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US2282129A - Alternating current signaling system - Google Patents

Alternating current signaling system Download PDF

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Publication number
US2282129A
US2282129A US269524A US26952439A US2282129A US 2282129 A US2282129 A US 2282129A US 269524 A US269524 A US 269524A US 26952439 A US26952439 A US 26952439A US 2282129 A US2282129 A US 2282129A
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US
United States
Prior art keywords
frequency
bias
valve
condenser
source
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
US269524A
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English (en)
Inventor
Hadfield Bertram Morton
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.)
Associated Electric Laboratories Inc
Original Assignee
Associated Electric 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
Application filed by Associated Electric Laboratories Inc filed Critical Associated Electric Laboratories Inc
Application granted granted Critical
Publication of US2282129A publication Critical patent/US2282129A/en
Anticipated expiration legal-status Critical
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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D213/00—Heterocyclic compounds containing six-membered rings, not condensed with other rings, with one nitrogen atom as the only ring hetero atom and three or more double bonds between ring members or between ring members and non-ring members
    • C07D213/02—Heterocyclic compounds containing six-membered rings, not condensed with other rings, with one nitrogen atom as the only ring hetero atom and three or more double bonds between ring members or between ring members and non-ring members having three double bonds between ring members or between ring members and non-ring members
    • C07D213/04—Heterocyclic compounds containing six-membered rings, not condensed with other rings, with one nitrogen atom as the only ring hetero atom and three or more double bonds between ring members or between ring members and non-ring members having three double bonds between ring members or between ring members and non-ring members having no bond between the ring nitrogen atom and a non-ring member or having only hydrogen or carbon atoms directly attached to the ring nitrogen atom
    • C07D213/60—Heterocyclic compounds containing six-membered rings, not condensed with other rings, with one nitrogen atom as the only ring hetero atom and three or more double bonds between ring members or between ring members and non-ring members having three double bonds between ring members or between ring members and non-ring members having no bond between the ring nitrogen atom and a non-ring member or having only hydrogen or carbon atoms directly attached to the ring nitrogen atom with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals, directly attached to ring carbon atoms
    • C07D213/78—Carbon atoms having three bonds to hetero atoms, with at the most one bond to halogen, e.g. ester or nitrile radicals
    • C07D213/86—Hydrazides; Thio or imino analogues thereof
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/02—Amplitude-modulated carrier systems, e.g. using on-off keying; Single sideband or vestigial sideband modulation
    • H04L27/06—Demodulator circuits; Receiver circuits
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q1/00—Details of selecting apparatus or arrangements
    • H04Q1/18—Electrical details
    • H04Q1/30—Signalling arrangements; Manipulation of signalling currents
    • H04Q1/44—Signalling arrangements; Manipulation of signalling currents using alternate current
    • H04Q1/444—Signalling arrangements; Manipulation of signalling currents using alternate current with voice-band signalling frequencies
    • H04Q1/446—Signalling arrangements; Manipulation of signalling currents using alternate current with voice-band signalling frequencies using one signalling frequency
    • H04Q1/4465—Signalling arrangements; Manipulation of signalling currents using alternate current with voice-band signalling frequencies using one signalling frequency the same frequency being used for all signalling information, e.g. A.C. nr.9 system

Definitions

  • the present invention concerns improvements I in or relating to alternating current signaling systems and more particularly to the reception of alternating current signals .in the form of pulses, whether of cyclic or non-cyclic character. and has for its object the translation of such signals into equivalent direct .current pulses with the minimum of distortion.
  • a frequency multiplying arrangement is provided for the purpose of increasing-the frequencyof the incoming signals, and thereby reducing the time of response of the tuned receiver.
  • the line frequency may be multiplied at the input of the receiver by any well-known system such as a frequency doubier or tripler, used singly or in series with or without thermionic valve amplifiers, until a frequency is attained where the transmission'time and the associated distortion are conveniently time,
  • W vcuit,rlserivedfi'ornthleline frequencyandthereof value proportional to the line level and "the with'the resonant circuit voltage to the ensuing t circuit response, is applied in series apparatus of any well-known type which eflectively operates and releases at the same voltage, due allowance having been made for the operating level of such apparatus.
  • multiplying m -mm ming frequency also multiplies the bandwidth by the same amount, so that the postulated constancy of the ratio between the bandwidth and frequency is maintained. likewise, variations in input level, above the initial response required on the resonant circuit to produce distortionless :re-
  • a suitable transformer to the first frequency multiplying stage.
  • This may consist of a frequency doubler. such as the well-known full wave rectifier using copper oxide-elements or a push-pull valve rectifier stage whose anodes are strapped together, or a frequency tripler, such as an inductance with an easily saturatable magnetic core.
  • the output at twice or three times the input frequency is utilised by a resonant circuit at this frequency to feed another frequency doubler or tripler stage, or to operate the ensuing apparatus. It may be arranged to tune each multiplying stage in order to reduce the input frequency component to the negligible quantities. In this manner the input of 750 cycles canrbe successively converted to 1500, 3000, 6000 cycles, etc.
  • the direct current component is preferably derived from a point in the frequency multiplyingstages where a reasonably uniform frequency response is obtainable. This may readily be effected in the case of a rectifier frequency doubier, by making use of the direct current component on a series resistance. This component is in the form of full wave rectified pulses and must be smoothed before being applied for the purpose of biasing. a It will be realised from the above, that the ditothiafrequencyandrespmdsthereto,
  • the back rerect current bias must be present to its full extent at or before the transmission time of the resonant circuit and must remain until this time has elapsed at the cessation of the input signal pulse.
  • the bias As the bias is generated by the signal pulse it must have a small charging time constant and a longer decay time constant.
  • the eifective bias applied to the ensuing apparatus must be less than that generated by an amount equal to the minimum operating level of the ensuing apparatus, as otherwise the postulated operation at the half maximum amplitude of the resonant circuit will not be maintained at all input levels.
  • the generated bias (at half maximum resonant circuit amplitude) is fed through a rectifier in the forward direction and via an opposing bias equal to the minimum operating level of the ensuing apparatus to a condenser across whose terminal is connected a further rectifier in the reverse direction.
  • the generated bias will not be effective until it assault a wed! the pposin bias.
  • the latter is Y prevented from appearing on the condenser when no signal is applied to the receiver, by the combined action of the two rectifiers: likewise when the generated bias exceeds the opposing bias it will charge the condenser rapidly, and the sistances of the rectifier-s when the si nal ceases, providing an eifective smoothing action in addition.
  • the drawing illustrates by way of example a specific embodiment by which the foregoing result may be achieved when the input signaling frequency is of the order of 500 to 1009 cycles such as is used for telephone systems.
  • TI, TI and TI represent transformers appropriately designed for the relative signal frequencies.
  • T3 is tuned by the condenser C3 to the multiplied signal frequency.
  • VI represents a frequency doubling arrangement employing a'pair of valves.
  • RD represents a second frequency doubling arrangement'employing metal rectifiers.
  • R represents a resistance in the output circuit of the frequency doubler RD.
  • RI and R2 represent rectifiers for controling the potential across the condenser C and bias for the valve V2.
  • P represents a potentiometer and VB. represents the connection to whatever responding device or circuit it is desired to control over the plate of valve V2.
  • This device or circuit forms no part of the present invention, and may be any suitable valve relay arrangement adapted to be operated by the impulse
  • the frequency of all currents received over lines ll and Z2 is doubled by the valve doubler VI so that a signaling frequency of say 750 cycles becomes 1500 cycles.
  • These currents are again doubled in frequency by the metal rectifier doubier RD thus bringing a line signaling frequency at, say 750 cycles, up to 3000 cycles, the latter frequency then being used to energise the resonant circuit T3CI.
  • the metal rectifier doubler RD also creates a potential across the resistance R which serves to provide a negative D. C. bias in opposition to the effect on the grid of the valve VI of the positive half-cycles of the alternating voltage on T3C3.
  • the tapped portion of the D. C. voltage on R is adjusted to be equal to one half the maximum resonant circuit amplitude in order to satisfy the before-mentioned relationship for distortionless reproduction, but as also mentioned before must not appear on the grid of V2 until it exceeds the operating level of valve V2, in order that thereafter operation and release of valve VI may continue to take place at the half peak resonant response of a resonant circuit TSCI.
  • this D. C. bias voltage must appear on the grid of valve V2 at or before the attainment of the half peak resonant response to an input signal and be maintained until at least this time has elapsed after the cessation of the input signal pulse. This time interval has been previously referred to as the transmission time of the circuit.
  • the application and control of the required signal bias voltage on resistance R to the grid of valve V2 in the manner described above can This bias is such as normally to prevent Operation of valve V2 (and consequently of the subse- 'quent valve/relay circuit), and exceeds the bias at which valve V2 would normally Just operate by an; amount pl. Consequently pi can be termed the operating level of valve V2.
  • the rev quired portion of the signal bias voltage on resistance R is denoted by P2 and tends rapidly to charge condenser-C via the forward. direction of R2 so that a negative signal bias appears on the grid of valve V2. in so doing the signal bias must first overcome the opposing bias voltage at pi and if the latter is made equal to the operating level of V2, the desired condition for maintenance of action at the half peak resonant response of resonant circuit TSCI is attained.
  • rectifier RI effectively shunts condenser C to any voltage other than the desired net signal bias which can be built up rapidly through R2 but will decay slowly via the back resistances of rectifiers RI and R2.
  • this controlling circuit also provides adequate smoothing of the fullwave rectifier potential on resistance R, as applied to the grid of valve V2.
  • the system described is not limited to the use of one signaling frequency but can be used with a plurality of frequencies provided each frequency. is treated in the manner described. Similarly, the system described is applicable to other forms of signaling using alternating ourcially immune from operation by speech, on i the well-known principle that the latter contains only a small percentage of the signaling frequency, and a large percentage of other frequencies. Thus all speech frequencies will produce a biasing effect which will substantially overcome the response of the ultimate resonant circuit to the smaller percentage of signaling frequency in speech.
  • each frequency multiplying, stage introduces some considerable loss of energy as between the input and the multiplied frequencies. This results effectively in a loss of voltage, which may be overcome by the employment of a transformer or auto-transformer winding on the resonant circuit or circuits, to overcome, this rents such as single or multi-channel voice frequency telegraphs with corresponding improvements in the response of the receiver.
  • a signal receiving circuit connected to said grid.
  • a resistor in said circuit a source of biasing potential having one side connected to the cathode of said valve, a bridge across said source comprising, in series, a unidirectional conductive device, said resistor and a second unidirectional conductive device, the first of said devices being connected in said bridge in a conductive direction with respect to said source and the second of said devices being connected in said bridge in a non-conductive direction with respect to said source, and a condenser bridging said first device and charged only when the 2.
  • a circuit over which signals having an alternating current component are received including, in series, a resistor and the primary winding of a transformer, a biasing circuit connected to the grid of said valve including, in series, a first source of biasing potential, a second source of biasing potential and a secondary winding of said transformer, means for connecting said resistor in shunt with one of said sources, said means including a unidirectional current carrying device poled to prevent current from said one source from traversing said resistor.
  • a source of fixed direct current potential means connecting said source to the grid of said valve to bias said grid negatively, a resistor, means connecting said resistor in shunt to said source, said last means including a unidirectional current carrying device poled to prevent current from said source from traversing said resistor, a circuit over which signals having an alternating current component are received, and means for causing said signals to traverse said resistor to produce therein a varying potential, said varying potential effective to vary the bias placed upon said grid by said source.
  • a source of constant direct current potential a source of intermittent undulating direct current potential
  • a condenser means permanently connecting said condenser and said two sources in a series circuit, said sources being poled in apposition to one another in said circuit, means always eflective to prevent said first source from charging said condenser, said second source effective to charge said condenser over said with any desired de ree. depending upon the.
  • said condenser varialny over-said circuit in ac cordance with the amount by which the potential or said other source exceeds that oi said one source.
  • tial is equal to or greater than the potential oi BER'I'RAM MORTON HADFIELD.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Electrotherapy Devices (AREA)
  • Interface Circuits In Exchanges (AREA)
  • Telephonic Communication Services (AREA)
US269524A 1938-05-07 1939-04-22 Alternating current signaling system Expired - Lifetime US2282129A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB13664/38A GB514520A (en) 1938-05-07 1938-05-07 Improvements in or relating to alternating current signalling systems

Publications (1)

Publication Number Publication Date
US2282129A true US2282129A (en) 1942-05-05

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Family Applications (1)

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US269524A Expired - Lifetime US2282129A (en) 1938-05-07 1939-04-22 Alternating current signaling system

Country Status (4)

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US (1) US2282129A (sv)
BE (1) BE434099A (sv)
GB (1) GB514520A (sv)
NL (2) NL64018C (sv)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2651679A (en) * 1947-02-07 1953-09-08 Int Standard Electric Corp Electric signaling system
US2698878A (en) * 1951-04-27 1955-01-04 Int Standard Electric Corp Voice frequency receiver
US4172215A (en) * 1976-09-27 1979-10-23 Hitachi, Ltd. Transformer coupling circuit providing for cancellation of D.C. fluxes

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2651679A (en) * 1947-02-07 1953-09-08 Int Standard Electric Corp Electric signaling system
US2698878A (en) * 1951-04-27 1955-01-04 Int Standard Electric Corp Voice frequency receiver
US4172215A (en) * 1976-09-27 1979-10-23 Hitachi, Ltd. Transformer coupling circuit providing for cancellation of D.C. fluxes

Also Published As

Publication number Publication date
GB514520A (en) 1939-11-10
NL93258C (sv)
NL64018C (sv)
BE434099A (sv)

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