US1563727A - Isochronizing and synchronizing system - Google Patents

Description

Dec. l, 1925- A. M. CURTlS lsOCHRONIZING AND SYNCHRONIZING SYSTEM Filed June '13. 1923 2 Sheets-Sheet 1 Q Rs a, DJHUIIHIIUIIHIIUIIIE l /27 Ven/0f." Ausf/'f7 M. Car/is by Af/y Dec. 1, 1925. 1,563,727

A. M. CURTIS l -ISOCHRONIZING vAND SYNCHRONIZING SYSTEM Filed June 13. 1923 2 sheets-sheet 2 I L/ZO 7# /7 //7 Ven/0r." AUS/fn M Cw//S Patented Dec. 1, 1925.

treo sr'rs AUSTEN 1li. CURTIS, OF EAST ORANGE, NEW JERSEY, ASSIGNOR TG WESTERN ELEC- 'ERIC COMPANY, INCORPORATED, O' NEW YORK, N. Y., (J0RPOPtAONl F NEW YORK.

ISOCBRONIZING AND SYNCHRONIZING SYSTEM.

Application led June 13, 1923. Serial No. ld.

To all whom t may' concern:

Be it known that l, AUSTEN M. CUR'rs, a citizen of the United States, residing at East Orange7 in the county ot Essex., State of New Jersey, have invented certain new vand useful improvements in lsochronizing and Synchronizing Systems, of which the .following is a full, clear, concise, and exact description.y

This invention relates to isochronizing and synchronizing systems and particularly to such. systems for use with high speed multiplex telegraph systems.

ln order to maintain synchronism between the distributors at distant stations of a multiplex telegraph system, it is customary to take advantage ot' the fact that the rate ot vibration ot' an electrically driven tuning' fork which in turn drives the distributors, can be changed slightly by changing its amplitude of vibration. A reduction in the amplitude of vibration of the fork results in an increase in the rate of vibration and conversely an increase in the amplitude of vibration causes a reduction in the rate of vibration. The adjustment of the driving contacts also affects the degree of change in rate ot vibration and it has been found that in some systems the rate of change of frequency is not the same when the fork driving circuit is changed to decrease the frequency as when it is changed to increase the frequency of the tuning fork. Varia tions in frequency are also caused by variations in contact pressure and chatterin of the contacts, each of which changes the riving force. Although this irregularity in the frequency of vibration of the fork and its rate of change of frequency causes a slight variation in phase between the distributors at the distant stations, it is not ot suicient magnitude to prevent satisfactory operation of the ordinary low speed multiplex telegraph system. However, in high speed multiplex systems the distributors must be maintained in more exact syn chronisrn in order to insure satisfactory operation. lThis has been Jfound to be particularly true for systems used with long in ductively loaded submarine cables in which case economical use requires that the speed ot transmission be raised to a value several ,times that of the ordinary multiplex systern. rEhe speed obtainable with a multiplex system over such a cable may depend nearly as much on the exactness of synchronism maintained as it does on the characteristics of the cable.

The object of the present invention is to enable high speed synchronization to be obtained with more exact synchronisrn than has been possible heretofore, and a higher rate of change of frequency than in the systems used at present.

lt is a further object in such systems to substantially reduce anydiliculty due to sparking at the contacts causing Contact trouble and the radiation of high frequency waves and to maintain a constant speed of operation.

To attain the main objects the invention contemplates a synchronizing system in which the tuning forks em yloyed to drive the distributors at the stations are regeneratively driven and by the use ot sharply tuned electric circuits may be maintained at the desired frequency within very close limits. By changing the tuning ot the driv-y ing circuit at the controlled station, the speed ot vibration of the tuning rorlr at that station is corrected when necessary so as to maintain very close synchronisni between the distributors.

The various .tea-tures of the invention may be more clearly understood b reference to the accompanying drawings 1n which Fig. l shows a synchronizing system employing the features of the invention and Figs. 2, 3, 4 and 5 shoviT various modifications of 'the tuning circuit disclosed in Fig. l.

Referring more particularly to Fig. l the synchronizin; equipment at station A which is the controlling station includes a phonic wheel l0, which is driven by electrical impulses from the grounded source ot energy il, alternately connected. by means ot the lower leg of the tuning fork l2 to the elec tromagnets lil-*3 and lll-let. Mounted in close proximity to one leg;n of the tuning fork is a polarized electroinagnet i5 in which an alternating; current is generated by the vibration ot the orlr. This elec de.: is connected the primary medir a n transformer i6, the secondary winding or which is connected to the input side of the amplifier ,Tl/l. The output side oii this amplitier is connected to electromagnet l?, which is the driving magnet that keeps the fork in vibration, the current through electroinagnet i9 heiniT in proper phase re lult;

liti:

lation, with respect to the movement of the fork. By means of the variable capacity 20, the variable inductance 21 and the vari- -able resistance 22, the circuit including these elements and electromagnet 15 is tuned to a frequency within the range of possible operation ofthe fork 12.

The phonic wheel 10 is employed to positively drive a rotatable brush arm 23 carrying a plurality of insulated brushes 24, 25 and 26 which upon rotation of the switch arm are adapted to sweep over the distributor segments. The distributor, a portion of which is shown developed, consists of a set of receiving segments 27 which are successively connected to a receiving ring 28 by means of the brush 24, a set of Acorrecting segments 29 which are successively connected to the correcting ring 30 by means of brush 25; and a set of transmitting segments 31 which are successively connected to the transmitting ring 32 by means of the brush 26. The receiving segments are connected directly to the magnets 33-33 of the printing mechanism and thc transmitting segments are connected to the contacts of the printing transmitter 34. The correcting segments, of which there are twice as many as of the transmitting or receixf'ing segments, are used only at the controlled station but are preferably included in the apparatus at each station so that, when desired, either station may be operated as the controlled station. The transmitting ring 32 is connected dif'- ferentially to the line relay 35 andan artificial line is preferably provided, as shown, to permit duplex working over the system.

At station B which is the controlled station, the equipment is similar to that of station A, except that additional means is rovided for automatically varying the tunlng of the oscillating circuit. The phonic wheel 10 is driven by the tuning fork 12' and the vibrations of the latter cause the generation of an electromotive force in magnet 15 resulting in the flow of an electrical current in the tuned circuit 15', 21', 22', 16', 20 which is amplified and. passed through magnet 19', thus maintaining the tuning fork in vibration. "lhe phonic wheel 10' is directly connected to the brush arm 23' which in its rotation causes brushes to sweep over a distributor consistin of receivingtcorrecting, and transmitting seglments, similar to `those of the distributor at station A. The transmitting ring 32' is connected differentially to the winding'of line relay 35' and the receiving ring 28' is connected to the upper contact of the line relay. The correcting segments are divided into two sets of alternate segments which are connected respectively to the outer terlninals of correcting relay 36. Assuming the direction of rotation of brush arm 2.- to be from right to left, the correctingr Segture of line relay 35' is connected to a grounded source of energy 41 and the midoint of the winding of correcting relay 36 1s grounded. The operation of relay 36 serves to connect or disconnect the con denser 42 in parallel with condenser 20 in the driving circuit of the tuning fork and thus change the tuning of the circuit.

In the operation of the system the tuning forks at the respective-stations are first set in vibration by hand. Since lthe operation of these forks is similar, only that at station A will bc considered. The vibration of the fork 12 generates an electromotive force in the magnetized electromagnet 15 which produces an alternating current in the tuned circuit composed of the transformer 16, inductance 21, and condenser 20. By means of the transformer the'voltage of this current is increased at the input terminals of the amplifier 17 which in turn produces a large lincrease in the current flowing throughthe electromagnet 19. The phase` relations between the current inthe generating magnet 15 and the drivingmagnet 19 are such that the current generated tends to maintain the vibration of the fork, Awhich increases its amplitude of vibration to a point where the energy dissipatedbecomes equal to the energizing force supplied, thus causing the fork to vibrate steadily at a given amplitude. The fork has a natural frequency of vibration which changes slightly with amplitude, being slower for larger amplitudes and vice versa. If the circuit 15, 16, 20, 21, 22 is tuned by meansof the inductance 21, resistance 22 and capacity 20 to a frequency within a certain frequency range which corresonds to a certain portion of the amplitu e range of -the fork and the suitable degree of amplification provided, the fork will be maintained in vibration at -a constant frequency and amplitude. The (method of maintaining the correct tuning-fof the circuit isf. as follows: Variable capacity 20 is disconnected and variable inducta-nce 21 and variable resistance 22 are short. circuited. The amplification is then increased until the fork vibrates freely. The inductance and resistance elements 21 and 22, respectively. are then increased in value until the amplitude of vibration of the fork is lllaterially reduced. The variable capacity 'any circuit w ich is sharply tuned.

denser 42 in parallel with condenser 20 of4 the tuning circuit.

In practice the operations occur in rapid succession and the receiving fork vibrates at a frequency intermediate the maximum and minlmum values coresponding to the change in the tuning circuit which is not often allouged to remain fixed for a time sufficient to stabilize the rate of vibration of the fork at either extreme.

In the method describedabove the change of frequencyof the fork is produced by detuning the tuned circuit by the addition of capaclty but it is of course obvious that the same result could also be obtained by changingthe other constants of the circuit. i A igs. 2 to 5 show various forms of tuned circuits which might be employed and which provide sharp tuning. In Fig. 2 the circuit shown is the same as the system shown in Fig. 1 consisting of the transformer 16 having a variable inductance 21 and variableresistance 22 in the limary circuit-and a condenser in para] el with the secondary circuit andthe input terminals of the amplier 17. In Fig. 3 the fixed inductance 50 is connected in series with the secondary Winding of 'transformer 16 and the variable condenser 20 is connected across the input terminals of the amplifier. In Fig. 4 an autotransformer 51 is `employed with a fixed inductance in series with the secondary windin and a condenser 20 'across the input teminas of, the-amplifier 17. In Fig. 5 an auto-transformer 51 is employed and a resistance 52 and finductance 53 connected in series with the primary portion of the winding, while a variable condenser 20 is connected in parallel with the secondary' sortion of the winding`which is connected irectly across the input terminals of the amplifier 17. These modifications are shown to exemplify suitable circuits Which-may vbe sharply tuned but; the invention is not limited to any particular tuning circuit since satisfactory o eration may be obtained with What is claimed is: 1. An isochronizing system comprising a distributor for impartin impulses to a line, a vibrating mechanism or driving said distributor, a receiving distributor, a variable the transmitting distributor to vary the tuning of said operating circuit whereby the distributors are maintained in isochronism.

2. A synchronizing system comprising a distributor for impartin impulses to a lme, a vibrating mechanism or driving said distributor, a receiving distributor, a variable vibrating mechanism therefor having a sharply tuned operating circuit, and means cont-rolled by the line current reversals and cooperating with the receiving distributor to automatically alterI the tuning operating circuit whereby the distributors are maintained in synchronism.

3. In a synchronizing system, a distributor for imparting electrical impulses to a line, a second distributor for receiving said impulses, a vibrating mechanism havin a sharply tuned operating circuit for driving said receiving distributor, and means for altering the tuning of said operating circuit to -vary the frequency of vibration of the vibrating mechanism.

4. In a synchronizing system. means for controlling the transmission of electrical imulses to a line, means for receiving said lmpulses, a vibrating mechanism havin a sharply tuned operating circuit for driving said receiving means, and means for altering the tuning of the operating circuit to vary the frequency of vibration of the vibrating mechanism.

5. In a synchronizing system, a distributor for imparting electrical impulses to a line, a vibrating ldevice for driving the distributor, a sharply tuned operating circuit for operatin the vibrating device at a predetermined requency, a line relay operable by current impulses received. over the line, a correcting relay, means dependent upon the operation of the line relay fork imparting a 'current impulse to cause the operation of the correctin relay, a second distributor for vcontrolling te direction of o ration of the correcting relay, a' vibrating evice for driving said second distributor, a sharply tuned t e control of the correcting relay for detuning said circuit.

In witness whereofyI hereunto subscribe my name this 7th day`of June A.. D., 1923.

AUSTEN M. CURTIS.

of said Y `o erating lcircuit therefor, and means under r

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