US2453461A - Code modulation communication system - Google Patents

Code modulation communication system Download PDF

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Publication number
US2453461A
US2453461A US677667A US67766746A US2453461A US 2453461 A US2453461 A US 2453461A US 677667 A US677667 A US 677667A US 67766746 A US67766746 A US 67766746A US 2453461 A US2453461 A US 2453461A
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output
selectors
selector
potential
voltage
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US677667A
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John C Schelleng
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AT&T Corp
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Bell Telephone Laboratories Inc
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Priority to BE477343D priority Critical patent/BE477343A/xx
Priority to FR955562D priority patent/FR955562A/fr
Priority to NL79787D priority patent/NL79787C/xx
Application filed by Bell Telephone Laboratories Inc filed Critical Bell Telephone Laboratories Inc
Priority to US677667A priority patent/US2453461A/en
Priority to GB1396/48A priority patent/GB651520A/en
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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
    • H03M1/00—Analogue/digital conversion; Digital/analogue conversion
    • H03M1/12—Analogue/digital converters
    • H03M1/34—Analogue value compared with reference values
    • H03M1/36—Analogue value compared with reference values simultaneously only, i.e. parallel type
    • H03M1/361—Analogue value compared with reference values simultaneously only, i.e. parallel type having a separate comparator and reference value for each quantisation level, i.e. full flash converter type

Definitions

  • This invention relates to communication systems for the transmission of complex wave forms of the type encountered in speech, music, telegraph, facsimile and televisionsignals.
  • ⁇ tions is not required, and in which the complexityV code form for transmission to a receiving station.
  • the amplitude of thecomplex wave in arbitrary units may be expressed as or represented by a binary number and currents or voltages which may be turned on or oif in different circuits are assigned to represent each digit, i. e., denominational order, of that number.
  • each digit voltage or current may by its presence indicate a 1 and by its absence a 0 in the corresponding or representative binary numbering system.
  • the amplitude of the complex wave to be transmitted Vis sampled periodically and the sample amplitudes are converted into a binary code group of voltages. ⁇ These code groups are transmitted to a receiving station at which equipment, carefully synchronized with that at the transmitter, is utilizedvto reconstruct the original complex wave.
  • This method of transmission has certain inherent advanta-ges.
  • the transmitted signal comprises either a voltage or no voltage or at least one or the other of two signalling conditions for each digital position ordenominational order of the code group. Consequently the receiver need only be capable of distinguishing between the two signalling conditions to permit faithful transmission of the complex Wave. Nonlinearity of the transmission link and vother amplitude distortion can be tolerated. ⁇
  • a low signal-to-noise ratio can. be accepted in the transmission path so long as the presence of the voltage representing the ls of therbinary code can be distinguished from the noise. ⁇ i
  • a communication system in which the amplitude of the complex waveto be transmitted Ais directlyv and continuously convert-v ed into a binary code group representation which is then transmitted to a receiving station at which the elements of the code group are combined to reconstructtheoriginal complex wave.
  • the invention relates to -a binary coder Which is operated continuously to produce a binary code group which at all times represents the instantaneous amplitude ofthe complex wave to be transmitted and to ⁇ receiving circuits for translating a code group into the complex Wave amplitude represented thereby.
  • Fig. 1 is a block diagram of a communication system in accordance with the invention; and" Fig. 2 is a schematic diagram partially inblock form of the binary coder utilized at the transnfiit ⁇ ting station of this communication system.
  • the communication system of the invention is shown as comprising a transmitting station, a transmitting link ⁇ and a receiving station.
  • the transmitting station complex wave voice-frequencyA currents from microphone l0 are applied to terminal equipment i2, which may comprise the necessary switching and transmitting devices including amplifiers and impedance matching devices to convey the complex wave form from source l0 to the coding and transmission system described herein.
  • Equipment I2 is also employed to add a bias tothe complex wave if-necessary to prevent it from having negative va1ues...As a result,f the output signal from equipment I2 is always of positive polarity.
  • the signal from the terminal equipment which will be referred to herein as the input signal is applied to a series of selectors I4 through 24 comprising over-biased and limited amplifiers or amplitude,v selective repeaters, each of which is responsive to a different fixed portion of the applied signal.
  • Each of these amplitude selectors or relays I4 through 24 is biased so that it is responsive only to input voltages. larger than ⁇ a. predetermined designated input voltage or threshold and is operative to produce zero output voltage for all input voltages less than the designated input voltage, andan output voltage equal to the designated input voltage for all inputs equal to or greater than. the designated input voltage.
  • the input signal is applied directly to selector I4, while the' diierence between the input signal and the output: oft selector I4 isv applied' to a secondselector I6.
  • Input connections similar to those to selector I6 are made to selectors I8', 2U', Z2 andZ, the signal'l applied to each of these'selecti've switching devices being the difference between the input signal andi the output of the preceding selective switches.
  • selectors' I4 through 24' are'related as descendingY powers of' two', selector It beingY responsive onlyA izo-input' voltages greater than 32: volts (two to' theffth power).
  • selectors I6, I8, 2D, 22 and 2&1 have designated inputfvoltages ofv 16, 8, 4, 2 and 1 Volt, respectively.
  • selector I4-l may have ank output potential of either zero or 32'volts while'selector I6 may'produc'eza'potential diierence'at its output: of ⁇ either zero orf16 volts:
  • selector I8A mayv produce av potential difference' of' either zero' or 8 volts. ⁇ Since-'the remaining: selectors operatefin the same manner, it will. be seen'. that any' input voltagezfrom to'63,volts, inclusive, may beexpressedy as the sum of. the potentialA diierences ther preceding selector in thev chain..
  • selectors I6l through 24 areprovided with auxiliary devices 2.6. through 36, respectively whichwillV be ⁇ referred to herein as digit grounders.
  • Each of these devices isv arranged. to convert the potential difference existing at the output of the selector with which it. is associated into a potential in respect tov ground.
  • the potentials in respect ⁇ to ground at the outputs of the several digit' grounders are positive when the associated selectors are operative and are zero at all other times.
  • the signal appearing at'v any one'. of these output terminals is a voltage corresponding to one of two signalling conditions, this voltage appearing and disappearing as necessary to express the instantaneous amplitude of the complex wave to be transmitted.
  • the six output signals are transmitted over separate ⁇ paths or channels, which may be wire transmissionlinks -or radio links operating at diiferent carrier frequencies, to a receiving station shown at the right in Fig. l.
  • a receiving station shown at the right in Fig. l.
  • signals from the six transmission paths or channels are applied to separate directcurrent amplifiers and limiters all through 6B.
  • each of these identical amplifier-limiter combinations is arranged to produce an output of 32 volts for any input signalexceeding a lower limit which is made high enough to exclude extraneous transmission noise', andto produce Zero output for inputs below this limit.
  • amplitude distortion or attenuation introduced by the transmission link donot affect the operation of the receiver unless the signals in one or more of the transmission paths are so reduced in amplitude that they do not exceed thevnoise-level threshold introduced by the-limiter.
  • ampliier-limiter 5u which is 32 volts or zero, depending upon whether or not selector lli-at the transmitter is operated, is applied through series resistor 6?. to resistor 63 which has'a ⁇ low ohmic value in relation to that o resistor 62.
  • The:l output of amplifier-limiter 52 which is also either 32 volts or zero, depending upon whether or not selector I6 at the transmitter is operated, is applied to an att'enuator 64 arranged to provide an output equal to one-half of the Voltage applied thereto or, 16 volts. This output voltage is applied through resistorv 66, which has the same resistance as resistor '62, to resistor 63.
  • Attenuators 63, 12,16 and are associated with amplifier-limiters 56, 56, 53 and 69, respectively and provide. output voltages of 8 volts, l volts, 2'volts or 1 Volt which are respectively applied n to'resistor 63 through resistors lll, lll, "i8 and B2 each equal in ohmic value to resistor 62, when signals are present in the corresponding transmission channels.
  • the resistive network comprising series resistors 62, 66, 10, Iii, it and. 82 and' resistor 63 is such that the outputs of the six receiving channels are eieotively combined for application to receiving terminal equipment 84", which comprises the amplifiers and other audio-frequency circuits necessary to provide a suitable-input for headphones 86.
  • the complex wave appearing at the output of terminal equipment I2 is translated into a 6element binary code, the digital positions or denominational orders of which are represented by output terminals 38 through 66, voltages appearing at each of.V these terminals as required to produce the proper'binary code representation of theinstantaneous amplitude of the complex wave to be transmitted.
  • the voltages existing at terminals 38 through I8 are transmitted to the receiver at which there is derived from each actuated channel a Voltage having an amplitude eoua-l to that to which the selector associated with the same channel is responsive. These voltages are then continuously added to reconstruct the complex wave applied to the transmitter.
  • Fig. 2 sive selectors in the chain are shown in Fig. 2. With the exception of operating potentials, the six selectors are similar and a detailed description of selector I4 will permit a ⁇ complete understanding of all of the selectors.
  • the output of terminal equipment I2 is applied directly to this selector which as described above has a designated input of 32 volts and is arranged to provide an output of either zero or 32 volts, depending upon whether the input voltage applied to it is less than 32 volts or is equal to or larger than 32 volts.
  • the input voltage is applied first through a series resistor 96 to a biased diode 04, battery 98 ⁇ serving to maintain a negative bias of 32 volts on the plate of diode 04. If the inputvoltage exceeds. 32 voltsdiode 94 becomes conductive and a voltage drop is developed across resistor
  • 00 is applied to a two-stage direct-'current amplifier comprising triode-type vacuum tubes
  • 02 is connected to ground, while the plate circuit includes a battery
  • 08 is applied to the grid of triode
  • the output of this directcurrent amplier is Aapplied to a limiter circuit comprising diodes
  • the cathode of ⁇ diode IIA is connected to the plate oi triode
  • a 50-volt bias battery IIB is connected between the plate of triode
  • 20 is maintained at 32 volts so long as the input signal is equal or greater than 32 volts.
  • 4 The potential appearing at output terminal
  • 30 provides a negative bias of 16 volts, while the tap to which the cathode of limiter-diode
  • selector 16 the output of terminal equipment I2 ⁇ less the output of selector I4 whether the output of selector I4 happens to be zero or 32 volts.
  • selector I6 is identical to that of selector I with the following exception produced by the changes in battery potentials and input connections described above. If the difference between. the instantaneous amplitude of the complex wave appearing at the output of terminal equipment I2 and the potential appearing at the output ter- ⁇ minal
  • the diierenoe between the output of terminal equipment I2 and that of selector I4 is less than 16 volts, zero potential grid-cathode drop of pentode selector terminals ,
  • 34, the output terminal of selector I6, is applied to the control grid of pentode
  • 42 is connected in series between the ⁇ plate of pentode
  • 36 is connected to the positive terminal of battery M6, the negative terminal of which is connected to the cathode, while the suppressor grid is connected directly to the cathode.
  • 36 is also connected through resistor
  • the output of selector III appearing at output terminal is applied to the control grid of pentode
  • the screen grid of this vtube is connected through battery .its to the cathode, while the suppressor grid is connected directly to the cathode.
  • 54 is also connected through a resistor
  • 55 in the platecircuit thereof are so proportioned that the voltage developed across cathode resistor
  • 34 of selector It is applied through resistor
  • selector I3, 20, 22 and 24 are similar to those to selector I6 and the digit grounders 28, 30, 32 and 36 are similar to digit grounder 26.
  • these 'digit ⁇ grounders provide output voltages in respect to ground of 4, 2, 1 and 1/2 volts, respectively, when the associated selectors are actuated and zero output at all other times.
  • the direct-current amplifier-limiter combinations 5t through 60 may conveniently be similar to those utilized in selector I4 with the exception of changes in certain of the applied battery potentials.
  • selector lll in Fig. 2 the potential of the selector bias battery (98 in Fig. 2) is made slightly greater than the largest noise voltage to be tolerated in the transmission link. Then, any signal voltage exceeding the noise level will cause the diode (9i) to conduct, providing an increase in the voltage app-lied to the direct-current arnplier.
  • This amplifier and the limiter may be identical in construction and operation to those employed in selector I4 and the unit as utilized at the receiver provides an output of 32 volts whenever the noise level is exceeded and zero output at other times. It will be understood that equivalent direct-current amplifiers and limiters may be substituted for those described above, both in the selectors and in the receiver.
  • , 66, 12, 'I6 and 80 may comprise resistors connected across the outputs of the corresponding arnplier-limiters and tapped at appropriate points to produce attenuations of 1/2, 1/4, 1/8, Tg and gli corresponding to output voltages of 16, 8, 4, 2 and 1 volts, respectively.
  • Other resistive attenuating networks of more complexity may be used if desired.
  • the system as described above is susceptible of modification and considerable simplification if high fidelity transmission links are available.
  • the amplifier-limiter equipment may be eliminated from the receiver of Fig. 1.
  • the signals transmitted from the digit grounders associated with the l, 2, 4, 8 and 16-volt selectors may be applied directly to the additive network comprising resistors 62, B3, 66, 10, 14, 18 and 82 of the receiver of Fig. 1.
  • selector Ill Since the digit grounders have outputs of either zero or one-half the designated voltages, depending upon whether the associated selectors are actuated, while selector Ill has an output of either zero or the designated voltage, means must be provided for reducing by one-half the signal applied to the additive network at the receiver by selector I4 at This may be accomplished in several Ways. Forv example, a potentiometer or other attenuator may be used either at the transmitter or at thereceiver to halve the signal in the channel controlled by coder I4.
  • selectors atthe transmitting station requires the provisionA of an equal number of transmission channels in the transmission link and also the 'addition ⁇ o ⁇ further direct-current -amplier-limiters and attenuators of appropriate value atthe receiving station.
  • each of said selectors having Zero Aoutput for inputs less .than the portion of the total magnitude to which it is responsive, and an Aoutputrequal ⁇ to that portionfor all other inputs, means for applying the waveto ⁇ be.transmitted to the ⁇ selector v:
  • Vand means for applying to each of the other selectors the diiTerence between the instantaneous magnitude of the wave to betransmitted, yand theoutput of the selector-resp-onsive to the nextxlarger .al
  • ⁇ a plurality of selective relays each responsive toa different iixed portion of thetotal possible magnitude ofthe complex wave, each of said relays having zero ⁇ output ⁇ for inputslless than the portion of the total possible magnitude to which it is responsive and being capable of producing a difference in 'potential equal' in magnitude to that portion for all other inputs, means for applying the wave to ⁇ be transmitted tothe relay responsive to the largestportion of the total possible magnitude, and means ⁇ for applying to each of the other relays a potential equalto the magnitude of the wave to be transmitted less the magnitude of the potential diierence at theoutput of the relay responsive to the next larger portion of theltotal possible magnitude.
  • a ⁇ plurality of repeaters each responsive to a different fixed portion of: the total possible magnitude of the complex wave, ⁇ each of ⁇ said repeaters having zerooutput for ⁇ inputs less than the portion of the total possible magnitude to which it is responsive -and being capable of producing a; difference in ⁇ potential equal in magnitude to that portion of thetotal possible magnitude for al1 other inputs, means for applying the wave to be transmitted to the repeater responsive to the largest fraction of the total possi..
  • a plurality of selectors each re'- sponsiveto a different portion of the total possible magnitude of the complex wave, each of said selectors having zero output for input voltages less than the portion of the total possible magnitude to which it is responsive and being capable of ⁇ producing a potential in respect to ground equal in magnitude to that portion of the complex wave for all other inputs, means for applying the complex wave to be transmitted to the selector responsive to the largest portion of the total possible magnitude, means for applying to eachof the other selectors, the difference between themagnitude of the wave t0 be transmitted and the output of the selector responsive to the next larger portion ofA the total, and means for transmitting the output potentials of the selectors to a remote station.
  • a communication system for transmitting complex waves comprising a plurality of selectors, each responsive to a diierent fixed portion 'of the total possible magnitude of the complex wave, each of said selectors having zero output for inputs less than the magnitude of the portion of the total possible magnitude to which it is responsive and being capable of producing an output proportional to the magnitude of that portion for all other inputs, means for applying the complex wave to be transmitted to the selector responsive to the largest portion of the total possible magnitude, means for applying to each of the other selectors ⁇ the difference between the waveto be transmitted and the output oi the selector responsive to the next larger portion of the total, means responsive to the outputs of the individual selectors for producing equal potentialsywith respect to ground, means for transmitting these potentials to a receiving station, means thereat for converting said last-mentioned potentials into potentials proportional to the output of the selectors associated with each, and means for adding ⁇ the potentials so derived together.
  • a plurality of selectors each controlling one of said fixed voltages and each being responsive only to input voltages at least as great as its output voltage, means for applying a complex wave to the selector responsive tothe largest input voltage, and means for applying to ⁇ each of the other selectors the voltage differences between the magnitude of the complex lwave and the output of all selectors responsive to larger inputs.
  • a group of selectors eachresponsive only to an input greater than its individual operating ⁇ input, the operating inputs of said selectors being related in magnitude as powers of two
  • v means for applying the message wave to the selector having the largest operating input, and means for applying to each of the other selectors an input signal equal to the magnitude of the message wave less the operating inputs of all operated selectors having larger operating inputs.
  • a group of selectors each responsive only to an input greater than a predetermined magnitude, the predetermined magnitudes of said selectors being related in magnitude as powers of two, means for applying the complex wave to the selector gespeiresponsive to the largest 'predetermined magnitude, other means for applying to another one of said other selectors an input signal equal to the magnitude oi the complex wave less a function of the output of a selector responsive to the largest predetermined magnitude and means for producing output signals for the selectors.
  • a group of selectors each responsive only to an input greater than its individual threshold, the thresholds of said selectors Ybeing related in magnitude as powers of two, means for applying the complex wave to the selector having the largest threshold, means for applying to each of the other selectors an input signal equal to the magnitude of the complex wave less the sum of the thresholds of all responding selectors having larger thresholds, means for producing output signals for the selectors, and separate channels for transmitting said signals to a receiving station.
  • a coder for generating binary code representations of the instantaneous amplitude of a complex wave to be transmitted, said coder comprising a plurality of selectors. each controlling an output signal representative of a different fixed portion of the total possible amplitude of said complex wave, means for applying the complex wave to all of said selectors and means for applying in opposition to said wave to each of said selectors, excepting that controlling the signal representing the largest portion of said total possible amplitude, voltages proportional to the sum of the amplitude portions represented by the outputs of all selectors corresponding to larger portions of said total possible amplitude.
  • a group of selectors each responsive only to an input greater than its individual operating input, the operating inputs of said selectors being ⁇ related in magnitude as powers of two
  • means for applying'the complex wave to the selectorhaving the largest operating input means for applying to each of the other selectors an input signal equal to the magnitude of the complex wave less the sum of the operating inputs of operated selectors having larger operating inputs
  • means 'for producing output signals for the selectors which are operated separate channels for transmitting said signals to a receiving station, means at the receiving station for converting the transmitted operating voltages into voltages proportional to the operating voltages of the selectors represented thereby, and means for adding the converted voltages together.
  • a communication system for transmission of complex waves in which a signal is generated as a difference in potential between two ungrounded points, means for converting said 1.2 difference fin-'potential 'into a :potential 'with 'respect to ground-comprising a converter for transforming the potential a't one 'of said pointsinto a potential ⁇ With respect to ground, a second converter fortransform'ing the potential at the other of -said points ⁇ into a potential with respect to ground, means for inverting the output of the second converter .and means Ifor averaging the output of theiir'st converter andthe inverted output yof ⁇ the secondconverter.
  • means for converting said difference in potential into a vpotential with respect to ground comprising a pair of cathode 'follower tubes e'a'ch Vhaving lat least a cathode, an anode and 'a control element, the cathodes b'eingigrounded ⁇ through load resistors and the anodes being connected to sources-of positivepotential, means for applying said difference in ⁇ potential between said control elements, means for inverting the cathode potential of one of said cathode followers and means for averaging said inverted potential with the 'cathode potential of the other of said cathode followers.
  • a vplurality of signaling means each of which may have either of two output conditions one of which in each case represents a different/component of the total possible amplitude 'range of said complex wave
  • means responsiv'e to said wave for deriving therefrom a plurality "of control ⁇ quantities equal in number to said amplitude components ⁇ and continuously indicative of the presence :or'absence of the corresponding 'components in the wave to be transmitted, and means for applying said quantities at all 'times .to control the output conditions of the corresponding signaling means.
  • a communication system for transmitting complex waves '-a plurality of signaling meanseach of which may have either of two output' conditions lone 'of which in each case represe'nts a y'different 'component of thetotal possible amplitude lrange 'of said complex wave, and the combinations of which represent all amplitudes in said ⁇ 'total l.possible range in integral steps determined by the smallest component represented in vany case, means Iresponsive to said Wave for deriving therefrom a plurality of control quantities continuously .indicative of the presence or absence of the corresponding components in the wave to be transmitted, and means for applying sai'dnuan'tities at all times to control the output conditions lof the corresponding signaling means.
  • a plurality of signaling means each of which may have either of two output conditions one of which in each case represents a different component of the total possible amplitude :range of said wave and the combinations ofwhich represent all amplitudes in said range in integral steps determined by the smallest componentfrepresente'd 'in any case, and means for 'applying said wave 4to said signaling means to continuously rcontrol the output conditions of said signaling -means in accordance with the presence or absence ofthe corresponding amplitude components in said wave.
  • a plurality of selectors each responsive to a different fixed component of the totalpossible amplitude of the wave to be transmitted, each of said selectors having zero output UNIT for inputs less than the ⁇ component of the total ED STATES PATENTS amplitude to which it is responsive and the same Number Name Date plying the Wave to be transmitted to the selector 5 2,282,046 GOldSmith May 5, 1942 means for applying said Wave to each of the other 2,403,210 Butement July 2, 1946 selectors eiectively subtracting from said Wave 2,430,139 Peterson NOV.

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US677667A 1946-06-19 1946-06-19 Code modulation communication system Expired - Lifetime US2453461A (en)

Priority Applications (5)

Application Number Priority Date Filing Date Title
BE477343D BE477343A (nl) 1946-06-19
FR955562D FR955562A (nl) 1946-06-19
NL79787D NL79787C (nl) 1946-06-19
US677667A US2453461A (en) 1946-06-19 1946-06-19 Code modulation communication system
GB1396/48A GB651520A (en) 1946-06-19 1948-01-16 Improvements in or relating to signalling systems

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US2453461A true US2453461A (en) 1948-11-09

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BE (1) BE477343A (nl)
FR (1) FR955562A (nl)
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US2531846A (en) * 1947-03-13 1950-11-28 Bell Telephone Labor Inc Communication system employing pulse code modulation
US2539623A (en) * 1947-02-12 1951-01-30 Bell Telephone Labor Inc Communication system
US2549422A (en) * 1949-01-06 1951-04-17 Bell Telephone Labor Inc Decoder for multiple carrier pulse code modulation signals
US2556200A (en) * 1948-02-26 1951-06-12 Int Standard Electric Corp Electrical translation system
US2586825A (en) * 1948-01-16 1952-02-26 Int Standard Electric Corp Signal compression and expansion arrangements in electric communication systems
US2592308A (en) * 1948-09-01 1952-04-08 Bell Telephone Labor Inc Nonlinear pulse code modulation system
US2595701A (en) * 1948-12-31 1952-05-06 Bell Telephone Labor Inc Recording system
US2603714A (en) * 1948-09-01 1952-07-15 Bell Telephone Labor Inc Percentage time division multiplex for pulse code modulation
US2632058A (en) * 1946-03-22 1953-03-17 Bell Telephone Labor Inc Pulse code communication
US2641698A (en) * 1948-11-13 1953-06-09 Gloess Paul Francois Marie Delay line decoder
US2646548A (en) * 1948-07-21 1953-07-21 Alsacienne Constr Meca Electron tube coder device
US2651716A (en) * 1947-11-08 1953-09-08 Int Standard Electric Corp Pulse code modulation demodulator
US2720557A (en) * 1948-12-24 1955-10-11 Bell Telephone Labor Inc Time division pulse code modulation system employing continuous coding tube
US2894214A (en) * 1952-08-28 1959-07-07 Int Standard Electric Corp Coding circuit
US3156913A (en) * 1962-01-18 1964-11-10 Raytheon Co Analog-to-digital converter system
US3188624A (en) * 1959-11-17 1965-06-08 Radiation Inc A/d converter
US3480881A (en) * 1966-08-19 1969-11-25 Westinghouse Electric Corp Circuitry for simultaneously modulating and amplifying a carrier signal
US3732495A (en) * 1970-07-20 1973-05-08 Radiation Inc Signal transmission and modulation technique therefor

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DE647468C (de) * 1925-03-11 1937-07-05 Berthold Freund Dipl Ing Verfahren zur Fernanzeige bzw. Fernuebertragung von elektrischen Stroemen veraenderlicher Intensitaet, insbesondere fuer die Zwecke der elektrischen Bilduebertragung, der elektrischen Tonuebertragung u. dgl.
US2272070A (en) * 1938-10-03 1942-02-03 Int Standard Electric Corp Electric signaling system
US2282046A (en) * 1939-09-01 1942-05-05 Rca Corp Multiplex signaling system
US2313209A (en) * 1938-11-08 1943-03-09 Valensi Georges Communication system
US2403210A (en) * 1942-12-04 1946-07-02 Butement William Alan Stewart Multiplex pulse modulation system
US2430139A (en) * 1944-01-08 1947-11-04 Rca Corp Pulse number modulation system

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE647468C (de) * 1925-03-11 1937-07-05 Berthold Freund Dipl Ing Verfahren zur Fernanzeige bzw. Fernuebertragung von elektrischen Stroemen veraenderlicher Intensitaet, insbesondere fuer die Zwecke der elektrischen Bilduebertragung, der elektrischen Tonuebertragung u. dgl.
US2272070A (en) * 1938-10-03 1942-02-03 Int Standard Electric Corp Electric signaling system
US2313209A (en) * 1938-11-08 1943-03-09 Valensi Georges Communication system
US2282046A (en) * 1939-09-01 1942-05-05 Rca Corp Multiplex signaling system
US2403210A (en) * 1942-12-04 1946-07-02 Butement William Alan Stewart Multiplex pulse modulation system
US2430139A (en) * 1944-01-08 1947-11-04 Rca Corp Pulse number modulation system

Cited By (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2632058A (en) * 1946-03-22 1953-03-17 Bell Telephone Labor Inc Pulse code communication
US2539623A (en) * 1947-02-12 1951-01-30 Bell Telephone Labor Inc Communication system
US2531846A (en) * 1947-03-13 1950-11-28 Bell Telephone Labor Inc Communication system employing pulse code modulation
US2651716A (en) * 1947-11-08 1953-09-08 Int Standard Electric Corp Pulse code modulation demodulator
US2586825A (en) * 1948-01-16 1952-02-26 Int Standard Electric Corp Signal compression and expansion arrangements in electric communication systems
US2556200A (en) * 1948-02-26 1951-06-12 Int Standard Electric Corp Electrical translation system
US2646548A (en) * 1948-07-21 1953-07-21 Alsacienne Constr Meca Electron tube coder device
US2603714A (en) * 1948-09-01 1952-07-15 Bell Telephone Labor Inc Percentage time division multiplex for pulse code modulation
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US2641698A (en) * 1948-11-13 1953-06-09 Gloess Paul Francois Marie Delay line decoder
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US2595701A (en) * 1948-12-31 1952-05-06 Bell Telephone Labor Inc Recording system
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US2894214A (en) * 1952-08-28 1959-07-07 Int Standard Electric Corp Coding circuit
US3188624A (en) * 1959-11-17 1965-06-08 Radiation Inc A/d converter
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US3480881A (en) * 1966-08-19 1969-11-25 Westinghouse Electric Corp Circuitry for simultaneously modulating and amplifying a carrier signal
US3732495A (en) * 1970-07-20 1973-05-08 Radiation Inc Signal transmission and modulation technique therefor

Also Published As

Publication number Publication date
GB651520A (en) 1951-04-04
FR955562A (nl) 1950-01-17
BE477343A (nl) 1900-01-01
NL79787C (nl) 1900-01-01

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