decilog

A unit proposed to replace the decibel

That the decilog received some attention in the 1950's but ultimately failed to take hold is evident in this Google n gram chart. (The results are somewhat confounded by the also-disappearing decilog scale of slide rules.)

sources

1

For such a purpose, it is suggested that the term 'decilog' might be used, the decilog (dL) being analogous in all respects to the decibel, except that there is no restriction on the nature of the quantities being measured.

Sir James Hopwood Jeans.
The Physics of the Universe.
Nature, vol 122 ??? (3 November 1928)?? page?
doi:10.1038/122689ao

2

Decilog (dg): The decilog is a division of the logarithmic scale used for measuring the logarithm of the ratio of two values of any quantity. Its value is such that the number of decilogs is equal to 10 times the logarithm to the base 10 of the ratio. One decilog therefore corresponds to a ratio of 100.1 (i.e. 1.25892 + ).

Note: The decilog is intended to supplement, and not to supplant, the decibel.

American Standard Definitions of Electrical Terms. ASA C42.
New York: American Standards Association, 1941.

3

The Much Abused “Decibel”

Discussion revolving around the terms “decilog” and “logit” has been going on for some time, and seems to be coming to a head. Despite the efforts of some stalwart purists, engineers have persistently used the “decibel” loosely, thereby causing painful errors.

E. I. Green, Chairman of the American Standards Association subcommittee concerned with communication terms, has proposed a new unit for logarithmic ratios to replace the overworked decibel. His thinking on this problem is incorporated in the ensuing article of his writing. [What followed is essentially a version of Green's article in the July 1954 issue of Electrical Engineering]

Transactions of the I.R.E. Professional Group on Antennas and Propagation, vol 2, no. 2, (April 1954), page 42
doi:10.1109/T-AP.1954.27971

4

“Gain and loss are generally stated in decibels. Because of long established usage in the audio field, amplification and attenuation ratios are expressed in terms of decibels in this standard, although the more recently introduced term ‘decilog’ is more appropriate.” Page 668.

“By long-standing audio practice amplification is frequently expressed in decibels by multiplying the common logarithm of the ratio by 20, although it would be more appropriate to express this ratio in decilogs.” Page 674.

“By long-standing audio practice attenuation is frequently expressed in decibels by multiplying the common logarithm of the ratio by 20 although it would be more appropriate to express this ratio in decilogs.” Page 681.

Subcommittee on Methods of Measurement of Gain, Amplification, Loss, Attenuation, and Amplitude-Frequency-Response 1949-1955.
IRE Standards on Audio Systems and Components: Methods of Measurement of Gain, Amplification, Loss, Attenuation, and Amplitude-Frequency-Response, 1956.
Proceedings of the IRE, May 1956.

 

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