US2373569A

US2373569A - Wave translating system

Info

Publication number: US2373569A
Application number: US473339A
Authority: US
Inventors: Walter F Kannenberg
Original assignee: Bell Telephone Laboratories Inc
Current assignee: AT&T Corp
Priority date: 1943-01-23
Filing date: 1943-01-23
Publication date: 1945-04-10
Anticipated expiration: 1962-04-10
Also published as: GB625532A; FR947860A

Description

w. F. KANNENBERG WAVE TRANSLATING SYSTEM April 10, 1945.

Filed Jan. 23, 1943 5 Sheets-Sheet 2 FIG. 35.

QL I

ash

FIG. 36.

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mvaw TOR WE KANNENBERG BK- J A TTORMEV April 1945- WI F. KANNENBERG 1 WAVE TRANSLATING SYSTEM Filed Jan. 23, 1:943 3 Sheets-Sheet 3 FIG. 3.1 FIG. a/r.

Patented Apr. 10, 1945 UNITED STATE 4 v Walter F. Kannenberg, Lyndh urst; N. 1., assignor to Bell Telephone Laboratories, Incorporated,

New .Yorlr, N. Y., a corporation of New York Application January 23, 1943, SeriaiNo. 473,339 13 Claims (cl. 118- 44) This invention relates to frequency changers which may be either modulators, demodulators, or detectors used in intelligence transmission systems of the carrier current type, and more particularly to such'irequency-changers embodying non-linear resistance elements.

Non-linear resistance elements employed in bridge form in modulators, demodulators, and

detectors offer the advantage that unmodulated carrier current can be suppressed in the output circuit without ancillaryapparatus. Such carrier current suppression can be accomplished when the bridge is balanced. This means that the individual non-linear resistance elements should possess substantially identical characteristics. This is a difllcult undertaking from a manufacturing standpoint, and ordinarily is incapable of achievement. Also, carrier suppression can be accomplished when one pair of bridge arms has a, given characteristic while the other pair of bridge arms has a different characteristic, provided the placement of the bridge arms is such that the ratios of the bridge arms are substantially equal. This is usually diflicult oi attainmentwithout considerable experimentation. In addition, carrier current suppression can be achieved with tour bridge'arms embodying dissimilar characterlsticsprovided the eflect of one type'ot dissimilarity. counterbalances the eflect of a different type of dissimilarity. This is only at-- tainableby sheer accident. l

In the absence of non-linear resistance elements possessing identical characteristics, carrier current suppression can be attained by controlling the ratiosoi the bridge arms such that the ratios are rendered substantially equal. This involves controlling the following three independent characteristics of the individual non-linear resistance element; namely. (1) resistivity during the forwardcurrent flow; (2) resistivity during the reverse current ilow; and (3) capacity during the reverse current now. In my Patent No. 2,271,078 granted January 27.1942, one arrangement is disclosed for controlling the resistivity character- The present invention 'is concerned with fre-.

quency changers embodying arrangements ior equalizing both theresistivity and capacity ratios non-linear bridge arm during the reverse current flow.

oithe arms of a non-linear bridge during the reverse current flow.

A further object is to control the capacity ratio of the arms of a non-linear bridge during the reverse current'flow.

I In one type of familiar modulator and demodulator embodied in a carriercurrent intelligence transmission system, a plurality of non-linear resistance elements are arranged in the bridge form such that one diagonal is applied to both a source of modulatingaltemating current and transmission system;

a load circuit, and the opposite diagonal is connected to a source of carrier current. The bridge erves to translate the modulating and carrier currents .into certain modulation components which are selected by the load circuit.

According to a specific embodiment of the present invention included in the above carrier current system, a resistor applied across one bridge diagonal has an adjustable contact extended to one terminal of the other bridge diagonal; and a double capacitor comprising a pair 0! stators and a rotor has both stators connected across a certain bridge diagonal and the rotor applied to on terminal of a difierent bridge diagonal. The resistor and lead associated therewith provide shunt paths around the non-linear elements of two adjacent arms whereby the resistivities of the elements in both latter arms are adjusted during the reverse current flow until the resistivity ratios of the bridge arms are substantially equal. The double capacitor also provides shunt paths around the non-linear elements of two further adjacent arms so that the capacities of the elements in both latter arms are adjusted during the reverse current flow until the capacity ratios of the bridge arms are substantially equal.

The invention will be readily understood from the following description when taken together with the accompanying drawings in which:

Fig.. 1 is a schematic circuit diagram showing a specific embodiment of the invention used in the modulator of a carrier current intelligence Fig. 2 is a schematic circuit diagram showing the specific embodimentci. the invention used in The mainobiect oi the invention is tosuppress unmodulated carrier currentin the output circuit of ac'arrier current iiitelli'genc'e transmission system. 2

another object is to equalizethfr'esistivity ratio the invention in Eigs. 1 and 2.

a simplified form of the specific embodiment of The same reference numerals are employed to designate identical elements appearing in the several figures of the drawings.

Fig. 1 represents a modulating carrier current intelligence transmission system comprising a plurality of non-linear resistance elements II, I I,

l2 and I3 arranged in the form of a bridge 9 whose vertical diagonal ll, 15 and 15 are connected in shunt relation to an input circuit l1 and an output circuit It. The input circuit Il includes in sequence a source. l9 of modulating alternating current waves, an input transformer \20, a low pass filter 2|, and a tuned circuit 22 '--which is interposed in one side of this input circuit. The output circuit l3 embodies in sequence a tuned circuit 25 in one side thereof. aband pass filter 25, an output transformer and a 'load circuit 28. A capacitor 29. is interposed in the vertical bridge diagonal intermediate the ter- 1 minals l3 and i5. Across the

horizontal bridge diagonal

23 and 24 is applied the seconda'rywinding of a carrier input transformer whose primary winding is connected to .a source 3| of alternating current carrier waves. Disposed in shunt of the secondary winding of the carrier input transformer is a serially connected inductance winding 32 and a variable resistor 33;

v The operation ofthe modulating system of 1 is briefly that modulating waves from the source i9, carrier waves from the source 3| and bridge 9 serve to produce rectified current together withother modulation components which include waves whose frequencies extend over a certain range, and which areapplied through the tuned circuit 25, band-pass filter 25, and output transformer 21 to the load 23. The tuned

networks

22 and 25 and the serially connected inductance 32 and variable resistor 33 provide the bridge 9 with optimum terminating impedances which have substantially the most favorable magnitudes and frequency characteristics for I I transmitting the modulation components of all frequencies in the certain range with substantially maximum amplitudes.

The capacitor 29 interrupts the flow of rectified current from the bridge 9 to the input and output circuits l1 and I9, respectively. In addition, the polarity of the charge on the capacitor 29 tends to control the resistivities of the individual elements in, II, l2 and I3 during the forward current flow and thereby to equalize the flow of rectified current in the parallel bridge paths 23, I and 24 and 23, I6 and 24. This tends to bring the bridge 9 more nearly into balance for rectified current. As the alternating current resistivity characteristics of the individual nonlinear elements tend to follow the rectified current resistivity characteristics during the forward current flow or conducting cycle, it is apparent that a corresponding improvement in the alterhating current resistance balance of the bridge 9 is likewise accomplished. As the alternating current voltage is proportional to the effective resistance of the non-linear elements, it is evident that the alternating current difference of potential across the bridge diagonal l4, I5 and IBsubstantiaily approaches zero. This tends to preclude a leak of the unmodulated waves from the carriersource 3| into the input and output circuits I1 and I8, respectively, during the forward current flow. A more complete description of the foregoing modulating system of Fig. 1 together with the operation thereof is contained in my patent, supra.

Fig. 2 represents-a demodulating carrier current intelligence transmission system comprising the bridge 9 whose vertical diagonal I 4, l5 and I5 is connected in shunt of input circuit 35 and output circuit 38. The input circuit 35 includes 5 in sequence a source 31 of incomingmodulated carrier waves, a band-pass filter 38, a resistance pad 39, and .a capacitor 40 in one side; while the output circuit 35 embodies in sequence a capacitor H in one side, a low pass filter 42, an output transformer 43, and a wave translating apparatus. Across the horizontal diagonal of the bridge 9 are disposed in sequence the serially connected inductance 32 and variable resistance 33, carrier input transformer 39, and carrier sourcez3l. Capacitor 29 is'also'connected in the vertical bridge diagonal.

The operation of the demodulating system of Fig. 2 is briefly that modulated carrier waves incoming from the source 31, carrier waves from thesource and the bridge 9 serve to produce rectified current and other modulation components which includes waves whose frequencies extend over a desired range which is equivalent substantially to that of the modulating waves supplied by the source l9,-Fig 1. Such modulation components are applied through the capacitor 4|,

low filter 42 and output transformer 43, to

the'tr'anslating apparatus. The serially connected inductance 32 and

variable resistor

33, 30 Fig. 2, pad 39, and capacitors l0 and 4| provide the bridge 9 with optimum terminating impedances which have substantially the most favorable magnitudes and frequency characteristics for transmittingito the translating apparatus 44 5 the modulation components of all frequencies in the desired range with substantially maximum amplitudes. In Fig. 2, the capacitor 29 serves to control the flow of rectified current in the bridge 9 so as to prevent a leak of unmodulated carrier from the source 3| into the input and output circuits 35 and 39, respectively, as previously-explained with reference to Fig. 1. A more complete description of the demodulating system of Fig. 2 together with the operation thereof is contained in my patent,- supra. r

In accordance with the present invention as illustrated in Fig. 1,,a resistor disposed across the horizontal bridge diagonal 23, 24 embodies an adjustable tap 5| which is connected over lead 52 to bridge terminal It. A double capacitor 53 is arranged such that stator 54 is applied over lead 55 to bridge terminal l5; stator 56 is connected over lead 51 to bridge terminal I6; and rotor 59 is connected over lead 59 to bridge terminal 24. This arrangement serves to balance the bridge 9 with reference to the resistlvities and capacities of the individual unidirectional elements during the reverse current flow in a manner that will now be explained.

The individual non-linear elements during the R-C networks as illustrated in Fig. 4 which is essentially the system of Fig. 1 in simplified form. In order toobtain bridge balance in Figs. 1 and 4, it is necessary that the following ratios should obtain:

reverse current flow are effectively individual 1 tion with Fig. 1.

in Equation 1, and as a consequence the'bridze, Fig. 4, is rendered unbalanced. The balanced condition can be restored to the bridge by arranging resistor 50, variable tap BI and lead 52 in the manner hereinbefore explained in connec- The tap ii is actuated in the value of rd is higher time that required to hold s the ratio in Equation 1, the latter may be releft-hand direction to decrease the magnitude oi the resistance inshunt or the bridge arm it,

23 in a path comprising bridge terminal 28, left; hand portion of resistor 50, tap lil, lead 52 and bridge terminal I8; and atthe same time tomdition can. e r store by'arrang'ing the double crease the magnitudeo'rthe resistance .in shunt of the bridge arm It, 24 in a ,pathcomprising T bridge terminal 24, right-hand portion ot ;.re--, sistor BIL tap ll, lead 52' and bridge terminal ll. This means that the amounts of rectifiedicurrent;

' that would normally" flow in the individualbridge arms I8, 23 and I6, 24 alone are now divided between the latter and the shunt pathg'associated therewith as previouslytraced.

\ As in the case of forward current flow in the nating and rectified current resistancecharacteristics of these elements tend to manifest similar trends. Hence it has been vfound that changes of the rectified current characteristics v y p in the direction of the. reverse current flow due to a control of 'the ;magnitude .oithe rectified current tending to now in the individual nonlinear elements will cause corresponding changes in the. alternating, current resistance character-- istics thereof. As mentioned in my patent, supra,

substantially no rectified current diflerence oi? potential tends to exist acros the bridge-vertical diagonal ll, ii and it when the individual non; linear elements possess substantially. identical rectified current and. voltage characteristics; .and a rectified current difference of potential tends to exist across the bridge vertical diagonalwhen suchcharacteristics are dissimilar.

Since the resistance or the shunt path associated with the bridge arm I6, 23 is decreased; then a decreased magnitude of rectified current is caused to flow in the latter arm; and since the resistance of the'shunt path associated with the bridge arm I6, 26 is increased, then an increased amount of rectified current is caused'to flow in y the latter arm. Thus, the rectified cur'r'entfltends. to decrease the magnitude of the effective value of. the resistivity of bridge arm I6, 23 and to increase the magnitude of the effective value of the resistivity of'bridge arm I8, 2|. This causes the bridge balance of Equation 1 to berestored whereby a condition of no rectified current difference of potential is caused to be established across the bridge vertical diagonal I4, I! and l6.

From the foregoing it is evident that as the alternating current resistance characteristics tend to follow closely the rectified current resistance characteristics of the non-linear elements in the reverse current flow, a corresponding 'improv'ement is effected in the alternating current ,re-

sistance'balance of the bridge. vSince the alter-- nating current voltage resistance oi the non-v, linear elements is proportional to the resistivities' thereof, as mentioned in mypatent, supra, it is apparent that the alternatin current diflerence of potential across the bridg diagonal, l5 and l8 approaches zero. 1 This tends to diminish substantially, or to preclude entirely, any leak or unfmodulated carrier wave from the source 3| to the circuits connected to the bridge terminals l4 and II in so far as the relativeresistiviti'es of'the non-linear'elements'during the reverse 3 current how is concerned. whentheieflective capacitor Jilin thefi'mann'er described previously concerning Fig. "The rotor ll; Fig. 4, is ac 'ated such;pthat itseflective capacity with EL -.-statorqfl while at the same time its eilective capacity with the stator II is increased This meansthat the efle'ctive capacity of bridge Farm-1L is decreased and thatlof bridge" arm Y non-linear elements pointed out above,the alterwaves from the source 3| tothe circuits connected 1.1 I 24 is increased. current potential characteristics or the individual l 80 long as the alternating non-linear elements are suchthat the ratio in Equation 2 obtains' then the alternating current diil'erence of potential across the vertical bridge diagonal I4, II and it substantially approaches zero; This tends to diminish substantially, or to preclude e tirely any leak of unmodulated carrier to the bridge terminals [4 and it, inso far as the relative capacities of the non-linear elements during the reverse current flow is concerned. When the efl'ective value of ca is higher than that required to hold the ratio in Equation 2, the lat- Wm 9 the e-. 1.: g. 4 applies in a similar manner tothe operationor bridge 9 in both Figs.

ter may be restored by actuating the rotor 58 in such direction as to decrease'the eifective capacity of the bridge arm It, 24, and at the same time to increase "the eil'ective capacity of tl'z'ebridge arm l5, 24. 'Ifhis likewise serves to est blisha condition of balance in the bridge, ig. 4, ior the purpose just :-explained, Although Fig. 4 is mentioned as a simplifledshowing of the modulatingsystem ofFl gr 1, the former is also a similar showing or the, bridge 9 of the demodulating v system of Fig.2; g

vfIha action de cribed-above regarding the oper- 1 and 2 during the reverse current flow, with ref-- erence to both theresistivity and capacitive characteristics of the individual non-linear elements.

Hence, substantially no leak of unmodulated ca'rner waves occurs from the carrier source 3| to the circuits connected tothe .vertical diagonal terminals H and It in Figs. fl and 2. The foregoing action also pertains to Figs. 1 and 2 when the bridges r Figs. 3A, 313, 3c, 3D, 3E, 3F, 3e 2.1, 3K, an 3M, n, s and 3B are suhstituted r m, excel) in t e res ect ently'pcinte'd out. p 'm will be pres Fig. 3A shows a bridge'which is similar to t of Figs. 1, 2 and 4 except the double Cassa t: 53 has its rotor 58 applied to the horizontal bridge terminal 23. Capacity adjustments are eifected with reference to the non-linear elements in the bridge arms I5, 23 and 18, 23'. Fig. 3B shows a bridge which issimllar to-those of Figs. 1, 2 and connected to'the vertical bridge terminal I I and 1ts stators SI and it applied across the horizontal bridge diagonal. Capacity adjustments are accomplished with respect to non-linear elements in the bridge arms s, 23 and Ian. Fig. sols similar to Fig. 33 except the rotor 58 is applied to the vertical bridge terminal I 6 so that capacity adJustments are made concerning the non-linear elements in the bridge arms It, 23 and I8, 24.

4. The wave translating system according to claim 2 in which said resistor is applied across terminals lying in the horizontal bridge diagonal and said connection has said one end attached bridge terminal i5. Resistivity adjustments are effected in each oi Figs.'3D, 3E, 3F and 3G with reference to the non-linear elements It and I I.

Figs. 3H, 3J, 3K and 3L show bridges which are similar to those in Figs. 1, 2 and 4, and Figs. 3A, 3B and 30, respectively, except the resistor 50 is disposed across the vertical diagonal of the bridge in each of the former figures and the lead 52 is extended to the horizontal bridge terminal 24. In Figs. 3H, 3J, 3K and 3L; resistivity adiustments are accomplished with reference to the non-linear elements II and I2. Figs. 3M, 3N, SP and 3R illustrate bridges which are similar to those in Figs. 3H, 3J, 3K and 3L, respectively,

except the lead 52 is extended to the horizontal to-non-linear elements Ill and I3.

What is claimed is:

1. A wave translating system comprising a plurality of non-linear rectifier elements arranged in the form of a bridge, a plurality of circuits to supply alternating current wavesto the diagonals of said bridge for translation into alternating current waves of certain frequency and rectified current, a load circuit to utilize said certain waves, means comprising a capacitor connected in series withonebridge diagonal to prevent a flow of said rectified current in circuits connected to said one bridge diagonal, means to establish shunt paths across each-'0! two certain bridge arms for said rectified current comprising a resistor applied across a certain bridge diagonal and a lead extending from a preselected'point on.

a double capacitor comprising a pair of stators and a rotor disposed across certain bridge termirials such that said stators are connected to terminals lying in a preselected bridge diagonal and said rotor is connected to a further terminal lying in a diflerent bridge diagonal.

2. A wave translating system comprising a plurality of non-linear. rectifier elements arranged in the form of a bridge, a plurality of circuits to supply alternating current waves to the diagonals of said bridge for translation into alternating current waves of certain frequency and rectified current, a load circuit to utilize said certain waves, and means to establish shunt paths for said rectified current across each of two certain bridge arms for balancing the resistivities of said elements during reverse current flow and thereby precluding a leak of waves from one circuit connected to one bridge diagonal into circuits connected to the other bridge diagonal, comprising a resistor applied across terminals lying in a certain bridge diagonal, and an electrical connection having one end attached to a further terminal lying in the opposite bridge diagonal and its other end adjustably attached to said resistor.

3. The wave translating system according to claim 2 in which said resistor is applied across terminals lying inthe horizontal bridge diagonal, and said connection has said one end attached to said further terminal which lies in the vertical bridgediagonal.

to said further terminal which constitutes the lower terminal or the vertical bridge diagonal.

5. The wave translating system according to claim 2 in which said resistor is applied across terminals lying in the vertical bridge diagonal, and said connection has said one end attached to said further terminal which lies in the horizontal bridge diagonal.

6. The wave translating system according to claim 2 in which said resistor is applied across terminals lying in the vertical bridge diagonal, and said connection has said one end attached to said further terminal which constitutes the left-hand terminal of the horizontal bridge diagonal.

7, A wave translating system comprising a plurality of non-linear rectifier elements arranged in the form or a bridge, a plurality of circuits to supply alternating current waves to the diagonals of said bridge for translation into alternating current waves of certain frequency, a load circuit to utilize said certain waves, and means'to balance the capacities of said elements during reverse current flow thereby controlling the leak 01 waves from one circuit connected to one diagonal into circuits connected to the other bridge diagonal, comprising a double capacitor comprising a pair of stators and a rotor connected to certain bridge terminals such that said stators are connected to terminals lying in the same bridge diagonal and said rotor is applied to a further terminal lying in the opposite bridge diagonal. v

8. The wave translating system according to claim 7 in which said stators are extended to terminals lying in the vertical bridge diagonal, and said rotor is applied to said further terminal which lies in the horizontal bridge diagonal.

9. The wave translating system according to claim 7 in which said stators are extended to terminals lying in the vertical bridge diagonal, and said rotor is applied to said further terminal which constitutes the right-hand terminal of the horizontal bridge diagonal. r

10. The wave translating system according to claim 7 in which said stators are extended to terminals lying in the horizontal bridge diagonal, and said rotor is applied to a further terminal lying in the vertical bridge diagonal.

11. The wave translating system according to claim 7 in which said stators are extended to terminals lying in the horizontal bridge diagonal, and said rotor is applied to said further terminal which constitutes the lower terminal of the vertical bridge diagonal.

12. A wave translating system comprising a plurality of non-linear rectifier elements arranged in bridge form, a plurality of circuits to supply alternating current waves to the diagonals of said bridge for translation into alternating current waves and rectified current, a load circuit to utilize said certain waves, means to balance the resistivities of said elements during the reverse current flow thereby precluding a leak of waves from a circuit connected to one bridge diagonal to circuits connected to the other bridge diagonal, comprising a resistor applied across a certain bridge diagonal, and an adjustable connection extending from a preselected point on said resistor to one bridge terminal lying in a diilerent bridge diagonal, and means to balance the eflective capacities of said elements during one bridge diagonal into said circuits connected to said other bridge diagonal, comprising a double capacitor comprising a pair of stators and a rotor connected across certain bridge terminals such that said stators are connected to terminals lying in the same bridge diagonal and said rotor is applied to a terminal lying in the opposite bridge diagonal.

13. A wave translating system comprising a plurality of non-linear rectifier elements arranged in the form of a bridge, a plurality of circuits to supply alternating current waves to the diagonals or said bridge for translation into alternating current waves of certain frequency and rectified current, a load circuit to utilize said waves 01' the certain frequency, means to balance the resistivities of said elements during the forward current flow to preclude a leak of waves from a circuit connected to one bridge diagonal into circuits.

connected to the other bridge diagonal, comprising a reactive element connected in series with said one bridge diagonal to prevent a flower said a the reverse current flow for preventing a further leak of waves from said circuit connected to said comprising a'resistor disposed across a certain bridge diagonal, and an adjustable connection extending from said resistor to a bridge terminal lying in a different bridge diagonal, and meansto balance the capacities of said elements during the reversecurrentflow to preclude an additional leak of waves from said circuit connected to said one bridge diagonal into said circuits connected to said other bridge diagonal, comprising a double capacitor comprising a pair of stators and a rotor connected across certain bridge terminals such that said stators are applied to terminals lying in the same bridge diagonal and said rotor is connected to a terminal lying in the opposite bridge diagonal.

WALTER F. KANNENBERG.-