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US2245565A - Wave translating system - Google Patents

Wave translating system Download PDF

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Publication number
US2245565A
US2245565A US210333A US21033338A US2245565A US 2245565 A US2245565 A US 2245565A US 210333 A US210333 A US 210333A US 21033338 A US21033338 A US 21033338A US 2245565 A US2245565 A US 2245565A
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US
United States
Prior art keywords
waves
loop
frequency
band
amplitude
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US210333A
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English (en)
Inventor
Harold S Black
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
AT&T Corp
Original Assignee
Bell Telephone Laboratories Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority to NL54676D priority Critical patent/NL54676C/xx
Application filed by Bell Telephone Laboratories Inc filed Critical Bell Telephone Laboratories Inc
Priority to US210333A priority patent/US2245565A/en
Priority to GB12783/39A priority patent/GB528151A/en
Priority to DEW3480D priority patent/DE875213C/de
Priority to FR855390D priority patent/FR855390A/fr
Application granted granted Critical
Publication of US2245565A publication Critical patent/US2245565A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10B—DESTRUCTIVE DISTILLATION OF CARBONACEOUS MATERIALS FOR PRODUCTION OF GAS, COKE, TAR, OR SIMILAR MATERIALS
    • C10B27/00—Arrangements for withdrawal of the distillation gases
    • C10B27/06—Conduit details, e.g. valves
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
    • H03F1/34—Negative-feedback-circuit arrangements with or without positive feedback
    • H03F1/36—Negative-feedback-circuit arrangements with or without positive feedback in discharge-tube amplifiers
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
    • H03F3/66—Amplifiers simultaneously generating oscillations of one frequency and amplifying signals of another frequency
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B3/00—Line transmission systems
    • H04B3/02—Details
    • H04B3/04—Control of transmission; Equalising
    • H04B3/06—Control of transmission; Equalising by the transmitted signal
    • H04B3/08—Control of transmission; Equalising by the transmitted signal in negative-feedback path of line amplifier

Definitions

  • This invention relates to wave translation, as for example, electric wave amplification, and relates especially to'retroactiveor feedback systems, as for example, negativefeedback amplifiers. J t
  • Objects of this invention are to control feedback and singing or production of self-sustained oscillations in such systems;
  • the 1 invention is .embodied in a broad band-vacuum tube amplifier with'large negativeffeedback.
  • prevention-of singing is a'major problem, but it is often relatively easy to-insure that the frequency at which the circuit does singisconsiderably beyond'or' outside-the used frequency band.
  • the singing frequency may be about 1,000,000
  • the amplifier in accordance with ter, as for example, the Thyrite, copper oxide the invention, is allowed to oscillate or sing around its negative feedback loop outside the used frequency bandv (since satisfying the requirements for preventing oscillation would be so difficult), but the amplitude of the unwanted oscillations circulating around that loop is limited to a value sufliciently 'small to avoid overloading the amplifier or reducing the gain of itsamplifying element, for example, a value so minute as to avoid appreciably reducing the useful output capacity of the amplifier even though it is thus oscillating.
  • the element that limits the amplitude of the oscillations is so' associated with that loop, for example, through a band suppression filter whose attenuation range is the used frequency band, as to be not acted upon or not appreciably affected by the utilized waves or waves, in the used frequency band that circulate around that loop. Therefore the amplitude limiting element does not prevent or interfere with the large negative feedback around that loop in that band, .(Although, for any greatly exceed thegamplitu'de of the oscillations,
  • the amplifierlis 'used for measuring purposes be small (for example even smaller than the amplitude of the oscillations), with the negative feedback nevertheless large.
  • the amplitude limiting means or. element may be a non-linear element of-any suitable characrectifier, or space discharge device referred to inthe above-mentioned Caruthers patent as exhibiting an overload or non-linear relation between current and voltage, or' any suitable temperature dependent resistance of the general type that varies its resistance greatly in response to change of its temperature.
  • suitable temperature-dependent resistors or so-called thermistors which change the magnitude of their resistance enormously in response to temperature' change, even when only heated by the current passing through them,.are resistors of silver sulphide, uranium oxide, cobalt oxide or boron.
  • non-linear resistance is used herein in the broad sense of resistance having a characteristic that isnon-linear, and includes resistances, such for example as these thermistors, which nevertheless are linear in the sense that they introduce no material amount of deleteriousmodulatiori in the useful frequency range, because the time required to alter their temperature ;and,hence, resistance, is appreciable as compared to the more rapid changes in instantaneous current or voltage at any frequency falling within the useful band of frequencies of the amplifier. 5 5
  • the amplitude limiting element may be anywhere in the negative feedback loop. However, ordinarily it preferably is in the forward or tageous because the smaller voltage at which limiting is desired the less readily the limiting isv accomplished, in practice. If the gain of the ,u-circuit is 120 decibels limiting in the output at Caruthers patent, connected in the loop.
  • the element 4 may be, for instance, a thermistor of any of the types mentioned above with negative temperature coefficient of resistance, or Thyrite or a copper oxide rectifier. As explained in the above-mentioned C'aruthers patent, if the voltage input to the bridge network had a certain predetermined value the.
  • non-linear resistance would balance they-bridge andlthe voltage output of the bridge network would be zero, and therefore (as also explained in the patent) the amplitude of the sustained oscillations at the vinput tothe bridge is slightly below that pre- 1 volt would be equivalent to limiting-at000001 volt at the input.
  • a feature of the invention is limitation'of'the amplitude of incidental, unwanted, self-sustained oscillations in a feedback system, as for example an amplifier with large negative feedback, to'a value below the overload point of the system.
  • Another feature is accomplishing such limitation without thereby necessitating limitation of feedback of utilized waves inthe system.
  • a further feature is reduction of the operating margin required against singing in a negative feedback system, as for example an amplifier with large negative feedback, or elimination of necessity for such margin.
  • Figs. 1 and 2 show two negative feedback'amplifiers of the type referred to above; and.
  • Fig. 1-A indicates a modification ofthe amplifier of Fig. 1.
  • the amplifier of. Fig. 1 may be for example, of the general type shown inFigs. 1,6 and 7. of my copending application Serial..No..114,390, filed December 5, 1936, for Wave translation systems, now Patent No. 2,209,955, issued August 6,1940. It comprises an amplifying path. including an amplifyin element or device having any desired number of cascaded vacuum tube stages, G and P designating the grid of the first tube andthe plate of the last tube (in this figure and also in Fig. 2), and comprises a feedback path I.
  • the amplifying path may be referred .to as the l-circuit and the feedback path may be referred to as the o-circuit, the significance of and ,8, as well a [L-CiI'Cuit and B-circuit being as indicated in my above-mentioned Patent 2,102,671.
  • An input bridge transformer or hybrid coil 2 couples the incoming circuit and the feedback'.
  • an output hybrid coil ,3 couples the output end of the amplifying path to the outgoing circuit and the feedback path. If desired, the
  • s may be of the order of one or more times decibels.
  • the amplifier may be designed to pass and a lplify frequencies from 12 to 60 kilocycles for 'g when the feedback connection is a de the amplifier may sing around the negative feedback loopat 1,000,000 cycles for instance. In this singing or oscillatory loop is included example, and
  • This means comprises a non-linear resistance 4 inpne arm 5 of a Wheatstone bridge network 6, such as the bridge of Fig. 3 of the above-mentioned the point of balance. of the bridge may be condetermined critical value.
  • Fig; 1 the element 4 is preceded by a band lsuppression network or filter 1 which attenuates or suppresses waves of the used frequency band,
  • the .amplituderof the sustained oscillations may thus be limited to a value sufficiently small to avoid overloading the amplifier or reducing the gain of its amplifying element, for
  • the filter 1 prevents the signal' Waves or waves of the used frequency band that circulate around the negative feedback oop from acting upon or appreciably aifecting the elementv 4 inthe same loop'.
  • the impedance of filter -'I viewed from the .bridge'network 6 maybe alow impedance outside the used frequency band. Whether it is high or low affects eitherthe poling of the transformers or the'bridge arm in' which it is; located. Accordingly, the filter I and amplitude limiting resistance ,4 may: preferably be in the arm. 5 of. the bridge network 6, asshown, rather. than in. the opposite arm, because when inthe arm 5 they are in the i-circuit of theamplifier.
  • Theamplifier of Fig; 1 oscillates or sings-weakly asdescribed above'at 1,000,000 cycles; and if 'there. is a lowfrequency phase cross-over as for example, at cycles (that is, ifat a frequency below the used'bandf'as for instance a frequency .of 100 cycles, the phase shift around the feedback loop. is zer /and the. gain around the loop exceeds Zero decibel) the amplifier will oscillate weakly atboth 1,000L000 cyclesand I00 cycles at the same'time if the bridge arm containing plication of the amplifier.
  • the amplitude limiting element be changed, for
  • the filter 1 is a -12 kilocycle low-pass filter, transmitting to its associated element 4 waves of frequencies below the used frequency band and attenuating waves of other.
  • the filter 1" is a high-pass filter with cut-off at 60 kilocycles, transmitting to its associated element 4 waves of frequencies above the used frequency band and attenuating waves of other frequencies.
  • the invention comprehends application in which unwanted oscillations may, without .01)- jection, be permitted to fall within the used frequency band, as well as applications in which the unwanted oscillations are outside the used band. Also, the invention comprehends applications in which an oscillation frequency may lie in an unused frequency range between two used frequency bands, as in the case of a two-band amplifier for a single-amplifier type of repeater for a multiplex carrier telephone system.
  • filters may be used to connect the amplifier to its attached incoming and outgoing circuits, for excluding the weak oscillations of sing frequencies from those circuits.
  • filters indicated in Fig. 1 as band filters 8 and 9 may be low-pass filters having cut-01f frequencies of 60 kilocycles to serve this purpose.
  • the filters for this purpose may be of any suitable type, for, instance 12-60 kilocycle band-pass:
  • filters or high pass filters attenuating frequencies below 12 kilocycles in case the sing frequency is below instead of above the used frequency range of 12-60 kilocycles.
  • the filter at the input or that at the output, or both, may be omitted, depending upon the specific ap- In the amplifier of Fig. 2 the band suppression filter 1 feeding the non-linear resistance 4 is shown across the plate circuit of the last tube and in the -circuit of the feedback am- Then the input impedance of filter I viewed from the amplifier ordinarily is preferably made high for the used frequency band.
  • the amplifier may be, for instance, a 12 to 60 kilocycle negative feedback amplifier similar to that of Fig. 1, and is shown by way of example with input bridge network l and output bridge equalizer network I 3 like those of A. L. Stillwell Patent 1,993,758, March 12, 1935, in-stead'of the input and output bridge transformers 2 and 3 of Fig. 1.
  • the equalizer bridge comprises arms designated R0, Z21, R and Z11 as in that patent, and functions as explained therein.
  • the amplifier operates in the same general manner as that For examof Fig.
  • the non-linear resistance limiting the amplitude of the oscillations of the sing frequency (for example 1,000,000 cycles) and the band suppression filter preventing the signal waves or waves of the used frequency band from acting upon or materially affecting the nonlinear resistance, as brought out above.
  • the filter 1 feeding the amplitude limiting element 4 in Fig. 2 may be connected across the -circuit of the feedback amplifier at an earlier point than shown.
  • amplitude discriminating means for. connection to said loop to limit the amplitude of waves pass- .ing around said loop, and frequency selective means for connecting said amplitude discriminating means to said loop, said frequency selective means having its attenuation. for transmission. from said loop to said amplitude discriminating means high throughout the signal frequency range, but low over a wide frequency range exclusive of the signal frequency range.
  • An amplifier comprising a forwardly transmitting path including a wave amplifying device and a feedback path forming with said first path a closed. loop path producing such large negative feedback of waves of such a wide frequency band to be amplified by said amplifying device that said loop path produces as--a consequence of the magnitude of said negative feedback and the width of said band self-sustaining oscillations around said loop path of a frequency above said band and simultaneously of a frequency below said band, a non-linear resistance, a frequency selective circuit connecting said resistancein said first path and having high attenuation for Waves of said band and waves of said frequency below said band but relatively low attenuation for waves of said frequency above said band, a second non-linear resistance, and a second frequency selective circuit connecting the latter resistance in said first path and having high attenuation for waves of said band and waves of said frequency above said band but relatively low attenuation for waves of said frequency below said band.
  • a wave translating system comprising a source of signaling waves of a wide frequency band to be amplified and a wave amplifying circuit connected thereto for amplifying said waves, said circuit comprising an amplifying device and afeedback path forming therewith a feedback loop path having its'loop propagation over said band such as to produce negative feedback of said signaling waves around said loop path, said loop path having its loop propagation at a given frequency such as to produce self-sustained oscillations at said frequency, and amplitude discriminative means non-linearly responsive to amplitude changes of impressed waves for limiting the amplitude of said oscillations to the exclusion of said signaling waves to a value sufficiently low to prevent said oscillations from materially reducing the load capacity of said system in amplifying said signaling waves.
  • a wave translating system comprising a source of signaling Waves of a wide frequency range to be amplified and a wave amplifying circuit connected thereto for amplifying said waves, said circuit comprising an amplifying device and a feedback path forming therewith a feedback loop path having its loop propagation over said range such as to produce negative feedback of said signaling waves around said loop path, said loop path having its loop propagation at a plurality of frequencies such as to produce self-sustained oscillations at all of said frequencies simultaneously, and amplitude discriminative means non-linearly responsive to impressed voltage changes for limiting theamplitudes of said oscillations at said frequencies'to the exclusion of said waves to values sufficiently low to prevent 'said' oscillations from materially reducing the load capacity of said system in amplifying said as to produce incidental singing around said loop at afrequency outside said'range and means to prevent said singing from rendering said amplifier useless and thereby increase the maximum amount of said negative feedback that can be usefully employed as compared to the non-singing condition, said means including
  • the method which comprises producing negative feedback of wanted waves around a closed loop path containing an amplifying element with the loop gain for said waves of so much greater order of magnitude than zero decibels over a frequency band so wide that selfsustaining feedback of other waves around said path is-produced at a frequency outside of said band-as a consequence of the magnitude of said band width and loop gain and producing a component of loop transmission varying non-linearly with amplitude of said other waves for maintaining the maximum amplitude of said other waves below the overload point of the amplifying element.
  • a wave amplifying device means for supplying thereto signal waves of a wide frequency band, a feedback path forming therewith a loop path having the loop gain of so much greater order of magnitude than zero decibels over a frequency range of said signal waves extending so far upwardly from a frequency at which the loop phase shift is 180 degrees that self-sustaining feedback of oscillations around said loop path results at a frequency above said band,'means in said loop path selective to frequencies including said oscillation frequency outside of said band and means responsive to the selected waves to produce a component of loop propagation varying non-linearly with amplitude variation of the selected waves for maintaining the amplitude of said oscillations below the overload value for said device.
  • a wave translating system comprising a source of signal waves of a Wide frequency range
  • an amplifier connected thereto for amplifying said waves, means forming with said amplifier a closed feedback loop path producing negative feedback of said waves around said loop path with the loop gain over said range oflarger order of magnitude than zero decibels, said loop,
  • a wave amplifying device means for supplying thereto a frequency band of signal waves, a feedback path for said'device forming therewith a loop path producing negative feedback of said wavesaround said'loop path with the loop gain of greater order of magnitude than zero band being sogreat that at a frequency outside of said'band for which the loop phase shift equals zero the loop gain is at least as great as zero decibels, frequency selective means responsive to oscillations of substantially said frequency outside of said band in said loop path and means responsive to the selected waves to produce a component of loop propagation varying non-linearly with amplitude-variation of the selected waves for limiting the amplitude of said oscillations to -a value below the overload value for-the ampli- 10.
  • Aowave amplifying device having a feedback path forming therewith a closed loop path producing'such'large negative feedback of waves of a given'frequency band to be amplified by said device that said loop path produces as an incidentof said negative feedback self-sustaining feedback of oscillations around'said loop path at a plurality of frequencies simultaneously, said oscillation frequencies being outside of said frequency band, means including a plurality of amplitude limiting devices, one for each of said frequencies, responsive to changeof amplitude of impressed waves to introduce non-linearly proportionalchange in transmission efficiency in a sportionjof-said loop path for limiting the amplitude of'said oscillationslat each of said frequencies tovalues below the. overload value for said device and a plurality of frequency selectors,
  • eachiselector transmitting to its associated limitingvdevice said oscillations of one of said frequenciesfto the exclusion of said oscillations of saidother frequencies and said Waves.
  • a wave amplifyingdevice having a feedback path .forming therewith a closed looppath producing negative feedback of waves of a used frequency band around said loop path, said negative feedbackibeing so great that said loop path produces self's'ustaining feedback of oscillations of frequency outsideof said band around said loop-pathas' an incident of said negative feedback, means in said loop path non-linearly responsive to impressed Waves to provide amplitude discrimination for limiting theamplitude of said oscillations; and means. comprising a band suppression filter attenuating waves of said'utilized frequencyhand'butf having relatively low attenuation for-waves of a wide frequency range above and below said band forexcluding from said limiting means waves of said band.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Power Engineering (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Amplifiers (AREA)
  • Coils Or Transformers For Communication (AREA)
US210333A 1938-05-27 1938-05-27 Wave translating system Expired - Lifetime US2245565A (en)

Priority Applications (5)

Application Number Priority Date Filing Date Title
NL54676D NL54676C (xx) 1938-05-27
US210333A US2245565A (en) 1938-05-27 1938-05-27 Wave translating system
GB12783/39A GB528151A (en) 1938-05-27 1939-04-28 Improvements in valve amplifying circuits
DEW3480D DE875213C (de) 1938-05-27 1939-05-24 Verstaerkeranordnung mit negativer Rueckkopplung fuer den zu verstaerkenden Frequenzbereich
FR855390D FR855390A (fr) 1938-05-27 1939-05-26 Systèmes de transmission d'ondes électriques

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US210333A US2245565A (en) 1938-05-27 1938-05-27 Wave translating system

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US2245565A true US2245565A (en) 1941-06-17

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US210333A Expired - Lifetime US2245565A (en) 1938-05-27 1938-05-27 Wave translating system

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US (1) US2245565A (xx)
DE (1) DE875213C (xx)
FR (1) FR855390A (xx)
GB (1) GB528151A (xx)
NL (1) NL54676C (xx)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2589184A (en) * 1949-09-13 1952-03-11 Bell Telephone Labor Inc Electronic impedance equalizer

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FR855390A (fr) 1940-05-09
GB528151A (en) 1940-10-23
NL54676C (xx)
DE875213C (de) 1953-04-30

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