution of end-office to end-office losses is 7,7 db with a standm'd deviation of 3.0 db, and that 60 per cent of all toll calls are shorter than 30 miles, while only 10 per cent span a distance of m01'e than 260 miles, The noise level Ve1'8'tlS distance and loss versus distance relaiionehip« are investigated and analyzed. The noise level is found to increase by 2.2 db for each doubling of the airline distance benceen end-offices, while the loss shows an increase of 0.6 db for each doubling of the distance. Finally, present performance of the Bell System toll plant is evaluated in terms of noise and volume grade-ofservice estimates.

Section: Lossmentioning

confidence: 99%

The 1962 Survey of Noise and Loss on Toll Connections

Nåsell¹

1964

A New Objective for Message Circuit Noise

Lewinski¹

1964

The reduction and control of noise on message circuits must be based on sound noise objectives. For many years the Bell System over‐all performance objective has been “26 dbrnc (20 dba) seldom to be exceeded at the telephone station set.” In this article the derivation of a more flexible and operationally feasible noise objective is presented. This objective specifies a limit of 20 dbrnc not to be exceeded on subscriber loops, and stipulates various distributions for noise originating beyond class 5 offices on built‐up connections. The objective is such as to provide Bell System customers with a noise grade of service ranging from 99 per cent good or better on short connections to 90 per cent good or better on intercontinental connections spanning distances up to halfway around the world.

The TM-l/TL-2 Short Haul Microwave Systems

Friis¹,

Jansen²,

Jensen³

et al. 1966

This paper describes the design and discusses the performance of the TM‐1 and TL‐2 radio relay systems designed for short haul service in the 5925 to 6425 megacycle and the 10,700 to 11,700 megacycle common carrier bands, respectively. Used as a crossband diversity pair, they provide a highly reliable broadband message channel for up to 600 circuits and require little maintenance and relatively low power. These systems are also used to transmit television.