US1412908A

US1412908A - Synchronizing system

Info

Publication number: US1412908A
Application number: US397982A
Authority: US
Inventors: Marl B Van Dyile
Original assignee: AMERICAN TELEPHONE AND TELECRA
Current assignee: AMERICAN TELEPHONE AND TELECRA; AMERICAN TELEPHONE AND TELECRAPH Co
Priority date: 1920-06-10
Filing date: 1920-06-10
Publication date: 1922-04-18
Anticipated expiration: 1939-04-18

Description

K. S. -VAN DYKE.

SYNQHRONIZING SYSTEM. APPUCATZON FILED IUNE 10, 2920 1,412,908. PamwdA r.18,1922.

INVENTOR 1m? aw/k M' TORNEY i aiely gcnerareil at :lili'hn igrnaliugg; sysccnr aizures the 'nvenlien rcwisien oi means whereby urrenls supplicil from M0 iiulev he muonia ically mainquency.

(:l the invention resides Wheri' i alternat- V. n: eiviag siiavtiun he inaiuiaiueil in c u ii is rccei veil ion.

wifih (fir earing, are 'mlh in the illustrated in ll e er few Yin q ilesci in she crawing, J1 designates reliu a frscuency generated at aliuu may re up the stat' i the figure. we the ciic i'nay he asse- Mun line ie cling to lon er .iuay he asseci i will! enua in the ease of raalir; jlllilfik; a'circuit for iransif," genera i frequency. in

m which ii is me he applied.

Epecificatiou ef Letters Patent.

ieatien. filed June 3.9, H526.

the

detector D may he of an l uieurcii Apr. i a 192" Serial No. 387,582.

erail'cd alt the local from time to time.

In order to insure that the frequencies supplied to the circuit L as the result elf i'ihc accion of the generator S shall be the same as the frequency incoming from the circuit L, an apparatus is provided for normally cleccciving the two frequencies traeting the difference between the and then adding or sub-- detected difference frequency frequency generated by the source 5 so as $0 preduce the resultans frequency which will he the same as that incoming from the circuit L This apparatus coinprises a (lcmmlulator er detector D,., m0 l ulator M amplifiers A and A and filters BR and BF and F The demodulator or 3 well known type anal for purposes if illustrzitien is disclosed as being a vacuum tube detector. The input circuit cal this detector is associated with the incoming circuit L through the amplifier A which sci-wk to amplify the received frevacuum tube amplifier. The frequency generated at the source is also applied in the input circuit If the detector D through a similar amplifier A in a manner more fully hereinafter described.

ln accordance with a well known principle the detector D, will produce in its output circuit frequencies corrcrponding to the sum and the clificrence of the frequencies ap plied to its input circuit, and if the frequency incoming to the circuit L be taken as f and ihe frequency generated by the seurce' S be taken as f the denuidulator D will impress upon iiis uutpufi circuit a lirequency "f -f assuming, of course, that the frequency f is lower ihan the frequency f A. filter BR may be arranged in the output circuit of the demodulator D for selecting this diflcrence frequency from the other frequencies appearing in the output circuit. The filter B1 may be of any Well known type such a hand filter of the general character disclosed in U. patenfs issued re Georg-re A. Campbell Nos. 1,22%",113 and 1,221,11 dated May 22, 1917.

The uuululater M is provied for the purpose (if adding the selected. difi'erence frequency to the S Cc'usequently a, circuit freguenc' may both vary,

10 is provided which leads from the filter L'BF to the input; circuit of the modualiltOl' M The source S is also associated with the input circuit of the modulator M The modulator M will then supply to its outputcircuit a frequency correspoiuling to the frequency 2, e iirequency corresyonding to the sum of the frequency f and the difference frequency trensmitied from the filter BF and :1 frequency corresponding to the difference of these two frequenciesu The frequency corresponding to sunu it will noted Will be icle cicel with the frequency f and this frequency may be selected by means of a sharply tuned circuit, F and in upon. the out rug circuit L in order than the L icncy f appearing" in the output circuit oi the modulator he tranemitted to the detector l e oranclr circuit 1i leads from the output the modulator M and in this branch circuit e filter BF is inserted this filter {Ifran 'ed to select only equencies in the n lilunhccd oi the frequency supplied by" the source S while suppressing the side L"requency resulting from the modulation frequency by the difi'erence frequency- 1 transmitted over circuit 10. i

7 The operation is as :l Hows;

For the best Working of the circuit frequency of the source S should dilier coo siclerarhly from the frequency received the circuit L For mple, assuming that; the" frequency incoming to the circuit L is 10,000 cycles per second, and that the source 8 is set to generate a frequency somewhere in the neighborhood of 9,000 cycles. The fre quency of 0000 cycles from source S will be impressed upon the modulator M and appearing in its output; circuit will he lected by the filter BF and amplified by the mnplificr A. At; the same time the frequency of 10,000 cycles from the circuit, L will be impressed upon tile empiifier A. liese two frequencies upon being". aniplitiedcre impressed upon. the input circuit of the do tector D, in the output of which will emileer frequencies of 10,000 and 9,000 respective at well their sum 10,000 and their [lit-- fer-once 1,000. ,The filter BF wiil he constructed as to transmit only frequencies inthe neighborhood of l,000 20 that the diiici'ence' frequency will be transmitted to the circuit 10 While the other frequencies will be suppressed.

The difference frequency of 1.000 cycles. is now impressed upon the input cir uit of the. modulatoriM simultaneously with the frequency of 9,000-cycles from the source In the output circuit of the modulator, therefore, frequencies oi 1,000 and 0.000 cycles appear, :is well as the diil'erence, H.000 cycles and the sum. 10,000 cycles. fre uency of 10.000 cycles it will he; noted is ii lcntical witlrthe frequency incomingto The sour eoucncies in the ueigli'iworliood oi the ireque cy in which it miq'lithe a bend ulcer uler to the filter B1 The filter Will, of course, so designed as to transmit a band in the neighborhood of the I c ueuoy f thereby accommodating any slight variation. in the frequency of the source 0 Likewise, since the difference frequency detected by the demodulctor D will he in the neighborhood. of 1,000 the F ier BF should be so designed 2;; to trans" 1ft a bend in the neighborhood (rt-1,000 ci-Tlcs- The width of the band tiunsinitte' by fitter BF should be about twice hev '2 of the hands transmitted by the and F since if both frequencies t, and. 1, i very silnuitzmeously in opposite cli' po "lility that; (lii cr 1 quency will iievegtwiceus greet "on as ei't er the frequencies f, or Elly uppe Ill.) mu; s1 fizhe dernoclulutor together with. the TEF determines difierence hetw the fIQQllEILClES f end f e"; unygiven insmnt regardless of how these frequencies may vary, and since the modulator M together with the filter F then adds this difference to the frequency f thc't'reeuency transmitted to the circuit L "will also be identical with incoming totlie circuit L regardless of any small variation from time to time lit the frequencies f and. y

It will lie obvious-that the general principle herein disclosed may be embodied in many other orgzn'iizutions widely diiierent from those illustrated without departing frour spirit of the ii'nentiou defined in the iowing cleir l lhuc is claim source, which co" sisteiu generating energy oi? a frequency us rEeur no practicable to the frequency ti'aum'nittcd from o. distant source, 1)I'()(ll.u1lf e, lrcqucncy equal to the dili'ererue if any, between the generated frequency and the frequency transmitted from the distant source, and combining the gzcncrntwl 't'requency and the (liil'crt-mce frequency to prmluce the desired frequency.

2. The method oi producing from a separate source ot' u t'requeucy correspoz'ulingg to that trimsinitlieal From. a distant 2 so it will transmit, a band of r source, which consists in generating energy of a frequency as near as practicable to the frequency of. the distant source, detecting a frequency equal to the difference, if any, between the generated frequency and the frequency of the distant source, and then modulating the generated frequency in accordance with the difference frequency to produce the desired frequency.

3. The method of producing from one source energy of a frequency corresponding to that of another source, which consists in generating, by said first mentioned source, energy of a frequency approximating that of said second mentioned source, combining the frequencies from the two sources to produce a frequency equal to'the difference, if any, between the frequencies of the two sources, and then combining the difference frequency with the frequency generatet'l by said first source to produce a frequency corresponding to said second mentioned source.

4. A method of producing from one source energy of a frequency corresponding to that of another source, which consists in generating, by said first mentioned source, energy of a frequency approximating that of sald second mentioned source, detecting a frequency equal to the difference, if any, between the frequencies of the two sources, and then modulating the frequency generated by said first mentioned source in accordance with said difference frequency to produce a frequency corresponding to that of said second mentioned source.

5. In a synchronizing system, two independent sources of oscillations generating approximately the same frequency, means to detect the difference, if any, between the fre uencies enerated b the two sources is y 7 and means to modulate the frequency'gem erated by one of said sources in accordance with said difference frequency, thereby producing a frequency corresponding to that of the other source. 7

(3. In assynchronizingsystem, two independent sources generating approximately the same frequency, means to combine the frequencies produced by the two generators so as to produce a frequency corresponding to their difference, if any, and means for combining the difference frequency thus obtained with the frequency generated by one of the sources to produce a frequency corresponding to that of the other source.

7. In a synchronizing system, means at one station for generating oscillations to be transmitted to a .distant station, means at the distant station for generating by a separate source oscillations of a frequency as near as practicable to the frequency transmitted .from the first station, means for detee-ting the difference, if any, between said frequencies, and means for modulating the oscillations generated at the distant station in accordance with said difference frequency the difference frequency thus obtained with the frequency generated at the distant station to produce a frequency to the frequency transmitted mentioned station.

9. In a synchronizing system including two separate sources of oscillations, the method which consists in generating by said sources energies whose frequencies approximate each other as near as practicable, detecting the difference, if any, between said frequencies, and then modulating the frequency of one of said sources in accordance with said difference frequency to produce a frequency corresponding to that of the other source.

10. In a synchronizing system including two separate sources of oscillations, the method which consists in generating by said sources energieswhose frequencies approximate each other as near as practicable, combining the two frequencies so as to produce a. frequency corresponding to their difference, if any, and then combining the difference frequency thus obtained with the frequency generated by one of said sources to produce a frequency corresponding to that of the other source.

In testimony whereof, I have signed my name to this specification this 1st day of June, 1920.

4 KARL S. VAN DYKE.

corresponding from said first