The reliability of short-wave radio telephone circuits

From empirical measurements of noise-to-signal ratio made during the routine operation of short-wave radio telephone circuits there is obtained a general relation between percentage lost circuit time and transmission improvement in decibels. In this relation “percentage lost circuit time” is the percentage of time that the noise-to-signal ratio is considered unsatisfactory. No attempt is made to define such a standard quantitatively. If, from past experience with a long-range, short-wave telephone, telegraph or broadcast circuit, it is known that the circuit is unsatisfactory a certain percentage of the time, the above-mentioned relation may be used to estimate the effect of transmission improvement upon this percentage of unsatisfactory or lost time. For a given circuit the variation in percentage lost circuit time, as the standard for the tolerable service is changed by a given number of decibels, may also be estimated. There are included estimates of the relation between the number of lost time intervals of various lengths and transmission improvement.