US2343759A - Electric signaling system - Google Patents

Electric signaling system Download PDF

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Publication number
US2343759A
US2343759A US447394A US44739442A US2343759A US 2343759 A US2343759 A US 2343759A US 447394 A US447394 A US 447394A US 44739442 A US44739442 A US 44739442A US 2343759 A US2343759 A US 2343759A
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Prior art keywords
amplifier
ringing
output
frequency
currents
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Expired - Lifetime
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US447394A
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English (en)
Inventor
Fairley Frank
Walsh Raymond
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International Standard Electric Corp
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International Standard Electric Corp
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • 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 selective electric wave receivers and-in particular those used for receiving ringing and dialing signals transmitted over telephone communication circuits.
  • the object of the present invention is to provide a simple and reliable signal receiver in which talk ing up is effectively prevented without the use of extra frequencies or guard circuits or relays. While its primary application is to ringing or dialing arrangements in connection with transmission systems, it is not limited to such arrangements but is applicable much more broadly to any cases where operation is desired by incoming signal waves having some particular type of frequency distribution of energy, and where operation must not occur when the incoming waves have some other type of distribution.
  • the invention in its preferred embodiment depends for its eifect on an arrangement whereby the incoming signals do not themselves operate the receiver, but cause local oscillations to be generated for this purpose, and then only if the frequency distribution of the incoming energy is substantially of some predetermined forms
  • the incoming energy which is to operate the receiver will be practically of a single frequency, but it might equally well consist of several single frequencies, or bands of frequencies.
  • no oscillations can be produced and generally the effect will be further to inhibit any tendency to oscil1ation.
  • the circuits of the invention would not receive dialing impulses satisfactorily. Therefore, in order to be able to take advantage of the invenion in a dialing receiver so that it shall not be subject to risk of talking up, a prefix signal would be used when dialing which signal would operate the device as described, causing suitable means to function to condition the receiver so as to enable it to receive the impulses for the duration of the dialing, after which it would revert to the safety condition.
  • a selective electric wave receiver comprises means for comparing the amount of received energy contained within certain ranges of frequencies with tire amount of received energy contained within certain other ranges of frequencies;
  • the signal receiving device may be operated by local oscillations which are caused to be generated on the receipt of signals having a predetermined frequency distribution of energy, such oscillations being prevented when signals with some other energy distribution are received: and slow act-.
  • thermally operated means may be provided for discriminating between signals having a predetermined energy distribution and those having some other energy distribution.
  • FIG. 1 and 2 are block schematic diagrams used for explaining the principles of the invention:
  • Figs. 3 and 4 are schematic circuits of preferred embodiments thereof.
  • valves are indicated as triodes with indirectly heated cathodes, the heating circuits not being shown in the interests of clearness.
  • the invention is not limited to the use of such valves, and pentodes, or any other convenient types, may be used if preferred.
  • a battery is shown by the conventional symbol to indicate the plate potential source, although this should not be taken to mean that the plate circuits are necessarily supplied in this way, nor that any particular voltage is implied.
  • the arrangements for biasing the control grids are shown in the form of the usual condenser-shunted resistance connected in series with the cathode, but this is likewise not an essential arrangement. It is to be understood that circuits operated in accordance with this invention may be provided with any suitable valves, and that appropriate arrangements may be supplied in any of the well known ways.
  • Figs. 1 and 2 are block schematic circuit diagrams which will be used to explain the principles involved.
  • Fig. 1 represents the circuit of a signaling receiver suitable, for instance, for receiving the ringing currents in a telephone transmission system employing voice frequency ringing.
  • the ringing currents are applied from the line L, and after passing through the receiver, cause the operation of a relay system of some suitable known type indicated at R.
  • the signals are applied to an amplifier AI and the relay system R is operated from an amplifier A2 which is provided with a feed back path through a Wheatstone bridge network W.
  • This network has four branches of which two comprise the constant resistances RI and R2 and the other two comprise resistances TI and T2 which are variable with the temperature.
  • TI and T2 are respectively provided with electrically insulated heater coils operated from the amplifier Al.
  • One pair of diagonal terminals of the network W is connected to the input of amplifier A2 and the other pair of diagonal terminals is connected to the output thereof.
  • the network W accordingly provides afeedback path for the amplifier.
  • the resistancesTl and T2 are preferably composed of material (such for instance as silver sulphide) whose resistance varies with the temperature and may be ,mounted in containing envelopes Trl and Tr! with the corresponding heater coils as indicated in Fig. 1.
  • they may constitute elements known as thermistors of the indirectly heated type, of which the resistance depends mainly on the current flowing through the heater coil and practically not at all on the current flowing through the resistance element itself.
  • Such thermistors have a negative temperature coefficient of resistance.
  • the heaters are each connected through a corresponding network NI or N2 to the output of amplifier Al. Any currents arriving from L will be amplified and will flow through the heaters of Trl and T11 after being attenuated' in the networks NI and N2.
  • the input circuits of these networks are shown in Fig. 1 connected in parallel. They could equally well be connected in series if preferred.
  • the amplifier A2 may then be caused to generate oscillations at a suitable frequency determined, for example, by a tuned circuit appropriately located in the amplifier, which oscillations can be used to operate the relays in R by a suitable rectifying circuit (not shown) located in R.
  • a suitable rectifying circuit not shown located in R.
  • the effect of applying ringing current to the input of amplifier Al is to cause (indirectly) the operation of the relays in R as desired.
  • the thermistor Trl will cool down and in a short time the feedback will again become negative and the oscillations operating R will cease.
  • the feedback introduced by the Wheatstone bridge network should be negative when no signals are being received: it may however be zero, or even positive so long as the amount of feedback is insufficient for there to be any risk of the amplifier oscillating.
  • the ringing receiver will be bridged across the line so that it will be subjected to the ordinary speech transmission currents as well as to the ringing currents.
  • T ese speech currents cover a band of frequencies perhaps 2700 cycles wide or more with a certain average type of energy distribution.
  • the ringing frequency will of course occur, but the energy associated therewith will generally be small compared with the total energy in the band.
  • the network N2 were so designed that it allows substantially the whole band to pass except the ringing frequency, and if NI were so designed that it blocks substanassa'no is applied.
  • circuit of the invention may be designed so that if the incoming currents contain any additional currents outside the predetermined frequency or band of frequencies, the relay device R is still prevented from operating by the presence of these outside frecurrents have thus operated to prevent the requencies although the predetermined frequency,
  • the networks Ni and N2 could for example be respectively complementaary narrow band pass and band elimination filters, the narrow band being central round the ringing frequency.
  • the thermistors Trl and Tr2 are relatively slow to operate and their temperature is chiefly determined by the instantaneous energy in the corresponding heater integrated over a period of time, which is controllable by suitable design, and which can be made long compared with the period or duration of any of the frequencies in the speech wave.
  • the speech energy should consist momentarily of only the ringing frequency at an abnormally high level (a condition which in many voice frequency ringing systems causes false ringing)
  • its effect on the thermistor Trl will be negligible as it will not have had time'to respond.
  • the system of the invention is entirely proof against talking up.
  • El and E2 are determined by the networks Ni and N2 and by the energy distribution of the band of frequencies applied to the input terminals.
  • the ratio Tl/T2 must change in a manner tending .to make the feedback positive when'Dl is applied, and
  • a proportion of the output of the amplifier A2 may be fed back to the input of amplifier AL.
  • the arrangement may be made to lock itself when once operated.
  • the ringing current be applied long enough to start the oscillations of amplifier A2 those oscillations will-be fed through the amplifier Al to the heater of TH and can be made to maintain its temperature at or near the temperature produced by the incoming ringing currents, so that the feedback is kept positive.
  • the relays in R will then remain operated until the arrangement is broken down by independent means (such as by momentarily cutting either of the feedback connections)
  • the feedback connection between the amplifiers A2 and AI may be made in any convenient way.
  • the oscillating frequency and the networks NI and N2 may be so chosen and designed that when som of the energy of the oscillations is fed back in the manner just described, and after ringing current has been applied, the ratio Tl/T2 is so modified that the feedback produced by the network W either is made more positive, or is unaltered, or is made less positive, than it otherwise would have been if the applied currents acted alone.
  • the arrangement may look itself permanently in operation; in the last case it may be made to operate intermittently while the ringing currents are applied, by suitable choice of the conditions, this being possible as a result of the relatively slow response of the thermistors. In the latter case, also, all operation ceases a short time after removal of the ringing currents.
  • Fig. 2 is shown another arrangement employing only one amplifier A.
  • the incoming signals are applied from the line L to the input of this amplifier which is provided with a feedback path through a Wheatstone bridge network W similar to that described in connection with Fig. 1.
  • the heaters of the thermistors Trl and Tr2 and in this case connected through the networks NI and N2 to the output of the amplifier A, and in this case an additional network N3 is interposed between the amplifier output and the relay system R. This network is necessary to ensure that the relay system B shall be operated by the cally generated oscillations and not directly by the incoming signal.
  • the networks NI and N2 will preferably be designed as before so that Ni substantially excludes the band of speech frequencies and N2 passes it, and so that th ratio TI/T2 changes to make the feedback more negative when speech currents are being received.
  • the network N3 should preferably be designed substantially to exclude the speech currents in order that the relay system R may not be in any danger of being operated directly by them.
  • a convenient though not essential arrangement would be to choose the frequency of oscillation so that it lies outside the band of speech and ringing frequencies.
  • NI could then, for example, be a relatively simple low pass or high pass filter.
  • variable resister By a modification of Fig. 2, the variable resisterably exclude the speech currents from R to prevent it from being directly operated by the speech currents.
  • circuits of Fig. 2 and the modification thereof have been explained for clearness in terms of a particular case of a line transmitting ordinary speech and using a single frequency ringing system.
  • these circuits are not limited to such a particular system, but may be designed to discriminate between two systems of currents comprising bands of frequency with different energy dis. tributions DI and D2, by proper design of the discriminating networks, according to the principles explained above in connection with Fig. 1.
  • the oscillations can be made to aifect the resistances of the elements TI and T2 of the bridge W, either directly, or through the heaters, provided that their frequency and the discriminatingnetworks are so chosen and designed that a proportion of the energy of the oscillations is allowed to how through one or both thermistors.
  • Ti and T2 are of self heated type, and are shunted respectively by discriminating networks MI and M2, the networks NI and N2 shown in Fig. 2 being removed.
  • Ti and T2 may for example be directly heated thermistors: that is.
  • Ti and T2 might also consist of other types of element whose resistance depends upon the current flowing through them, such as lamps, and may have a positive or a negative temperature coeflicient of resistance.
  • the networks MI and M2 will be two terminal impedances designed to shunt the elements TI and T2 in a selective manner. All the other elements will be shown in Fig. 2 and operate in the same way.
  • Mi and M2 might be designed so that the ringing current passes through TI, but substantially none of it through T2, thereby making the feedback positive; and so that the speech currents fiow through T2 but practically none through Tl making the feedback more negative; oscillations for operating R being produced in the first case but not in the second.
  • Network N3 as in the case of Fig. 2 should prefunaffected.
  • the circuit may be made to lock in operation after application of the ringing currents, and in the second case intermittent operation can be made to occur durinl the period of application of the ringing currents.
  • Figs. 3 and 4 show the circuits of two preferred embodiments of the invention according to Figs. l and 2 respectively, in which corresponding elements are given the same designations; and as the operation of such elements has already been fully explained they will not be again described in detail.
  • the amplifier Ai comprises a thermionic valve VI provided with input and output transformers ITI and OTi.respectively. Incoming signals are applied from the line to the input terminals A, B connected to the primary winding of the transformer ITI, and the secondary winding of the transformer OTi is connected to the networks N I and N2.
  • the amplifier A2 likewise comprises a thermionic valve V2 with input and output transformers IT2 and GT2 respectively.
  • the diagonals of the Wheatstone bridge network are connected respectively to the primary winding of the transformer IT2 and to a secondary winding of 0T2.
  • the relay system R is connected to another secondary winding of 0T2.
  • a condenser CI is shown connected across the first mentioned secondary winding of 0T2 for the purpose of providing a tuned circuit for fixing the oscillation frequency of the valve V2.
  • Cl could be connected across the primary winding of IT2; and any other conline to input terminals A and B connected to the primary winding of IT.
  • One pair of diagonal ferminals of the Wheatstone bridge network W is to the opposite branches of the bridge network connected to the control grid circuit of the valve V in series with the secondary winding of IT, The other pair of diagonal terminals is connected to the secondary winding of OT in parallel with the input circuits of the networks NI, N2 and N3. Feedback is thus directly obtained between the plate and grid circuit of the valve.
  • the circuit operates exactly as explained in connection with Fig. 2.
  • a selective electric wave receiver comprising filter networks of unlike frequency outputs, output connections from the respective filter networks to the opposite branches of a Wheatstone bridge network including resistances having neg- -ative temperature coefficient of resistance, and
  • a signal receiving device connected to the output side of the bridge network and said receiving device being operative when the ratio of energy of one branch circuit to the other is greater than a given value.
  • a selective electric wave receiver comprising filter networks of unlike frequency output, output connections from the respective filter networks to the opposite branches of a Wheatstone bridge network including thermistor resistances having negative temperature coefiicient of resistance, an amplifier connected to the opposite branches of the bridge network to establish a feedback circuit thereto and a signal receiving device connected to the output side of the amplifier and said receiving device being operative whenthe ratio of energy of one branch circuit to the other is greater than a given value.
  • a selective electric wave receiver comprising a plurality of filter devices of unlike frequency output, output connections from the respective filter devices to the opposite branches of a Wheatstone bridge network including slow acting thermistor resistances having negative temperature coefiicient of resistance, an amplifier connected to the opposite branches of the bridge network to establish a feedback circuit thereto and a signal receiving device connected to the output side of the amplifier.
  • a selective electric wave receiver comprising an amplifier, filter networks of unlike frequency characteristics connected to the output of said amplifier, output connections from the respective filter networks to the opposite branches of a Wheatstone bridge network including thermistor resistances having negative temperature coefficient of resistance, a second amplifier connected to establish a feedback circuit thereto and a si nal receiving device connected to the output side of the second amplifier and said receiving device being operative when the ratio of energy of one branch circuit to the other is greater than a given value.
  • a selective electric wave receiver comprising an amplifier, filter networks of unlike frequency output, output connections from the respective filter networks to the opposite branches of a Wheatstone bridge network including indirectly heated thermistor resistances having negative temperature coefiicient of resistance, a second amplifier connected to the opposite branches of the bridge network to establish a feedback circuit thereto and a signal receiving device connected to the output side of the second amplifier and said receiving device being operative when the ratio of energy of one branch circuit to the other is greater than a given value.
  • a selective electric wave receiver comprising an amplifier, filter networks of unlike frequency output connected to the output of the amplifier, output connections from the respecan amplifier, a pair of filter networks of unlike frequency output connected to the output of the amplifier, a Wheatstone bridge network including thermistor resistances having negative temperature coefiicient of resistance, output connections from the respective filter networks to heater coils of the thermistor resistance, an amplifier connected to the opposite branches of the network to establish a feedback circuit thereto and a signal receiving device connected to the output side of the second amplifier.
  • a selective electric wave receiver comprising an amplifier, filter networks of unlike frequency output connectedto the output of the said amplifier, a Wheatstone bridge network including thermistor resistances having negative temperature coeificient of resistance, output connections from the respective filter networks to heater coils of the thermistor resistance, a second amplifier connected to the opposite branches of the bridge network to establish a feedback circuit thereto, said second amplifier having frequency oscillation range corresponding to the frequency output of one of the filter networks and a signal receiving device connected to the output side of the second amplifier and responsive to the operative when the ratio of energy of one branch circuit to the other is greater than a given value.
  • a selective electric wave receiver comprising a thermionic valve amplifier having associated input and output transformers, filter networks of unlike frequency output connected to the secondary of said output transformer, a Wheatstone bridge network including thermistor resistances having negative temperature coefficient of resistance, a second thermionic valve amplifier having associated therewith input and output trans-- formers, the latter having its primary winding connected in series with the plate circuit of the first thermionic valve and having a secondary winding connected to the first pair of diagonals of the bridge network and said latter input transformer having a primary winding connected to the input of the receiver and having a secondary winding connected to the control grid circuit of said second valve and in series with the second pair of diagonals of the bridge network, and a signal receiving device connected to another secondary of the latter output transformer.
  • a selective electric wave receiver comprising a thermionic valve amplifier having associated input and output transformers, filter networks of unlike frequency output connected to the secondary of said output transformer, a Wheatstone bridge network including thermistor resistances having negative temperature coefficient of resistance, a second thermionic valve amplifier having associated input and output transformers, connections from the diagonals of the bridge network respectively to the primary of the latter input transformer and to the secondary of the latter output transformer and a signal receiving device connected to another secondary of the latter output transformer.
  • a selective electric wave receiver comprising a thermionic valve amplifier having associated input and output transformers, filter networks of unlike frequency output connected to the secondary of said output transformer, a Wheatstone bridge network including thermistor resistances having negative temperature coefficient of resisting a thermionic valve amplifier having associated input and output transformers, filter networks of unlike frequency output connected to the secondary of said output transformer, a Wheatstone bridge network including thermistor resistances having negative temperature coefil- I cient of resistance, a second thermionic valve amplifier having associated input and output transformers the latter having its primary connected in series with the plate circuit of the first thermionic valve, and having a secondary winding connected to the first pair of diagonals of the bridge network, a condenser shunting the latter secondary and said latter input transformer having a secondary winding connected to the control grid circuit of said second valve, connections from the other diagonals of the bridge network to the primary of the latter input transformer and a signal receiving device connected to a secondary of the latter output transformer.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Amplifiers (AREA)
  • Interface Circuits In Exchanges (AREA)
  • Inductance-Capacitance Distribution Constants And Capacitance-Resistance Oscillators (AREA)
US447394A 1941-09-15 1942-06-17 Electric signaling system Expired - Lifetime US2343759A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB11782/41A GB551951A (en) 1941-09-15 1941-09-15 Improvements in or relating to electric signalling systems

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US2343759A true US2343759A (en) 1944-03-07

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US447394A Expired - Lifetime US2343759A (en) 1941-09-15 1942-06-17 Electric signaling system

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US (1) US2343759A (xx)
BE (1) BE479786A (xx)
CH (1) CH254957A (xx)
FR (1) FR933246A (xx)
GB (1) GB551951A (xx)
NL (1) NL70720C (xx)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2476311A (en) * 1943-02-01 1949-07-19 Sperry Corp Ultra high frequency discriminator and apparatus
US2533286A (en) * 1946-07-22 1950-12-12 Univ Minnesota Heat sensitive circuits
US2577755A (en) * 1947-02-07 1951-12-11 Int Standard Electric Corp Alternating-current signaling system
US2706272A (en) * 1949-11-03 1955-04-12 Jones Lloyd Voltage stabilizing circuit
US2801290A (en) * 1951-09-17 1957-07-30 Telefunken Gmbh Calling signal responder arrangements
US2957950A (en) * 1954-11-18 1960-10-25 Bell Telephone Labor Inc Transistor selective ringing circuit
US2987713A (en) * 1957-07-12 1961-06-06 Kidde & Co Walter Sensitivity control of apparatus for detecting distrubances in an enclosure

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2476311A (en) * 1943-02-01 1949-07-19 Sperry Corp Ultra high frequency discriminator and apparatus
US2533286A (en) * 1946-07-22 1950-12-12 Univ Minnesota Heat sensitive circuits
US2577755A (en) * 1947-02-07 1951-12-11 Int Standard Electric Corp Alternating-current signaling system
US2706272A (en) * 1949-11-03 1955-04-12 Jones Lloyd Voltage stabilizing circuit
US2801290A (en) * 1951-09-17 1957-07-30 Telefunken Gmbh Calling signal responder arrangements
US2957950A (en) * 1954-11-18 1960-10-25 Bell Telephone Labor Inc Transistor selective ringing circuit
US2987713A (en) * 1957-07-12 1961-06-06 Kidde & Co Walter Sensitivity control of apparatus for detecting distrubances in an enclosure

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Publication number Publication date
GB551951A (en) 1943-03-17
BE479786A (xx)
NL70720C (xx)
CH254957A (de) 1948-05-31
FR933246A (fr) 1948-04-14

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