BE478024A - - Google Patents

Description

       

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  PULSE SELECTION AND SYNCHRONIZATION DEVICE
ELECTRICAL.



   The present invention relates to electrical pulse reception systems and relates to the former. Chief arrangements for selecting from the signal a particular train of pulses the exclusion of other trains of pulses which it may contain as well as interference.



     The invention comprises as a characteristic; secondary devices for subdividing the frequency of a pulse train.



  In some embodiments of the invention, there will also be added means for extracting the modulator signal from the pulses.



   The device which is the subject of the invention comprises an electronic door which will not open to allow impediments to pass.

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 desired pulses that at the very moment when these pulses occur, all other pulses or interference being thus eliminated.



  The opening of the electronic door is determined by the impulses which have already passed through said door and which in the system control the generation (the other impulses intended to open the door. A certain number of practical difficulties have been encountered. - Trues in the realization of such a system and the main object of the invention is precisely to overcome these difficulties which are mainly related to the risks of small slips or variations in the operation which would put the circuit outside the The rate of the incoming pulses It is also necessary to avoid the continuous operation of the control devices These difficulties will be explained in detail when the various means which have been employed to overcome them are described.



   In accordance with the principles of the invention, there is provided a device capable of selecting a train of regularly spaced electrical signaling pulses. The device comprises means for applying the pulses to a circuit in which an electronic gate is located, means for generating a sine wave, means for deriving from the sine wave pulses applied to the electronic gate for the purpose of open it for the admission of the impulses that one wants to receive and exactly at the moment when. they arrive and finally means so that the pulses which have passed through the electronic gate can synchronize] - 'sine wave on the selected pulse train.



   The invention thus provides a device for selecting a particular train of regularly repeating electrical signaling pulses contained in a signal in which there are also other trains of pulses or interference.



  The device includes an electronic gate capable of passing any signal; means synchronized by the pulses of this signal, to generate a sine wave; means for

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 to generate pulses by means of this sine wave and to use these pulses for due, the electronic gate 'is. prohibited to any signal other than the particular train of pulses that one wishes to admit.



   The invention also provides a frequency divider of a train of electrical pulses in which a sine wave is generated, the frequency of which is exactly, the nth sub; multiple of the repetition frequency of the incoming pulse train, where n is an integer. The sine wave thus generated will then be transformed into pulses '' which will be used to control the opening of an electronic door which will only have to be opened at the arrival of each nth external pulse, the pulses having thus been allowed to pass through the electronic gate serving to synchronize said sine wave.



   The invention also comprises a device for receiving a system of electrical signaling pulses with multiple tracks, each of the tracks of this system working, with the same repetition frequency and at least one of the trains. 'system pulses being identified by a. tone; modulated identification.

   The invention provides the means for selecting a train of pulses so designated to the exclusion of all others, these means using an electronic gate and a method for generating a sine wave as well as for deriving therefrom. pulses which will open the electronic door at the exact moment when the pulses to be selected occur. The invention also uses synchronization means, normally inactive, to bring the sine wave into synchronism with the train of pulses to be selected and means controlled by the identification tone to make the synchronization effective.



   The invention also provides an arrangement capable of synchronizing an oscillation generator by means of a source of regularly repeated synchronizing pulses, this source being connected to the generator.

 <Desc / Clms Page number 4>

 generator by a normally blocked circuit. Means are provided so that the oscillations of the generator generate trains of derived pulses, and to use the latter to unblock the circuit connecting the source to the generator, this unblocking being done in such a way that only one of the pulses synchronization will be admitted by cycle of the oscillations of the generator in order to synchronize it.



   The invention also provides an arrangement for synchronizing several oscillation generators in an assembly where said generators are interconnected by one or more communication lines and where a source of regularly repeated electric synchronization pulses delivers. on the track (s) leading to the generators. The arrangement comprises several normally blocked circuits respectively connecting the generators to the track or to the communication channels.

   Each of the generators delivers sinusoidal currents from which derive trains of pulses are drawn, which serve to unblock the corresponding connection circuit in such a way that only one synchronization pulse will pass during each cycle of the oscillations of the generator for the purpose. to synchronize it.



   The invention will be explained in a number of its preferred embodiments. The descriptions will be accompanied by the following drawings: Figure 1, which is a block diagram showing the basic arrangements which are used in all of the described embodiments of the invention; FIG. 2 which gives the electric diagram of a simplified embodiment in which a selective filter chooses the fundamental component of the incoming pulse train, and where only one electronic gate is used ;

   FIG. 3 which represents a very satisfactory and a little more complicated embodiment Ci '-1. two doors are used

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 electronic; FIG. 4, which shows a preferred embodiment in which use is made of three electronic gates; FIG. 5, which provides the curves defining the shapes of the pulses used in the operation of the circuits of FIG. 4; FIG. 6, which diagrammatically represents the electrical circuit of an assembly using a simple oscillator generating a sine-wave synchronized by the train of driven pulses.

   This assembly has a single electronic door; FIG. 7, which shows an improvement of the assembly of FIG. 6, in which two electronic gates are used; Figures 8, 9, 11 and 12 are respectively derived from Figures 2, 3, 6 and 7 to which means have been added to prevent "pumping" of the drift compensating elements; Figure 10 shows a modification of the part, of Figure 9 located above the line X ... X.

   This modification consists in replacing the filter of FIG. 9 by an oscillator; Figure 13 is a modification of Figure 12; the circuits of figure 13 are adapted to the selection of a pulse train characterized by an identification tone; FIG. 16 provides the electric diagram of a circuit capable of compensating for the phase change introduced by a selective element; finally, figure 17 is a modification of figure 16.



   Figure 1 shows the basic 'arrangement' for selecting a particular train of pulses from a composite signal arriving through wire 1. The composite signal is assumed to contain a number of pulse trains repeating at various frequencies. - these and it can also mix with other elements of signals due to interference.



   The pulses can be single polarity pulses

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 single, or high frequency wave trains.



   The pulses arriving via wire 1 are first applied to an electronic gate GC circuit, which must only open at the instants of arrival of the pulses to be kept. The pulses (passed through the electronic gate are applied to a SWG device in which a sine wave is generated at a frequency which must be exactly the same as the repetition frequency of the pulse train which has crossed the electronic gate and which is obtained either under the direct action of the pulses applied to it, or under the control thereof.



   The sine wave coming out of SWG can be applied to an NLN nonlinear grating which will produce a phase change there depending on the amplitude of the sine wave, but the NLN grating is only needed in certain variants of the sine wave. invention and its purpose will be explained in detail later. The sine wave, then passes through a limiter L which transforms the sine waves into rectangular waves and the rectangular waves coming out of L are applied to, a pulse generator PG capable of producing pulses of short duration exhibiting the same character than those arriving in the receiving system: by wire 1.

   The pulses leaving the PG are sent to the rear in the GC circuit where their role is to open the electronic door at the exact instants of the impulses transmitted by the external line 1 and which must be able to cross this door. The latter, after passing through the door, will be routed by wire 2 to suitable devices (not shown), in which they will be demodulated or processed in any useful way.



   It is also possible, if desired, to obtain pulses which can be used externally - for a wire 4 exiting from the generator PG.



   By studying the figures which will now be described, we will not always be able to easily identify the blocks represented in figure 1, because the same organ can be used for several

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 functions in some assemblies. FIG. 1 nevertheless provides the main characteristics of the assemblies using the invention.



   In the following description, some of the difficulties involved in the operation of the system will be clarified. We first see that the electronic door through which the pulses must pass must be opened under the command of the pulses which have already passed through this door. It is however evident that a suitable means must be devised to start this operation, otherwise there would be no reason for the reception of the pulses to even begin.



   The SWG element can be realized, as will be explained, in two different forms: or that of a narrow band pass filter capable of selecting the fundamental sinusoidal component of the pulse train and removing all of them. harmonics, or else that of an oscillator generating a sine wave whose frequency is exactly the same as the pulse repetition frequency, this oscillator being synchronized by the pulses which have passed through the electronic gate.



   FIG. 2 represents an electrical diagram of a device in accordance with the invention. The electronic gate included in the GC element is a V-pentode biased at the break of its plate current by a source B1 placed between its cathode and earth. The signals coming from the transmission line are applied at point 1 to the control gate, which is connected to earth through a resistor R3. The potential of the reject grid is controlled by the pulses exiting the element P, which open the tube at the desired times, as will be explained.

   The anode circuit is coupled by a transformer T with the element SWG and the secondary winding of T is tuned by the capacitor C5 to the frequency of. repetition of pulses. In the assembly of FIG. 2, the SWG element is of the eroit band-pass filter type. If the frequency of pulse repetition is low enough, for example

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   example 1000 pulses per second, a very con-
 EMI8.1
 venable comprises two coils L1 and L2 electromechanically coupled by a steel tuning fork F tuned to the pulse repetition frequency.

   It is known that such a process provides an extremely selective filter which only allows frequencies very close to the natural frequency of the tuning fork to pass with an appreciable amplitude. We can
 EMI8.2
 c el.-, endar it to choose a filter of any other form suitable for the repetition frequency of the pulses and, for example, a wave filter of the usual type, or a piezoelectric crystal or any other resonant system.



   Coil L2 is tuned by capacitor C4 to the pulse repetition frequency and is connected to limit L, which is constructed according to well-known principles and transforms sine waves into perfectly rectangular waves.
 EMI8.3
 lgires. The limiter L can consist, for example, of two stages - the lamps on each of which there will be only a weak or even zero polarization. The first stage will already make the wave roughly rectangular and the second stage will complete the operation. Others
 EMI8.4
 more stages will be added if necessary. Appropriate amplifiers (not shown) can be introduced before or after the SWG element if this is considered necessary.



  The output of limiter L is connected to the pulse generator PG which, in FIG. 2 consists of an area of differentiating circuits (Cl, R1) and (C2, R2) each composed of a con-
 EMI8.5
 densifier and resistor and capable, according to well-known principles, of producing brief alternating positive or negative pulses from rectangular waves. The irnulsions .: negative ones produced on RI have no effect and we can neglect them, but the positive impulses, through the intermediary of the capacitor
 EMI8.6
 C3, of great capacity, will open the electronic door constituted by the V tube. Capacitor C has them linked to the suppression grid of this tube.

   This grid is, on the other hand, connected to

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 the cathode by a high resistance R4 shunted by a rectifier X which has been represented in FIG. 2 as being a diode, but which can also be! '' a selenium rectifier, or copper oxide, where! other type. The anode of the diode X is connected to the reject grid of the tube V.



     Suppose there is no signal applied to point 1 by the transmission line; the rejection grid of the V tube will be located at the same potential as the cathode and the tube will pass any signals which come up, in other words, the electronic gate is constantly open. When the signals arrive at point 1, they can also contain trains of pulses other than the one to be selected, as well as interferences, but they will be filtered by the tuning fork F which will select the fundamental sinusoidal component. pulses to be received and the PG element will be able to provide opening pulses to the V-tube reject gate.

   Diode X acts as a peak rectifier and a negative bias potential builds up on the reject gate each time capacitor C3 is recharged. The tube V will be brought to the cutoff in the interval which separates the pulses, but just at the moment of the peak of the positive pulses the potential of. the rejection grid will rise sufficiently for the tube to be conductive and allow the impulses arriving at this moment to pass on its control grid. The way the load settles in the C3 conductor is as follows:
The positive potential differences which develop in resistor R1 quickly charge capacitor C3 through diode X since this diode is conductive when the potential applied to its anode is positive.

   When the positive voltage disappears, the capacitor C3 remains charged; and the voltage of the anode of the diode 'becomes negative, this diode ceases to be conducting and the capacitor 03. Can only discharge through resistance: high R4.

   As the time constant C3 x R4 is raised by

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   With respect to the period of the pulses, the capacitor rapidly continues to charge by the following pulses so that the maximum negative potential which will be applied to the grid suppresses :. of tube V will be approximately equal to the peak potential of the positive pulses. Each time one of these positive pulses arrives, the potential of the reject gate will be briefly raised to, zero with respect to, la, ca, thode and the tube will be mentally made conductive.



   We see, in summary, that the electronic door which is open to all signals at rest closes as much as there are signals containing the trains of pulses that one wishes to receive for all other signals that these.



   It is obvious that the impulses which control the opening of the electronic door must be suitably located in time so that this door is opened at the appropriate times. It is also necessary that this correspondence is maintained and it is for this last purpose that one can make use of the network NLN of figure 1. An NLN network has not been positively represented in FIG. 2, but the functions of this network can be performed in several ways by the organs which exist in the figure.



   One can, for example, notice that the average forces: magnetic attraction between the tuning fork F and the coils L1 and L2 vary with the amplitude of the vibration and this results in a slight variation of the natural frequency of the tuning fork. But this phenomenon is accompanied by a variation of the phase of 1, the sine wave leaving SWG with respect to the phase of pulses at the entrance of SWG. If the pulses applied by PG to the electronic gate tended to shift from the pulses applied to the V-tube control grid, the forces acting on the tuning fork would decrease and the frequency of the tuning fork would vary, slightly.

   We show that this variation is in the direction

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 suitable for correcting the phase shift of the pulses exiting the element PG. There is therefore no tendency, for these last ones, to shift.



   Another method to achieve the same result is to use the variations in the tuning of the circuit L2, C4, due to the variations in the magnetization of the iron core of L2 as the amplitude varies. One can arrange for this effect to produce a phase corrective shift. in the sine wave coming out of SWG, one could also operate on another tuned circuit, analogous to the circuit L2, C4, but not shown 'in figure 2' and 'the result would be the same.



   Yet another method would be to increase the polarization on the first stage of limiter L, so that the negative part of the rectangular wave in the anode circuit is of shorter duration than the positive part when the signals are weak. For strong signals, these two staves would tend to take equal durations. This would obviously lead to a displacement in time of the pulses generated in the element PG with respect to the sine wave exiting SWG.



   The normal equilibrium state of the system of Figure 2 is that in which each pulse of the signal applied to the V-tube control gate overlaps the edge of a pulse exiting the PG to open the electronic gate. As the front of these last pulses moves, the gain of the V-tube can vary considerably and the level of the received signals is then adjusted automatically, while the coincidence of the two categories of pulses. rest assured ..



   The elements of the circuit (C1, R1) are chosen so that the pulses generated in PG are of sufficient duration to make the tube V conductive for the time which is necessary to let in the pulses which the we want to select. The circuit '(C2, R2) will be calculated to provide on the

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 terminal 4. of the pulses that will be used, with suitable fine ends.



   Figure 3 is a modification of Figure 2 in which two electronic gates are provided which are opened at slightly different times, respectively. The pulses that one wishes to select preferably pass through one or the shaft of these gates, depending on whether they are early or late. However, the instants of opening of the electronic doors automatically tend to catch up with the coincidence with the instant of arrival of the pulses to be selected, so that they finally pass indifferently through the two doors.



   The two tubes VA and VB which constitute these doors are mounted like the tube V of FIG. 2. The grid resistor e R3 is common with two tubes VA and VB, as well as the battery B2 of negative polarization. We could also have positively polarized the cathodes. The suppression gates are connected to the cathodes by resistors R4A and R4B, which are shunted by rectifiers XA and XB.



   The SWG device may be the same as in Figure 2 although the tuning fork can be replaced by any other suitable type of filter. In FIG. 3, the device SWG is supplied directly by the transformer TB, the primary of which is in series in the anode circuit of the tube VB. The secondary of transformer TB is connected by a capacitor C6 to the secondary of transformer TA, the primary of which is in series in the anode circuit of tube VA. This shifts to 90 one of 1. ' other the fundamental components of the voltages applied to SWG: by the two tubes VA and VB. The reason for this feature will be explained later.



   The output of SWG supplies in parallel three limiter tubes LVA, LV3 and LV '. The grids of these tubes are earthed through a common resistor R5 and three resistors

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 individual R7A, R7B and R7. The waves are connected to the positive voltage source HT through the individual resistors R6A, R6B and R6.



   As in the assembly of FIG. 2, it is possible, if desired, to insert) amplifiers (not shown), either before or after the SWG device.



   Three differentiating circuits (R1A, ClA (R1B, C1B) and (R2, C2), which will produce pulses of short duration, are respectively connected to the anodes of the three limiter tubes LVA, LVB, and LV. The circuits (R1A, C1A) and (R1B, C1B) are connected, also respectively to the suppression gates of the doors: electronic VA and VB. The circuit (R2 ', C2) is connected to a terminal 4
The cathode of the limiter tube LVA is weakly polarized with respect to earth by a positive source BA, the cathode of the limiter tube LVB, on the contrary, is negatively polarized and weakly also by a source BB. The cathode of the third LV limiter tube is directly earthed.

   The polarization differences of the three voltage limiting tubes are small, but sufficient to produce a slight time shift between the front or rear sides of the rectangular waves respectively produced in their anode circuits.



   When signals are. applied to terminal 1 by the external transmission line, the two electronic gates VA and VB are, initially, both open eb the impulses pass through these gates to start the tuning fork of the device SWG If the vibrations of the latter are of low amplitude, the pulses generated in the anode circuits of LVA, LVB and LV will be wide and the two trains applied by LVA t'LVB to the suppression gates of the two doors VA and VB will be offset appreciably l 'relative to each other, as the amplitude of the tuning fork's vibrations increases, the' considered pulses become narrower and sharper '. and the pulse trains

 <Desc / Clms Page number 14>

 are.

   more and more coincidence.



   The phase shift of the circuits at the input and at the output of the tuning fork must be such that, in one of the series, the pulses applied to the suppression gates of the electronic gates appear there slightly before the pulses of the train to be selected and that, in the other series, they appear slightly later.



  The third series, the one collected on terminal 4, must coincide exactly in the temple with the pulses of the train to be selected.



   Thus the electronic door VA is the one which opens in advance and the door VB the one which opens late. The circuit connections are such that, whatever the electronic gate through which the impulses coming from the external transmission line pass, the result will be to shift the impulse trains applied to the reject gates in such a way. that each pulse coming from outside is more and more symmetrically placed between the two corresponding pulses on the suppression gates.

   These last two meet when the amplitude of the vibration of the tuning fork is sufficient and the impulses applied from the outside will therefore have always been solidly framed by those which act on the rejection grids until all are practically in coincidence. .



   The pulses supplied to terminal 4 by the anode circuit of the tube LV then coincide exactly in time with the pulses arriving at the control gate of the electronic gates VA and VB. The pulses taken on terminal 4 will be used to open an electronic further door (not shown in the figure) and this is where the selection of the external pulses will be made, which can then be demodulated or processed in any suitable way. .



   The way the tooth system works will be best understood by assuming that the circuit receives a continuous train of pulses.

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 to select. As has already been said, these are trapped in time between the pairs of pulses on the reject gates of the VA and VB tubes, so that the pulses arriving at the control gates partly pass through each of the two electronic gates which open at slightly different times. The capacitor C6 causes a phase shift of 90 between the two excitation bends supplied to the tuning fork, by the two tubes VA and VB, the resulting excitation wave will therefore be in advance of 45 'in relation to the wave arriving from tube VB.

   Arrangements are made so that the phase delay introduced by passing through the filter and by the circuits up to the gates of the tubes LVA, LVB and LV is equal to 45.



   Suppose alos that a small offset occurs and tends to further delay the pulses applied to the reject grids of the VA and VB tubes. Such a shift may have its origin in the circuits of Figure 3 or even in the pulses, coming from outside. The impulses coming from the outside will tend, then, to pass through the VA tube instead, since this one, which was the electronic gate opening in advance, will now return to associate a little later. A small one will result. phase advance in the wave supplied to the SWG filter and this will slightly advance the pulses applied to the suppressor grids of the VA and VB tubes. We will therefore have an automatic correction.



   If the initial offset had been large enough for the pulses arriving by the external circuit to arrive there completely outside the opening time of the electronic gates (arriving too early or too late to pass through any of these gates;) then the tuning fork would no longer be maintained and would lose its amplitude of vibration, which would have the effect of widening the impulses applied to the grids, suppressing so that the impulses arriving at the grills: the control ones could be replace between the opening pulses and go through one of the electronic doors again.

   The tuning fork would therefore be excited again by one

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 phases and the pulses applied to the suppression grids would shrink and shift, still framing the pulses coming from the outside, as has already been explained.



   A load resistor RL can be placed, if desired, between the positive pole of the high voltage source HT and the point common to the primary windings of the two transformers TA and TB. This makes it possible to collect on a terminal 5, connected to the common point of the primary dice of the two transformers by a capacitor K, the pulses which have passed through the electronic gates.



   FIG. 4 shows a preferred embodiment which is similar in several respects to that of FIG. 3, but which comprises three electronic gates. The two electronic gates VA and VB in figure 4 correspond respectively to ¯ doors VA and VB in figure 3, but they are closed at rest and remain closed except at times when ¯ they are opened by the impulses that the system will send. , on their rejection grids. The electronic gate VC, which is the third gate, is opened when the system is at rest and operates as explained in figure 2, closes as soon as signals arrive, except at times when the system is at rest. will receive impulses on its rejection grid.

   It is therefore this gate alone which will allow starting, but then if the pulses follow one another continuously, the three electronic gates are then also used to let them pass.



   The assembly of the VC tube is quite similar to that of figure 2. Its reject grid is connected to the cathode by a resistor R4C in parallel with a rectifier XC. Both VA and VB tubes (leading tube and lagging tube) do not have a straightener. The three cathodes are positively polarized when the plate current is cut off by the source B3. The three control gates receive external signals via terminal 1 and are connected to the earth through a common resistor R3.



     The SWG filter in figure 4 does not present anything special.

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 EMI17.1
 



  Amplifiers (not shown) can be provided, if necessary, before or after this filter. The voltages supplied to the filter
 EMI17.2
 SWG come in part from the tube VC by the transformer TC, the secondary of which is tuned by the capacitor C5C and are transmitted by the capacitor C6, the role of which has already been studied in the assembly of figure 3. The other power supply of the SWG filter is made by the transformer TD, the secondary of which is tuned by the capacitor C5D and to the primary winding of which the anodes of the two tubes VA and VB are connected in opposition.

   The anodic current of the VA and VB tubes comes from the high voltage battery HT, the HT + pole of which is connected to the midpoint of the primary of the transformer TD. The voltages that VA and VB apply to the SWG filter are
 EMI17.3
 therefore respectively ahead or behind by 90 on that Y2 which is applied to it by the tube VC. '
The assembly of figure 4 comprises 3 limiting tubes mounted in cascade. ;, ¯ The first of cestubes, LVC is commanded by the
 EMI17.4
 output of the filtered SWG and generates trapesoidal waves. These trapezoidal waves are applied to the other two tubes LVA and'LVB by - which are produced respectively, rectangular waves
 EMI17.5
 staggered! 180 .., ', shifted 180 v.



  The pulses derived from the LVC tube by differentiation in the circuit (R1C, C1G) are applied, by capacitor 030, to the reject grid of the VC tube.



   The special unblocking pulses which are applied by the LVA and LVB tubes to the reject grids of the VA and VB tubes
 EMI17.6
 will be the subject of further explanations.



  Pulses from the LVB tube and the differentiator circuit (.R2, C2) can be collected on terminal 4. The use of these impulses is free, as has been explained with regard to FIG. 3. The resistors R6A, R6B and R6C are in series, respectively on the anode circuits of the three limiter tubes.
 EMI17.7
 The resistors, R5A and R5B are load resistors for the

 <Desc / Clms Page number 18>

 LVA and LVB tubes and resistors R7A and R7B are the grid resistors of these tubes.



   The operation of the circuits of FIG. 4 will be explained with the aid of the diagrams of FIG. 5 which represent the shapes of the electric waves W1 to W7. The points where these waves appear are also designated in FIG. 4 by the letters W1 to W7.



     The external impulses arriving at point 1 and which one wishes to select constitute the waves% il. The trapezoid waves, the W2, are obtained in the anode circuit of the first LVC limiter tube. As is known, they originate from sine waves exiting the SWG filter to be applied to the control grid of the LVC tube.

   After differentiation by the circuit (R1C, C1C) the W2 waves become) acute pulses, W3, alternately positive and negative., The positive W3 pulses, alone, are used to open the electronic gate VC at the instant they pass through their maximum, as has been explained with regard to FIG. 1. As has also already been explained, these pulses block the tube VC as soon as the external signals arrive on its control grid.



   The trapezoidal waves W2 are also applied to the second limiting tube LVA of the anode from which emerge practically rectangular waves W4 with a phase opposite to that of the waves W2. W4 waves of opposite phase to that of W2 waves. The W4 waves are applied to the LVB tube and produce in the anode circuit thereof. another series of rectangular waves they which are, in 1 - hase with the waves W2.



   The W2 waves of LVC are also applied in parallel to the two differentiating circuits (R1A, C1A) and (R1B, CIB) through - -, rers which they produce pulses similar to the W3 pulses which are respectively added to the waves. W4 and W5 after these have been appropriately weakened by the networks

 <Desc / Clms Page number 19>

 (R8A, R1A) and (R8B, R1B). The resulting waves, referred to as ,. the names of W6 and W7 are applied to the suppression grids of electronic doors VA and VB.



   It can be seen in FIG. 5 that the waves W6 comprise positive points a which are separated by horizontal parts of negative points which play no role in the operation of the system. The rear flank of the tips a is very steep, while the front flank is much less, being the same as the front flank of the W3 pulses. The W7 waves also have) 'positive points b corresponding, in time, to the points a of W6 waves, but here it is the front flank' which is very stiff, while the rear flank is much less so. . The stiffness of these flanks is increased by the presence of capacitors C7A and C7B which shunt resistors R8A and R8B respectively.



   The electronic gates.VA and VB are respectively released by the points a of the anode W6 and b of the anode W7. As the . front flank of points b is steeper than. that of the points a, it follows that the electronic door.VB will open later than the electronic door VA. We will enter in the same way as the electron gate! - that VB must close, later than the electronic gate VA.



   The W6 and W7 pulses occur naturally only when the amplitude of the tuning fork vibrations is large enough.



   We can well realize the stabilizing role of circuits by supposing that we receive a continuous pulse train.



  These pulses will pass through the electronic gate VC and also, and approximately equally, through the two electronic gates, VA and VB.



  The excitation voltage component of the tuning fork transmitted by these two tubes through the transformer TD will be practically zero since the anodes of VA and VB are connected in opposition on the primary of TD The excitation of the tuning fork therefore comes almost entirely from du, tube VC and is about 90 ahead of the pulses coming from the outside line because of the

 <Desc / Clms Page number 20>

 capacitor C6). Assuming now that a time shift occurs and that the pulses W6 and W7 are relatively late, the pulses W1 will tend to. pass more through the electronic gate VA rather than through the gate VB and the transformer TD will apply to the tuning fork an excitation component which will change the phase thereof.

   The direction of the transformer windings should be such that, under these conditions, the phase of the tuning fork is advanced, which will automatically correct the original offset. The opposite effect would, of course, occur if the original pulse offset
 EMI20.1
 W6 and W7 had been a phase lead.



   It has already been said that the introduction of amplifiers before and after the SWG filter in the arrangements of Figures 2, 3 and 4 is possible, but is not essential. However, it is preferable to
 EMI20.2
 Drop an amplifier tube before the S, IG filter so that the bransformateur which excites the :! filter can work on a practically infinite impedance. This avoids having the filter play the role of load on the transformer, which could have repercussions on the phase settings of the circuits.



   Fig. 6 shows a circuit arrangement with a single electronic gate but differing from that of Fig. 2 in that the SWG tuning fork filter of this figure has been replaced by an independent oscillator which is synchronized by the pulses.
 EMI20.3
 iue 7¯ 'on,: lézi1; '; . 7.e rnonta years,; e of the. fifure 6 on 1 - need for the NLN non-linear u network which was shown schematically in figure 1.



     Examining FIG. 6, we see there the tube V whose cathode is polarized, below the cut-off of the plate current, by the source B. The rejection grid of this tube does not need here to be associated with a rectifier. Electronic gate V is closed at rest. The external signals are applied in 1 to. the control grid, which is connected to earth through resistor R5.



   The SWG filter is here constituted by an oscillator whose tube VO is mounted in a conventional manner. The oscillating circuit includes

 <Desc / Clms Page number 21>

 the secondary winding of the transformer T and the capacitor CO.



  This oscillating circuit is tuned in the vicinity of the frequency .. of repetition of the pulses to be received: Resistor R9 is the gate resistor of tube VO and capacitor K is the usual blocking capacitor.



   The pulses coming from the outside and which pass through the electronic gate V are supplied to the primary of the transformer T and serve to synchronize the oscillations of the tube VO. These are applied to a limiter tube LV which provides roughly rectangular waves which are differentiated by the circuit (C1, R1) to provide pulses to be applied to the reject grid of the tube V. The resistors R6 and R7 are the anode and grid resistors of the LV tube. '
The pulses supplied by the wire 3 to the rejection grid of the tube V must unblock the electronic gate constituted by this tube just at the instants when the pulses that are to be selected appear on its control grid.



   It is necessary that the oscillating circuit of VO is tuned so that 'when VO is not' synchronized, its frequency is not quite 'the same as the pulse repetition frequency,' but is quite close to it. so that they can hang the oscillator. As has already been explained, the electronic gate V is initially closed and the free oscillations of the oscillator VO generate pulses which periodically make the tube V conductive. When the first pulses to be selected appear on the control gate, they will generally find the electronic gate closed because they will not coincide in time with the pulses from VO on the blanking gate.

   But, because of the slight difference in frequencies this coincidence will not take long to occur and then, as soon as the impulses applied to the control gate will have been able to pass through the electronic gate, the oscillator will be synchronized and

 <Desc / Clms Page number 22>

 the coincidence in time of the two categories of pulses will be maintained.



   It will be noted that when the pulses to be selected have ± crossed the electronic gate, they tend to. excite the VO tube in quadrature with the oscillations it generated. Assuming that the oscillator circuit of VO was initially tuned so that the phase of the pulses applied to the suppression grid of V were constantly lagging behind the phase of the pulses at. to select, it will therefore be necessary to arrange so that the effect of the additional control wave is a phase advance of the oscillations of VO, which will correct, indeed, the tendency to delay of these oscillations.



  This is due to a suitable choice of the direction of the primary winding of the transformer. The device is very stable.



   It is possible to collect on terminal 2 the impulses which have passed through the electronic door and on terminal 4 those which will open the electronic door. We will use both in the way we deem appropriate.



   The assembly of FIG. 6 only makes it possible to correct a tendency to phase shift which is either constantly forward or constantly backward, since each of these two cases corresponds in the assembly to the choice of a different direction for the. primary winding of transformer T. If we can be sure that the natural frequency of the oscillator will always be a little higher or even always a little lower than the repetition frequency of the pulses to be received, we can be satisfied with this solution.



    However, these conditions may cease to exist in favor of slight changes in the operation of the circuits and it is preferable to adopt the assembly represented by FIG. 7, which combines with that of FIG. 3, in that it There, use is made of two electronic gates producing compensation effects in opposite directions.



   The assembly of figure 7 is similar to that of the

 <Desc / Clms Page number 23>

 FIG. 6, except that the two electronic gates VA and VB have their anodes connected in opposition to the primary winding of the transformer T. The differentiator circuit directly supplies the opening pulses of the gate VA to the rejection grid of this tube, but it supplies them to the rejection grid of the tube VB only through a delay network DN of which the characteristic impedance is, equal to R1. The VA tube therefore constitutes the electronic advance gate and the VB tube the electronic delay gate.



   If it is assumed that the oscillator has shifted and that the pulses to be received are passing through the VA tube, the oscillator VO will receive a quadrature excitation and the direction of the primary winding of the transformer T must be as in this case, the phase is advanced at the output of the oscillator. This will tend to slightly advance the pulses applied to the electronic gate suppression gates and, therefore, the pulses to be received will now tend to pass through VB, which will provide a tendency to delay at the oscillator VO. It can therefore be seen that the system is stabilized and that the pulses to be received are trapped between the two series of pulses for opening the electronic gates, whatever the tendency to phase shift in one direction or the other.

   Compensation is automatic.



   The terminal 5 makes it possible to collect the pulses which have passed through the electronic gates: this terminal is connected through a blocking capacitor K to the load resistor, RL, which is in series on the anode power supplies of the VA and VB tubes.



   The terminal 6 makes it possible to collect pulses which coincide with the pulses to be received on a prïse situated in the middle of the network DN.



   The oscillator shown in Figures 6 and 7 is of a very simple type. It is obvious that other types of oscillators can be used provided only that they can be controlled in the manner which has just been explained by the pulses to be selected.

 <Desc / Clms Page number 24>

 



  The very simple oscillator of Figures 6 and 7 may not be sufficiently stable to allow one to be selected with certainty. train of pulses given when the latter is mixed with other trains' whose repetition frequencies are close to its own.



  This is why an oscillator controlled by a crystal or by a dia- sion and having a great stability, can be regarded as more suitable.



     In addition, it may be desirable to provide a wave filter (not shown) between the electronic gates and the oscillator in order to remove the latter from the control action of the transients.



   The arrangements which have been described so far sometimes have a tendency to "pump", that is to say that there is a continual swaying backwards and forwards of correction. .Lion. A phase shift of the opening pulses of the electronic doors immediately leads to a corrective reaction by the waves supplied to. the SWG element (filter or oscillator).



  The effect of this corrective reaction is not instantaneous and therefore persists until the correct phase is restored. At the time this occurs, however, the phase of the electronic gate opening pulses can be rapidly varying and may exceed the correct value before the reverse correction has taken effect.

     To be able to cope with large phase changes in filters or frequency changes in oscillators, as well as to achieve high accuracy in coincidences, it is necessary that the corrective forces are large enough and act quickly. and since the systems on which these forces act are lazy, the result is a continual swing in the circuits that are said to be pumping it out.



   The arrangements which will be described offer the possibility of applying the corrective forces in such a way that they cannot change rapidly. The control system will therefore no longer be lazy with regard to the control and the circuits will not "pump".

 <Desc / Clms Page number 25>

 



   Figure $ is a modification of Figure 2 where means are added to prevent pumping. The parts which are common to the two figures do not need to be described again.



  The excitation of the SWG filter comes from a pair of amplifier tubes A1 and A2 whose anode circuits are connected in parallel.



  Tube A2 is polarized beyond cutoff by cathode source B3. This tube will preferably be of the variable gain type.



  The Al tube is biased for constant amplification by a resistor of the normal type shunted by a capacitor and placed on the cathode. The pulses which have passed through the electronic gate V are applied directly to the control grid of tube A1 and through a small capacitor C6 to the control grid of tube A2, so that these two tubes are excited in quadrature.



   A rectifier Q, which can be a diode (or any other type of rectifier) is associated with resistor R1O and capacitor C1L so that the bias potential of the grid f grid of tube A2 is unidirectional, although provided by the pulses transmitted by the transformer T. This potential should make the control grid positive and counterbalance the positive potential of the cathode. The circuit L3, C9 is tuned to the frequency of repetition of the pulses to be received and its role. is to prevent grounding of the control grid by signal waves.



     We see that, when the control pulses start to pass through the electronic gate V, the tube A2 is blocked, but it unlocks when the positive polarization is established on its control grid and the tube A2 then applies to the tuning fork SWG excitation waves of increasing amplitude and in quadrature with those applied to it by amplifier AI. The resulting excitation wave will therefore advance in phase until equilibrium is reached.



   The time necessary to obtain this equilibrium will depend on the time constant of the circuit R1O, C1O which must be

 <Desc / Clms Page number 26>

 tall enough. Any subsequent shift of the pulses opening the electronic gate V produces a change in the amplitude of the pulses passing through the transformer T, but this change is not immediately reflected on the tube A2, because of the time constant of the circuit (R10 , C10). When the change of excitation by A2 occurs, the phase of excitation of SWG will be changed and the offset correction will be obtained but at. Due to the delay introduced in the application of the corrective force, the circuit cannot pump.



   It will be understood, of course, that the network, u NLN of figure 1 is not necessary with the assembly of figure 8, since the desired changes of the phase correction are produced by the tube A2 as we have just explained. . With the exception of the delay effect introduced to avoid the pumping effect the circuits of figure 8 operate like those of figure 2 and equilibrium occurs when the pulses to be received coincide with the front of the pulses of electronic door opening.



   FIG. 9 represents a modification of the circuits of FIG. 3, in which the means intended to avoid pumping have been introduced. The process is the same as for, figure 8. Items which correspond in both Figures 9 and 3 have the same reference numerals and will not be described again.



   The electronic gates VA and VB are connected to the tuning fork SWG by a pair of amplifier tubes A1 and A2 with variable gain and by a rectifier circuit mounted in differential and comprising two similar rectifiers QA and QB of any type, for example diodes. The anodes of the VA and VB tubes are connected to each other by two equal resistors R11A and R11B, the common point of which goes to the primary of the transformer TA then through it to a load resistor RL and to the HT + pole of the high voltage HT source. The resistors R11A and R11B therefore constitute a differential mounted output load for the anodes of the tubes.

 <Desc / Clms Page number 27>

 VA and VB and transformer T is in the common branch of this differential assembly.



   The differential rectifier circuit comprises the two rectifiers QA and QB, the resistors R13A and R13B and the capacitors, C11A and C11B. These elements are connected to a pair of load resistors R12A and R12B in series and equal and whose common point is to earth. Each of the load resistors R12A and R12B is shunted by a capacitor K.



   The amplifier tube Al is driven directly by the secondary winding of the transformer TA Tube A2 operates in quadrature of A1 because of the capacitor C6. The cathodes of the tubes A1 and A2 are polarized by a resistor of the normal type, in series and a condensate eur. The control gates receive a variable polarization by the circuit of the rectifiers, according to the way in which the pulses pass the electronic gates: VA and VB.

   Under normal conditions, when equilibrium has been established, the impulses also pass through the two gates and the opposing voltages which develop in resistors R11A and R11B are equal, so that under these conditions , no bias voltage is applied to the control gates of the
A1 and A2. The tubes A1 and A2 therefore then have exactly the same amplification gain.

   But if a shift occurs and the external pulses tend to pass through tube VB rather than tube VA, the rectifier circuit makes the grid of Al slightly positive and that of A2 slightly negative, so that the flow rate of Al exceeds that of A2, which delays the phase of the force operating the tuning fork SWG and will correct the offset. A reverse shift would have produced the opposite effect, but, as in the case of Figure 8, the time constant of the rectifier circuit delays the application of the corrective force, thus suppressing the pumping effect as. we have already explained it.



   Note that the choke coil LB corresponds,! in the

 <Desc / Clms Page number 28>

 figure 9 to the transformer TB of figure 8 and that it is tuned by the capacitor C5B on the repetition frequency of the pulses to be received.



   Figure 10 shows a modification of the part of the figure 9 located above the. line X --- X The conductors crossing this line are identified in the two figures by the same reference letters a, b, c, d, e. In figure 10, the SWG element is an oscillator a, rather than a filter as in 1a. figure 9. It has already been explained with reference to FIG. 6 that when an oscillator is used the electronic gates are initially closed. The rectifiers XA and XB of figure 9 are therefore not necessary and are omitted with the assembly of figure 10.



  The circuit of the rectifiers QA and QB applies a variable bias potential to the control gates of A1 and A2. The transformer TA is tuned by the capacitor C5A to the repetition frequency of the pulses to be received. The two K capacitors are blocking capacitors.



   The oscillating tube VO is mounted as seen in FIG. 7. The anodes of the amplifier tubes A1 and A2 are connected in parallel to the primary winding of the transformer T of the oscillator. The oscillator flow is applied to the limiter tubes as in Figures 3 and 9.



   When stable equilibrium has been reached, the signals also pass through the two electronic gates and there is no bias voltage generated in the circuit of the rectifiers QA and QB for the control gates of the amplifier tubes Al and A2 which then have the same gain. The control action of the oscillator by the transformer T is therefore zero, since the two tubes A1 and A2 are in opposition to this transformer.

   If a shift occurs in the pulses to be received and they tend to pass -¯car VB rather than VA, the control grid of A2 will become slightly positive and that of Al slightly negative (as a result of

 <Desc / Clms Page number 29>

 the action of the rectifier circuit QA and. QB). The transformer
T will therefore apply to the oscillator a small control force whose phase is determined by A2. If, on the contrary, the pulses tended to pass through VA rather than through VB the phase of the action exerted by the transformer T sure the oscillator would be opposed, since it is the tube Al which would determine it.



   It has already been explained with regard to FIG. 7 that the phase of the action exerted by the transformer T on the oscillator is in quadrature with the oscillations generated by the latter and that the direction of the windings of the transformer T must be chosen from such that this action corrects the effects of the lag. As before, the delay resulting from the time constant of the rectifier circuit will be sufficient to prevent the system from pumping.



   Figure 11 shows a modification of the assembly of Figure 6. In figure 11 the transformer T is not part of the oscillating circuit but it supplies waves which are rectified in a circuit comprising the rectifier Q, the resistor R1O 'is the capacitor C1O, which supplies the control grid with the amplifier A2 a variable positive bias voltage (across the tuned circuit (L3, C9). The secondary of transformer T, as well as inductance L3 and C9, on the repetition frequency of the pulses to be received. The arrangement of these elements in Figure 11 is the same as in Figure 8.

   The oscillating tube
VO is associated with a normal oscillating circuit (LO, CO) which is tuned to a frequency close to the repetition frequency of the pulses to be received and provides tube waves. LV limiter exactly as in figure 6.



   The control grids of the A2 and VO tubes are lightly coupled to one another by a small capacitor C16 whose role is to supply the amplifier A2 with a power supply, in quadrature. that of the oscillator. The anodes of these two tubes are connected directly to each other so that the oscillating circuit

 <Desc / Clms Page number 30>

   (L10 'C10) receives from tube A2 a control wave which is in quadrature with the oscillations.



   The amplification of the tube A2 is controlled by the signals: it passes through the electronic gate V. Any shift in the pulses which open this gate automatically produces a compensation, because of the variation in polarization which results from the, va. - amplitude riation of the pulses that can pass through the electronic gate. All this has already been explained, and the delay effect is added by the rectifier circuit.



   A load resistor RL can, as before, be added in the anode circuit of the tube V, in series with the primary of the transformer T. The finished ,! 5 is connected through capacitor K to the point common to this resistor and to the primary winding of T, and the pulses which have passed through the electronic gate can be collected on this terminal. It is also possible: if a resistance RL has not been fitted, these pulses can be collected on a terminal 2 mounted as seen in FIG. 2.



   In certain multi-channel and pulse transmission systems, trains of pulses having the same repetition frequency are used for the various channels and which are transmitted simultaneously but spread out over time so that all the pulses of all the trains are sent at different times. Such trains are sometimes identified individually by modulating each train by a characteristic wave, that is to say by a sine wave having a particular frequency 'which will identify the train and which can be conventionally referred to as no. 'of "identification tone".

   The modulation method employed can be any, for example amplitude modulation, time modulation or phase modulation, or a combination of these various methods.



   The identification tone can be added to the modulating wave constituting the message. For example, in the case of a

 <Desc / Clms Page number 31>

 telephone channel, the identification tone can be a 50 p / s sine wave or any other; infra-vocal frequency. It is also possible, in the case of a pulse distributor system, to reserve one channel exclusively for phase identification and to use the synchronized reception system to provide the other channels with suitable electronic gate covers or the de-energizing waves. - modulation.



   The setup of Figure 11 can be used to select a particular train of pulses in an ID tone pulse transmission system. The only modification to be introduced is that the transformer and the coil L3 must be tuned by the capacitors C5 and C9 on the frequency of the identification tone, instead of being tuned on the repetition frequency. impulses.



   Assuming that the VO tube has been set to oscillate at a frequency a little lower than the pulse repetition frequency, the pulses generated for the opening of the electronic gate V are continuously shifted so that their phase lags. compared to that of the pulses applied to the control grid of this tube. This takes place until the two categories of pulses coincide and it can;

  'appear amplified pulses in the anode circuit of the V tube. If the signals to be received were amplitude modulated or long-term, it is obvious that the amplified pulses would have the same modulation.' If the applied signals were modulated in phase they would appear at a variable instant on either side: from the rear flank of the impulses and opening of the electronic door. In all cases, of course, the pulses which will pass through the anode circuit of the V tube will be amplitude modulated by the identification tone; The modulating component will be extracted therefrom by the tuned transformer T and rectified by the circuit (Q, RIO, CIO) to control the amplifier tube A2.

   It's obvious that

 <Desc / Clms Page number 32>

 
 EMI32.1
 the modulating tone \. which appears in the anode circuit of the tube V manifests itself there with an amplitude whose variations are similar to those of the amplitudes of the pulses themselves (va-
 EMI32.2
 riation which corresponds to the variation of:,: 1} 8, s: e of the electronic gate opening pulses). The operation of the rectifier circuit is the same as that which has been described, except that the frequency of the wave which will control the tube A2 is here that of the identification tone instead of being the repetition frequency. impulses to be received.
 EMI32.3
 



  Thus, when the si :::: nal applied to the tube V contains at the same time several trains of pulses all having the same repetition frequency of pulses, it is only, among all these trains, that which has the identification tone on which is granted the transformer T which can pass through the electronic door; then-
 EMI32.4
 that it is only this train that can operate amplifier A2.



   The pulses modulated by the signals constituting the mes-
 EMI32.5
 sage and which have passed through the electronic gate V, can be collected on terminal 5, they can also be received and unmodulated in a circuit sy; ccis.l (not shown on fl5-j; vi% # u 11), which would be controlled by pulses collected at terminal 4, for example.



     FIG. 12 is a modification of FIG. 7, comprising the use of a differential rectifier of the type shown in FIG.
 EMI32.6
 9. Also shown in Figure 12 W1 Lype of oscillator lamp controlled by a. tuning fork, although any other type can CéJJ r:; ro1 <: iYt, be used.



  The anodes of the two amplifier tubes A1. and A2 30nt connected in parallel with the input coil L1 of the oscillating circuit (Ai, C17) tuned by the capacitor C17 to the repetition frequency of the pulses to be received. The tube control grid
 EMI32.7
 oscillating goes is slightly coupled, by a small capacitor Cl6,

 <Desc / Clms Page number 33>

 to the two control grids of the tubes A1 and A2. This capacitor C16 is in series with the primary of a TE transformer, the secondary of which is tuned by the capacitor C15 to the repetition frequency of the pulses to be received. This assembly provides a quadrature excitation of the two tubes A1 and A2 by the oscillator.



   When the pulses also pass through the electronic gates VA and VB, the bias voltages of the control grids of the tubes Al and A2 are zero, so that the flow rate of these tubes is zero and that 1 il ln 1 y has no control anode applied to the oscillator.

   Sm an offset occurs, the voltages applied by the electronic gates VA and VB to the differential rectifier circuit cease to balance and the control gates of the tubes A1 and, .A2 are polarized in opposite directions from each other. , which causes the application to the ocillator of a control wave in quadrature with its own wave and corrects the offset. '
FIG. 13 represents an assembly similar to that of FIG. 12 but adapted to the selection of a train, of pulses designated by an identification tone in a transmission system with several channels of the species. which was mentioned in connection with the examination of Figure 11.

   The assembly of figure 13 differs from that of figure 12 in that the oscillating circuit associated with the tube VO is here of the type of that of figure 11 and ,,, is connected to the transformer T2 by a winding L4 strongly coupled to the LO winding instead of it ', be connected by a capacitor such as the capacitor C16 of figure 12. These differences are arbitrary and one could just as easily have adopted in figure 13 the same mode of coupling of the oscillator as in figure 12.



   The differential rectifier circuit which controls the two amplifiers A1 and A2 of FIG. 13 essentially consists of two rectifier circuits similar to that of FIG. II and mounted in opposition. The resistors R14A and R14B connect them respectively to the control gates of the tubes A1 and A2. The numbers

 <Desc / Clms Page number 34>

 reference already used in Figure 11 have been retained for the corresponding elements of Figure 13 by adding the letter A or the letter B as appropriate. The resistors R12A and R12B, each of which is shunted by a capacitor K, form for the two rectifiers, a load whose midpoint is earthed.



   The anodes of the VA and VB electronic gates are raised by the primary windings of the transforma Their TA and TB at the two ends of the primary of a TF transformer, the medium of which is supplied by the positive pole HT of the high voltage battery through the primary d A transformer TG The secondary windings of transformers TA and TB are strung by capacitors C5A and C5B on the frequency of the identification tone. Rectifiers QA and QB connect to these two matched circuits.



   It will easily be understood from the explanations provided with regard to FIGS. 11 and 12 that the opening pulses of the electronic doors will "slide" in phase until the train of external pulses marks by the identification tone. tion has been received. Then the identification tone will be selected by transformers TA and TB rectified and applied to the control gates of tubes A1 and A2. As long as the pulses coming from the outside are symmetrically framed by the two series of pulses, opening the electronic gates the voltages applied to the gates of the two tubes A1 and A2 will remain equal.

   If a shift occurs and the pulses from outside tend to go through VA rather than VB, the gate voltage will rise on Al and fall on A2; from which will result, as one explained, a corrective force which will be exerted on the oscillator.



  If the offset had been in the opposite direction, the corrective force would also be in the opposite direction.



   The role of the TF and TG transformers is to extract the modulation from the pulses which have passed through the electronic gates.

 <Desc / Clms Page number 35>

 



  The TF transformer being differential connected will be used when the phase of the external pulses is time modulated, because in this case the flow of the two electronic gates will provide a resulting constantly variable flow despite the opposition. As will be understood, the delay due to the rectifier circuits will be sufficient to prevent the opening pulses of the electronic stations from following the rapid variation of the phase modulation, over time.



   When the external pulses are modulated in amplitude or in duration, it is the transformer TG which will be used since in this case the rates of the two electronic gates both vary in the same direction as the modulation.



   If we know in advance what will be the type of modulation of t; external impulses which one will have to receive, one can of course eliminate one of the two transformers TF or TG.



   In all the embodiments of the invention which have been described so far, the division of the frequencies of the train of pulses applied to the electronic gate can be obtained by tuning the filter circuit or that of the oscillator to a sub -harmonic of the pulse train offered. The frequency of repetition of the opening pulses of the electronic door will then be 1 / nth of that of the external pulses and the door (s) will only be opened to let the nth pulse of the; train. The device will operate as if all the other pulses in the train did not exist.



   The assemblies which have been the subject of Figures 8 to 13 contain a rectifier circuit whose time constant was high to introduce a certain delay and thus provide protection against the pumping effect. When, in the composite wave applied to the electronic gate, there are trains of pulses the repetition frequency of which is very close to that of the train that one wishes to receive, or else when there is has a lot of interference, it is necessary to make the assemblies with a very selective filter,

 <Desc / Clms Page number 36>

 or a very stable oscillator, so as not to risk selecting a train that is not the one you want,

   or else to suppress interference. In these cases one must use a tuned circuit (or any other resonator) of very low decrement, for example a tuning fork with electromagnetic excitation, or a crisper.
 EMI36.1
 tal pié7, Electric. These low decrement resonant elements are a cause predisposing circuits to the pumping effect because they involve a delay in the response to. the force that promotes pumping.



   It can be shown that this pumping tendency can be greatly reduced by mounting a small aperiodic shunt on the resonant element. This only modifies very slightly the characteristic curve of the resonant element in the vicinity of the
 EMI36.2
 resonance and said shunt is however sufficient to guarantee a response without inertia to sudden variations of excitation.

   The effect of a sudden change of excitation is then to produce at the output of the resonant element a small but instantaneous change, which will thereafter vary only very slowly, while the resonant element assumes its new regime. 'balanced. The leakage in said shunt must therefore be sufficient for the. small quick action that
 EMI36.3
 is sufficient itself to suppress the pumping.



  Figure 14 provides an embodiment of the shun- <> i, ç.e,; ji çié 1; = ç1xe 1 # n. Thread, tx ci-ii, j;: ar vexer: 1.1 Lili t ;;. 'Circuit. ; e The SF block designates a selective filter, such as, for example, an electromagnetic control analogous to that of the figure, or an oiésoé7¯etric crystal, ue or any other resonant system with low decrement which would considerably weaken the waves of all frequencies, except those which are in the immediate vicinity of the frequency: resonance.

   Between the input terminals of the SF block
 EMI36.4
 is derived from. diagonal of a bridge of i, r? ea, tSt01'le constituted by the primary bearing with central tap of a transformer ti in parallel with 1019 a potentiometer P with variable tap and a differential capacitor CD. The secondary of the TH transformer is in series

 <Desc / Clms Page number 37>

 on the output of the SF block.



   If the bridge: ': is balanced, exactly no effect will occur. But if the bridge has been slightly unbalanced, either by the potentiometer P or by the capacitor CD, a small fraction of the waves entering. $ 0 will be diverted to the bridge with an amplitude and a phase which will depend on the mode and the mode. degree of imbalance of the bridge. This provides a means to obtain aperiodic bypass which is not affected by the selective action of the SF element.



   Note that the bridge circuit of FIG. 14 is connected in parallel on the input of SF and in series on the output of SF. It is obvious that it can be connected in series or in parallel at will, either on the input or on the output of SF.



   It is also evident that even in the absence of a special bridge circuit, there is still a small direct transfer of energy between the input and the output of the SF element by capacitors or other couplings. who cannot; always be completely avoided. We could, if we wanted, adjust the bridge -to neutralize the direct transfer and, in this case, the tendency of the circuits to pump se-. rait maximum. Such neutralization is obviously undesirable.



   The unbalance adjustment of the bridge is done as follows: we start by preventing any transfer by the element, SF - for example, by blocking the tuning fork if the element SF is diapason, or by disconnecting a wire. suitable if this element is a filter. The potentiometer P and the capacitor CD are then adjusted so that the "leak" is zero. The potentiometer is then moved in a direction such as the trailing line; which will manifest itself is of the same phase as the normal output of the resonant element SF. The exact equilibrium which was first achieved by the operation of the capacitor CD cancels all the quadrature currents which would bypass the resonant element SF and it is thus ensured that the phase of the flow of SF remains constant. while it is established.

   If the balance of resistances remained also exact the circuits which control

 <Desc / Clms Page number 38>

   automatically phase in the various assemblies which we have described would tend to produce a slow pumping of the phase due to rapid changes of phase in the frequencies close to the resonance for which the resonant element on the contrary marks a strong inertia. By making a small leak through the bridge in phase with the flow rate of the SF element, it is possible to reduce the magnitude of the phase change in the total circuit and thus prevent slow pumping. But, if we made an excessive leak,

   it would tend to. rapid pumping, or throbbing, occurs due to loss of selectivity resulting from the magnitude of the leak. One can, in practice, find a suitable setting which will seriously reduce the tendency of the circuits to pump.



   FIG. 15 represents another assembly of the bridge in which a piezoelectric crystal constitutes a selective filter provided with an aperiodic leak according to the principle used in FIG. 14. The bridge consists of the two halves of the secondary winding of the transformer. TH, tuned by the variable capacitor 022, and by the two parts of the potentiometer P, one of which is shunted by the crystal Z and the other by the variable capacitor CI '!!.

   If the bridge is balanced for a frequency far from the resonant frequency of the crystal, the flow of the system (whose output terminals OUT are on the diagonal of the bridge) will be zero, except when we are in the vicinity of the resonant frequency. , to which the crystal will effectively short-circuit one of the arms of the bridge. The aperiodic leak is created, as explained in connection with FIG. 14, by slightly moving the grip of the po- tentioneter with respect to the equilibrium position.



   In the arrangements of Figures 14 and 15, capacitor keys (not shown) can be bypassed; if necessary, between the input terminals or between the output terminals of the device, in order to tune the device. The details of the assembly adapt 2. the particular nature of the element: -elective

 <Desc / Clms Page number 39>

 SF. It is possible, as required, to add amplifiers (not shown) to the input or to the output thereof.

   By connecting the input terminals and the output terminals by a suitable amplifier, the circuits of Figures 14 or 15 constitute an oscillator which can be used in any setup where the rectangle SWG is an oscillator and not a filter and which overcomes the tendency to pump the selective element, due to the aperiodic leak.



   The arrangement of Figure 14 is found to be particularly effective in the assembly of Figure 12. In this arrangement, in fact, the tuning fork oscillator cannot create a rapid beat because of the time constant of the rectifier circuits. By then adjusting the leak as has been explained, the slow pumping balances which could be transmitted by the control circuit are eliminated.



   In the arrangements of Figures 1 to 13 the; The rate of frequency change within which synchronization can be maintained depends on the amount of phase control that can be achieved and the magnitude of the change in phase change in the selective element. If the latter cause could be eliminated, it would be possible to increase the importance given to phase control.



   Figure 16 shows a selective amplifying circuit, in which the selectivity provided by a tuning fork will be equivalent to that of the arrangement to be had in figure 2, but without the variation in frequency of the phase change which was inherent in the simple arrangement. in figure 2.



   Figure 17 is a modification of the part of Figure 16 framed by a broken line. This modification makes it possible to use for the selectivity a piezoelectric crystal mounted as seen in FIG. 15. The wires a, b, c, d, e, f which cross the frame in broken lines carry the wires. same reference letters in both figures 16 and 17.

 <Desc / Clms Page number 40>

 



   The circuits of Figures 16 and 17 could possibly be modified to employ other types of resonant element, the principle of operation remaining the same.
 EMI40.1
 



  Looking back. 1a fi [J; ure 16, we see there, an electrically excited tuning fork F mounted like that of FIG. 2, except as coil 15 loosely coupled with coil L1 and an (optional) capacitor C17 intended for tune the input circuit.



     The energy coming out of the tuning fork circuit excites in parallel
 EMI40.2
 lele the control gates of the two amplifier tubes with variable j-gain Al and A2, by means of resistors and capacitors R18, Cl8 and R19, 019 which are chosen so that Al is excited with a phase delay of 45 - The anodes back two tubes are connected in - '.' a3'alICZ.C: and reach the HT pole of a high voltage source through the primary of the transformer
 EMI40.3
 TJ. The cathodes of both tubes are biased for normal amplification by the usual capacitor-resistance circuit.
 EMI40.4
 



  The control gates receive a voltage of 1..ola "L, isa, - tion variable by the circuit of the bridge rectifiers in which there are the rectifiers QA and QB; the resistors RIOA and Ri oB, and the capacitors C10A and C10B mounted exactly as in figure 15. The resistors R20A and R20B are load resistors for the rectifier circuit They are shunted by condensers.
 EMI40.5
 ; ya.ieu: =; 5 He and their common point is connected to the earth.



  The rectifiers QA and QB are excited in opposition by a
 EMI40.6
 transformer TK whose loose-fitting primary L6 is connected Il '' The secondary winding S2. of the transformer TJ forms the diagonal of the bridge c <> i "isi, ii .iu,>, ar the circuit of the rectifiers. The bo- bines Ll and L2 as well as transformers TJ and TK are tuned to the frequency of repetition of the pulses by the capacitors
 EMI40.7
 Gl'7, 04, 021 and C '? 0.



  When the tubes 1 \ :. and A2 have equal polarizations, t:?. 10Y? J3X ';: fcl will be in';, j * a, a (; with the Jé0iL of the circuit a Ji8¯e, sor ;.

 <Desc / Clms Page number 41>

 in the 'coil L2 as well as' with the voltage' centered in the circuit of the tuning fork. As the two voltages applied by transformers TJ and TK to the rectifier circuit are quadrature, there will be no potential difference between points A and B and the control gates, of the two tubes A and B will be at same potential.



   Now suppose that. the pulse repetition frequency increases slightly. This causes a delay in the phase of the voltage at TJ so that the voltage applied to QB is greater than that applied to QA. Point B becomes positive with respect to point A which increases the gain of A2 and decreases that of Al '. This, in fact, slightly increases the phase of the voltage applied to TJ and the variation is compensated for. The opposite effect would obviously occur if the pulse repetition frequency were to decrease.

   Thus, the flow which is collected on the secondary Sl of the transformer TJ is always exactly in phase with the energy applied to the terminals of L1 at the input of the system, despite the phase variations introduced by the circuit of the tuning fork when the energy applied to the input experiences variations in frequency. Clearly, phase correction will occur for any variation resulting from a difference between the resonant frequency of the tuning fork and the frequency of the pulses, applied across L1.



   Similar results are obtained whatever the nature of the resonant system, placed inside the box with dashed lines in figure 16. For example, with a crystal filter of the type shown in figure 15, and the slightly modified assembly of which is the subject of figure 17. Coil L5 is, as in Fig. 16, loosely coupled to transformer TH and still provides the quadrature link to transformer TK. The L8 choke coil, which replaces the L2 coil in Figure 16, serves as a shock coil to prevent the crystal from being short-circuited through the rectifier circuit. The assembly of figure 17 operates in a completely analogous fashion to that of figure 16.

 <Desc / Clms Page number 42>

 
 EMI42.1
 



  It is obvious that the 1 =, on.> Aj <; = 4.e la: "1 = re 16 with any type of resonant element can be used in the embodiments of figures 1.] µ l Oll17 y constitute the SWG element when it is a filter, or else as an oscillating circuit when i (ji "l G is an oscillator. In addition. de é 1. éS. explained ;; jā, z. the figures 14 and b 1 can, if desired, add an aperiodic shunt to this assembly.



   Finally, it should be pointed out that if the invention was mainly considered as offering a means of selecting a train by
 EMI42.2
 particular impulses in a signa ,! arriving composite; it i:, <ut also serve to synchronize an oscillation generator.



  Thus, for example, a certain number of oscillators situated in different places and connected to one another by transmission lines, or by radio junctions or by any other communication channels.
 EMI42.3
 communication; can be synchronized by transmitting a t, -Fp, i, v of pulses on the link channels. The oscillator VO in the figure can r <-; i: oeé.sent-er, for example, the oscillator of one of the stations.



  It will be provided with a suitable output circuit by means of an additional winding, not shown on the transformer. The synchronization pulses will be applied to terminal; m 1.



  If all the oscillators of the network are mounted from <; ; 1 1:; way, the flow rates of each will be exactly synchronized. Note that it is possible to tune an oscillator to a sub-mul-
 EMI42.4
 tuple of the repetition frequency of the synchronization pulses and that the oscillators in the network can all be
 EMI42.5
 tuned on different sub-multipds.



   It is obvious that any of the other arrangements described above and in which SWG is an oscillator could be adapted analogously to the control by a train of synchronization pulses.
 EMI42.6
 



  The expression "electronic gate". Which has been used is er; '' j .. 'nd J.' un> 1, 'uii.> Which are t. # ;. ; , l, 1 <.; i> .Il: 1:; des; s 1; j. he. r # L o; .i from

 <Desc / Clms Page number 43>

 outside and which is polarized at the cut-off (or may become so) so that the signals which are applied to it cannot pass, but which is periodically unblocked to allow only certain pulses to pass. The tube is released by special impulse trains which have been called electronic door opening impulses.


    

Claims (1)

ABSTRACT. The invention relates to systems for receiving electrical pulses and makes it possible to select a particular train of pulses from a complex signal to the exclusion of other trains of pulses as well as interference. The invention allows, on a subsidiary basis', to subdivide the frequency of a train of pulses. The device of the invention comprises a tube operating as an "electronic gate" that is to say only becoming conductive to allow the desired impulses to pass and at the very moment when these impulses occur, all other impulses or interference thus being found. eliminated. According to the principles of the invention, a device is provided capable of selecting a train of regularly spaced electrical signaling pulses. The device includes means for applying the pulses to one. circuit where there is an electronic gate, means for generating a sine wave, means' to derive from the sine wave pulses applied to the electronic gate in order to open the latter for the admission of the pulses which the we want to receive and exactly when they arrive and finally means so that the pulses which have passed through the electronic gate can synchronize the sine wave on the selected pulse train. The invention also provides a frequency divider <Desc / Clms Page number 44> EMI44.1 of a train of electrical pulses in which a sine wave is inserted, the frequency of which is exactly the n-th sub-multiple of the repetition frequency of the train of incoming pulses, n being an integer. The sinusoidal wave thus generated will then be transformed into pulses which will be used to control the opening of a EMI44.2 electronic door which must not be opened until the arrival of each nth external impulse, the impulses having been thus admitted to. pass through the electronic gate used to synchronize said sine wave. EMI44.3 The invention also comprises a device for the rc8} jlJiün of a signaling pulse system; This is a multi-track system, each of the channels of this bern system working with the same repetition frequency and at least one of the pulse trains of the system being identified by a modulated identification tone. It also uses synchronization means, normally inactive, to bring the sine wave into synchronism with the train of pulses to be selected and means controlled by the identification terminal to make it effective. synchronization. The invention also provides an arrangement capable of syn- EMI44.4 chronize a yenerator of oscillations 3 ;; ràc <a to a source of regularly repeated synchronizing pulses, this source being linked to the generator by a normally blocked circuit. Means EMI44.5 are provided so that the oscillations of the generator a, h iî7.r; rlt. of the derivative pulse trains, and to make use of the latter EMI44.6 to unblock the circuit connecting the source to the generator, this d0l)] (JCB.é,; 8 being made in such a way that only one of the synchronization pulses will be admitted per cycle of the oscillations of the generator in the-) aim to synchronize this one. The invention further provides an arrangement for synchronizing EMI44.7 several oscillations generators, in 1) n TJonl: 'é3.C' '' j or lesdius' "<3- ne'CD.tll1J.;: S 50: nL linked together by one or more lines of com- munication and where a source of the electrical impulses of <Desc / Clms Page number 45> regularly repeated synchronization debits on the 'or channels leading to the generators. The arrangement comprises several normally blocked circuits respectively connecting the generators to the track or to the communication channels. Each of the generators delivers sinusoidal currents from which trains of derived pulses are drawn, which serve to unblock the corresponding connection circuit so that only one synchronization pulse will pass during each cycle of the oscillations of the generator. generator in order to synchronize it.