US2516752A - Coding tube for pulse code modulation signals - Google Patents

Coding tube for pulse code modulation signals Download PDF

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Publication number
US2516752A
US2516752A US52088A US5208848A US2516752A US 2516752 A US2516752 A US 2516752A US 52088 A US52088 A US 52088A US 5208848 A US5208848 A US 5208848A US 2516752 A US2516752 A US 2516752A
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United States
Prior art keywords
code
pilot
coding
main
grid
Prior art date
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Expired - Lifetime
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US52088A
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English (en)
Inventor
Robert L Carbrey
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AT&T Corp
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Bell Telephone Laboratories Inc
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Filing date
Publication date
Priority to NL76624D priority Critical patent/NL76624C/xx
Application filed by Bell Telephone Laboratories Inc filed Critical Bell Telephone Laboratories Inc
Priority to US52088A priority patent/US2516752A/en
Priority to GB24490/49A priority patent/GB679730A/en
Application granted granted Critical
Publication of US2516752A publication Critical patent/US2516752A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J31/00—Cathode ray tubes; Electron beam tubes
    • H01J31/02—Cathode ray tubes; Electron beam tubes having one or more output electrodes which may be impacted selectively by the ray or beam, and onto, from, or over which the ray or beam may be deflected or de-focused
    • H01J31/06—Cathode ray tubes; Electron beam tubes having one or more output electrodes which may be impacted selectively by the ray or beam, and onto, from, or over which the ray or beam may be deflected or de-focused with more than two output electrodes, e.g. for multiple switching or counting
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
    • H03M1/00—Analogue/digital conversion; Digital/analogue conversion
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B14/00—Transmission systems not characterised by the medium used for transmission
    • H04B14/02—Transmission systems not characterised by the medium used for transmission characterised by the use of pulse modulation
    • H04B14/04—Transmission systems not characterised by the medium used for transmission characterised by the use of pulse modulation using pulse code modulation
    • H04B14/044—Sample and hold circuits
    • 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
    • H03M1/22—Analogue/digital converters pattern-reading type

Definitions

  • the present invention relates to the automatic generation of pulses in code combinations indicative of instantaneous signal amplitude, under the direct control of signals to be coded. More specifically, the invention relates to automatic generation of code pulses by an electron beam coding tube in which the beam when deflected by different amounts by difierent signal amplitudes is caused to impinge upon certain ones of a set of electrodes in difierent combinations corresponding to the difierent digits of the code and to set up pulses on these electrodes.
  • Objects of the invention are, increased speed of coding, simplification of apparatus requirements, and improved operation.
  • Electron beam coding tubes of the kind to which the invention is applicable have made use of a quantizing grid and a feedback control from this grid to the beam deflecting means, for limiting the beam position to the grid aperture to which the beam was moved by the signal and for preventin the beam from assuming a position overlapping two grid apertures or only partially illuminating the intended grid aperture.
  • Each grid aperture is lined up with a horizontal row of apertures in a code plate.
  • registry of the beam with an aperture in the quantizing grid also causes proper registry of the beam with a given row of code apertures.
  • the digit electrodes are located back of the code plate so that i the beam in passing through apertures in the plate strikes the corresponding digit electrodes.
  • the gating function is performed within the tube by blanking the electron beam used for the codin until such time as the pulses are to be impressed on the output circuit of the coding tube.
  • an auxiliary, or pilot beam is provided together with a relatively narrow quantizing grid arranged in the path of the pilot beam but out of the path of the main or coding beam.
  • the same beam deflecting means serves in common for both beams. This allows the feedback control, through the agency of the pilot beam, to establish the necessary conditions on the deflecting means such as will cause proper registry of the main beam with a given row of apertures when the main beam is unblanked.
  • the main beam may be turned on at the instant when the code pulses are to be generated and not until then. It is left on for the duration of a code pulse and is then turned off until the next code combination is to be generated.
  • the main beam is used both to generate the pulses in proper code combinations and to time the occurrence and duration of the pulses.
  • One advantage following from this action is that the gating amplifiers heretofore used may be dispensed with and if amplification as such as needed it can be supplied in a common amplifler, for example in the output of the distributor as will appear from the fuller description to follow.
  • Fig. .l is a perspective view of the electrode structure of an electron beam coding tube of one form according to the invention.
  • Fig. 1A shows a detail of the electron gun used in the construction shown in Fig. 1;
  • Fig. 2 is a schematic plan view of the electrode structure of a modified electron beam tube according to the invention.
  • Fig. 3 is a schematic view, in plan, of a tube of the Fig. 1 type showing the manner of connecting the tube into a pulse code transmitting system;
  • Fig. 4 shows a timing diagram to be referred to in the description of Fig. 3.
  • Fig. 1 shows the electrode structure of a cathode beam tube, looking away from the small end of the tube at which the beam-forming means is provided toward the large end of the tube where the target electrodes are located. Provision is made for producing a pilot beam 30 of relatively narrow ribbon form and a main or coding beam 3
  • the code plate 36 is divided functionally into two distinct parts.
  • the first part comprises the quantizing grid 31 which is in the path of the pilot beam 30 but is to the left and out of the path of the main beam 3
  • the other portion comprises the coding section of the plate 36, this portion being in the path of the main beam 3
  • Positively biased concentrating electrodes l, 2 and- 3 are provided to shape the electron beams and to assist in maintaining the spacing. thereof.
  • All of the apertures in the code plate 316 are arranged in horizontal rows. In a seven-digit system, assumed in this figure, there will be- 128 horizontal rows.
  • the quantizing grid 31 has 128 apertures arranged in a vertical column.
  • the plate 3t differ in number in eachhorizontal row'from none to a maximum of seven in accordance with a binary system to form a permutation code and are positioned in seven vertical columns. A few of these apertures are shown at 38.
  • to 41', inclusive, are located just back of the cod'epl'ate 38- in position to be struck by portions of the beam 31- which pass through aperturesin the correspond-- ing column.
  • the beams 36 and 3! are shown in the figure in their middle position corresponding to zero applied signal They can be deflected upward or downward to any chosen horizontal row of apertures by the application ofproper voltage to the deflecting plates 32", 34. These voltages may be applied over the leads 49 and 5! respectively: 7
  • Fig. 1 is a modification of that shown in United States patent to A. M. Skellett 2,293,567 granted August I8, 1942.
  • the structurein Fig. I differs from that in the Skellett patent in that electrostatic focusing is used in Fig. 1 in place of magnetic focusing shown in the patent.
  • electron gun comprises an elongated linear cathode 22, which may be of the indirectly heated equipotential type as shown or may be of other forms, for example, filamentary, a cy- 4 quiz desired focusing. Portions of the shield are broken away in Fig. 1 to show the two grids 23 and 33 as distinct and separated from each other. If desired, suitable shield means may be included in the space between the two grids within the shield member 24.
  • a signal sample is applied across the leads it, 5! for the deflector plates 32, 34.
  • the circuit arrangements for carrying out the functions in this brief description will be given in Fig. 3.
  • the pilot beam 38 is not blanked at this time.
  • the pilot beam is therefore deflected. under control of the signal voltage to the vicinity of a particular aperture in the quantizing grid 3'! depending upon the amplitude of the signal.
  • the beam may fall into exact registry with one of these apertures or may be only partially: in register with an aperture and part-way between two apertures.
  • the portion of the beam that passes through an aperture strikes the target electrode Ml from. which a voltage is fed back through an amplifier to the deflector plates 32, 3 such as to exert feedback control on the: pilot beam- 30
  • This feedback control is such as to shift the beam 33 slightly when necessary tochange from the condition of partial registry of the beam with a given apertureinto full registry of the beam with that aperture.
  • are of widely different dimensions does not prevent the type of control just described from taking place.
  • the important thing is to have the accelerating potentials for the two beams maintained equal and this result is achieved by generating the beams from a common cathode the digit electrodes 4
  • the signal which may be speech or other suitable signal is shown as comingin on lead 93 to the signal sampling circuit 92a ⁇
  • the latter may be an electronic switch of the type which permits conduction in either direction when closed. Such switches are sometimes referred to as two-way clamps. The switch would be biased open to prevent conduction except for the time during which a signal sample is to be taken and applied to the storage condenser 95.
  • the timing control for the sampling circuit 92 and for other functions to be carried out would in practice be accomplished by means of electronic timing circuits under the prime control of a crystal oscillator of highly constant frequency, with the various timing periods determined by capacitance-resistance timing circuits operating in conjunction with vacuum tubes in a manner generally well known in the art. For simplicity of illustration in Fig.
  • the timing control is shown as obtained from rotating brushes IOI, I02, I03 cooperating with segmented rings.
  • a negative voltage from battery I05 is shown as applied to the common shaft I04 for the three brushes.
  • the sampling circuit 92 is biasedopen during the portion of the cycle in which the brushis in contact with the conducting portion 98 of the segmented ring but this bias is removed during the time the brush IN is in contact with the insulating segment I06. It is during this latter interval that the sampling circuit 92 is allowed to take a sample of the impressed signal in lead 93 and store it upon the condenser 95.
  • and the pilot beam 30 are suppressed by the application of high negative voltage to the grids 23 and 33 by brushes I03 and I02 in contact with respective conducting segments I00 and I01.
  • the pilot beam is shut off during this period to allow the voltage conditions on storage condenser 95 to become stabilized.
  • the high negative bias is removed from grid 33 near the end of the sampling period, allowing the.
  • the signal voltage stored on the condenser 95 isamplified in the push-pull amplifier 9
  • the pilot beam 30 is thus deflected to an extent determined by the signal amplitude.
  • and deflector plates 32, 34 cooperate in the manner above described to position the pilot beam 30 in full registry with the aperture corresponding to the nearest quantized value of the signal.
  • a considerable time is allowed during which this feedback quantizing operation is being carried out in order to permit the pilot beam to become fully stabilized in its finalposition.
  • the brush I03 is traversing the segment I00 and maintaining high negative bias on grid 23 thus suppressing the main beam. After a time sufficient for stabilizedconditions to be reached, brush I03 arrives as quite short.” After the projection of the main beam both beams are again suppressed and switch IOI permits sampling circuit 92 to take a new sample of the applied signal.
  • the sampling period is shown as lasting for about half a microsecond.
  • the pilot beam is shown as coming on near the end of the sampling period and lasting throughout the remainder of the first 1.3-microsecond interval.
  • the main beam is represented as not being turned on therefore until near the end of the 1.3-microsecond interval.
  • the coder therefore produces a main beam ulse near the end of every coding period and pulses of the duration of the main beam pulse, shown as .186 microsecond, will appear simultaneously on those of the digit electrodes 4
  • Typical code groups of pulses obtained by distribution in time of the simultaneously appearing pulses are shown in Fig. 4 for channels 96 and I.
  • Fig. 3 shows a type of distributor suitable for use in distributing the code pulses sequentially in time so as to make them suitable for transmission over a single channel. This is done by the use of delay circuits 88, 89, etc. individual to the seven-digit targets 4
  • the first delay line D1 shown at 88 is represented in dotted outline indicating that this line may have zero delay and therefore that the delay line may be omitted, if desired.
  • the amount of delay increases in succeeding delay lines D2, D3, etc. by .186 microsecond, the time interval between the beginning of one pulse and the beginning of the next pulse.
  • a common amplifier 90 is shown as serving for the transmission of the various permutation code pulses. This may also inelude shaping circuits to standardize the code pulse amplitudes if desired.
  • Some of the distributed code pulses are represented in the timing diagram of Fig. 4. At the end of thecoding cycle immediately prior to time 0 the main beam pulse is assumed to have set up a coding pulse on each of digit electrodes 4
  • - Fig. 2 shows a modified type of electrode construction in which eight individual electron beams are used, one of these, 64 in the figure, being the pilot beam and. the other seven being beam; deflecting; platea of; which-theaupuer; Qne-.is.
  • an electrombeam. pulse code producer, meanato,1r0duc.e.;t ⁇ vo electron beams parallel to each other, common, ,defiectimg; means, ion both. beams. aquantizin grid. losatedr in,-.the pathof. the-first .orpilotbeam but out, oi the pathr-ofi the.
  • an. electronlbeam coding: tuba, a main: beam, a. pilot-b.eam,-,.common-.deflecting means; for saidv beams,. a. quantizine. grid in; thevpath saidz pilot. beambutoutiet .the:-p.ath-.ofi said'main, beam; a feedback.beamacentering:control from-said: grid-. to:saiddefiectingmeans;coderdetermining;target. areas positioned to be engaged-mysaidmainrbeam; when deflected by successiveramounts; said areas coordinated spatially with the grid apertures. suchthat said control centers,the-mainbeamonrespective code-determining areas, and means: to suppress said main beamzindependently of'said pilot beam.
  • an electron beam codingtube means: to-produce amain beam, a plurality of. targetex-- posureareas arranged in patterns according to-a" code, means to defiectthe main beam under con-- trol of a signalvoltage'to-becoded, so as toibe intercepted by certain of said exposure areas. depending upon the signaii amplitude, meanszto suppress said beamexcept for times duringwhich; codes are to be generated; means-"to produce: a: pilotbeam, special target exposure: areasar but toz turn. onsaid main.
  • negister of said main; beam-with;.said. certain exposure areas.
  • said. quantizing. electrode a. controls voltage. for. application tozsaid deflecting-means;
  • A-bcam tubeefors producing permutation; code. pulses, comprising means to project. a-main beam and a pilot. beam side by, sidawithin and along said. tube, common deflecting means for bothbeams, aseparate and-independently controllable. beam. suppressing; meansforsaid main beam, said maintbeam. being many times. wider than its yer ticalor thicknessdimension, targetexposure areasarranged in horizon-tall rows one above. another,
  • the;v individual areas being arranged. in a ,pattern.
  • main target areas and pilot target areas aligned therewith means for initially directively projecting a pilot beam, under control of a signal voltage to be coded, against one of said pilot target areas while maintaining the main beam suppressed, a feedback control from said pilot target for the pilot beam for properly centering the pilot beam on said one pilot target area, and means subsequently operative under control of said signal voltage and feedback centering control for projecting the main beam against the respectively aligned main target area.
  • a two-beam electron coding tube including code determining target areas and guide target areas aligned therewith, means to produce a pilot beam and a coding beam, beam deflecting means, means for initially suppressing said coding beam and for causing said deflecting means to direct said pilot beam, under control of a signal voltage to be coded, against one of said guide target areas, a feedback control from said guide target area to said deflecting means for establishing proper register of said pilot beam on said guide target area, and means including said deflecting means subsequentl operative under control of said signal voltage and feedback control for projecting said coding beam against the corresponding codedetermining target area.

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  • Engineering & Computer Science (AREA)
  • Theoretical Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Electron Beam Exposure (AREA)
  • Testing Or Measuring Of Semiconductors Or The Like (AREA)
US52088A 1948-09-30 1948-09-30 Coding tube for pulse code modulation signals Expired - Lifetime US2516752A (en)

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Application Number Priority Date Filing Date Title
NL76624D NL76624C (enrdf_load_html_response) 1948-09-30
US52088A US2516752A (en) 1948-09-30 1948-09-30 Coding tube for pulse code modulation signals
GB24490/49A GB679730A (en) 1948-09-30 1949-09-23 Improvements in or relating to electron beam coding tubes and signal encoding systems using such coding tubes

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US52088A US2516752A (en) 1948-09-30 1948-09-30 Coding tube for pulse code modulation signals

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Cited By (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2597677A (en) * 1950-10-17 1952-05-20 Rca Corp Quantizing apparatus
US2615142A (en) * 1950-01-19 1952-10-21 Zenith Radio Corp Deflection control electron discharge device
US2617075A (en) * 1949-04-09 1952-11-04 Hartford Nat Bank & Trust Co Electric discharge tube comprising means for producing and deflecting an electron beam
US2642547A (en) * 1950-11-30 1953-06-16 Hartford Nat Bank & Trust Co Device of the kind comprising an electronic tube having a ribbonshaped beam which is deflected and held in different positions
US2689314A (en) * 1951-07-12 1954-09-14 Norman R Gunderson Cathode-ray tube
US2713650A (en) * 1951-11-20 1955-07-19 Bell Telephone Labor Inc Electron discharge devices
US2728007A (en) * 1953-07-01 1955-12-20 Rca Corp Cathode ray tube gun structure
US2733379A (en) * 1950-10-12 1956-01-31 Device of the kind comprising an elec-
US2742531A (en) * 1951-08-17 1956-04-17 Philco Corp Pilot signal controlled, color registration system
US2768319A (en) * 1951-09-15 1956-10-23 Zenith Radio Corp Electron-discharge device
US2781468A (en) * 1952-02-18 1957-02-12 Zenith Radio Corp Television receiver
US2793249A (en) * 1953-12-04 1957-05-21 Vilbig Friedrich Synthesizer for sound or voice reproduction
US2795376A (en) * 1951-08-17 1957-06-11 Stevens Res Foundation Computing unit for addition and multiplication
US3062984A (en) * 1959-03-05 1962-11-06 Philips Corp Pulse-counting device and counting tubes for such devices
US3181026A (en) * 1960-03-28 1965-04-27 Itt Character generating tube
US3202864A (en) * 1961-05-26 1965-08-24 Bell Telephone Labor Inc Electron beam device having divergent emission electron gun
US3878532A (en) * 1972-06-05 1975-04-15 Westinghouse Electric Corp High-frequency analogue to digital conversion apparatus

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2108097A (en) * 1934-08-31 1938-02-15 Rca Corp Television transmitter
US2179205A (en) * 1936-01-30 1939-11-07 Toulon Pierre Marie Gabriel Television receiving apparatus
US2180944A (en) * 1935-03-11 1939-11-21 Rca Corp Television and like receiver
US2289205A (en) * 1939-01-24 1942-07-07 Nagy Paul Light modulating device
US2449339A (en) * 1945-11-13 1948-09-14 Rca Corp Cathode-ray tube
US2451484A (en) * 1943-10-05 1948-10-19 Bell Telephone Labor Inc Cathode-ray signal utilizing means

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2108097A (en) * 1934-08-31 1938-02-15 Rca Corp Television transmitter
US2180944A (en) * 1935-03-11 1939-11-21 Rca Corp Television and like receiver
US2179205A (en) * 1936-01-30 1939-11-07 Toulon Pierre Marie Gabriel Television receiving apparatus
US2289205A (en) * 1939-01-24 1942-07-07 Nagy Paul Light modulating device
US2451484A (en) * 1943-10-05 1948-10-19 Bell Telephone Labor Inc Cathode-ray signal utilizing means
US2449339A (en) * 1945-11-13 1948-09-14 Rca Corp Cathode-ray tube

Cited By (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2617075A (en) * 1949-04-09 1952-11-04 Hartford Nat Bank & Trust Co Electric discharge tube comprising means for producing and deflecting an electron beam
US2615142A (en) * 1950-01-19 1952-10-21 Zenith Radio Corp Deflection control electron discharge device
US2733379A (en) * 1950-10-12 1956-01-31 Device of the kind comprising an elec-
US2597677A (en) * 1950-10-17 1952-05-20 Rca Corp Quantizing apparatus
US2642547A (en) * 1950-11-30 1953-06-16 Hartford Nat Bank & Trust Co Device of the kind comprising an electronic tube having a ribbonshaped beam which is deflected and held in different positions
US2689314A (en) * 1951-07-12 1954-09-14 Norman R Gunderson Cathode-ray tube
US2742531A (en) * 1951-08-17 1956-04-17 Philco Corp Pilot signal controlled, color registration system
US2795376A (en) * 1951-08-17 1957-06-11 Stevens Res Foundation Computing unit for addition and multiplication
US2768319A (en) * 1951-09-15 1956-10-23 Zenith Radio Corp Electron-discharge device
US2713650A (en) * 1951-11-20 1955-07-19 Bell Telephone Labor Inc Electron discharge devices
US2781468A (en) * 1952-02-18 1957-02-12 Zenith Radio Corp Television receiver
US2728007A (en) * 1953-07-01 1955-12-20 Rca Corp Cathode ray tube gun structure
US2793249A (en) * 1953-12-04 1957-05-21 Vilbig Friedrich Synthesizer for sound or voice reproduction
US3062984A (en) * 1959-03-05 1962-11-06 Philips Corp Pulse-counting device and counting tubes for such devices
US3181026A (en) * 1960-03-28 1965-04-27 Itt Character generating tube
US3202864A (en) * 1961-05-26 1965-08-24 Bell Telephone Labor Inc Electron beam device having divergent emission electron gun
US3878532A (en) * 1972-06-05 1975-04-15 Westinghouse Electric Corp High-frequency analogue to digital conversion apparatus

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NL76624C (enrdf_load_html_response)

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