US2424971A - Frequency-shift radio telegraph transmitting system - Google Patents

Frequency-shift radio telegraph transmitting system Download PDF

Info

Publication number
US2424971A
US2424971A US545934A US54593444A US2424971A US 2424971 A US2424971 A US 2424971A US 545934 A US545934 A US 545934A US 54593444 A US54593444 A US 54593444A US 2424971 A US2424971 A US 2424971A
Authority
US
United States
Prior art keywords
phase
frequency
tube
tubes
telegraph
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
US545934A
Other languages
English (en)
Inventor
James R Davey
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
AT&T Corp
Original Assignee
Bell Telephone Laboratories Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority to BE480495D priority Critical patent/BE480495A/xx
Priority to NL67418D priority patent/NL67418C/xx
Priority to FR957756D priority patent/FR957756A/fr
Application filed by Bell Telephone Laboratories Inc filed Critical Bell Telephone Laboratories Inc
Priority to US545934A priority patent/US2424971A/en
Application granted granted Critical
Publication of US2424971A publication Critical patent/US2424971A/en
Priority to CH265359D priority patent/CH265359A/de
Priority to GB5100/48A priority patent/GB645436A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03C—MODULATION
    • H03C1/00—Amplitude modulation
    • H03C1/52—Modulators in which carrier or one sideband is wholly or partially suppressed
    • H03C1/60—Modulators in which carrier or one sideband is wholly or partially suppressed with one sideband wholly or partially suppressed
    • 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 radio transmitting systems and, more particularly, to improved keying means for shiftin the frequency of the output waves produced by a radio transmitter back and forth between two different values in accordance with the signals to be transmitted.
  • Another object of the invention is to provide a radio telegraph transmitting system with improved means for selectively transmitting alternatively wave energy of two different frequencies which are symmetrically disposed on opposite sides of a base frequency.
  • a further object of this invention is to provide improved keyin means for shifting the frequency of the output waves produced by a radio transmitter back and forth between two different values in accordance with the signals to H be transmitted.
  • phase reversing means for reversin the phase of a portion of the modulating wave energy, used to modulate the carrier wave energy, in accordance with the type of signal to be transmitted at a particular instant.
  • This portion of the modulating wave energy is applied in phase opposition to control grids of a balanced modulator.
  • Another portion of the modulating wave energy, which is not acted upon by the phase reversing means, is passed through a phase shifter and is applied in phase opposition to control grids of a second balanced modulator.
  • the phase shifter is so adjusted that the modulating wave energy applied to the second modulator is in phase quadrature with the modulating wave energy supplied to the first modulator; that is, when the instantaneous alternating value of the voltage is zero in the input to the first modulator, it is a maximum in the input'to the second modulator and vice versa.
  • Radio frequency carrier wave energy is also supplied in phase quadrature relation to the modulators.
  • the balanced modulators suppress the carrier wave and tend to produce two side frequencies. However, since their outputs are connected together, one side frequency is cancelled due to the above-mentioned differences in phase. Therefore, only one side frequency will be delivered to the utilization circuit, the particular side frequency delivered at any given instant being determined by the phase of the audio frequency wave energy delivered at that time to the first balanced modulator.
  • telegraph signals of two different types are produced by manually operating the key I between its contacts 2 and 3.
  • Positive battery 4 is connected to contact 2 and negative battery 5 is connected to contact 3.
  • the key I constitutes a source of telegraph signals since its operation causes direct current polar telegraph signals, consisting of direct current which flows in one direction for marking and in the other direction for spacing, to be transmitted along conductor 6 to the phase reversing network 1.
  • any other suitable means may be employed for producing telegraph signals and applying them in the form of positive or negative current to the phase reversal network 1.
  • the phase reversal network 7 comprises two pairs of voltage sensitive variable resistance elements, such as copper oxide disc rectifiers 8, 8 and 9, 9, connected in the manner shown in the drawing so that the pair of rectifiers B, 8 present a low resistance to positive current from conductor ES and a high resistance to negative current while the pair of rectifiers 9, 9 present a low resistance to the flow of negative current from conductor 6 and a high resistance to positive current.
  • voltage sensitive variable resistance elements such as copper oxide disc rectifiers 8, 8 and 9, 9
  • An audio frequency generator It of any suitable design produces wave energy having a frequency of 425 cycles.
  • One portion of this wave, energy is supplied by a transformer H to a potentiometer I2 and another portion is delivered by the transformer H to a phase shifter I33
  • the phase shifter I3 is a bridge network comprising condensers and resistances designed to shift the phase of the voltage of the wave energy supplied thereto by transformer l I so that the voltage in conductor [4 will be degrees displaced from the voltage in the primary winding of the transformer ll While the voltage in conductor IE will be displaced 2'70 degrees.
  • the voltage having a phase shift of 90 degrees is delivered by conductor 14 to a grid of a tube It and the voltage having a phase shift of 270 degrees is applied by conductor IE to a grid of a tube ii.
  • the voltages in conductors i l and i5 are approximately equal.
  • Tubes l6 and i1 constitute a balanced modulator as will be discussed in more detail hereinafter.
  • the phase reversing network l which acts as a reversing switch.
  • transformer l9 delivers some of this audio frequency wave energy over a conductor 20 to a grid of a tube 22, the voltage of this portion being 180 degrees out of phase with that in the primary winding of the transformer I I.
  • Another portion is supplied over a conductor 2
  • are approximately equal.
  • the phase reversing network I functions as a reversing switch to reverse the phase of the audio frequency inputs to the balanced modulator constituted by the tubes 22, and 23.
  • the modulating voltage applied to tube 22 is always 90 degrees out of phase with the modulating voltage applied to tube I6, and the voltage applied to tube 23 is always SO'degrees out of phase with the voltage applied to tube H.
  • a quadrature phase relation is always maintained between the audio frequency inputs to the balanced modulator tubes I6, I1, 20, and 2!,
  • a radio frequency oscillator 24 of any appropriate design produces wave energy having a frequency of 2,000,000 cycles. Itis to be understood thatthis specific value and the specificvalue of the audio frequency wave energy have been set forth for purposes of explanation and that the invention is not restricted to these specific values.
  • This wave energy is supplied by means of a transformer 25 to a phase shifter 26 which is a bridge network comprising condensers and resistances.
  • This phase shifter 26 is'designed to produce a 90 degree hase diiference between the voltages at its output terminals so that the voltage of the wave energy flowing along the conductor 21 is in phase with that in the primary winding of the transformer 25, whilelthe voltage in conductor 28 is 90 degrees out of phase, that in conductor 29 is 180 degrees out of phase, and that in conductor 30 is 270 degrees out of phase.
  • the voltages in these four conductors are approximately equal.
  • the balanced modulator constituted by tubes 16 and I7 is supplied with two other portions of the radio frequency energy which are also 180 degrees out of phase. There is thus a quadrature phase relation between the four radio frequency inputs to the balanced modulators.
  • both the radio frequency 7 input and the audio frequency input to tube I6 are always degrees out of phase with their respective generator outputs while both the radio frequencyand audio frequency inputs to tube I1 are always 279 degrees out of phase. In other words, both inputs to tube I6 are always degrees out of phase with the corresponding inputs to tube I'I.
  • the radio frequency input to tube 23 is always in phase with its source but the audio frequency input to tube 23 is either in phase with its source or 180 degrees out of phase depending on whether the key I is engaging its contact 2 or its contact 3.
  • the radio frequency input to tube 22 is always 180 degrees out of phase with its source while the audio frequency input to tube 22 is either 180 degrees out of phase with its source or in phase depending on the position of the key I.
  • both the radio frequency and audio frequency inputs to tube 23 will be in phase with their respective sources and both inputs to tube 22 will be 180 degrees out of phase with their respective sources and also 180 degrees out of phase with the corresponding inputs to tube 23
  • the key I is operated against its contact 3
  • the audio frequency input will .be 180 degrees out of phase with its source
  • the radio frequency input to tube 22 will. remain 180 degrees out of phase with its source while the audio frequency input will now be in phase with its source.
  • the parallel output circuits of the balanced modulators are connected to an intermediate amplifier 33, which has its output. connected to the final power amplifier 34.
  • the amplified signals from the power amplifier 34 aredelivered to the transmitting antenna 35 which radiates them through space.
  • the potentiometer I2. is so adjusted as to cause the amplitude of the side frequenciesproduced in; the balanc d modulator constituted by the, tubesZZ and 23 to, be approximately equal to theamplitude of. the side frequencies produced in the balanced modulator constituted. by the tubes I6 and I1. q
  • the screen grids 36 of the balanced modulator constituted by tubes 22 andizflgare suppliedv with positive-voltage from battery-31 through a potentiometer 3 8-and the screen grids 39 0f the balanced modulator constituted by tubes I6 and I! are similarly supplied with positive voltage from battery 31 through a potentiometer 40.
  • both the potentiometers 38 and 40 are adjusted to supply the screen grids 38 and 39, respectively, with voltages of the proper magnitudes so that the carrier wave, or base radio frequency of 2,000,000 cycles, will be suppressed in a manner well known to those skilled in the art.
  • the radio frequency and audio frequency wave energies are supplied to each balanced modulator in a push-pull manner so that in each balanced modulator the potential on the grid of one of the modulator tubes is positive while the potential on the grid of the other tube is negative at any particular instant. Since the two modulators can be adjusted for a nearly perfect balance in the manner described above, the output currents in the parallel-connected output circuits of the modulators will therefore neutralize or balance each other in a manner well known to those skilled in the art so that the radio frequency carrier wave of 2,000,000 cycles will be suppressed or eliminated. However, the output of each balanced modulator will contain upper and lower side frequencies of 2,000,425 cycles and 1,999,575 cycles due to the modulation of the radio frequency wave energy by the audio frequency modulating energy.
  • the lower side frequency waves produced by both balanced modulators will have a zero phase difference, whereas the upper side frequency wave produced by one balanced modulator will be 180 degrees out of phase with the upper side frequency wave produced by the other balanced modulator. This can be seen from the following table of the side frequency phase differences existing at this time.
  • the values in column 3 are the sums of the corresponding values in columns 1 and 2 while the values in column 4 are the differences between the corresponding values in columns 1 Since the output circuit of the second balanced modulator is connected in parallel with theoutput circuit of the first balanced modulator, the upper side frequency will be canceled, or balanced out, and only the lower side frequency will be supplied at this time to the antenna 35 for radiation. 7
  • the antenna 35 will transmit wave energy having either a frequency of 2,000,425 cycles or a frequency of 1,999,575 cycles in accordance with the marking and spacing polar telegraph signals selectively produced by the key I.
  • a carrier shift telegraph transmitting system comprising in combination a source of carrier waves, a source of low frequency oscillations, a pair of balanced modulators having a common output circuit, a plurality of input circuits for coupling each of said sources with said modulators for impressing thereon said carrier waves and said low frequency oscillations in such phase relationships as to produce a single side frequency in said common output circuit, said system being characterized by having control means for changing the wavelength of said single side frequency in accordance with telegraph signals, said control means including a telegraph key, a source of bias voltages, phase reversing means interposed in one of said input circuits, and circuit means for impressing the biasing voltages on said phase reversing means for reversing the phase of the electric wave energy impressed by said input circuit in accordance with the operation of said telegraph key.
  • a carrier shift telegraph transmitting system comprising in combination a source of car-. rier waves, a source of low frequency oscillations, a pair of balanced modulators having a common output circuit, a plurality of input circuits for coupling each of said sources with said modulators for impressing thereon said carrier waves and said low frequency oscillations in such phase relationships as to produce a single side frequency in said common output circuit, said system being characterized by having control means for changing the wavelength or said single side frequency in accordance with telegraph signals, said control means including a telegraph key, a source of bias voltages, phase reversing means comprising a Wheatstone bridge structure of voltage sensitive variable resistance elements interposed in the low frequency input circuit of one of said modulators, and circuit means for impressing the biasing voltages on said variable resistance elements for unbalancing the bridge in one direction when said key is in one position and for unbalancing the bridge in the other direction when said key is in another position.
  • a carrier shift telegraph transmitting systern comprising in combination a source of carrier waves, a source of low frequency oscillations, a pair of balanced modulators having a common output circuit, a plurality of input circuits for coupling each of said sources with said modulators for impressing thereon said carrier waves and said low frequency oscillations in such phase relationships asto produce a single side frequency in said common output circuit, a telegraph signal source for producing marking and spacing polar telegraph signals alternatively, said system being characterized by having control means for changing the wavelength of said single side frequency from one Value when marking signals are produced by said telegraph signal source to another value when spacing signals are produced, said control means comprising a phase reversing network interposed in one of said input circuits, and circuit means for impressing said marking and spacing polar telegraph signals on said phase reversing network, said phase reversin network comprising four voltage sensitive variable resistance elements connected in a lattice structure, one pair of said elementsbeing connected for presenting a low resistance to marking signals and
  • a single sideband modulating system having in combination a source of carrier waves, a source of single frequency audio waves, a first balanced modulator comprising two electronic tubes, 2, second balanced modulator comprising two other electronic tubes, said modulators having a common output circuit, first circuit means for applying said carrier waves to said four electronic A 8 tubes in phase quadrature, second circuit means for applying said audio waves to the two tubes of one modulator in phase opposition, third circuit means for applying said audio waves to the two tubes of the other modulator in phase opposition, phase shifting means for establishing a phase quadrature relation between said audio inputs to said four tubes whereby the carrier and one sideband are suppressed and only one sideband appears in said output circuit, said system being characterized by having control means for interchanging the suppressed sideband and the sideband appearing in said output circuit, said control means comprising a source of bias voltage, a phase reversing network interposed in said second circuit means for reversing the phase of the audio waves applied by said second' circuit means, said phase reversing network comprising a Wheatstone

Landscapes

  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Transmitters (AREA)
US545934A 1944-07-21 1944-07-21 Frequency-shift radio telegraph transmitting system Expired - Lifetime US2424971A (en)

Priority Applications (6)

Application Number Priority Date Filing Date Title
BE480495D BE480495A (enrdf_load_html_response) 1944-07-21
NL67418D NL67418C (enrdf_load_html_response) 1944-07-21
FR957756D FR957756A (enrdf_load_html_response) 1944-07-21
US545934A US2424971A (en) 1944-07-21 1944-07-21 Frequency-shift radio telegraph transmitting system
CH265359D CH265359A (de) 1944-07-21 1947-12-30 Frequenzgetasteter Telegraphiesender.
GB5100/48A GB645436A (en) 1944-07-21 1948-02-20 Improvements in radio telegraph transmitting systems

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US545934A US2424971A (en) 1944-07-21 1944-07-21 Frequency-shift radio telegraph transmitting system

Publications (1)

Publication Number Publication Date
US2424971A true US2424971A (en) 1947-08-05

Family

ID=24178130

Family Applications (1)

Application Number Title Priority Date Filing Date
US545934A Expired - Lifetime US2424971A (en) 1944-07-21 1944-07-21 Frequency-shift radio telegraph transmitting system

Country Status (6)

Country Link
US (1) US2424971A (enrdf_load_html_response)
BE (1) BE480495A (enrdf_load_html_response)
CH (1) CH265359A (enrdf_load_html_response)
FR (1) FR957756A (enrdf_load_html_response)
GB (1) GB645436A (enrdf_load_html_response)
NL (1) NL67418C (enrdf_load_html_response)

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2483271A (en) * 1946-11-30 1949-09-27 Frederick W Frink Frequency modulation transmitter
US2571957A (en) * 1946-11-02 1951-10-16 Westinghouse Electric Corp Single side-band demodulator system
US2576429A (en) * 1950-01-31 1951-11-27 Jr Oswald G Villard Single side-band signal generator
US2596612A (en) * 1943-06-12 1952-05-13 Hartford Nat Bank & Trust Co Signal receiver for carrier-wave telephony systems
US2635226A (en) * 1950-01-20 1953-04-14 Collins Radio Co Phase modulation system and apparatus
US2659051A (en) * 1952-04-29 1953-11-10 John F Honey Carrier insertion
US2678385A (en) * 1951-04-16 1954-05-11 Rca Corp Diversity receiver
US2726368A (en) * 1952-08-16 1955-12-06 Bell Telephone Labor Inc Broad-band phase-shifting circuit
US2797313A (en) * 1951-03-27 1957-06-25 Hoffman Electronics Corp Radio communication by neutral frequency deviation
US2927159A (en) * 1955-05-03 1960-03-01 Lab For Electronics Inc Frequency-shift keying
US2935692A (en) * 1954-03-08 1960-05-03 Nathaniel L Cohen Phase control system
US3141066A (en) * 1956-11-08 1964-07-14 Itt Double side band, suppressed-carrier, phase shift type telegraph system
US3274591A (en) * 1947-05-08 1966-09-20 Torrence H Chambers Phase rotation system for use in velocity cancellation moving target radar systems

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE961718C (de) * 1954-04-02 1957-04-11 Siemens Ag Verfahren zur Frequenzumtastung fuer die UEbertragung zweier Nachrichten, insbesondere fuer die Zweifach-F 1-Modulation von Funksendern
DE1221667B (de) * 1963-01-03 1966-07-28 Telefunken Patent Verfahren zur Erzeugung eines Farbtraegers

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1666206A (en) * 1925-01-15 1928-04-17 Western Electric Co Modulation system
US1773116A (en) * 1928-01-24 1930-08-19 American Telephone & Telegraph Single-side-band system
US1831516A (en) * 1928-01-10 1931-11-10 Ralph B Stewart Modulating system and method
US1892383A (en) * 1930-05-06 1932-12-27 Soc Fr Radioelectrique High frequency signaling
US1976393A (en) * 1929-05-18 1934-10-09 Jr John Hays Hammond Side band reversal transmission system
US2118917A (en) * 1936-09-03 1938-05-31 William G H Finch Dual tone telegraphy system
US2198248A (en) * 1936-09-01 1940-04-23 Rca Corp Method of and means for communication

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1666206A (en) * 1925-01-15 1928-04-17 Western Electric Co Modulation system
US1831516A (en) * 1928-01-10 1931-11-10 Ralph B Stewart Modulating system and method
US1773116A (en) * 1928-01-24 1930-08-19 American Telephone & Telegraph Single-side-band system
US1976393A (en) * 1929-05-18 1934-10-09 Jr John Hays Hammond Side band reversal transmission system
US1892383A (en) * 1930-05-06 1932-12-27 Soc Fr Radioelectrique High frequency signaling
US2198248A (en) * 1936-09-01 1940-04-23 Rca Corp Method of and means for communication
US2118917A (en) * 1936-09-03 1938-05-31 William G H Finch Dual tone telegraphy system

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2596612A (en) * 1943-06-12 1952-05-13 Hartford Nat Bank & Trust Co Signal receiver for carrier-wave telephony systems
US2571957A (en) * 1946-11-02 1951-10-16 Westinghouse Electric Corp Single side-band demodulator system
US2483271A (en) * 1946-11-30 1949-09-27 Frederick W Frink Frequency modulation transmitter
US3274591A (en) * 1947-05-08 1966-09-20 Torrence H Chambers Phase rotation system for use in velocity cancellation moving target radar systems
US2635226A (en) * 1950-01-20 1953-04-14 Collins Radio Co Phase modulation system and apparatus
US2576429A (en) * 1950-01-31 1951-11-27 Jr Oswald G Villard Single side-band signal generator
US2797313A (en) * 1951-03-27 1957-06-25 Hoffman Electronics Corp Radio communication by neutral frequency deviation
US2678385A (en) * 1951-04-16 1954-05-11 Rca Corp Diversity receiver
US2659051A (en) * 1952-04-29 1953-11-10 John F Honey Carrier insertion
US2726368A (en) * 1952-08-16 1955-12-06 Bell Telephone Labor Inc Broad-band phase-shifting circuit
US2935692A (en) * 1954-03-08 1960-05-03 Nathaniel L Cohen Phase control system
US2927159A (en) * 1955-05-03 1960-03-01 Lab For Electronics Inc Frequency-shift keying
US3141066A (en) * 1956-11-08 1964-07-14 Itt Double side band, suppressed-carrier, phase shift type telegraph system

Also Published As

Publication number Publication date
CH265359A (de) 1949-11-30
NL67418C (enrdf_load_html_response)
FR957756A (enrdf_load_html_response) 1950-02-25
GB645436A (en) 1950-11-01
BE480495A (enrdf_load_html_response)

Similar Documents

Publication Publication Date Title
US2424971A (en) Frequency-shift radio telegraph transmitting system
US2461456A (en) Frequency shift keying
US2436834A (en) Phase and frequency modulation
GB859002A (en) Improvements in or relating to phase modulators for carrier communication systems
US2379395A (en) Fm transceiver
US2714634A (en) Modulated radio frequency signal amplifier
US2756282A (en) Directional amplifier system and apparatus
US3384824A (en) Phase quadrature transmission system with receiver detectors controlled in response to presence of pilot waves appearing as crosstalk
US3430143A (en) Communications system wherein information is represented by the phase difference between adjacent tones
US2374000A (en) Phase modulator
US3378773A (en) Frequency and amplitude modulation transmitter and modulator
US2045107A (en) Phase modulation
US3946337A (en) Phase modulator for phase shift key communications systems
US2511204A (en) Frequency shift keying channeling
US2480705A (en) Frequency shift keyer
US2545214A (en) Locking circuit and control
US2645710A (en) Radio transmission and carrier wave modulation
US2239776A (en) Balanced modulator circuit
US2864953A (en) Microwave pulse circuits
US2382015A (en) Demodulator for frequency and amplitude modulation
US2036165A (en) Phase and frequency modulation
US1991474A (en) Radio beacon system
US2186146A (en) Side band suppression system
US3032611A (en) Combined frequency-phase modulation telegraph system
US2468832A (en) Signaling system