US2153202A - Electrical filter - Google Patents

Electrical filter Download PDF

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US2153202A
US2153202A US740285A US74028534A US2153202A US 2153202 A US2153202 A US 2153202A US 740285 A US740285 A US 740285A US 74028534 A US74028534 A US 74028534A US 2153202 A US2153202 A US 2153202A
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circuit
ti
grid
t2
impulses
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US740285A
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Harry J Nichols
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International Business Machines Corp
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    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04BTRANSMISSION
    • H04B1/00Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/06Receivers
    • H04B1/16Circuits
    • H04B1/1638Special circuits to enhance selectivity of receivers not otherwise provided for

Description

April 4, 1939. H. J. NICHOLS ELECTRICAL FILTER Filed Aug. 17,

2 Sheets-Sheet 1 [N VENTOR 9 76 4f, A TTOR/VEYS April 1939- H. J. NICHOLS 2,153,202

ELECTRICAL FILTER Filed Aug. 1'7, 1954 2 Sheets-Sheet 2 INVENTOR A TTORNEYS Patented Apr. 4, 1939 UNITED STATES smc'rmcar. mama Harry J. Nichols, Dayton, Ohio, assignor to International Business Machines Corporation, New York. N. Y a co poration of New York Application August 17, 1934, Serial No. 140,285

4 Claims.

This invention relates to electrical filters and particularly to anti-interference filters for telegraph apparatus. p

The invention is described mainly with reference to printing telegraph signal impulses, but it is generally applicable to the elimination of interference in impulse circuits, and in reshaping, and counting impulses.

In the operation of printing telegraph apparatus over radio systems, it is particularly desirable to eliminate the effects of static and other forms of interference before they reach the printing telegraph apparatus since not only are erroneous characters printed, but faulty operation of the printing apparatus as to shifting, carriage return, piling up of typebars, etc. is also liable to occur.

It is therefore a general object of the invention to eliminate the undesired effects above mentioned, and thus to minimize the chance of improper operation.

A further object is to provide a filter effective to eliminate unwanted interference and which will at the same time amplify the desired signals.

A further object is to provide means for reshaping and grouping impulses.

Other objects and features will be in part obvious and in part hereinafter pointed out in connection with the following description, the accompanying drawings, and the appended claims.

In the drawings,

Fig. 1 shows in graphic formthe general character of interference signals, the signal impulses, and the shaped output impulses respectively.

Fig. 2 shows in diagrammatic form one embodiment of the invention illustrating the basic elements and the principle of the filtering action.

Fig. 3 shows in diagrammatic form another embodiment of the invention employing the electronic filter arrangement of Fig. 2 applied to the grid circuit of a three element amplifying tube.

Fig. 4 shows a dual arrangement of the circuit shown in Fig. 3 adapted to transmit bi-directional impulses.

Fig. 5 shows an embodiment of the invention employing a gaseous-discharge triode applied to the grid circuit of a three element amplifying tube.

Fig. 6 shows another embodiment of the invention utilizing a grid-controlled, gaseous-discharge tube of the triode type.

Fig. 7 shows another embodiment of the invention which may be used as a timed signal excluding device to group or count periodic signal impulses.

Fig. 8 shows a filter arrangement in accordance with the invention, adapted to group or count periodic signal impulses.

Fig. 9 shows a circuit arrangement according to the invention particularly adapted to eliminate interference signals and to amplify wanted signal impulses in a printing telegraph transmission system.

Fig. 10 illustrates graphically the currents and voltages in certain branches of the circuit arrangement shown in Fig. 9.

In the several figures, like characters represent like parts.

Referring now to Fig. 1, line A indicates graphically the general character of static or other forms of interference signals which are to be eliminated, and will be referred to as the unwanted or interference signals. Such signals are characteristically of varying frequency and amplitude, but their frequency is ordinarily of a higher order than the equivalent frequency of printing telegraph signals. Line B indicates generally the incomingsignal impulses, referred to as the wanted signals, which are to be passed on in amplified form. Line C indicates an amplified, regenerated pr squared" impulse as passed on by the filter-amplifier to the output circuit and will be referred to as the outgoing impulse.

Referring now to Fig. 2 in detail, the basic arrangement of the invention comprises a signal receiving input circuit designated by numeral it, an integrating or filtering capacitor C! across the terminals of which are applied electrical variations representing the received signals, impedance Zl representing the equivalent series impedance of the input circuit to Cl, impedance Z2 representing the parallel impedance across 05, a relay device Tl, current limiting means Z3 controlling the discharge of current through Tl, a steady potential source of electrical energy represented by BI, and an output circuit 20.

TI is preferably an electronic relay device such as a gaseous discharge tube or a vacuum tube biased to or below cut-01f, but may be any relay device which operates to energize an output circuit upon the application of a predetermined threshold potential to its input circuit. Because of the low energy requirement for actuation, its quick response, and possible high amplification factor, a gaseous discharge tube is the preferred relay device.

The voltage of BI is preferably less than the operating or break-down voltage of Ti, this voltage difference being referred to for convenience as the voltage margin.

As previously stated, Zl represents the equivalent series impedance of the input circuit to Cl including the fixed impedance of associated circuits and apparatus and any variable impedance added for corrective or control purposes. Likewise, Z2 represents the parallel impedance across Cl including any variable additions for control purposes. Zl is always a material factor in the filtering action, while Z2 may in some cases be a negligible factor. The variable impedance additions may be omitted, especially in established applications, but it is usually found preferable to have a variable component of either Zl or Z2, or both, to facilitate precise adjustment of the filtering action.

The values of Cl and Zl, and Z2 if present, should be suitable to the duration of the wanted signal impulses, since the filtering action is mainly dependent upon the, time constant of the input circuit including Cl. It is to be observed that increasing Zl increases the time of charging Cl, while increasing Z2 has the opposite effect, hence Zl and Z2 are complementary in action. Until TI is energized, the output circuit is virtually isolated from the input circuit, hence the effect of the output circuit on the filtering action is usually negligible.

Z3 represents in general the means used to limit the duration and/or amplitude of the outgoing impulses, and may comprise a limiting impedance, or may include a relay or other cut-off to the input circuit. Their effect is to charge Cl in varying degree depending mainly upon' the capacitance of Cl, the impedances Zl, Z2, and the amplitude and duration of the signal waves composing the train. Only the positive portions of the waves tend to charge CI in a direction to aid Bl and during intervening negative portions of the waves, Cl is charged in opposition to Bl. Furthermore, the effect of"Cl, Zl and Z2 is to smooth out potential variations in the input circuit, and such smoothing effect is more pronounced in respect to waves of high frequency. Hence so long as a single positive wave does not charge Cl above the voltage margin, Tl remains un-ionized and no signals appear in the output circuit. Signals of brief duration, even though of high amplitude, may be effectively filtered out by the arrangement shown.

Assume next that a signal impulse as illustrated by line Bl of Fig. 1, either alone or as a mixed signal containing interference signals, is applied to input circuit I0. In this case Cl is charged mainly in a positive direction, and after an interval its potential is raised above the voltage margin and TI is tripped or ionized. It is a characteristic of gaseous-discharge tubes that when ionized the cathode-anode impedance is greatly lowered, and a comparatively large current may be caused to fiow in the cathode-anode circuit. Such flow of current may be effectively regulated by the discharge limiting impedance Z3 (assuming that the output circuit is of comparatively high impedance), and under suitable conditions Z3 will also cause TI to de-ionize or cut-off after an interval. By proper selection of circuit constants, the outgoing impulse may be caused to have a square top, as indicated by line C of Fig. 1. and the outgoing impulse may be of greater amplitude and duration than the incoming signal. Such amplified, squared" impulses are particularly desirable in the operation of various types of telegraphic instruments.

Various characteristics and adjustments of the basic arrangement shown are available to control its filtering action, to obtain amplification, and to control the shape and duration of the outgoing impulse. The manner of manipulating these factors to obtain desired results in particular applications will be evident to those skilled in the art, and therefore does not require detailed discussion.

Referring now to Fig. 3, the basic arrangement of Fig. 2 is shown as applied to the grid circuit of a three-element vacuum amplifier tube T2 of conventional type having an anode or plate, cathode, and control grid. The input circuit I0 is shown as coupled to the filter arrangement comprising integrating capacitor Cl and timing resistor R2 by means of transformer ll, although other coupling means may be employed if desired. A grid suppressor resistor R4 is connected in series with the grid of T2 to limit the grid current on positive swings and to eliminate the possibility of TI being held ionized by current flowing through the cathode to grid circuit of T2. A potentiometer PI provides a steady potential for the plate circuit of T2 and for Tl, while potentiometer P2 provides a negative bias for the grid of T2.

The operation of the circuit is as follows: Assume that potentiometer PI is adjusted to provide a potential somewhat below the breakdown voltage to TI, and potentiometer P2 is adjusted to bias T2 to the cutoff point. Under the assumed conditions, the plate current of T2 fiowing through the" output circuit 20 is negligible. Now assume that a signal impulse of the proper amplitude and duration is applied to the input circuit l0, chargingCl positively in excess of the voltage margin, thus causing TI to become ionized. Current flows from Pl through Cl, Tl, R3 and return to Pl via P2. Tl being of low impedance when ionized, the potential at the junction of R3 and R4, and hence at the grid of T2, becomes more positive and remains so until Cl becomes charged sufficiently to cause TI to cut oil, restoring initial conditions. Plate current fiows through T2 so long as the grid of T2 is positive relative to the cut-ofi point, causing a current pulse to flow in output circuit 20. Due to the operation of the ClR2 combination, signals not meeting the requirements as to amplitude and duration are excluded from the output circuit. Hence, as in the arrangement shown in Fig. 1, unwanted signals do not appear in the output circuit, while wanted signal impulses appear in the output circuit in amplified form,and reshaped, if desired. It will be understood that a double amplification of the wanted signals may be obtained, the first amplification resulting from the ability of TI when ionized to swing the grid of T2 to a more positive degree than that due to the input signal impulses alone, while the second amplification results from the amplifying properties of T2. The overall amplification factor is the product of the amplification factors of TI and T2.

By adjustment of R3 various wave forms for the output signal impulses may be obtained.

Referring now to Fig. 4, the arrangement shown is a symmetrical, dual arrangement of the circuit of Fig. 3 adapted to filter and amplify both positive'and negative signal impulses, TI and T2 being responsive to positive impulses and T3 and T4 to negative impulses or vice versa. The operation of each half of the dual arrangement is similar to the circuit of Fig. 3, and will be manifest from the description thereof. Resistors R5 and R6 are shunted across output circuit 20 in-order to produce single positive and negative outgoing impulses.

Referring now to Fig. 5, TI is a grid-controlled, gaseous-discharge tube of triode type having a cathode, grid, and anode or plate. In this type of tube, the breakdown voltage is mainly a function of the potential of the grid, whilethe tubedrop voltage when ionized is comparatively low, being usually of the order of to 25 volts. The grid is provided with a suitable bias by potentiometer P2, while a suitable plate voltage is provided by potentiometer PI. Since the grid of this type of tube loses control when the tube is ionized and is normally unable to cause the tube to cut oil, separate cut-off means must be provided. The preferred means is a cut-off relay L connected in the anode-cathode circuit as shown, although other alternative means may be employed. The filter arrangement comprises inteter PI supplies plate potential to both tubes.

grating capacitor CI and timing resistor R2 whose operation is identical with that described in connection with prior figures, and hence does not require further description. The function of resistor R4 is to limit the grid current when tube TI becomes ionized. The grid has'a negligible effect on the flow of plate current, hence the amplitude and form of the output impulse must be controlled by the output circuit, while the duration is controlled by the cutting off of the plate current by relay L. Since L performs the function of limiting the duration of the outgoing impulse, it is equivalent in function to R3 in the other arrangements.

The arrangement shown in Fig. 5 is characterized by the high amplification factor and heavy plate current obtainable.

Referring to Fig. 6, TI is a grid-controlled gaseous-discharge triode, similar to TI of Fig. 5, but preferably of lower current rating. A triode amplifier tube T2 of vacuum type. has its grid a circuit coupled to the plate circuit of TI by means of transformer I2. Potentiometer P2 supplies a steady grid bias to TI and T2, while potentiome- T2 is preferably biased to cut-off, while TI is biased in such manner that the potential rise of Ci due to the wanted signal impulses will exceed the voltage margin between the voltage supplied by PI and the breakdown voltage of TI. The filter arrangement comprising integrating capacitor C I and timing resistor R2 is preferably connected in the cathode-plate circuit of TI as shown. Limiting resistor R3 is connected in the same circuit and assists capacitor CI in cutting off the discharge current of TI. Limiting resistor R3 should be of relatively high value in order to cooperate with Cl and R2 in their cutoff action.

The operation is as follows: The wanted signals raise the potential of Cl above the voltage margin causing TI to ionize; unwanted signals are filtered out by the CIR2 combination as before. When TI becomes ionized and conducting, the ionization current flows through the primary of transformer I2, the secondary of which swings the potential on the grid of T2 causing a current pulse inthe plate circuit of T2, and hence in the output circuit 20. The flow of current in the cathode-anode circuit of TI charges CI until the back E. M. F.,across CI plus the IR drop across R3 causes TI to cut oil. It is to be observed that the wave form and duration of the outgoing impulse are under the control of the grid of T2, which in turn is controlled by the secondary voltage of transformer I2. There is therefore no direct relation between the impulses in the input and. output circuits, and a wide variety of output impulse forms, together with high amplification, may be obtained. Since the breakdown voltage of TI is closely controlled by the bias on the grid of Ti, the voltage margin may be adjusted within close limits.

Referring now to Fig. 7, an impulse filtering circuit is shown which is characterized by a definite exclusion period readily cariable between wide limits. The circuit comprises an input circuit ID, a timing condenser CI, a timing resistor RI connected in series therewith as shown, a gaseous discharge tube TI, and discharge limiting resistor R3. A transformer I4 or other coupling device, is connected in series with TI in such manner as to cause an impulse to appear in output circuit when TI is passing current. CI is connected across the circuit containing TI and both are held at a potential somewhat below the breakdown voltage of TI by a battery BI or other source of constant potential.

The operation is as follows: Assume that uni-, form periodic impulses of magnitude just adequate to charge CI above the voltage margin are impressed in aiding manner on the input circuit. Tl will be tripped by the first impulse and CI will discharge through TI down to the cutoff voltage of TI, whereupon TI will be de-ioniwd. The discharge current of CI through TI will produce a brief impulse in the output circuit the form and duration of which is mainly controlled by R3. The discharge of CI drops the voltage across TI, thereby materially increasing the voltage margin; hence if succeeding impulses arrive before the normal voltage margin is restored by the recharging of CI, TI is not tripped, and such impulses are not transmitted to the output circuit. The charging rate of Ci is controlled by RI, hence if RI is large, a considerable interval may be' made to occur before CI is again charged sufficiently to restore the normal voltage margin and permit TI to be tripped by the signal impulses. By varying RI, the number of impulses missed before the tripping of TI and the consequent passing of an impulse to the output circuit may be selected at will over a considerable range, which range may be further extended by varying Ci. Since the elements controlling the charging of CI are of stable character, the ratio of passed to excluded signals when established remains constant, provided the input signals are substantially uniform, and the circuit shown may be used to group or count periodic impulses or waves which are too rapid in occurrence for ordinary counting methods. The input signals may, for example, be produced by a photo-electric counting device actuated by rapidly moving objects, or by other preferred means generating uniform rapid impulses.

Referring next to Fig. 8,.T2 is a vacuum tube biased below cutoff by potentiometer P2 via input circuit I 0. In the plate circuit of T2 is a filter arrangement which comprises a capacitor CI,

lows: Since T2 is'biased below catch, the plate current which normally flows through T2 is negligible, and practically all the drop through the plate circuit of T2 occurs across the internal anode-cathode circuit of T2.

therewith. Now assume that a signal of sumcient amplitude to raise the grid of T2 above cutofl is applied to input circuit I0. The impedance of T2 is thus lowered, and plate current begins circuit. 20 during the current discharge through Tl, the wave form being dependent in part upon the electrical constants of the circuits, including transformer l3. The duration of this discharge may be controlled by adjustment of R3.

In case the signal applied to input circuit I is not of sufiicient amplitude and duration to permit sufficient current to fiow through T2 to cause CI to be charged sufiiciently to trip Tl no output impulse occurs between incoming signal impulses, and the charge on Cl leaks off through R2. Hence a filtering action similar to that provided by the arrangement shown in Fig. 1 is obtained.

Another type of action similar to that of the arrangement shown in Fig. 7 may be obtained by suitable adjustment of the circuit constants. Assume that a series of periodic impulses are applied to input circuit l0, each impulse being of sumcient magnitude to raise the grid of T2 above the cutoff point, but not of sufiicient magnitude to charge CI above the voltage margin. Under such conditions each impulse causes T2 to add an increment of charge to CI, part of which charge leaks oil through R2 during the interval between impulses. After a certain number of such impulses, TI is tripped and an impulse is transmitted to output circuit 20. It is thus evident that the arrangement shown in Fig. 8 can be caused to group or count rapid periodic impulses'in the same manner as the arrangement shown in Fig. 7. Furthermore, the arrangement shown in Fig. 7 may be connected between the original impulse source and the arrangement shown in Fig. 8, thus providing a cascaded counting circuit of high ratio.

Referring now to Fig. 9, the arrangement of Fig. is shown as applied to the receiving circuit of a single impulse printing telegraph system. Three stages of the receiving circuit are shown, namely the rectifier stage, limiting stage, and filter-amplifier stage, associated with electron tubes T3, T2, and TI respectively.

' T3 is shown as a triode vacuum tube, but represents any rectifier device. Its function is to apply unidirectional voltage variations to the grid of limiting tube T2, and may be omitted when unidirectional voltage variations are otherwise obtained. T3 is preferably supplied with a negative bias normally holding the grid at or near the cut-ofi' potential, hence the plate current flowing through load resistorRS is increased by received signals.

T2 is preferably a vacuum tube biased to provide a certain normal level of plate current, and has its grid circuit so coupled to rectifier tube T3 that an increase of plate current in T3 causes the plate current in 1'2 to fall below the normal level. As shown, T2 is self biased by cathode Hence very little voltage exists across Cl-R2, and TI in shunt resistor R1. although other well known means may be used. C2 is the coupling condenser between the plate circuit of T3 and the grid circuit of T2, and R8 is the grid leak resistor for T2.

TI is a triode gas discharge tube similar to that described in connection with Fig. 5. The input circuit to the grid of TI is preferably coupled to the plate circuit of T2 by means of transformer II. The input circuit of TI thus comprises the secondary of transformer ll, integrating condenser Cl, and resistor RI. For reasons presently to be described, the natural period of this circuit when connected as shown is prefererably made twice the duration of the wanted signal impulses. The grid TI is held at proper normal bias by potentiometer P2, while potentiometer Pl provides a steady source of potential for the anode-cathode circuit of TI. R4 is a grid current limiting resistor, while L is a cut-oil. relay, all as described in connection with Fig. 5.

The operation of the arrangement is as follows: The incoming signals, including interference signals, are applied to rectifier tube T3, and produce increased plate current through R8. The rise in current in R9 in response to incoming signal impulses is shown graphically as ii in the first line of Fig. 10. An increase in current through R9 causes a drop in potential at the connection of C2 with the plate circuit of T3, hence the grid of T2 is made more negative, and the plate current flowing through the primary of transformer II is diminished as indicated by i2 of Fig. 10. It is to be noted that since i: can only vary between the normal value and zero, the current variations through the primary of l l are limited toa certain range regardless of the strength of thesignals rectified by T3, hence the designation of T2 as the limiting tube.

The input circuit to Tl, having inductance and. capacitance, is oscillatory in nature, and the voltage across Cl due to a current variation in the primary of II as indicated by is will be of the general form indicated by e of Fig. 10. It is well established that when an oscillatory circuit is excited by an impulse of the proper duration in relation to its natural period, the second alternation of the voltage surge across the capacitance may exceed the first alternation in amplitude, the theoretical limit being twice the amplitude of the first alternation. The secondary of transformer I I is so connected to the input circuit that the first alternation produces a charge on CI in a direction opposing the tripping of TI, while the second alternation is in an aiding direction. Referring to Fig. 10, let E represent the voltage margin, then when e becomes equal to E, TI is ionized or tripped. is represents the outgoing impulse produced by tripping TI, and it will be observed that this impulse occurs after the expiration of the signal impulse.

Established theory shows that when the ratio of the duration of the exciting impulse to the natural period of an undamped oscillatory circuit is within the limits of .2 to .8, the second alternation will exceed the first alternation in amplitude. Damping of the circuit due to resistance will narrow the range of this ratio somewhat, and in practice it can be taken as a basis of design that the natural period of the input circuit to TI should be approximately twice the duration of the wanted signal impulses. While RI has some effect on the natural period of the input circuit, the main function of RI is to provide a means of controlling the damping of the input circuit, and in established applications aiuaaoa may be omitted, the correct amount of damping being obtained by proper design of transformer The arrangement shown in Fig. 9 is effective in filtering out interference signals of different time characteristics than the wanted signals even if much stronger than the wanted signal impulses since all signals are limited in effect by limiting tube T2, and signals materially difl'ering in time characteristics from the wanted signal impulses will not produce sufiicient voltage across CI to trip Tl. Limiting tube T2 also acts as an automatic volume control, and can be adjusted so that signal impulses weakened by fading or by other causes will be effective to trigger Ti.

The arrangement shown in Fig. 9 is particularly adapted to printing telegraph systems operated over radio or carrier frequency channels.

It is to be observed that the various embodiments of the invention possess in common an integrating capacitor Cl, a timing impedance Zl controlling the charging of CI, a gaseous-discharge tube Ti, a discharge limiting device Z3 controlling the discharge of TI and a steady potential source. Also that each arrangement is capable of exercising a filtering or selective action on the signals passing therethrough, and is capable of amplifying the incoming signal. The arrangements shown also provide means for producing outgoing impulses of a wide variety of shapes and durations at will.

In the various arrangements, the impedance of the input circuit to Cl has an effect on the action oi. that combination, and in some instances, the input circuits may in themselves have suiilcient capacity or impedance so that a separate timing element is not required. By the well understood principle of equivalent circuits it is clear, however, that such instances are special cases of the basic circuits herein disclosed, in which and Z represent the equivalent capacitance and impedance of the input circuit, however distributed. In like manner, the function of discharge limiting impedance Z3 may in some instances be embodied in the output coupling device or circuit, and in such cases 23 represents the equivalent discharge limiting device applied to gaseous discharge tube Tl What is claimed is:

2. An electrical impulse filter arrangement comprising an input circuit including a normally unexcited oscillatory circuit, an electron discharge device having an input and output circuit associated therewith, a grid control element included in the input circuit and means normally to bias the grid element to render the device nonconductive, and means to impress the discharge or the oscillatory circuit upon the input circuit of the device upon excitation of the oscillatory circuit by signal conditions includng means whereby the second alternation of the oscillatory circuit discharge is eflective solely to overcome the bias of the grid element thereby rendering the electron discharge device conductive.

3. An electrical impulse filter arrangement comprising an input circuit including a normally unexcited oscillatory circuit, an electron discharge device having an input and output circuit associated therewith, said device being characterized by continued operation unaflected by grid potential after starting, means to impress normally a grid bias potential upon the device to render it non-conductive, means to impress the discharge of the oscillatory circuit upon the input circuit of the device upon excitation of the oscillatory circuit by signal conditions including means whereby the second alternation of the oscillatory circuit discharge is efiective solely to overcome the grid bias potential thereby rendering the electron discharge device conductive, and means in the output circuit of the device to restore the device upon operation thereof to a non-conductive the last mentioned means comprises relay means.

HARRY I. manor-s.

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US2597352A (en) * 1944-10-10 1952-05-20 Us Sec War Decoding device
US2601289A (en) * 1946-04-26 1952-06-24 Int Standard Electric Corp Reiterating system
US2603715A (en) * 1948-06-29 1952-07-15 Bell Telephone Labor Inc Pulse position call or dial receiver
US2653274A (en) * 1945-09-06 1953-09-22 Horace W Babcock Cathode-ray deflection circuit
US2666849A (en) * 1945-10-12 1954-01-19 Harold L Johnson Short-pulse modulator
US2668236A (en) * 1944-09-23 1954-02-02 Philco Corp Electrical pulse-width discriminator
US2686876A (en) * 1945-09-05 1954-08-17 Robert G Mills Random pulse generator
US2711094A (en) * 1949-06-25 1955-06-21 Celanese Corp Stop motion
US2713639A (en) * 1950-02-21 1955-07-19 Bendix Aviat Corp Shock-excited oscillatory circuit
US2724776A (en) * 1945-01-04 1955-11-22 Chalmers W Sherwin Signal generator
US2802942A (en) * 1954-05-21 1957-08-13 Hoffman Electronics Corp Pulse integrator and amplifier circuits or the like
US2845610A (en) * 1952-08-29 1958-07-29 Bell Telephone Labor Inc Magnetic data storage system
US3009108A (en) * 1951-07-06 1961-11-14 Lufttechnischen Ges M B H Measurement of electric charges put on a condenser
US3010094A (en) * 1957-09-30 1961-11-21 Honeywell Regulator Co Electrical data handling apparatus
US3034060A (en) * 1958-04-02 1962-05-08 Western Electric Co Keyer circuit using rectified cut-off bias
US3044054A (en) * 1956-05-16 1962-07-10 Multitone Electric Company Ltd Receiver for electromagnetic signals
US3065425A (en) * 1957-08-13 1962-11-20 Gen Electric Pulse delayer using shock-excited l-c resonant circuit having sinusoidal output effecting threshold triggering of neon bulb
US3135896A (en) * 1961-06-06 1964-06-02 Us Instr Corp Narrow band sensing circuit
US3138738A (en) * 1960-10-19 1964-06-23 Nat Rejectors Gmbh Currency detectors

Cited By (64)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2442612A (en) * 1941-12-19 1948-06-01 Gen Electric Oscillator
US2492368A (en) * 1942-04-01 1949-12-27 Rca Corp Frequency measuring circuit
US2471836A (en) * 1942-06-08 1949-05-31 Gen Electric Electronic signal generator
US2422766A (en) * 1942-11-30 1947-06-24 Gen Motors Corp Peak transient meter
US2442769A (en) * 1942-12-30 1948-06-08 Sperry Corp Electronic delay circuits
US2440547A (en) * 1943-01-23 1948-04-27 Gen Electric Pulse generator
US2495780A (en) * 1943-04-02 1950-01-31 Sperry Corp Damped shock excited variable width pulse gate generator
US2442770A (en) * 1943-04-20 1948-06-08 Sperry Corp Pulse generator
US2435579A (en) * 1943-05-10 1948-02-10 Oliver T Francis Voltage magnitude discriminator circuit
US2433863A (en) * 1943-05-13 1948-01-06 Bell Telephone Labor Inc Pulse generation circuit
US2440278A (en) * 1943-05-15 1948-04-27 Standard Telephones Cables Ltd Pulse selecting and eliminating system
US2444455A (en) * 1943-09-09 1948-07-06 Standard Telephones Cables Ltd Static reducing pulse receiver
US2428989A (en) * 1943-09-15 1947-10-14 Western Electric Co Multicomponent wave generator
US2434920A (en) * 1943-11-23 1948-01-27 Standard Telephones Cables Ltd Pulse generator system
US2448027A (en) * 1943-11-23 1948-08-31 Standard Telephones Cables Ltd Static reducing pulse receiver
US2468058A (en) * 1943-11-23 1949-04-26 Standard Telephones Cables Ltd Blocking system for multichannel operation
US2480878A (en) * 1943-12-20 1949-09-06 Bell Telephone Labor Inc Telegraph signal distortion measuring apparatus and system
US2537065A (en) * 1944-04-18 1951-01-09 Sperry Corp Gate generator
US2444437A (en) * 1944-07-29 1948-07-06 Standard Telephones Cables Ltd Modulating system
US2535061A (en) * 1944-08-19 1950-12-26 Standard Telephones Cables Ltd Electrical pulse width shaper and selector
US2668236A (en) * 1944-09-23 1954-02-02 Philco Corp Electrical pulse-width discriminator
US2597352A (en) * 1944-10-10 1952-05-20 Us Sec War Decoding device
US2458283A (en) * 1944-10-23 1949-01-04 Automatic Elect Lab Impulse generator
US2434921A (en) * 1944-11-02 1948-01-27 Standard Telephones Cables Ltd Pulse amplitude selective system
US2434922A (en) * 1944-11-02 1948-01-27 Standard Telephones Cables Ltd Pulse amplitude selector system
US2418375A (en) * 1944-11-06 1947-04-01 Rca Corp Production of delayed pulses
US2576634A (en) * 1944-12-01 1951-11-27 Hartford Nat Bank & Trust Co Electrotherapeutic impulse generator
US2522110A (en) * 1944-12-21 1950-09-12 Philco Corp Pulse detector system
US2499234A (en) * 1944-12-28 1950-02-28 Rca Corp Pulse forming circuit
US2724776A (en) * 1945-01-04 1955-11-22 Chalmers W Sherwin Signal generator
US2479652A (en) * 1945-01-11 1949-08-23 Rca Corp Receiving system for code signals
US2443619A (en) * 1945-02-08 1948-06-22 Bell Telephone Labor Inc Pulse generator of the shockexcited type
US2454415A (en) * 1945-02-24 1948-11-23 Rca Corp Autoamtic gain control circuit
US2509237A (en) * 1945-02-26 1950-05-30 Standard Telephones Cables Ltd Radiobroadcasting system
US2549776A (en) * 1945-03-10 1951-04-24 Claud E Cleeton Pulse discriminating apparatus
US2570236A (en) * 1945-04-28 1951-10-09 Conrad H Hoeppner Discriminator circuit
US2524175A (en) * 1945-06-28 1950-10-03 Mini Of Supply Keying of high-frequency oscillators
US2496283A (en) * 1945-07-14 1950-02-07 James E Gall Electronic generator circuit
US2502343A (en) * 1945-07-26 1950-03-28 Stewart Warner Corp Pulse generator
US2686876A (en) * 1945-09-05 1954-08-17 Robert G Mills Random pulse generator
US2653274A (en) * 1945-09-06 1953-09-22 Horace W Babcock Cathode-ray deflection circuit
US2532843A (en) * 1945-09-10 1950-12-05 Rca Corp Pulse selective system
US2666849A (en) * 1945-10-12 1954-01-19 Harold L Johnson Short-pulse modulator
US2572083A (en) * 1945-10-25 1951-10-23 Roger E White Delayed signal generator
US2512699A (en) * 1945-12-06 1950-06-27 Us Sec War Radio pulse receiver interference eliminator
US2548818A (en) * 1945-12-10 1951-04-10 William R Rambo Thermionic overvoltage protection circuit
US2589851A (en) * 1946-01-03 1952-03-18 Us Sec War Pulse length discriminator
US2449792A (en) * 1946-01-31 1948-09-21 Rca Corp Cathode-ray-tube scanning circuit
US2601289A (en) * 1946-04-26 1952-06-24 Int Standard Electric Corp Reiterating system
US2579217A (en) * 1947-02-07 1951-12-18 Ferris Instr Lab Harmonic electrical alternating-current generation
US2560709A (en) * 1947-07-22 1951-07-17 American Telephone & Telegraph Clipping amplifier
US2513428A (en) * 1947-10-20 1950-07-04 Philco Corp Superregenerator
US2603715A (en) * 1948-06-29 1952-07-15 Bell Telephone Labor Inc Pulse position call or dial receiver
US2711094A (en) * 1949-06-25 1955-06-21 Celanese Corp Stop motion
US2713639A (en) * 1950-02-21 1955-07-19 Bendix Aviat Corp Shock-excited oscillatory circuit
US3009108A (en) * 1951-07-06 1961-11-14 Lufttechnischen Ges M B H Measurement of electric charges put on a condenser
US2845610A (en) * 1952-08-29 1958-07-29 Bell Telephone Labor Inc Magnetic data storage system
US2802942A (en) * 1954-05-21 1957-08-13 Hoffman Electronics Corp Pulse integrator and amplifier circuits or the like
US3044054A (en) * 1956-05-16 1962-07-10 Multitone Electric Company Ltd Receiver for electromagnetic signals
US3065425A (en) * 1957-08-13 1962-11-20 Gen Electric Pulse delayer using shock-excited l-c resonant circuit having sinusoidal output effecting threshold triggering of neon bulb
US3010094A (en) * 1957-09-30 1961-11-21 Honeywell Regulator Co Electrical data handling apparatus
US3034060A (en) * 1958-04-02 1962-05-08 Western Electric Co Keyer circuit using rectified cut-off bias
US3138738A (en) * 1960-10-19 1964-06-23 Nat Rejectors Gmbh Currency detectors
US3135896A (en) * 1961-06-06 1964-06-02 Us Instr Corp Narrow band sensing circuit

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