US678363A - Telegraph and cable code. - Google Patents

Description

Nrrnn STATES PATENT ()rricn.

ADOLPHUS W. GREELY, OF WASHINGTON, DISTRICT OF COLUMBIA.

TELEGRAPH AND CABLE CODE.

SPECIFICATION forming part of Letters Patent No. 678,363, dated July 16, 1901.

Application filed August 1, 1900. Serial No. 25,577. (No model.)

To all whom it may concern:

Be it known that I, ADoLPHUs W. GREELY, brigadiergeneral and chief signal oflicer United States Army, residing at Washington, District of Columbia, have invented certain new and useful Improvements in Telegraph and Cable Codes, of which the following is a description.

The object of my invention is to use telegraphically characters of the present telegraph and cable alphabets in such order of arrangement as to insure the maximum rate of transmission and the minimum chance of errors, omissions, &c. and a further object is to construct from such characters so arranged, classes of codewords, each containing an equal number of letters, the class of words of shorter length being used for the largest proportion of telegraphic traffic, thus producing a telegraph and cable code superior in character to any heretofore developed.

It is well understood that in the present cable alphabet some of the letterssuch as and quire successive signals of the same sign 1n their construction, whereas others-such as (AD-e made up of successive signals of opposite sign, while others stillsuch as l and y )are made up of different combinations of signals of opposite sign, in which, however, there are successive signals of the same sign.

It has been determined by actual trial that from an electrical standpoint those letters which are wholly made up of successive signals of opposite sign are superior telegraphically to either of the other two classes above mentioned, and also that in the case of consecutive letter combinations those combinations are most effective in which the first signal of the succeeding letter is of opposite sign to the last signal of the preceding letter. The

theoretically-perfect alphabet is made up of successive signals produced by plain signwave alternating current, in which the cable is alternately charged and discharged in a perfectly regular manner.

It is the object of this invention to employ these principles deduced from actual experiment in the make-up of individual characters and combinations of characters into codewords.

In carrying out my invention I make use of those letters of the present telegraph and cable alphabet now in use which are made up of successive signals of opposite polaritythat is, in the telegraph-alphabet made up of dot following dash or dash following dot, and in the cable-alphabet a swing to the right following a swing to the left, and a swing to the left following a swing to the right-and Icombine such letters into a series of code-words conforming to the international telegraphic rules, which require that words of definite meaning and of presented languages must be used. The code-words so made up will, by reason of the fact that they are made up of successive signals of different polarity, be transmitted with the least possible chance for errors and with the greatest possible speed,

and in order to reduce, as far as possible, the chance of error in transmission as well as to facilitate the speed of transmission I arrange the code-words thus made up into special series, according to the number of letters in the words.

The code-words now generallyin use average from eight to nine letters. I substitute for these code-words special series of codewords consisting of three letters each, four letters each, five letters each, and six; letters each, the words selected being of the character above mentionedthat is, made up of letters in the formation of which successive signals of different sign are used.

Examples illustrating the several special series of codewords are as follows:

Threedetter Four-letter Five-letter Six-letter words. words. words. words.

act cent cater canker art area crate tinker and cake enter twenty ate wand track winter end karn treat writer ear tree under turned ken tank trend tended tea tart wreak wended ten wart creak mended wet mate smart create wen make The three-letter code will be applied, so far as possible, to that class of cable business which not only demands the highest possible speed, but also comprises the greatest percentage of the cable business. It will be especially applicable to the interchange of stock business between great financial centers-such as London, New York, Paris, Berlin, and Rotterdam-in which speed and accuracy are of the utmost importance. For this class of business the gain in speed of transmission by the use of my code is apparent when a cablegrain of, say, ten words of my three-letter code is compared with an ordinary code-message of ten eight-letter words. It is evident that the three-letter-code message could be transmitted and received in much less than half the time. The three-letter code could also be used between bankers and others for special purposes where speed and accuracy are of importance. The fourletter code and the five-letter code may be used in sequential order for less expensive class of cable business and the six-letter code for still less expensive business.

A very great advantage which results from i thus dividing the general code into special codes of respectively three, four, five, and.

six letters is that greater certainty as to the receipt in correct form of the message transmitted is insured.

letters or three letters in a message delivered to him must be an error. So, too, where the iive-letter code is used a word containing either less than or more than five letters will;

at once be recognized as an error.

A further feature of my invention is the provision of means for transmitting byasiu D2 0, F 30, K l0, L 50, N 60, R 70, T280, and VV29O.) It will be observed that so far as possible I make use in this feature of my invention of the successive signals of For instance, when a banker uses with his correspondents the four-} letter code he would know that a word of five opposite sign, which forms the main feature of the invention of this application. It will also be observed that the vowels and consonants used are arranged in alphabetical sequence, this arrangement being calculated to facilitate translation by memory.

The absence of any figure having the value of ten is indicated by the use of any conso nant other than one of the nine selected, or in the beginning of a Word by the absence of any consonant, the assigned unit vowel standing first in the word. By suitable combinations two or more sets of such even code nu mbers can be sent bya single code-word. For exam ple:

Having thus described my invention, what Iclaim, and desire to secure by Letters Pat cut, is-

1. In a telegraph and cable code, a code-word consisting of letters made up of successive signals of opposite polarity; substantially as described.

2. In a telegraph and cable code, a series of code-words each having the same number of letters and each consisting of letters made up of successive signals of opposite polarity; substantially as described.

3. In a telegraph and cable code, an even code-number system, in which the even units from zero to eight are represented respectively by a vowel and the tens from ten to ninety are represented by consonants made up of successive signals of opposite sign; substantially as described.

In testimony whereof I aflix my signature in presence of two witnesses.

ADOLPI'IUS IV. GREELY.

\Vitnesses:

GEORGE O. SQUJRE, EUGENE O. FEoI-rEr.