US2462111A - Multichannel pulse distributor system - Google Patents

Multichannel pulse distributor system Download PDF

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Publication number
US2462111A
US2462111A US602803A US60280345A US2462111A US 2462111 A US2462111 A US 2462111A US 602803 A US602803 A US 602803A US 60280345 A US60280345 A US 60280345A US 2462111 A US2462111 A US 2462111A
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United States
Prior art keywords
pulses
pulse
channel
network
valve
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Expired - Lifetime
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US602803A
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English (en)
Inventor
Levy Maurice Moise
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International Standard Electric Corp
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International Standard Electric Corp
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J3/00—Time-division multiplex systems
    • H04J3/02—Details
    • H04J3/04—Distributors combined with modulators or demodulators
    • H04J3/042—Distributors with electron or gas discharge tubes

Definitions

  • the present invention relates to multi-channel electrical pulse communication systems.
  • the channels are discriminated by the times of occurrence of the respective pulses within a cyclic period and the intelligence or" a channel is transmitted as a modulation of the pulses, for example the pulses of a channel are time-phased within predetermined time intervals in accordance with the instantaneous amplitude of the signal wave of that channel.
  • Arrangements for successively and cyclically bringing the channels into use are known as distributors, there being normally a distributor at the transmitting and receivingends of the system workin in co-operation.
  • the distributor may take the form of a delay network.
  • a delay network may comprise a four terminal passive transmission network or artificial line which retards the passage of an electrical current propagated therethrough, and comprises a plurality of series connected cells made up of electrical condensers and inductances and preferably alike each of which retards the current by predetermined, preferably equal time intervals. If an electrical pulse is applied to the input terminalsoi the delay network, .at various tapping points along the network pulses may be obtained which are delayed by time intervals depending upon the number of cells through which the pulse has passed up to a specified tapping point. The pulses obtained at the various tapping points are then applied to bring the channels of a multichannel system successively into use. If the network has a large number of cells and theoretically, an-infinite number, then being equivalent to a transmission line, the pulses suffer very little distortion.
  • the distor- .tion is small if'the cut-off frequency of the network-is greater than, for example megacycles andconsists of some 3000 cells. Such a number of cells is too great for practical purposes, and the fewer the cells for the same delay, the greater the distortion of the pulses which involves the shaping and timin of the pulses and their durations with consequential efiects on the time-phas ingand periods of the channels resulting in interference, cross-talk between adjacent channels and noise.
  • the object of the present invention is to utilise a practical number of cells and to provide means to compensate or eliminate the efiects due to distortion;
  • V :iI'he present-invention accordingly provides a multi-channel electrical communication system utilising a distributor comprising a delay network and means for applying to said network a regularly repeated wave form and means for connecting points on said network to the respective channel apparatus by means for compensating or eliminating effects due to distortion of said wave form as said Wave form travels along said network.
  • the said wave form may consist of a sawtooth wave form, rectangular wave form or pulses whose durations may determine a channel period, that is, the portion of each distributor cycle allotted to the respective channels.
  • Figure 1 shows various graphical curves used in the description and Figure 2 shows schematically the circuit arrangements of one embodiment of the invention.
  • FIG. 3 shows in block schematic form another embodiment of the invention and Figure 4 are explanatory curves used in the description of Figure 3.
  • the distortion of the pulses produced by a delay network involves an increase in the pulse duration due to the fact that the instant of commencement of the pulse is advanced and the instant of termination of the pulse is retarded, with respect to the mean pulse time.
  • This is illustrated in Figure 1.
  • a pulse of rectangular wave form as shown at a, Figure l is applied to the input terminals of the delay network, for example as shown at I, Figure 2, and as the pulse travels along the network, the leading and trailing edges of the pulse become less and less inclined to the time axis and the duration of the pulse is increased, as shown at b, c, d, and 6, Figure l, which show the pulses at successive points along the delay line.
  • the amplitude of the pulse radually decreases and the pulse proceeds along the network. Further oscillations at the cut-oil frequency of the network appear as shown in curves d and e, Figure 1, and may distort the leading and trailing edges of the pulse, as shown in curve 7, Figure 1.
  • pulses preferably of rectangular wave form are derived under the control of the distorted pulses, in such manner that the derived pulses are synchronised as to their leadin'g edges or trailing edges to the vol age value which the distorted pulses pass through at the correct moment that is the moment at which the leading or trailing edge would occur in the absence of distortion.
  • This feature may be carried out in practice, for example as illustrated in Figure 2, by applying the distorted pulses to the grid of a valve amplifier which is suitably biassed so that the valve commences to pass current only at the said voltage value occurring at the correct moment in the duration of the distorted pulse, If the amplitude remains substantially constant this voltage value is approximately the mid-amplitude voltage of the pulse.
  • the delay network is shown as comprising a plurality of series connected cells comprising series inductance 2 and shunt capacities 3. Mutual inductance between adjacent coils may be employedif desired.
  • the construction of such network is, of course, well known.
  • the cells are made alike and are designed to have the desired time delay constant so that if a tapping is taken every 122 cells, for example, and a pulse is applied to the input terminals 4, the pulses at the tapping points 5, 5, 'l and so on will be delayed or time phased with respect to each other, in the absence of distortion, by equal intervals of time, which has hereinbefore been called the channel period.
  • the channel period the intelligence waves of the respective channels are transmitted.
  • the voltage source ll may be of any adjustable type, and is illustrated only schematically as a battery source.
  • the amplitude of the pulses applied to valve In should be considerably greater than the grid cut-off bias of the valve and the pulses obtained from the tapping points of the delay network may therefore require amplification. If a power pulse generator of the kind described in the specification of my co-pending United States application, Serial No. 602,450, filed June 30, 1945, now abandoned, for Generators of short duration electrical pulses is employed amplification will not be necessary. Pulses of rectangular wave form may be obtained in the anode or cathode circuit of valve l0.
  • the valve It may be desirable to produce a rectangular pulse to maintain open a gate" circuit during the channel period.
  • the valve It! may be desirable to shape the pulse to pro-, cute for example, trapezoidal wave forms for modulation purposes as described in the specification of my co-pending United States application, Serial No. 602,804, filed July 2, 1945 for Multi-channel electrical pulse communication systems.
  • a network is included in the anode or cathode circuit of the valve 10.
  • valve I0 In cases where no shaping of the pulse is required, that is when the leading or trailing edge only is required to effect an operation the valve I0 can be omitted.
  • the leading or trailing edge of the slice is used to trigger a multivibrator circui-t and the time modulation is produced by and in the multivibrator itself an example of which will now be given.
  • This pulse modulator comprises a multivibrator circuit arrangement 18 consisting of two interconnected valves 19 and 20 and designed to have one stable condition. Assuming the'a-pplication of positive pulses to the-delay line -I this stable condition would be with current flowing in valve The application of a positive pulse to the control grid 2! of valve :9 causes the multivibrator circuit to trip over, current flowing in valve t9 and ceasing in valve 20. The arrangement returns to its stable condition after a time interval depending upon the time constant of the circuit CR1R2 as is well known, and this time constant which determines the durations of the pulses'may be adjusted by adjusting the bias voltage on .con. trol grid 22 of valve 20 by means of asource of potential 23 for example.
  • the intelligence wave of the channel to be transmitted for. example, from a microphone 24 is applied at terminals 28 to the grid 22 and varies the duration of the generated pulses insaccordance .with-ithe amplitive channel periods.
  • valve I9 is shown as having a source i! of biassing voltage which is adjusted to such value that the pulse applied to the control grid 2! trips the multivibrator circuit as the pulse passes through a voltage value at the correct moment.
  • the time constant of the multivibrator circuit may then be correctly adjusted by means of the source 23.
  • valve 29 may be common to a plurality of multivibrators associated with respective channels and it is necessary to adjust the bias of valve is differently for the respective channels it will be necessary to provide for each of the channels a valve and its associated circuits as hereinbefore described, the output pulses obtained from valves HZ being applied to the grid of the valve H! which will be tripped successively by the pulses from the valves I'O.
  • correct timing of the derived pulse may be obtained by taking the slice of the pulse obtained from the network I, from which slice the derived pulse is developed, at a suitable voltage level. This may be effected by suitably biassing the valve [0, or [9 as the case may be,
  • the leading or trailing edge of the derived pulse may be advanced or retarded by taking the slice of the pulse from the network from which slice the derived pulse is developed, at a suitable voltage level.
  • the derived pulses from the output of the valves may be used to develop further pulses of short constant duration, for example by differentiating the pulses in the output of ill, which short pulses define the beginning of the respec-
  • longer pulses whose respective durations are equal to the periods of the respective channels may be used to define the channel periods or the leading or trailing edge of a derived pulse may be used to define the beginning of a channel period.
  • Such an arrangement may be similar to that shown in the rectangle I5 of channel 1 without the input speech arrangement 24, 25 and the multivibrator time constant adjusted to have the same value as the respective channel periods.
  • any known type of generator of pulses of rectangular waveform may be employed to feed the delay line I.
  • this pulse generator takes the form of the well known multivibrator circuit 42 comprising two interconnected discharge valves 43, 44 so shown.
  • valves ill and I9 The voltage limits between which the slice of the pulses is taken by valves ill and I9 are approximately equal to the cut-off voltage and the voltage at which grid current appears, and the difference is equal to. about 5 volts for a high slope valve (i. e. a valve having a steep anode current grid voltage characteristic) such as a pentcde and pulses of an amplitude at least 10 times greater should be fed to the input of the delay network.
  • a high slope valve i. e. a valve having a steep anode current grid voltage characteristic
  • the network for producing trapezoidal wave form pulses is included in the cathode circuit, for example, as described in the aforementioned United States application Ser. No. 602,804, pulses of much greater amplitude are required. Since the impedance of the delay network is always low, some thousands of ohms usually, a high power pulse generator is required. Such a generator may be for example, the power multivibrator circuit described in the aforementioned United States application Ser. No. 602,450.
  • the multivibrator arrangement is designed to produce rectangular pulses at a repetition period substantially equal to the distributor period and may be stabilised to this end in any well known manner.
  • the oscillation generator 42 may be synchronised by the pulse from the output of the delay line I after amplification and re-shaping, if necessary, in an amplifying valve 45, the output of which is fed to the control grid of one of the valves 43, 44 depending upon the sign of the pulses, positive or negative, to control the generator as will be understood by those versed in the art.
  • an amplifying valve 45 the output of which is fed to the control grid of one of the valves 43, 44 depending upon the sign of the pulses, positive or negative, to control the generator as will be understood by those versed in the art.
  • the output from the multivibrator 42 is taken from a resistance 41 in the cathode circuit of valve 64, the pulses having the form shown at 34, and being used for transmission as synchronising pulses for use at the receiver, as well as for feeding into the delay line I.
  • Int Qek dia ram show in F g e. 2. mem e o i c tfe msasi fi r 2a given the same reference characters asin that -.fis
  • the block 48 represents a master oscillator which has a verystable frequency and may be for example a piezo-eleotric crystal controlled oscillation generator, of which many are well kn own in the art.
  • This master oscillator .48 is designed to have afrequency which is a harmonic of the desired distributor frequency multiplied by half the number of channels.
  • the oscillationsgenerated in 48 are fed to a circuit arrangement represented by block 49 for squaring the sine wave oscillations fed thereto.
  • Thissquaring arrangement may comprise an'electron discharge amplityin tube biased to work at anode current saturation ior positive potentials applied to its control grid, or a multivibratorcircuit having two stable congtlitioris, arranged to be triggered by the sinusoidal wave from 48 as it passes through zero or other prearranged value.
  • the output from the squaring circuit 49 is fed to the master multivibrator.
  • the output from the squaring cir-' 'cuit 49 is reversed in phase, or otherwisedelayed bybne half-period of the master oscillator ,to provide the .two outputs as indicated at 50 and .5l delayed the one with respect to the other by a half period.
  • the two outputs a may be-obtained directly, for example, one from the cathode circuit and the other from the anode circuitot the output valves.
  • These outputs may be, and preferably are, passed through a purifying amplifier to obtain the desired pure rectangular wave forms.
  • a purifying amplifier comprises an electron discharge amplifier arranged to cut a'slice, so to speak from the appliedpulses.
  • are applied to the alternate channel equipments 3, 5 etc. and 2, 4, 6 etc., together with the outputs from the respective points 5, 1, etc. and 6, 8 etc. respectively of the delay network, so that the pulses 50 or 5! and the pulses from delay network I are efiectively 'in series. 7
  • the pulse from the master multivibrator passes vdown the delayinetwork it selects the channels I successively.
  • v Curve a represents one of the series of pulses 50 or 5
  • arnplifi er lfl in Figure 2 or the valve IQ of modulator J8 (block 15) Figure 2 may perform this function n.
  • This amplifier is so biassed, however, as to cut a slice, so to speak, between the lines 7 52 and 53. This is done by negatively biasslng the amplifier so that it commences'to pass currentat'the voltage represented by line 52 .and is at saturation at .theyoltage represented by line 53
  • Theresulting wave form in the output circult of thevalve is'then represented by curve d,
  • the master oscillator 48 maynot be required, and its function may be performed by 'the synchonising pulses, means beingprovided to 'derivefrom the selector pulse frequency, the desired harmonic corresponding to the frequency of the pulse train 50 or 5
  • the synchronising pulses a. may be employed to synchronise the master 'multivibratorfat' the re'ceiverin additionto the feedback pulses and pulses "derived from the squaring arrangement.
  • the'modulating and demodulating'arrangements at the transmitter andreceiver respectively may be such as ,only to. require marking pulses to mark the beginning and ends of the'respective channels, or
  • marking pulses marking the commencement of the'cha'nnels may be required.
  • These marking pulses may ,-be obtained by difierentiating the outputpulses from, thessquaring. device 49, or by utilising a suitably designed multivibrator' type of circuit having onestable condition and of small time constant arranged-to be trigger'ed. into the unstable condition by the sine waves from the ,oscillator; 48.0r equivalent source of the desired ,nel equipment at the'transmitter and receiver may.
  • a distributor system comprising a delay network, means associated therewith to provide timed phase pulses for rendering the channels cyclically and successively operative, means for applying to the respective channel equipments auxiliary electrical pulses of rectangular wave form whose durations define the channel periods, said auxiliary pulses having a repetition frequency equal to the number of channels fed in parallel multiplied by the distributor frequency, said channel equipments being arranged so as to be operated only when a distributor selector pulse and an auxiliary electrical pulse occur together at said channel equipments.
  • a distributor system comprising a delay network, means associated therewith to provide timed phase pulses for rendering the channels cyclically and successively operative, means for applying to the respec-- tive channel equipments auxiliary electrical pulses of rectangular wave form whose durations define the channel periods, said auxiliary pulses being applied to the equipments of alternate channels in parallel and having a repetition frequency equal to one-half the number of channels multiplied by the distributor frequency, the auxiliary pulses applied to one set of channel equipments being timed phased by one-half of the repetition period with respect to the auxiliary pulses applied to the alternate set of channel equipments, said channel equipments being arranged so as to be operated only when a distributor selector pulse and an auxiliary pulse occur together at said channel equipments.
  • a distributor system comprising a delay network, means associated therewith to provide timed phase pulses for rendering the channels cyclically and successively operative, means for applying to the respective channel equipments auxiliary electrical pulses whose durations define the channel periods, said auxiliary pulses having a repetition frequency equal to the number of channels fed in parallel multiplied by the distributor frequency, said channel equipments being arranged so as to be operated only when a distributor selector pulse and an auxiliary electrical pulse occur together at said channel equipments.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Cable Transmission Systems, Equalization Of Radio And Reduction Of Echo (AREA)
  • Optical Communication System (AREA)
  • Electrotherapy Devices (AREA)
US602803A 1944-05-26 1945-07-02 Multichannel pulse distributor system Expired - Lifetime US2462111A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB10305/44A GB587939A (en) 1944-05-26 1944-05-26 Improvements in or relating to multi-channel electrical pulse communication systems

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US (1) US2462111A (it)
BE (1) BE478252A (it)
CH (1) CH272428A (it)
ES (1) ES177446A1 (it)
FR (1) FR956072A (it)
GB (1) GB587939A (it)

Cited By (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2554112A (en) * 1947-12-18 1951-05-22 Libois Louis Joseph Multiplex transmission system by means of electrical impulses
US2610295A (en) * 1947-10-30 1952-09-09 Bell Telephone Labor Inc Pulse code modulation communication system
US2614218A (en) * 1949-11-23 1952-10-14 Collins Radio Co Timing device
US2614247A (en) * 1947-12-26 1952-10-14 Fr Sadir Carpentier Soc Pulse modulating system
US2626987A (en) * 1944-09-13 1953-01-27 Int Standard Electric Corp Automatic switching system for electrical telecommunications
US2678425A (en) * 1950-02-21 1954-05-11 Raytheon Mfg Co Analogue computer
US2767312A (en) * 1950-12-26 1956-10-16 Moore And Hall Signal distribution system
US2799728A (en) * 1953-05-07 1957-07-16 Ericsson Telefon Ab L M Time division multiplex transmission system
US2840705A (en) * 1954-11-26 1958-06-24 Monroe Calculating Machine Sequential selection means
US2844718A (en) * 1953-01-24 1958-07-22 Electronique & Automatisme Sa Pulse generating and distributing devices
US2867722A (en) * 1954-02-19 1959-01-06 Gen Electric Co Ltd Electric pulse distributors
US2906869A (en) * 1953-02-19 1959-09-29 Emi Ltd Electrical pulse generator chain circuits and gating circuits embodying such chain circuits
US2912577A (en) * 1954-12-07 1959-11-10 George G Kelley Multichannel analyzer
US2917584A (en) * 1950-02-16 1959-12-15 Siemens Ag Arrangement for distributing and demodulating impulses
US2930848A (en) * 1954-06-29 1960-03-29 Thompson Ramo Wooldridge Inc Television synchronizing pulse generator
US3792255A (en) * 1971-02-05 1974-02-12 Atomic Energy Authority Uk Radiation detection circuitry with delay sampling

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1003836B (de) * 1952-04-09 1957-03-07 Siemens Ag Anordnung zur selbsttaetigen Registerregelung fuer Mehrfarben-Rotationsdruckmaschinen
DE1059518B (de) * 1952-04-19 1959-06-18 Standard Elektrik Lorenz Ag Anordnung zur Umwandlung phasenmodulierter Impulse in laengenmodulierte Impulse
DE975509C (de) * 1952-04-25 1961-12-14 Standard Elek K Lorenz Ag Anordnung zur Demodulation fuer Zeitmultiplex-UEbertragungssysteme mit Pulsphasenmodulation

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1655543A (en) * 1924-04-18 1928-01-10 Western Electric Co Transmission system
US1672215A (en) * 1923-08-15 1928-06-05 Western Electric Co Wave varying and transmitting
US2199634A (en) * 1938-06-21 1940-05-07 Rca Corp Secret communication system
US2262838A (en) * 1937-11-19 1941-11-18 Int Standard Electric Corp Electric signaling system
US2265996A (en) * 1938-04-25 1941-12-16 Emi Ltd Thermionic valve circuits
US2403561A (en) * 1942-11-28 1946-07-09 Rca Corp Multiplex control system
US2408077A (en) * 1944-08-25 1946-09-24 Standard Telephones Cables Ltd Multichannel system

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1672215A (en) * 1923-08-15 1928-06-05 Western Electric Co Wave varying and transmitting
US1655543A (en) * 1924-04-18 1928-01-10 Western Electric Co Transmission system
US2262838A (en) * 1937-11-19 1941-11-18 Int Standard Electric Corp Electric signaling system
US2265996A (en) * 1938-04-25 1941-12-16 Emi Ltd Thermionic valve circuits
US2199634A (en) * 1938-06-21 1940-05-07 Rca Corp Secret communication system
US2403561A (en) * 1942-11-28 1946-07-09 Rca Corp Multiplex control system
US2408077A (en) * 1944-08-25 1946-09-24 Standard Telephones Cables Ltd Multichannel system

Cited By (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2626987A (en) * 1944-09-13 1953-01-27 Int Standard Electric Corp Automatic switching system for electrical telecommunications
US2610295A (en) * 1947-10-30 1952-09-09 Bell Telephone Labor Inc Pulse code modulation communication system
US2554112A (en) * 1947-12-18 1951-05-22 Libois Louis Joseph Multiplex transmission system by means of electrical impulses
US2614247A (en) * 1947-12-26 1952-10-14 Fr Sadir Carpentier Soc Pulse modulating system
US2614218A (en) * 1949-11-23 1952-10-14 Collins Radio Co Timing device
US2917584A (en) * 1950-02-16 1959-12-15 Siemens Ag Arrangement for distributing and demodulating impulses
US2678425A (en) * 1950-02-21 1954-05-11 Raytheon Mfg Co Analogue computer
US2767312A (en) * 1950-12-26 1956-10-16 Moore And Hall Signal distribution system
US2844718A (en) * 1953-01-24 1958-07-22 Electronique & Automatisme Sa Pulse generating and distributing devices
US2906869A (en) * 1953-02-19 1959-09-29 Emi Ltd Electrical pulse generator chain circuits and gating circuits embodying such chain circuits
US2799728A (en) * 1953-05-07 1957-07-16 Ericsson Telefon Ab L M Time division multiplex transmission system
US2867722A (en) * 1954-02-19 1959-01-06 Gen Electric Co Ltd Electric pulse distributors
US2930848A (en) * 1954-06-29 1960-03-29 Thompson Ramo Wooldridge Inc Television synchronizing pulse generator
US2840705A (en) * 1954-11-26 1958-06-24 Monroe Calculating Machine Sequential selection means
US2912577A (en) * 1954-12-07 1959-11-10 George G Kelley Multichannel analyzer
US3792255A (en) * 1971-02-05 1974-02-12 Atomic Energy Authority Uk Radiation detection circuitry with delay sampling

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Publication number Publication date
GB587939A (en) 1947-05-09
FR956072A (it) 1950-01-24
BE478252A (it)
CH272428A (de) 1950-12-15
ES177446A1 (es) 1947-05-01

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