US2483411A - Pulse synthesizing system - Google Patents

Description

@et 4, 1949. D. D. GRIEGI PULSE SYNTHESIZIN G SYSTEM 3 Sheets-Sheet l Filed Dec. 19,51945 Oct.' 4, 1949.

Filed Dec. 19, 1945 WAVE -TO BE DIVIDED FROM SHAPER FROM DELAY DEVICE FROM SCAN FREQUENCY.-

DIVIDER FROM SCAN SAW TOOTH GENERATOR FROM DOUBLE CLIPPERL- FROM SWEEP FREQUENCY DIVIDER- FROM MARKER CIRCU IT TO TRANSMITTER FROM COUNTER SCAN' CIRCUIT FROM swEEP CIRCUIT D. D. GRIEG- 2,483,411

PULSE SYNTHESIZING SYSTEM 3 Sheets-Sheet 2 SCAN FREQUENCY l DIVIDER INVENTOIL v DONALD D. GRI E G ABY A TTORA/Y Oct. 4, 1949. D. D. GRIEG 2,483,411 PULSE SYNTHESIZING SYSTEM I Filed Dec. 19, 1945 s shets-sheet s DEBLOCKI NG WAVES:

PROV. DELAY MULTI- I I 'I CHO BRATOR FDR a n, y FROM DELAY b-- /lu Hl: Il FROM DELAY c I I la FROM DIFFERENTIATDR l CLIPPER q IN MXER CLIPPERS:

| n Q I lav b I l |25 I IIJ |29 d l I "lillf 4|30 l m.. :Jh: f| |I ll Lf Y sa FROM SWEEP CIRCUIT- |46 FROM SAW TOOTH GENERATOR' -I///,/'/|l/|47 FROM MIXER A INVENToR. D DONALD D. `@Furie Patented Oct. 4, 1949 2,483,411 PULSE SYNTHESIZI-NG SYSTEM Donald D. Grieg,

Forest Hills, N. Y., assigner to Federal Telephone and Radio Corporation,

New York, N.

Y., a corporation of Delaware Application December 19, 1945, Serial No. 636,023 Claims. (Cl. 178-44) This invention relates to a method and apparatus for synthesizing similar recurring undulations on an electromagnetic Wave. More particularly, it deals with a system for dividing the undulations into segments to produce a train of pulses, utilizing or transmitting the train of pulses, and then recombining the pulses of the train to reproduce the original undulations.

It is an object of this invention to recombine a train of pulses comprising segments of undulations to reproduce said undulations in a novel and effective manner.

Another object of this invention is to divide, and then reproduce undulations in a novel and eiective manner.

Another object is to divide, transmit, and reproduce similar recurring undulations with substantial simulation of shape of the original undulations.

Another object is to provide means for carrying out the above objects;

Still other objects and features of this invention will appear from time to time in the description which follows:

Generally speaking, this invention comprises a method for dividing periodic recurring undulations into segments to produce a train of pulses having widths corresponding to the widths of the undulations at corresponding segmenting levels; transmitting and receiving or otherwise utilizing the train of pulses without distorting the time location of the edges thereof; and then combining the pulses of the train to reproduce the original undulations. The more numerous the segments in which the original undulation is divided, the more accurate is the reproduction of the original undulation. The undulations which are segmented should be recurrent, although their frequencies need not be constant.

Segmentation or division of the undulations may be accomplished by double clipping segments at different amplitudes from a plurality of recurring undulations to produce the above-mentioned train of segment pulses.

The reproduction of the original undulations from the train of pulses may comprise a deblocking circuit for separating the pulses correspending to the same clipping level into separate pulse trains. These pulse trains are then de-v layed and combined so that the different segments may be superimposed to reproduce the originally segmented undulation.

In order to select the proper segment pulses in the pulse trains, marker pulses may be placed at regular intervals along the original pulse train.

These marker pulses may be produced from the original undulations before they are segmented and may be eliminated in the deblocking circuit. The marker pulses may comprise pulses of very short duration which either have a greater amplitude than the segment pulses of the original pulse train, or comprise a pair of pulses closely spaced together which have the same amplitude as the segment pulses on the original pulse train.

If desired, an indicating device may be employed both in the circuit which divides the pulses and in the circuit for recombining the pulses. This indicating device may comprise a cathode ray tube with viewing screen upon which the pulses may be superimposed to produce a pattern related to the shape of the original undulation. The sweep circuits for such an indicating device may be controlled by the marker pulses produced from the original undulations.

These and other objects and features of this invention will become more apparent upon consideration of the following detailed description of the embodiments to be read in connection with the accompanyingv drawings in which:

Fig. 1 is a schematic wiring diagram partially in block for producing the original pulse train of this invention;

Fig. 2 is a schematic wiring diagram of another embodiment of the marker pulse circuit shown in Fig. 1;

Fig. 3 is a graph of wave forms useful in eX- plaim'ng the operation of the systems of Figs. v1 and 2;

Fig. 4 is a schematic block Wiring diagram for synthesizing recurring undulations from a train of pulses; and

Fig. 5 is a graph of wave forms useful in explaining the operation of the system of Fig. 4.

Referring to Figs. 1 and 3 a wave containing similar recurring undulations, such as wave l shown in Fig. 3, is introduced into the system of Fig. 1 through line 2 and is passed to a variable delay device 3 and a shaper 4. Variable delay device 3 may comprise any suitable circuit for delaying the Wave l without distorting the shape of undulations, such as a network of inductances and condensers to simulate a transmission line. From the delay device 3 is withdrawn the delayed wave 5 which is passed through line 6 to the amplitude double clipper 1.

The shaper 4 may comprise circuits for producing the pulse waveV 8 from the undulations of the wave I, such as clippers, differentiators, amplifiers, etc. Pulsewave 8 is withdrawn from shaper 4 through line 9, passed to the scanning circuit and to marker pulse circuit II.

The scanning circuit IEB comprises a variable scanning frequency divider I2 which may comprise a multivibrator, to produce the wave i3 which is then passed through line I4 to the sawtooth wave generator I5. From generator I5 is withdrawn the sawetooth wave 16 through line I1 which is passed to amplitude double clipper 1.

The amplitude double clipper 1 may comprise a double diode I8 and suitable coupling circuit as shown. The delayed pulse train 8 and the saw-tooth wave I5 are both applied to the plate I9 of the tube I8. Successive pulses of the train 5 are clipped at gradually increasing amplitudes, as shown along the line 20 in Fig. 3, due to the increasing voltage along the sloping edge of the Wave I6. The width of the clipping segment 2I is determined by the adjustment of the resistance 22 in the cathode circuit of the tube I8. From the plate 23 of the tube I8 is withdrawn the train of pulses 24, corresponding to the shaded segments above the line 23 and corresponding in width to the width of the corresponding undulations of the wave 5 at the corresponding clipping levels. The pulses on the pulse train 24 are withdrawn from the amplitude double clipper circuit 'I through line 25 and thence into a mixer 25.

For producing a double marker pulse, the marker pulse circuit II may comprise a variable frequency divider 21 and/or a decoupler delay line 28 and 29. If desired, however, the pulses from Shaper 4 may be passed directly to the mixer 23 through line 33 having switch 3l and line 32. In the specific wave form shown, there are two different types of alternately recurring undulations on the wave I which may be considered together, therefore the pulse wave 8 is passed through the frequency divider 21 from which is removed the pulse wave 33 which is then passed through line 34 to join with line 32 coupled to the mixer 2B. Pulse Wave 33 when mixed in mixer 23 with the pulse train 24, produces Wave 34 which is then withdrawn through line 35 to a transmitter or similar utilization circuit.

Instead of producing a single marker pulse 36 shown on wave 34, which marker pulse has an amplitude greater than that of the segment pulses from wave 24 thereon, a diierent type of marker pulse maybe produced, such as a double marker pulse by passing the pulse wave 33 through switch 31 into the decoupler and delay line circuits 28 and 29. The decoupler 28 may comprise a suitable tube 38 which prevents any reections from the reflecting delay line 29 from feeding back into the other circuits of the system. The delay line comprises a network of inductances and condensers 39 and 40, respectively, with a balanced resistance 4I across kthe one end. The other end of the delay line is open to prevent inversion of the reflected Wave. By combining the original pulse wave 33 with the reected pulse wave from the network 29 there is produced a double marker pulse wave 43 which is withdrawn through line 44 and passed through line 32 to the mixer 26. The mixing of the double. marker pulse Wave 43 with the wave 24 produces the pulse wave 45 having double marker pulses 45 between each pair of segment pulses. Both the segment pulses and the marker pulses in the wave 45 may be of the same amplitude.

Instead of the scan circuit in producing the saw-tooth wave 2S each undulation or adjacent pairs of undulations on the wave 5 may be clipped along a step wave, such as wave 41, produced in the scan counter circuit 48 shown in Fig. 2. This circuit 48 may comprise a scan frequency divider l2a, similar to divider I2, a pair of unidirectional valves or diodes 49 and 54, a condenser 5I, a very large condenser 52, a very large resistance 53, and a gas filled triode 54 biased through a battery 55. In this embodiment the scanning frequency divider IZa is adjusted to produce a wave similar to 33 shown in Fig. 3. Each positive pulse on the wave 33 puts a charge on the condenser 5I which charge is passed through the valve 53 and is applied to the larger condenser 52. The charge on the condenser 52 is gradually built-up in steps by each additional pulse in the pulse wave 33 until a voltage is reached which causes the gas filled tube to discharge the condenser 52. The steps of the wave 41 gradually diminish in amplitude as the charge on the condenser 52 is increased. The diode 49 in the plate circuit potential of the tube 5t, prevents any negative pulses or'other variations in the pulse W'ave 33 from effecting the charge build-up on the large condenser 52. The resistance 53 between the condenser 58 and the gas illed tube 54 must be very large to prevent leakage of the condenser 32. The gas filled tube 54 is biased through a battery 55 so that when the voltage on the condenser 52 reaches the amplitude 59 shown on Wave 41, the tube becomes conductive and discharges the condenser 52 along the line Si) of the step shaped pulse on the Wave 41. When the condenser 52 is completely discharged the tube 54 again becomes non-conductive and the next successive pulse of the wave 33 starts building up charges to produce a new step shaped pulse on the Wave 41. The wave 41 is withdrawn from the circuit 48 through the guard condenser 5I and then passed through line I5 entering the amplitude double clipper 'I shown in Fig. 1. The step shaped pulse wave 41 is shown to clip successive pulses of the wave 5 above the step line 62 in Fig. 3. The shaded segments which are clipped from these pulses produce a segment pulse train similar to train 24. One advantage of the circuit 48 over that of circuit I5 is that the segments from the pulses are taken parallel to the base of each pulse. However, if the angle of the sloping edge of the sawtooth wave IB is sufl'iciently small, very little, if any, distortion will be caused by the sloping segments produced therefrom. This is also true if the pulse which is being clipped by the wave I6 is of short duration.

If desired, the pulse produced by the system described above in Fig. i may be indicated on a suitable cathode ray indicating device, the sweep circuit of which may be operated by the pulse wave 33 coupled to the frequency divider 21 through line 53. The pulses produced in the circuit in line 25 are applied to the vertical deection plates 54 of the cathode ray device 65 through line 66. The sweep circuit 6l' coupled to line 53 may comprise a saw-tooth wave generator, similar to that of I5, which may comprise a triode 58 the grid of which is suitably biased to cut-off through the resistor 69, and a condenser 10 coupled across the triode 68 which is charged through resistance 1I by the plate voltage supply. When the leading edge of a positive pulse of the wave 33 is passed through line 63 on to the grid of the tube 63, the tube 68 is caused to conduct current and the condenser 10 is discharged. But since the pulses on the wave 33 are of short duration the tube 38 is immediately cut-oir by the trailing edge of the positivepulse. The condenser 18 is again permitted to charge gradually from the plate voltage supply through resistance 1I to produce the sloping edge of the saw-tooth of the wave 12. 'I'his wave 12 is withdrawn from the circuit 61 through the line 13 and applied across the horizontal deflecting plates 14 of the tube 65. The value of condenser 18 is adjusted so that the slope of the teeth on wave 12 will be substantially a straight line in order to eiect an evensweep across the plates 14 of the device 65. The pulses of the original pulse train 24 produce the pattern 15 shown on the screen of the device 65 in Fig. 1. Since different sloping edge of the undulations on the wave I produce various spacing between the vertical lines of the patterns 15, a. definite correlation may be made between the shape of the pattern and the shape of the undulations. For example, the straight edge 16 of the pulse 11 on wave I produces a heavy line 18 in the pattern 15 while the sloping edge 19 of the same pulse produces evenly spaced vertical lines 88 in the pattern 15. Similarly, the curved edges of the recurring undulations 8| on the wave I form differently spaced vertical lines in the second portion 82 of the pattern 15 shown on the screen of the device 65.

After utilization or transmission, the wave or produced in the circuit shown in Fig. 1 or any similar pulse wave may be synthesized by the circuit shown in Fig. 4. For convenience the waves 34 and 45 are reproduced again as Waves 83 and 84, respectively in Fig. 5. The different amplitude sections clipped from the original wave are lettered as sections a, b, c, d above corresponding portions of the waves 83 and 84.

If the wave 84 is received over line 85 in Fig. 4, it is passed through line 86 into the mixer shaper circuit 81 which may comprise a decoupler and delay line 88, similar to 28 and 29 shown in Fig. 1, from which is withdrawn the complex wave 89. Two of the double marker pulses have thus been superimposed upon each other to produce the larger amplitude pulses 98. However, since a number of segment pulses on the wave 84 are also superimposed to produce stepshaped pulses of equal amplitudes, such as pulses 9 I, it is necessary to select and segregate the pulses 98 from the wave 89, by dilerentiating the wave 89 in the differentiator 92 from which is removed pulse wave 93. Pulse wave 93 is then clipped in clipper 94 along level 95 to produce a pulse wave only of the pulses 98. This pulse wave is then passed through line 96 to the deblocking circuit 91 for separating the diierent sections a, b, c, and d from the received wave 84.

If the wave 83 is received, it is not necessary to pass it through the circuits 88 and 92, but only through the clipper 94 which may be done by closing the switch 98 and opening the switch in line 86 from the line 85. Marker pulses 99 are then clipped from the wave 83 along the clipping level I 88 to produce a wave only of pulses 99, similar to the wave of pulses 98.

, The deblocking circuit 91 may comprise a short variable delay device |8|, a multivibrator circuit |82, a series of delay devices |83, I 84, |85, and a series of mixerclippers |86, |81, |88 and |89. The short delay device |8| delays the wave of pulses 98 or 99, so that it is out-of-phase with the marker pulses on the waves 83 and 84. Then delayed pulses 98 or 99 are caused tc trigger the multivibrator circuit |82 to produce the deblocking wave H8. Wave I I8, is aligned to deblock the section a from either wave 83 or 84. The other sections b, c and d of the received wave 83 or 84 may be deblocked by passing the wave I I 8 through the delay device |83, |84 and |85 to produce deblocking wave III |I2, A| I 3', respectively.

Deblocking waves ||8, II2, ||3, are then mixed in the mixer clippers |86, |81, I 88, and |89, respectively with the original wave 83 or 84 from line through line ||4. On these mixer clippers are produced waves II5, |I6, ||1, |I8 corresponding to segments a, b, c, and d, which Waves are clipped along the line II9, |28, |2I, |22 to produce a series of pulse trains corresponding to segment pulses of sections a, b, c, and d, respectively.

Segments a, b, c, and d may be combined or superimposed to reproduce the original undulations -from which they were divided by delaying the clipped pulse trains, corresponding to segments a, b, and c in delay devices |23, |24, |25 so that the pulses of each train are synchronized and in phase with each other and with pulse segments d withdrawn from mixer clipper |89 through line |26. The resulting synchronized pulse trains |21, 28, |29 and |38 are derived for sections a, b, c and cl respectively. A11 of these trains are now introduced into the mixer |3| which may comprise a parallel network of triodes to prevent the impulses from one delay device from feeding back into the circuit of another. The aligned pairs of pulses are thus superimposed to reproduce undulations similar to undulations 11 and 8| of the original pulse wave I, shown on wave |32 which may be withdrawn to suitable utilization circuits through line |33. The utilization circuits coupled to line. |33 may comprise modulation circuits, control circuits, and other circuits wherein the slope and shape of the true leading and trailing edges of undulations are im- Iportant in their operation. The system of this invention is particularly useful in breaking down a pulse of a denite shape so that it may be transmitted and operated upon by circuits which would distort its shape, and then recombining the pulses so operated on toreproduce the original undulation having a given shape.

Although the frequency of the undulations on wave |32 is not as great as that in the original pulse wave the true shape of the undulations 11 and 8| are reproduced. The four different amplitude sections were merely chosen here to illustrate this invention, however, in accurate reproductions |8 or more diierent amplitude sections should be taken.

An indicator circuit |34 also may be coupled to lines 85 and 96 through lines |35 and |36 respectively to indicate the type of pulses received. The circuits |34, may comprise a scanning frequency divider |31 and saw-tooth wave generator I 38, similar to the scanning circuit I8 shown in Fig. l, and the sweep generator |39 for a cathode ray device such as |48, may be similar to circuit 61 shown in Fig. l. The original received wave 83 or 84 may be mixed in mixer I-4I with the saw-tooth wave |42 from the saw-tooth wave generator |38 to produce the wave |144 which is applied across the deflection plates |41 of the device |48. The sweep circuit |39 coupled to the output of clipper 94 through line |36 comprises a saw-tooth wave generator which produces the wave |46 which is applied across the deection plates |45 of the device I 48. The resulting pattern |48, produced on the screen of the cathode ray device |48 in Fig. 4 shows the separate segment pulses of the received train superimposed one upon the other.

An indicating device, such as a cathode ray oscillograpli, may be connected directly to line 133 if desired so that the exact undulation synthesized in the circuit of Fig. 4 may be observed.

Although the above invention refers to means for utilizing a given undulation in circuits which ordinarily would distort the amplitude and slopes of the edges of the undulatons, the system disclosed in Fig. 4 may be employed for recombining any series of pulses of different Widths to produce an undulation, that is, for synthesizing pulses of one type from a series of pulses of another type. v

While the above is a description of the principles of this invention in connection with specific apparatus and particular modifications thereof, it is to be clearly understood that this description is made only by Way of example and not as a limitation on the scope of this invention as deiined in the objects and accompanying claims.

I claim:

1. A method of transmitting periodic recurring undulations of an electromagnetic Wave comprising: clipping horizontal segments from a plurality of similar successively occurring undulations at different amplitudes to produce a train of pulses of the same amplitude, the widths of which correspond to widths of the undulations at corresponding clipping levels, transmitting and receiving said train of pulses, and vertically combining successive pulses of the received train to reproduce said undulations.

2. A method of utilizing periodic recurring undulations of an electromagnetic wave comprising: dividing said'undulations into segments at different amplitudes to produce `a train of pulses, producing a train of marker pulses from said undulations which are Out of phase withthe train of pulses, combining the marker pulses and pulses on a single pulse wave, and then vertically combining the pulses on the single pulse Wave controlled by said marker pulses to reproduce said undulations.

3. In a system for producing a single recurring undulation on an electromagnetic wave from a train of pulses of a repetitive series of pulses of given Widths interleaved with marker pulses, comprising: means for separating said marker y pulses on said train,means. for producing a separating Wave from said separated marker pulses, means vfor producing a plurality of separated waves out of phase with each other and in phase with each of the pulses of each series on said train of pulses, means for combining said separating and delayed separated Waves With the original train of pulses to produce a plurality of pulse trains corresponding to each pulse in said series, means for phasing the pulses on the resulting pulse trains, and means for vertically combining the phased pulse trains to produce said single recurring undulation.

4. The system of utilizing periodic recurring undulations of an electromagnetic Wave comprising: means for dividing said undulations into segments at different amplitudes to produce a train of pulses, and means for vertically combining, the pulses on said train to reproduce said undulations.

5. A system for transmitting periodic recurring undulations of an electromagnetic Wave comprising: means for clipping horizontal segments from aplurality -of similar successively recurring undulations at diierent amplitudes to produce a train of pulses of the same amplitude, the widths of which correspond to the Widths of the undulations at corresponding clipping levels, means for transmitting and receiving said train of pulses, and means for separating and vertically combining the pulses on said train to reproduce said undulations.

- DONALD D. GRIEG.

REFERENCES CITED VThe following references are of record in the iile of this partent:

UNITED STATES BATENTS

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