US2330593A - High frequency communication system - Google Patents

High frequency communication system Download PDF

Info

Publication number
US2330593A
US2330593A US450499A US45049942A US2330593A US 2330593 A US2330593 A US 2330593A US 450499 A US450499 A US 450499A US 45049942 A US45049942 A US 45049942A US 2330593 A US2330593 A US 2330593A
Authority
US
United States
Prior art keywords
resistance
potential
receiver
cathode
signals
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
US450499A
Other languages
English (en)
Inventor
Edwin W Kenefake
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.)
General Electric Co
Original Assignee
General Electric Co
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 BE476953D priority Critical patent/BE476953A/xx
Application filed by General Electric Co filed Critical General Electric Co
Priority to US450499A priority patent/US2330593A/en
Application granted granted Critical
Publication of US2330593A publication Critical patent/US2330593A/en
Priority to FR950377D priority patent/FR950377A/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/38—Transceivers, i.e. devices in which transmitter and receiver form a structural unit and in which at least one part is used for functions of transmitting and receiving
    • H04B1/40—Circuits
    • H04B1/54—Circuits using the same frequency for two directions of communication
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/38—Transceivers, i.e. devices in which transmitter and receiver form a structural unit and in which at least one part is used for functions of transmitting and receiving
    • H04B1/40—Circuits
    • H04B1/44—Transmit/receive switching
    • H04B1/46—Transmit/receive switching by voice-frequency signals; by pilot signals

Definitions

  • This invention relates to high frequency communication apparatus, and more particularly to that type of such apparatus, called duplex equipment, inwhich the transmission and re ception of signals is accomplished at the same carrier frequency.
  • Duplex high frequency communication equipment is frequently connected to telephone lines to transmit'and receive signals over such lines. If the input of the high frequency transmitter and the output of the high frequency receiver are both connected to such a telephone line, some means must be provided to prevent oscillations caused by the transfer of energy from the output of the receiver to the input of the transmitter and from the output of the transmitter to the input of the receiver. Hybrid coils are sometimes used for this purpose, between receiver output and transmitter input, and sometimes an arrangement is provided whereby the telephone line may be switched either to the transmitter or to the receiver.
  • a. switching arrangement' is provided whereby the transmitter is rendered operative only when signals are transmitted over the telephone line and the receiver is at the same time rendered inoperative so as to prevent oscillations by reason of the transmitter input and receiver output.
  • the apparatus is also arranged to render the receiver operative and the transmitter inoperative when high frequency signals are received by the receiver, similarly to prevent such oscillations. It is a. further object of my invention to provide improved and simplified means for performing such switching in proper sequence and in reduced time such that no noticeable loss of signals occurs due mg.
  • a high voltage power transmissionline I0 is illustrated as connected at a particular station through a coupling capacitor H to a carrier current transmitter represented by rectangle I 2 and receiver represented by rectangle l3, this transmitter and receiver being arranged respectively to transmit signals from and receive signals for a telephone hand set M.
  • Signals from the hand set l4 are caused to modulate a desired characteristic, such as the intensity, of a carrier wave in transmitter I2, which carrier wave is impressed on the transmission line It at condenser II, for reception at another station.
  • the transmitter includes an electron discharge device l5, which acts, as a master oscillator, and a second such device "5, which acts as a power amplifier for the carrier wave, the output of the device l6 being transferred through a tuning inductance I1 and coupling condenser l8 to the power line H).
  • the transmitter also includes electron discharge amplifierdevices I 9, 20, 2! and 22 for amplifying signals from a telephone hand set 23 and connected telephone line 24, and for modulating the intensity of oscillations in the device IS in accordance with such signals.
  • Fig. 1b includes an electron discharge device 25, acting as a frequency converter, an electron discharge device 26, acting as an intermediate frequency amplifier, a double diode rectifier 21 for demodulating carrier waves, received from the power line 10 through coupling trated in Fig. lb, which condenser l8 and tuning inductance I1 and amplifled through devices 25 and 26.
  • the receiver also includes signal amplifier devices 28 and 29 which, under certain conditions, amplify signals detected by the detector device 21 and transmit such amplified signals through the telephone line 24 to the hand set 23.
  • the transmitter and receiver are so arranged that they never operate simultaneously.
  • the carrier wave generated by the transmitter therefore is never demodulated by the receiver, and the demodulated carrier intensity variations fed from the output of devices 28 and 29 through the telephone line connections to the input of discharge device l9, so as to modulate the carrier wave intensity in the same sense as the change of intensity which was detected by device 21, thus resulting in continuous oscillation of the entire system.
  • Control .means provided to prevent such oscillation, is effective to prevent the transmitter and receiver from operating simultaneously.
  • the electron -discharge amplifier device 30 amplifies signals from the hand set 23 and energizes a vapor discharge device represented at 3
  • the master oscillator device i5 When signals are not present in the system from the hand set 23, the master oscillator device i5 is inoperative and the frequency converter 25 is operative. Under such conditions an electron discharge device 32 in the receiver is effective upon the reception of a signal by the receiver to make the amplifier devices 28 and 29 operative, these devices being normally inoperative, to transmit such received signal to the hand set 23.
  • Such received signal is simultaneo'usly detected by a diode rectifier 33 in Fig. 1a and is amplified by a continuous potential amplifier device 34 to prevent the vapor discharge device 3
  • reception of signals by the receiver is effective to prevent operation of the transmitter, and at the same time opens up the channel from the receiver to the hand set 23.
  • the master oscillator of the transmitter illusincludes the discharge device 15, is arranged to be rendered operative or inoperative by switching means in Fig. la.
  • This switching means is connected between ground and a conductor 40, a cathode biasing resistance 4
  • a bypassing condenser 43 is connected between the cathode 42 and ground, to maintain cathode 42 at ground potential for high frequency currents.
  • the master oscillator circuit in Fig. 1b includes an inductance 44 which has one terminal connected to the anode 45 of the oscillator discharge device l5, and the other terminal'coupled through a suitable coupling condenser 49 to the control electrode 46 of device l5.
  • a tuning condenser 39 is connected in shunt to the inductance 44, thereby forming 'a resonant circuit 39, 44 tuned to the frequency at which the oscillator operates.
  • An intermediate tap 38 of the inductance 44 is connected to a positive This control means is judged if the negative aesaaoa voltage tap of a source 41 of operating potential, whose negative terminal is connected to ground.
  • a grid leak resistance 48 is connected between the control electrode 46 and cathode 42 of device I5.
  • the tuned circuit 39, 44 is thus arranged so as to maintain alternating potentials of opposite phase and of the desired frequency on the anode 45 and control electrode 46 of device l5.
  • switching means connected to conductor 40 is arranged, when it does not connect conductor 40 to ground to impress a positive potential thereon of such magnitude as to make the cathode 42 positive in potential with respect to ground by an amount at least within ten volts of the positive potential applied to the second, or screen, electrode 31 of device l5.
  • This electrode 31 is connected to a suit able tap 36 of source 41 of substantially less positive potential than the tap to which the anode 45 is connected.
  • the screen electrode and anode of the discharge device are supplied with positive potentials having a more or less fixed relation therebetween.
  • the cathode 4.2 is made less negative with respect to the screen electrode 31 and anode 45 of device I5
  • this relation between screen electrode voltage and anode voltage of the discharge device is substantially undisturbed, while the oscillation intensity is smoothly decreased by the smooth decreasingof anode voltage and mutual transconductance of the discharge device.
  • Oscillations produced by the device IS in the tuned circuit 39, 44 are impressed on the control electrode 50 of the amplifier device 16 through a serially connected condenser BI and resistance 62.
  • the device I6 is suitably connected to amplify such oscillationa'thereby producing amplified oscillations across the inductance 63, connected between the anode 64 of device l6 and a tap' 65 on the secondary of the transformer 66, to be described hereinafter.
  • One terminal of the secondary of transformer 66 is connected to the positive tap of the source 41 to which tap 38 of inductance 44 is connected, whereby operating current is supplied to the device I6.
  • Amplified oscillations appearing across the inductance 63 are coupled'through a condenser 61 .discharge current for the devic I6. flows.
  • the first control electrode 72 of the device I9 is connected to an adjustable tap 73 on the voltage dividing resistance II, and one terminal of the resistance "II is connected through a by-passing condenser I4 to the cathode I5 of device I9.
  • the same terminal of the resistance II is also connected to the third, or gain control, electrode 16 of the device I 9, and through two serially connected resistances I1 and 18 to ground.
  • the cathode I5 is connected through a biasing resistance 80 to ground; a by-passing condenser 8
  • a by-passing condenser 82 is connected in shunt to the resistance I8 to prevent voltage changes on resistance 18 from occurring rapidly.
  • Discharg current for the device I9 is supplied to the anode 83 thereof through a. resistance 84 from a suitable tap 85 on the source 41 of operating potential. Voltage across resistance 84 is impressed on the control electrode 86 of device 28 through a coupling condenser 6T, electrode 86 being connected to ground through a resistance 88. The cathode 89 of device 20 is con-- nected to ground through a resistance 90, the flow of discharge current through such resistance providing suitable operating bias potential for the control electrode 86.
  • of device 20 is supplied through a resistance 92 from the tap 85 of source 41.
  • discharge current for the other anode 93 of device 20 is supplied thereto through a resistance 94 from the tap 85.
  • the other cathode 95 of device .20 is I resistance I22 to a point between the 25.
  • and 22 ar connected in push-pull relation, their respective control electrodes I00 and IM being coupled respectively to the anodes 9i and 93 of device 20 through condensers I02 and I03.
  • the control electrodes I00 and IM are-respectively connected to the control electrode 98 of device 20 through resistances I 04 and I05.
  • the respective cathodes I06 and I 07 of the devices 2i and 22 are connected together and to ground through a suitable biasing resistance I08.
  • the anodes I09 and I I0 are connected to the respective terminals of the primary of transformer 66, the center tap of such primary being connected to.the positive terminal of source 41 thereby tosupply discharge current for the operation of the device's 2i and 22.
  • the amplifier acts to amplify signals from the hand set 29 and to modulate the discharge current supplied from source 41 to the carrier wave amplifier I6 in accordance therewith.
  • a resistance I I2 is coupled through a coupling condenser III between the anode I09 .of device 2I and the cathode 89 of device 20.
  • the resistance 2 is made as small as possible without causing oscillation in the amplifier, in order to produce a maximum amount of degeneration fromthe output of the push-pull stage including devices 2I and 22 to the input of the device 20.
  • degeneration is well known to increase the fidelity of amplification of an amplifier.
  • the cathode I20 of a rectifier H9 is connected to that terminal of the secondary of transformer 66 opposite the'terminal which is connected to the source 41 of operating potential.
  • the anode I2I of the rectifier H9 is connected through a resistances I1 and I8, described above in connection with the device I9.
  • the resistance I22 and the condenser 82 together form a low pass filter circuit, so that when the rectifier H9 passes current, such currentbeing passed only during alterate sistance 18.
  • the transmitter described is effective, when the conductor 40 is grounded, to generate carrier waves which are transmitted over the power line I 0, and to modulate such carrier waves in accordance with signals from the hand set 23.
  • the transmitter is-inoperative, that is, when the conductor 40 is not grounded, carrier waves may be received over the power line I0 and demodulated by the receiver, the demodulated signals being supplied to the hand set 23.
  • a resistance I3I and a vapor discharge device I 32 are connected serially between an adjustable tap I33 of the resistance I30 and ground.
  • the vapor discharge device I32 is of the type through which a discharge current passes only after a voltage greater than a critical value has been applied to the electrodes, and which has very low resistance once such discharge current passes.
  • the device I32 acts to prevent large carrier wave voltages, as from the power amplifier half cycles, a continuous potential appears across the; re-
  • Carrier voltage across the device I32- is impressed through a doubly tuned circuit I34 between the third or signal control electrode. I35 of the converter device 25 and ground.
  • the converter device 25 is arranged, in well known fashion, to generate, in conjunction with suitable tuning and coupling circuits I36, a local oscillation, and to heterodyne such local oscillation with the signal wave on the control electrode I35 and thereby produce a wave of intermediate frequency.
  • suitable tuning and coupling circuits I36 a local oscillation
  • heterodyne such local oscillation with the signal wave on the control electrode I35 and thereby produce a wave of intermediate frequency.
  • the wave impressed on the tuned circuit I34 may be within the range from 50 to 150 kilocycles, to use a local oscillator circuit I36 tunable between 225 and 325 kilocycles and a fixed intermediate frequency of 1'75 kilocycles.
  • Coupled circuits I40 and MI are arranged to transfer the output of converter device 25 to the control electrode I42 of device 26.
  • Additional fixed tuned circuits I43 and I44 are arranged to transfer the amplified oscillations of such fixed frequency from device 26 to the rectifier, or detector device 21.
  • the detector 21 has two separate diodes, respectively including cathode I50 and anode II and cathode I52 and anode I53, which perform two separate functions.
  • the first diode including cathode I50 and anode I5I rectifies the amplified carrier wave from tuned circuit I44, when the intensity of that wave is above a predetermined value, and produces a continuous potential for automatic volume control purposes.
  • the other diode including cathode I52 and anode I53 rectifies the carrier wave from the tuned circuit I44 to produce audible signals.
  • the cathode I50 is maintained at a positive potential with respect to ground by a connection from the cathode I50 to a positive voltage tap I54 on a source I55 of potential, whose negative terminal is grounded.
  • the anode I5I is coupled by a condenser I56 to one terminal of the tuned circuit I44, the other terminal of circuit I44 being grounded.
  • the anode I5I is connected through two serially connected resistances I51 and I58 to ground, the resistance I58 being by-passed for high frequency currents by condenser I59.
  • the resistance-condenser combination I51, I58, I59 serves as a low pass filter, so that voltage variations across resistance I58 correspond only to variations in the average carrier wave 'intensity.
  • the anode I53 is coupled to the ungroundedv terminal of the tuned circuit I44 through a condenser I60, and the cathode I52 is coupled to ground through a similar condenser I6I.
  • Four re istances I62, I63, I64 and I65 are serially connected in that order between the anode I53 and cathode I52.
  • Each of the resistances I63 and I64 is by-passed for currents of carrier frequency by condensers I66 and I61, respectively, and a point between these two resistances I63 and I64 is connected to ground. Audible signals appear across the resistances I63 and I64 in push-pull, or balanced, relation.
  • the balanced signal voltages across the resistances' I63 and I64 are amplified through devices 28 and 29, which are connected in pushpull or balanced relation.
  • the cathodes I10 and HI of. the devices 28 and 29 are connected together, and through a resistance I12 to a positive voltage tap I13 on the source I55.
  • the respective control electrodes I14 and I15 of the devices 28 and 29 are connected to adjustable taps on voltage dividing resistances I16 and I11.
  • One terminal of each of the resistances I16 and I11 is connected through a resistance I16 to the tap I13 on the source I of potential.
  • each of the resistances I16 and I11 is connected respectively through coupling condensers I19 and I80 to a point between resistances I62 and I63 and a point between resistances I64 and I65, thereby impressing the detected signal voltages in push-pull relation between the control electrodes I14 and I15.
  • the anodes I8I and I82 of the devices 28 and 29 are connected to opposite terminals of the primary of a transformer I83, the center tap of the primary being connected to the positive terminal of the source I55.
  • the secondary of transformer I63 is connected to telephone line 24 to transfer signals amplified through the devices 28 and 29 to the hand set 23, where they are reproduced as sound.
  • the device 32 which is arranged to prevent the transmission of energy through the devices 28 and 29 to the hand set 23 when no carrier wave is received by the receiver, is operated'in accordance with the average potential developed across the resistance I63 in the diode detector circuit of the receiver.
  • the cathode 190 of the device 32 is connected to ground, and the control electrode I9I is connected to ground through a condenser I92, and through a resistance I93 to a point between resistances I62 and I63.
  • the anode I94 of the device I32 is connected to a point between resistances I16,- I11 and I18, and is thus supplied with discharge ourrent from the tap I13 of source I55 of operating potential.
  • a condenser I is connected in shunt to resistance I18 for a purpose to be e plained in detail hereinafter.
  • the resistance I10 was made sufilciently large I that it took about six milliseconds after reception of a carrier wave for the voltage to disappear from condenser I95 suificiently to allow devices 28 and 29 to reproduce signals in the hand set 23.
  • This delay in allowing the devices 28 and 29 to reproduce signals is desirable in order to allow transients in the distant transmitter, in the power line, and in the receiver circuits to die out before energizing the hand set 23 from the re- Such transients are caused by the extremely rapid switching utilized in transmitters and associated equipment according to my invention.
  • the six milliseconds delay in energizing the hand set 23 from the receiver, added to the inevitable delay in starting the transmitter in response to signals to be transmitted is sufliciently short that the loss of even the beginning of the first syllable at the beginning of a trans mission is avoided.
  • the condenser I92 in conjunction with the resistance I93 serves to prevent very rapid changes in the conductivity of device 32, which might be caused by noise pulses appearing across the resistance I63 and lasting only for very short times.
  • the low pass filter including resistance I93 and condenser I92 serves to prevent any voltage change on the control electrode I9I in response to such voltages of short duratiom'and thus to prevent false operation of the noise suppression circuit including the device 32 in response to such short voltage pulses.
  • additional means is provided to prevent operation of the transmitter while a carrier wave is being received by the receiver.
  • a carrier wave is received the receiver so that a voltage of intermediate frequency appears across the tuned circuit I44, this voltage is impressed across the rectifier device 33 in Fig. 1a through a coupling condenser 200 205 connected between suchanodeand cathode.
  • the resistance 205 is shunted by a condenser 206 whose reactance is low at the intermediate frequency to which tuned circuit I43 is resonant,- but whose reactance is high at frequencies at which the intensity of the intermediate frequency carrier wave changes. Consequently such intermediate frequency carrier waves are rectified in the device 33 and a unidirectional potential appears across the resistance 205 within a short time afterthe reception of carrier waves by the receiver, this time being, for example, in'the order of 1 millisecond or less.
  • This unidirectional voltage across the resistance 205 is utilized to prevent operation of the transmitter, which operation might otherwise be caused by signals from the hand set 23 impressed on the transmitter, or byreceived signals from the receiver.
  • the apparatus'which initiates operation of the transmitter in response to signals from the hand set 23, and which is blocked by voltage across the resistance 205, includes a transformer 2I0, the primary of which is energized through telephone line 24 by signals from the. hand set 23. That is, the primary of transformer H0 is connected in parallel with the primaries of transformers I0 and I83, all three primaries being connected to the telephone line 24.
  • a voltage dividing resistance 2 is connected in shunt to the secondary of the transformer 2
  • the control electrode 5H2 of discharge device 30 is connected through a resistance 2I3 to an adjustable tap 2I4 of the resistance 2
  • the anode 2I8 of the device 30 is connected through a pair of serially connected resistances 2I9 and 220 to the positive terminal of a source 22I of operating potential, an intermediate tap 222 of which is ground.
  • a point between resistances 219 and 220 is connected to ground through a condenser 223 to maintain such point at ground potential for signal frequency currents.
  • Another condenser is to prevent the production of parasitic oscillations by the device 30, or the amplification of high frequency energy which may be picked up from the transmitter mounted in close proximity,
  • the device 30 was a 6SQ7
  • the condenser 224 was 0.001 microfarad and 'resistance 2 I 9 was 100,000 ohms.
  • 9 by the amplifier 30 are impressed on the control electrode 230 of the vapor discharge device 3
  • is grounded, and the control electrode 230 is connected through two serially connected resistances 233 and 234 to a suitable tap 235 of the source 22
  • the negative potential between the tap 222 and 235 is sufficient, when no signal is applied to the control electrode 230, to maintain the device 3
  • Discharge current is supplied to the anode 235 of the device 3
  • Signals amplified by device 30 which appear across the resistance 2!!! are impressed through the coupling condenser 23
  • and resistance 233 are so proportioned that signals of all frequencies from the hand set 23 are impressed on the control electrode 230 of device 3
  • was 0.001 microfarad and the resistance 233 of 250,000 ohms.
  • was a type 2051 gas tetrode. With such values, transmission of signals from resistance 2
  • has a second control electrode 231 which, during normal operation of the device 3
  • Means is provided to prevent the initiation of the flow of discharge current in device 3
  • a unidirectional potential appears across the resistance 205.
  • This potential across resistance 205 is amplified through the continuous potential amplifier device 34 and, after amplification, maintains the control electrode 231 negative with respect to cathode 232, whenever a unidirectional potential exists across resistance 205.
  • the continuous potential amplifier device 35 may, as illustrated, include two triode amplifier sections, and may, for example, be a 608G twin triode, the control electrode 240 of one section being connected ot a point between resistances 204 and 205.
  • the cathode 2 of this triode sec tion is connected through a resistance 242 to the cathode 202 of rectifier device 33, and to a tap 243 on the source 22
  • the anode 244 of this triode section is connected to the control electrode 2450f the other triode section, and is also connected through a resistance 246to a tap 241 on the source 22
  • the cathode 248 of the other triode section is connected to a tap 249 on the source 221 whose negative potential is intermediate in value the negative potentials of the taps 241 and 243.
  • the anode 250 of this other triode section of the device 33 is connected through a voltage dividing resistance 25
  • is connected to an adjustable .tap 252 on the voltage dividing resistance 25 i
  • the continuous potential amplifier is supplied with discharge current from the source 22 I.
  • the control electrode 240 is at a minimum negative bias potential with respect to the cathode 24l, so that a maximum discharge current flows throughthe anode 244.
  • the size of resistance 246 and the potentials of the taps 241, 249 and 243 with respect to each other and with respect to ground are so adjusted that the control electrode 245 is sufliciently negative with respect to the cathode 248 that substantially no discharge current flows in the anode 250, and consequently the control electrode 231 of the vapor discharge device 3
  • is caused to carry discharge current and initiate operation of'the transmitter, and is not prevented by a negative potential on control electrode 231.
  • control electrode 240 Whenever the carrier wave receiver is receiving a signal and a continuous potential exists across the resistance 205, the control electrode 240 becomes more negative with respect to the cathode Ni and reduces the discharge current in' the anode 244. The potential of control electrode 245 then becomes less negative with respect to the cathode 248 and discharge current flows in the anode 250.
  • the potential of the cathode 248 is fixed at a negative value with respect to ground, the potential of the anode 250 when discharge current flows therein becomes negative with respect to ground and the voltage dividing resistance 25
  • the intensity of this negative potential on the control electrode 231 may be adjusted by the adjustable tap 252, so as to prevent discharge current from flowing in the vapor discharge device 3
  • may be reduced by suitable adjustment of the tap 252 of voltage dividing resistance 25
  • allows the control equipment to be adjusted, therefore, in either manner, so that the transmitter can never'be operated when the receiver is operating, or alternatively so that the transmitter can be operated by shouting or whistling into the hand set 23 even when the receiver is operating.
  • may also be made where it is desired to force the transmitter into operation in the presence of received noise of high intensity.
  • random noise voltages and the like may be received by the receiver and detected by the rectifier device 33 so as to apply a negative bias potential on the control electrode 231 of the vapor discharge device 3
  • and the relay including operating coil 231 and armature 238 are so connected and arranged, together with the master oscillator device l5, that, immediately after the vapor discharge device 3
  • the relay is also arranged so that it is operated in response to the flow of discharge current in the vapor discharge device 3
  • the relay is also arranged to apply an alternating potential to the anode 236 of vapor discharge device 3
  • and relay together are arranged to block the operation of the carrier wave receiver even before the oscillator device I5 is made to operate.
  • a coil 266 is provided, in
  • , and an adjustable resistance 265 are connected in series, so that, when the operatingcoil 231 is deenergized, current tends to continue flowing in the coil 2'66 and resistance 265, thereby maintaining the armature 236 in operated position for a time determined by the adjustment of resistance 265.
  • a delay of about to 300 milliseconds may be provided between the deenergization of operating coil 23! and the opening of switches 26
  • Switch 2620f the relay is arranged to reduce the negative bias potential on control electrode 236 of vapor discharge device 3
  • the switch dered conductive 262 and a resistance 266 are connected serially between ground and a point between the resistances 233 and 234. Resistances 234 and 266 act as a voltage dividing resistance, so that, when switch 262 is closed, only a portion of the negative potential between tap 235 of the source 22
  • Switch 264 of the relay is arranged to apply an alternating potential to the anode 236 of vapor the deenergized position of the relay conductor 40 of Fig. lb'is connected through switch 263 to, the anode 236 of vapor discharge device 3
  • the oscillating discharge device l5 produces carrier frequency oscillations.
  • is also effective, when device 3
  • the oscillating device I5 is effectively prevented from producing oscillations.
  • Switch 263 of the relay is also arranged so as to connect conductor 40 directly to ground whenever the relay is in its energized position.
  • it is necessary for the vapor discharge device 3
  • the oscillating device l5 by this direct connection to ground is maintained in operation so long as the relay is in its energized position, which persists for a predetermined time after the vapor discharge device 3
  • This delay in turning oil the carrier wave generator of the transmitter is desirable so that the transmitter does not turn ofi between syllables or between words of a message, but turns off only when a message is finished. It is generally found that a delay in turning ofi the carrier wave generator of the transmitter of 150 to 300 milliseconds, as mentioned previously, is suflicient for this purpose.
  • the relay including switch 263 operate as fast as possible, preferably within 8 milliseconds after its energization, in order that the cathode 420i the master oscillator discharge device shall be connected directly to ground through switch 263 before the noise suppression circuit of the distant receiver shall energize the hand set It at that receiver. If these time relations are not observed, and the noise suppression circuit in receiver I3 opens the channel to hand set !4 before the relay including switch 263 operates, the operation of switch 263 causes the master oscillator device !5 to stop operation .for an instant as the switch 263 passes between its contacts.
  • another continuous potential amplifier device 28! is provided which is responsive to changes of potential on the conductor 40 for rendering the converter device 25 in the receiver operative or inoperative.
  • the device 28! may conveniently be a type 6C8G twin triode unit similar to the device 34.
  • the control electrode 282 of one section of the device 28! is connected to the adjustable tap of a voltage dividing re,- sistance 283, which is connected between the conductor 40 and the negative terminal of the source 22!.
  • Another voltage dividing resistance 284 is connected between the negative terminal of source 22! and ground, the cathode 285 of the first section of the twin triode device 28! being connected to a tap 286 on the resistance 284.
  • this section is connected to the control electrode 288 of the other triode section of device 28!, and is also connected through a resistance 289 to another tap 290 on resistance 284 which is less negative in potential than the tap 286.
  • the cathode 298 of this other triode section of device 28! is also connected to the tap 290, and the anode 29! of this other triode section is connected through a resistance 292, shunted by a condenser 293, to ground.
  • the twin triode device 28! and its associated connections as thus described are -so adjusted that when the potential of the anode 236 of vapor discharge device 3! plus the negative potential with respect to ground of source 22! are impressed across resistance 283, substantially no potential exists across the resistance 292. Also, when the conductor 40 is connected to ground, either through the vapor discharge device 3!, when it is conductive, or through the switch 263 directly to ground, a. potential appears across the resistance 292 such that the anode 29! of the second triode unit in device 28! becomes nega tive with respect to ground.
  • this negative voltage is applied to the control electrodes 294 and 299 of device 25, these two control electrodes being connected together and to the anode 29! of the second triode section of device 28! through a grid resistance 295.
  • the control electrodes 294 and 299 are coupled to the tuned circuit I36 of the oscillator section through a coupling condenser 296. That terminal of the resistance 295 opposite the control electrode 294 is connected to ground at the converter device 25 through a by-passing condenser 29'! which is small with respect to the condenser 293.
  • the condenser 29'! should have a reactance which is low at the frequency of operation of the tuned circuit I36.
  • the time within which a negative voltage is built up across the condenser 293 depends on the size of the condensers 293 and 29! and the anode to cathode resistance of the second triode section of device 28! including the anode 29! and cathode 298. It is desirable that the time of charging this condenser 293 to a sufiiciently negative potential to prevent the operation of converter device 25 be small, as for example 2 milliseconds.
  • the voltage dividing resistance 284 also contributes to the time constant of the circuit including the condenser 293. If the power delivering capability of the source 22! be made relatively small, so that the voltage dividing resistance 284 must be relatively large, it may be that the resistance 284 is larger than the anodeto-cathode resistance of one section of the device 28!. In any case the charging time of the condenser 293 should be small, and preferably 2 milliseconds or less.
  • the condenser 293 was made 0.1 microfarad.
  • the condenser 29'! was much smaller than condenser 293
  • condenser 296 was, about 200 micromicrofarads
  • resistance 295 was about'l00,- 000 ohms.
  • the converter device 25 shall remain inoperative for a relatively long period, in the order of 25 to 50 milliseconds.
  • the resistance 292 must be relatively large, so that the condenser 293 discharges therethrough relatively slowly. In the particular case described, this resistance 292 was 1 megohm.
  • taps 286 and 290 are more nearly fixed, whereby the condenser 293 may be made larger and its charge time still remain small, with the result that the resistance 292 may be made smaller, thereby reducing the possibility of superregenerative blocking action in the oscillator section of converter device 25.
  • the blocking of the receiver is brought about by impressing a large negative bias potential on the control grid of the oscillator section of the frequency converter device 25 as well as on the control grid of the mixer, or heterodyne, section of the frequency converter device 25.
  • a large negative bias potential on the control grid of the oscillator section of the frequency converter device 25 as well as on the control grid of the mixer, or heterodyne, section of the frequency converter device 25.
  • Control means is provided responsive to signals received in the receiver for preventing or allowing the first control means to control generation of a carrier wave in response to signals from the hand set 23.
  • control means is'provided responsive to signals received in the receiver for transferring such signals from the receiver to the hand set 23.
  • the eight operating times of these four control means are so correlated as to make it possible to connect the hand set 23 directly with the transformers Ill and I83 without producing oscillation between the transmitter and receiver.
  • the other condition being that of reception of a message.
  • two sets of operating times are involved, one occurring at the beginning of the message and another at the end of the message.
  • an operation is performed both on the transmitter and on the receiver to make one operative and the other inoperative, or, at the end of a message, to put the receiver into condition to receive a signal.
  • the potential of the cathode 42 of oscillating discharge device l5 reaches a value such that oscillations are generated, and are modulated in the carrier wave amplifier device 64 in accordance with the signals from the hand set2'3 which initiated operations.
  • the receiver may, for
  • oscillations to be modulated in accordance with such signals in about 3 milliseconds.
  • allows the condenser 293 to discharge again.
  • the device 25 may, for example, become operative within 25 or 30 milliseconds after the transmission of the carrier wave discontinues.
  • the frequency converter device 25 in. the receiver is first blocked and then the oscillating device i5 is caused to begin the transmission of a carrier wave. Under no COllQitiOIl can the receiver be operative when a carrier wave is being transmitted. There is thererore no possibility of oscillation through the transmitter and receiver even though both are connected directly to telephone line 24.
  • the receiver Upon the reception of a carrier wave over the power line It], as from a distant station including the hand set M, the receiver first energizes the rectifier device 33 in the control apparatus of Fig. la, and, through the continuous potential amplifier device 34, blocks the vapor discharge device 3
  • set 23 from received signals aiter reception of the carrier wave by the receiver should be in the order of 6 milliseconds in order to allow surges of various sorts in the system to die out.
  • a bias potential may 7 appear on the control electrode 231 of the vapor discharge device 3
  • the period after reception of a carrier wave by the receiver before the device 32 operates should be as short as possible, so that the time and the transmitter may b made toj genrate elapsing between initiation of a signal at the
  • the continuous potential amplifier device 34 should be effective to put a bias potential on the control hand set l4 and its reception at hand set 23 is small enough to avoid losing any significant part of the beginning of a message.
  • This time should be sufficiently long to allow surges in the carrier wave transmission system and in the automatic volume control circuits of the receiver to die out substantially before the device 32 makes the amplifier devices 28 and 29 operative. In view of the desirability of allowing time for such surges to die out, it is desirable that they be initiated in minimum time.
  • the transmitter be turned on in minimum time after the impression of a signal on the associated hand set. If, as explained previously, the transmitter is effective to transmit a modulated carrier wave in about 3 milliseconds after impression of a signal on the associated hand set, the receiver may be made to demodulate such signal and impress it on the associated hand set in about 6 milliseconds after reception of the carrier wave, this period being sufiicient to allow surges to die out substantially. Under such conditions, the total time of transmission of a signal from one of such hand sets to the other is only about 9 milliseconds, which is an acceptably short time, within which no appreciable portion of the beginning of a syllable is lost.
  • the noise suppression circuit including the device 32 When the receiver no longer receives a carrier wave from the distant station, the noise suppression circuit including the device 32 first operates to block the amplifier devices 28 and 29. This action may take place in about 3 milliseconds after the carrier wave is no longer received. Thereafter, for example, in about 6 milliseconds, the bias disappears from the control electrode 231 of vapor discharge device3l, thereby leaving the apparatus as a whole in its standby condition.
  • the time within which the negative bias disappears from the control electrode 231 is determined by the sizes of resistance 205 and condenser 206. The larger the resistance 205, the longer it takes for the charge to disappear from condenser 206.
  • the total time from the point of time when sound impinges on the hand set until such sound is reproduced by the hand set l4 in a distant station includes only the time required for the cathode 42 of the oscillating device l5 to reach its proper potential, and the time for the noise suppression circuit including the device 32 in the distant receiver l3 to energize the hand set [4 at that station.
  • adjustable tap 252 of the voltage dividing resistance 25l which determines the intensity of negative bias potential on the control electrode 231 of the vapor discharge device 3
  • the high speed starting of the transmitter is accomplished by connecting the cathode 42 of the oscillating device I5 to ground directly through the vapor discharge device 3
  • This high speed operation is made possible by the even higher speed operation of the continuous potential amplifier 28
  • the high speed operation of the receiver i accomplished by the high speed operation of the noise suppression circuit including device 32, which is possible because the amplifier stage on which the noise suppression circuit operates is balanced with respect to ground, and therefore does not reproduce the rapid grid bias potential changes caused by device 32 in making operative or inoperative the amplifier devices 28 and 29.
  • This high speed operation is also aided by the rapid operation of the rectifier device 33 and continuous potential amplifier device 34 in preventing operation of the vapor discharge device 3
  • continuous potential arranged to supply discharge current to said discharge device, means for impressing-signals from said first source on said control electrode to render said device conductive whenever the intensity of said signals exceeds said bias potential, means for reducing said bias potential on said control electrode in response to conduction of said discharge device to make said signals more effective in rendering said device conductive, and means responsive to conduction of said discharge device for impressing upon the discharge path thereof an alternating potential whose peak intensity exceeds the continuous potential of said second source, whereby, upon the cessation of signals from said signal source, the bias potential on'said control electrode is effective to render said discharge device nonconductive.
  • a signalling system having a signal transmission channel and a signal transmitter, of means for connecting said transmitter to said channel in response to signals from a signal source, said means comprising a vapor discharge device arranged to connect said transmitter to said channel when current flows through its discharge path and having a control electrode, and a relay arranged to connect said transmitter to said channel in the operated position, means for impressing a negativ bias potential on said control electrode to maintain said discharge device nonconductive and for impressing signals from said source on said control electrode to render said device conductive in the presence of said signals, means for operating said relay in response to conduction of said discharge device, and means for maintaining said relay operated for a substantial time after said device hecomes nonconductive in the absense of signals.
  • a source of signals a vapor discharge device having two control electrodes, means for impressing signals from said signal source on one of said control electrodes to upon the discharge path thereof an alternating potential whose peak intensity exceeds the continuous potential of said second source, whereby, upon the. cessation of signals from said signal source, the bias potential on said control elec trode is effective to render said discharge device make said discharge device conductive, means responsive to conduction of saiddischarge device for operating said transmitter to transmit signals from said source through said channel, and means responsive to signals received by said receiver through said channel for impressing a bias potential on the other of said control electrodes to prevent said device from becoming conductive to operate such transmitter and make said receiver inoperative in the presence of signals simultaneously from said transmitter and channel.
  • a signal transmission system having a signal channel and a signal transmitter including an oscillating discharge device, said device having an anode, a cathode and a control electrode, said anode and control electrode being connected to opposite terminals of a tuned circuit of which an intermediate tap is maintained at fixed potential, means for impressing a positive potential on said anode, and means for reducing the potential of said cathode to initiate oscillation in said device and tuned circuit and for substantially uniformly increasing the potential of said cathode with respect to said anode to decrease uniformly the intensity of oscillations of said device and tuned circuit, said increase in potential of said cathode being effective to reduce such oscillations to small intensity before extinction.
  • a signal transmission system having a signal channel and a signal transmitter connected thereto and including an oscillating discharge device, said device having an anode, a cathode. a control electrode and a screen electrode, said anode and control electrode being connected to opposite terminals of a tuned circuit of which an intermediate tap is maintained at a fixed potential, means for impressing positive potentials on said anod and screen electrode in such intensities as to provide optimum conditions for oscillation of said device and tuned circuit when the potential of said cathode with respect to said anode is decreased, means for decreasing the potential of said cathode with respect to said anode to initiate oscillation in said device and tuned circuit, and means for increasing the potential of said cathode with respect to said screen electrode and anode at a substantially uniform rate to reduce the intensity of oscillations insaid device and tuned circuit substantially uniformly to a low intensity before the extinction of such oscillations.
  • a signal transmission system comprising a signal transmitter and a signal receiver connected to the same signal transmission channel, said receiver being of the superheterodyne type and including a frequency converter having a 10- cal oscillator and a mixer, said local oscillator and mixer each including an electron discharge device having a control electrode, a source of signals, means responsive to signals from said source for impressing a negative bias potential on both of said control electrodes to block operation of said receiver and for subsequently initiating operation of said transmitter to transmit such signals through said channel.

Landscapes

  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Selective Calling Equipment (AREA)
US450499A 1942-07-11 1942-07-11 High frequency communication system Expired - Lifetime US2330593A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
BE476953D BE476953A (enrdf_load_stackoverflow) 1942-07-11
US450499A US2330593A (en) 1942-07-11 1942-07-11 High frequency communication system
FR950377D FR950377A (fr) 1942-07-11 1947-07-21 Système de communication à haute fréquence

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US450499A US2330593A (en) 1942-07-11 1942-07-11 High frequency communication system

Publications (1)

Publication Number Publication Date
US2330593A true US2330593A (en) 1943-09-28

Family

ID=23788338

Family Applications (1)

Application Number Title Priority Date Filing Date
US450499A Expired - Lifetime US2330593A (en) 1942-07-11 1942-07-11 High frequency communication system

Country Status (3)

Country Link
US (1) US2330593A (enrdf_load_stackoverflow)
BE (1) BE476953A (enrdf_load_stackoverflow)
FR (1) FR950377A (enrdf_load_stackoverflow)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2510117A (en) * 1941-04-11 1950-06-06 Int Standard Electric Corp Carrier wave signal system
US2516361A (en) * 1945-08-21 1950-07-25 Gen Railway Signal Co Voice frequency signal device

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2510117A (en) * 1941-04-11 1950-06-06 Int Standard Electric Corp Carrier wave signal system
US2516361A (en) * 1945-08-21 1950-07-25 Gen Railway Signal Co Voice frequency signal device

Also Published As

Publication number Publication date
BE476953A (enrdf_load_stackoverflow)
FR950377A (fr) 1949-09-26

Similar Documents

Publication Publication Date Title
US2462181A (en) Radio transmitting system
US2189317A (en) Diversity antenna system
US2547024A (en) Selective calling system
US2147595A (en) Ultra high frequency transceiver
US2527561A (en) Selective calling system
US2363571A (en) Radio signaling
US2431167A (en) Radio alarm and two-way telephone system
US2632812A (en) Carrier-current intercommunication apparatus
US2024138A (en) Radio signaling system
GB670703A (en) Improvements in or relating to a selective control system
US2330593A (en) High frequency communication system
US2047900A (en) Multiple signaling system
US2369351A (en) Telephone substation circuit
US2657304A (en) Duplex radio apparatus control
US2533543A (en) Off-channel squelch circuit for radio receivers
US2165062A (en) Communicating system
US2706242A (en) Noise control in combined radio transmitting and receiving apparatus
US2125953A (en) Receiver of telephonic or telegraphic signals
US2794857A (en) Control circuit for communications apparatus
US2484680A (en) Railway train communication and alarm system using modulated carrier currents
US2367947A (en) Signal transmission system
US1955095A (en) Telephony and telegraphy signaling device
US1687933A (en) Electrical signaling system
US1937108A (en) Transmission system
US2514087A (en) Modulated oscillator