US2901598A - Radio-transmitter for frequency-shift telegraphy made operative in response to modulation - Google Patents

Radio-transmitter for frequency-shift telegraphy made operative in response to modulation Download PDF

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Publication number
US2901598A
US2901598A US427781A US42778154A US2901598A US 2901598 A US2901598 A US 2901598A US 427781 A US427781 A US 427781A US 42778154 A US42778154 A US 42778154A US 2901598 A US2901598 A US 2901598A
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US
United States
Prior art keywords
resistor
transmitter
telegraphy
frequency
pulses
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
US427781A
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English (en)
Inventor
Bourgonion Louis Raymond
Johannes Van Sandwijk
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.)
US Philips Corp
North American Philips Co Inc
Original Assignee
US Philips Corp
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 US Philips Corp filed Critical US Philips Corp
Application granted granted Critical
Publication of US2901598A publication Critical patent/US2901598A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/10—Frequency-modulated carrier systems, i.e. using frequency-shift keying
    • H04L27/12—Modulator circuits; Transmitter circuits

Definitions

  • This invention relates to radiLtrn's'mitters' for frequency-shift telegraphy and has for' its object to provide a transmitter of such constructiony as to be operative only on the occurrence of a train of tclegr-aphy pulses.l to be transmitted.
  • a radio-transmitter comprises a switching device Vwhich blocks at least one ⁇ of Vthe *transmissiony stages and c o-mprises al grid-controlled switch tube and a switch voltage generator, the latter comprising an input resistor, provided in the control-grid circuit of the switch tube, and a holding capacitor connected in series with a series resistor, to which capacitor the telegraphy pulses are supplied via a biased diode to produce the switching voltage.
  • a bias source normally cutting olf the switch tube, and a grid-current limiting resistor are connected in series with the input resistor in the controlcircuit of the switch tube.
  • the reference numeral 1 denotes a crystal-controlled generator whereof the output voltage is applied via a frequency-multiplication stage 2 to the suppressor grid of a pentode 3 acting as a mixer tube. Coupled to the control-grid of said pentode is a highfrequency generator 4 which is tuned to a comparatively low frequency and whose output frequency is shifted by means of a variable reactance 5 in accordance with the telegraphy pulses delivered to the input terminal 6.
  • the anode of the mixer tube 3 is coupled via a bandpass lter 7 to the control-grid circuit of a pentode amplifier 8.
  • the amplified voltage is taken from a tuned anode circuit 9 of said tube and supplied through a coupling capacitor 10 to a transmitter output stage 12 connected to an antenna 11.
  • the transmitter so far described is normally blocked by means of the screen grids of the pentodes 3 and 8.
  • said screen-grids are earthed via a switch contact a1.
  • the telegraphy pulses delivered to the input terminals 6 are supplied to the variable reactance 5 and, by way of a lead 13, to a triode 14.
  • the control-grid of said triode is connected to the cathode through a grid-resistor so that the triode is normally conductive and passes current via an anode resistor 16.
  • anode of a diode 17 Connected to the anode of the triode 14 is the anode of a diode 17 whereof the cathode is connected to earth via a resistor 18 and a potentiometer resistor 19.
  • the cathode of the diode 17 is connected also through a gridcurrent limiting resistor 20, tothe control grid of a triode "ice 2, 21 acting as a switch tube;
  • the cathodeA ofv switch tube 21 is connected tor the potentivorrreter resistor 19 through a cathode resistor 22;
  • They resistors 22' and 19 together with a further resistorz constitute a potentiometer which is connectedv to" theanode voltage conductor.
  • They anf- 'de' circuit of switch trioden 21' comprises a' quick-acting relay A wliic'li operates the aforesaid contact al' included in the screenagridr circuits of the transmittertubes and 8.
  • the trio ⁇ de ⁇ 14- is conductive and: the anode of: the diode 17, which anode isv coxmectecr tothe anoder of said triode; attains acomparatively low -potentials
  • the series-combination of a series resistor 24 and a holding capacitor 25 Connected in parallel with the input resistor 18 is the series-combination of a series resistor 24 and a holding capacitor 25.
  • the holding capacitor 25 On the occurrence of a telegraphy pulse across the input resistor 18 the holding capacitor 25 becomes comparatively rapidly charged through the series resistor 24 which has a value of resistance that is comparatively low as compared with the input resistor 18.
  • the series resistor 24 slightly delays the initial charging of the capacitor 2S so that the leading edge of the first telegraphy pulse quickly renders the switch tube 21 conductive.
  • the diode 17 is again cut oi and no voltage drop occurs on account of a current flowing through the resistor 16 and the diode 17.
  • the switch triode 21 is continuously conductive and the relay A is energised, thus actuating the closed circuit contact a1 with the eiect that the screen-grids of the transmitter tubes 3 and 8 are connected via a screen-grid resistor 26 to the anode-voltage conductor and the transmitter tubes 3 and 8 are released.
  • the circuit-arrangement Upon termination of a series of telegraphy pulses the circuit-arrangement resumes its initial condition in a retarded manner in order to prevent the transmitter from becoming disengaged during a short pause in a series of telegraphy pulses to be transmitted.
  • said delay in disengagement is obtainable in a simple manner by a suitable choice of the discharge constant of the holding capacitor 25.
  • the operating time of the quick-acting relay A is approximately 1 millisecond.
  • the delay in disconnecting the transmitter which delay is mainly caused by the holding capacitor, amounts to w'ell above 200 milliseconds, which is suiicient to prevent disconnection of the transmitter during the transmission of a telegraphic dispatch.
  • a radio transmitter for frequency-shift t'elegraphy comprising a transmitter stage, a source of telegraph signals connected as an input signal to said transmitter stage, and a switching device connected to normally block said transmitter stage, said switching device comprising a grid- 4 controlled switch tube having a cathode and having an output electrode connected to control the blocking of said transmitter stage, means for biasing said tube to normally block said transmitter stage, a switch-voltage generator circuit connected between the grid and cathode of said switch tube and comprising an input resistor for said grid and a series combination of a series resistor and a capacitor, said series combination being connected in parallel with said input resistor, and means including a biased diode connected to feed said telegraph signals to said switch-voltage generator whereby said capacitor becomes charged by said signals thereby to bias said tube so as to render said transmitter stage operative and whereby siad series resistor delays the initial charging of said vcapacitor so that the leading ⁇ edge of the 'rst of said telegraph signals quickly renders said switch tube
  • said series resistor having a smaller value of resistance than said input resistor, and said capacitor and resistors having a time constant suiciently large to cause said transmitter stage to remain operative during normal pauses between said telegraph signals.

Landscapes

  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Transmitters (AREA)
  • Circuits Of Receivers In General (AREA)
US427781A 1953-05-18 1954-05-05 Radio-transmitter for frequency-shift telegraphy made operative in response to modulation Expired - Lifetime US2901598A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NL750061X 1953-05-18

Publications (1)

Publication Number Publication Date
US2901598A true US2901598A (en) 1959-08-25

Family

ID=19823012

Family Applications (1)

Application Number Title Priority Date Filing Date
US427781A Expired - Lifetime US2901598A (en) 1953-05-18 1954-05-05 Radio-transmitter for frequency-shift telegraphy made operative in response to modulation

Country Status (6)

Country Link
US (1) US2901598A (fr)
BE (1) BE527481A (fr)
DE (1) DE952989C (fr)
FR (1) FR1100719A (fr)
GB (1) GB750061A (fr)
NL (2) NL95529C (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3020399A (en) * 1959-01-09 1962-02-06 Rixon Electronics Inc Reduction of multipath effects by frequency shift

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SE8600030L (sv) * 1986-01-03 1987-07-04 Atlet Ab Sett vid datakommunikation med radio

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2232080A (en) * 1938-03-19 1941-02-18 Lorenz C Ag High frequency transmitter system
US2259532A (en) * 1940-04-13 1941-10-21 Nat Union Radio Corp Method and circuit for reducing the effect of noise pulses
US2287862A (en) * 1940-12-24 1942-06-30 Rca Corp Transmitting system
US2372005A (en) * 1942-06-22 1945-03-20 Gen Electric Electric control circuit
US2549873A (en) * 1944-09-01 1951-04-24 Williams Frederic Calland Thermionic valve circuits
US2730617A (en) * 1946-02-28 1956-01-10 Bell Telephone Labor Inc Timing circuit
US2738381A (en) * 1952-08-01 1956-03-13 Itt Telegraph signal-operated carrier off and on system

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2232080A (en) * 1938-03-19 1941-02-18 Lorenz C Ag High frequency transmitter system
US2259532A (en) * 1940-04-13 1941-10-21 Nat Union Radio Corp Method and circuit for reducing the effect of noise pulses
US2287862A (en) * 1940-12-24 1942-06-30 Rca Corp Transmitting system
US2372005A (en) * 1942-06-22 1945-03-20 Gen Electric Electric control circuit
US2549873A (en) * 1944-09-01 1951-04-24 Williams Frederic Calland Thermionic valve circuits
US2730617A (en) * 1946-02-28 1956-01-10 Bell Telephone Labor Inc Timing circuit
US2738381A (en) * 1952-08-01 1956-03-13 Itt Telegraph signal-operated carrier off and on system

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3020399A (en) * 1959-01-09 1962-02-06 Rixon Electronics Inc Reduction of multipath effects by frequency shift

Also Published As

Publication number Publication date
DE952989C (de) 1956-11-22
GB750061A (en) 1956-06-06
NL95529C (fr)
NL178382B (nl)
BE527481A (fr)
FR1100719A (fr) 1955-09-23

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