US1556750A - Electrical signaling - Google Patents

Description

Patented Oct.v 13, 1 925.

f LOUIS -B.BENDER, or' WASHINGT, ms'mrc'rfor coLuMBIA. l

. nLncrnicALsieNAmNG.

Application filed August v29, "1.923. ',"Ser'ival' Nol 659,971.

To all whom it c''rri/cern.'A y

Beit `knownthat I, LoUisfB. BENnnR, a

citizen ofy *Y the United States,` residing l .at. A`Wa`sliington, in the 'District of Columbia, `have'inventedV certain new and Luseful Ime' provem'ents in Electrical Signaling,A of' which the following is a specification.

This invention relates to an improved. system'A for: the transmission and reception ofv radio signals.

jrT'he object of this inventionl isV to provide a radio systeinwhereby the ,signals trans-p mitted, the' dots and dashes, y are yof the vsamey intensity. and same time vduration and char' acterized byv a. 'difference' in carrier fre qllencyfk n y i i I in a paper pibii's'hd in iiiegiurnai 0i the Franklin.Institiite,"May, 1923,-Gen. G. O.

Squier proposed a new `telegraph transmise' sion vsystem in which 'the'dots .and dashes of General Squier providing the improvement of having t-he'sa'me` signal intensity for thek dot andv the dash f and` effecting a di't'erei'itial tionV betwelfthein a `difference in fref quencies.

providel at the transmitting station a' C.

radio transmitter lcap-able 0f generating and radiating two radio frequencies,the change= froi'n one frequency to'anotlier ,being obl" tained by'a Vchange inAk one of the Vconstants of, the oscillating circuit', the'radioffre-jy quency'cu'rrent being modulated by a cur# rentvk of low frequency, 'sinejwave form. j

' At the receiving station I propose topro-f videtwo receiving systems, each'being tuned 1 to receive a signal of a different frequency,V that is, one'system responding only, to the` dot frequency signal and the'other respond# ing to the dash frequency 4signal'.v

In yorder that my invention maybe jkm'ore clearly'.V understood, it isf described 1 in more j detail withftheaid oflthe accompanying drawings, in whichf-f l l i Figure 1 represents thecharacter'ofy trans mitted signals using different carrier fre-f quencies for dots and dashes and these" carriersl modulated by. arlow frequency of s ne wave form Without spacing between e ements -of amletter, but with'one halfv cycle" between let-ters themselves. After rectificationin -the receiving system, only the upper,

or lower-'half of the envelope-would remain.'

`Figure 2 shows the necessary combinationy ofvC, radiojtransmitter, automatic tape transmitter and vmodulation [generator vi'rhereinw3 the .tape .transmitter controls .the' oscillation of the radio transmitter at `v two frequencies or yprevents oscillation entirely. K

Figure 3' shows the essential, elementsv and arrangement of;1ftl ie` Vreceiving system .required Vfdr receiving and recording fniodiilatedfradio'signals 'at-two carrier frequencies. Xy

Referring more particularly Ato the draw--` TiiigFgfure 2`Lrepres'ents a C.-'W. radio transmitter of-,any'rforin in which, an inductanceE 1s so yconnectedas tocontrol the cs cillation of the system 'andv the frequency of the oscillations.V vC"represents the feed wheel of'r anr aiitom'obilev ftape" transmitter, n S the punched tape being f-fed through theautomatictape transmitter, Y land X the'pecker ins of this transmitterwhich vcome into contact with Z when the. punched tape will permit.' When neither Y' nor X' is in contacty with Z, the circuit through E is open and n0 oscillation" generated. This is the condition existing when yspacesv lb'etween letters and words 'on' the tape are passing under Z', Whena perforation in the tape S permits pecker pin Y' to comev into contact with'Z,

the`oscillating circuit is completedthrough the whole of in ductance E-and a Idefinite radio frequency' is generated andi'adiated from the antenna N.' ThisY is the condition soY existing when a perforation representing a dot is passing under Z. When pecker. 'pin Xcomes into contact with"Z,'only'a portiony of'inductance Eis infcircuitand a higher radio frequency is generated and' radiated. ThisYV lis the condition when a perforation representing a dash is passing under Z. The

tape is so perforated that pecker pins X and Y can never bein contact with Z at the Sametime]'Thefl feed wheel isv driven atl constant speed by'any. convenient'form of motor' M; Coup-led "to the Cfeed-.wheel C' thron'gh'adj iistable coupling yK is Y a single 1 phase, low kfrequency generator :D which generates Va current/wave of substantially sine form. The 'output' of generator AD; isI

connected `to the 4modulation transformer F of fthe cradio .transrnitter T. The coupling K` ion is so adjusted that full modulation and minimum radiation of theradiofrequencyv` energy4 from transmitter yT O'cCllrS juSl'n 21S.

the tape S disengages'one pecker pin or Y) from contact ywith Z and permits a 'new' engagement. lZeroV modulation0 'andi` maximum radiation occurs midway betweenrthe malrerlK on a Contact. blloclrA. i 'I herefare two independent coils in the moving, system, one coil being connected. to J andtheA otherto Jf in such manner that. energy from J. will. deflect the pointer K to the4` right and energy from J will deflect it to the left or vice-versa.. The pointer K normally rests on an insulatingsection separating the two contact surfaces. ofthe block Ag. When the pointer K is deflected vtothe right the potential of battery G is applied to the grid of vacuum tube Oy with respect to its filament. This action results in a flow of current in the plate circuit o f tube Ov through relay The latter relay is then closed and completes acircuit from the battery E through the-variabile resistance R and, the coil B of a siphon recorder or similar recording mechanism. AAdjustment of the variable resistance R. permits any desired amplitude. of

signal to be recorded o-nlthe tape Q. Deflection of the pointer K to the left results in similar `action of the vacuum. tube O andl relay M, the variable resistance permitting adjustment of the amplitude'of the recorded signal. These resistances R and R furnish the means ofadjustingthe relative height of the recorded signals and thereby making the Morse code'reappear. A condense-1l inrv series with, a resistance is shunted across the winding of each relay M and M to improve the operation. The output circuits of J and JIL', may be connected directlyl to the coils off relay- P as shown'iiiy Figure y In the former case, the relay. P would be actuated. by the reduction inplate andcoil current'due to a received signal; in the latter Ac`.as'e,the coils ofrelay P would carry 'no current until the vsignal was received and the action would be `or may' be connected thereto. through transformers.

Morse code. No time interval separates the elements of a letter, the elements of letters following each other withoiitfspacing. Between letters, words, and sentences, time inte'rvals equal to some multiple of the time unit represented by'on'e 'halfoycle on the modulation generator are employed. During these intervals the radio transmitter is not radiatingA energy, -tlieunpfunched tape at the automatic tape transmitter preventing oscillation of the antenna circuit.

Avtelegraphic printer designed kto operate onA Morse code signals, such as theQreed Printer]l andI similar designs, may fbe'-` subf-v stituted forl the siphon recorder only` a'. slight.` incillifiaitioll 0f. the mecha-l'y nism.

I claim: v

1'. Iny a system of. telegraphy, means fory offtwo receivers tune to receive signals of different. carrier frequencies', bothl of. said receivers being connected toa single relay of.. thel suspendedrdouble coil type having a con-` tact maken moving over a 'double Contact block, each ofthe two sectionsA of saidbjloclr` being, connected through vacuumtube relays,to a single Siphon recordervfor recording on a tape-the received signals.

2;. In a system of telegraphy, means', forl transmitting and receiving two .radio fre;- quency currentsfjmodulated byk a 10W' firequency alternating current of constant` ame plitude, said means consisting of. a radio transmitter, anwautomatic tape transmitter, a sine wavel generator' ofy low frequency, means for maintaining said generator in synchronismv with said tape transmitter, and a receiving apparatusconsisting of, two receivers tuned to receive signals of.

different carrier frequencies, both of. said receivers being connecte-d to a single relay of the suspended double coil type having a Contact maker moving overa double contact, block, each :of the two sections of said block being connected through mechanical relays to Suitable mechanism for recording. on a tape the received signals, the pointer on said Contact block being throvvnin opposite directions'by the two radio frequency'sig'- nals', and the two signals being distinguished on the tape of the siphonrec'order by their `distinctive amplitudesobtainable by adjustment of resistances in the relay circuits -ac-` tuating said recording mechanism.

In testimonywhereof I affix my signature. f LOUIS B;

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