US2614247A - Pulse modulating system - Google Patents

Pulse modulating system Download PDF

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Publication number
US2614247A
US2614247A US66644A US6664448A US2614247A US 2614247 A US2614247 A US 2614247A US 66644 A US66644 A US 66644A US 6664448 A US6664448 A US 6664448A US 2614247 A US2614247 A US 2614247A
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Prior art keywords
impulses
tube
grid
source
voltage
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Expired - Lifetime
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US66644A
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English (en)
Inventor
Boisvieux Jacques
Chaumeron Jacques
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FR SADIR CARPENTIER SOC
FRANCAISE SADIR-CARPENTIER Ste
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FR SADIR CARPENTIER SOC
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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03K—PULSE TECHNIQUE
    • H03K7/00—Modulating pulses with a continuously-variable modulating signal
    • H03K7/02—Amplitude modulation, i.e. PAM

Definitions

  • ing such a modulation consists in sending unmodulated impulses to the controlling grid of a 'pentode tube, the suppressor grid of which receives the modulating voltage in addition to a suitable negative bias. It is thus possible to obtain an amplitude modulation of the impulse but the amplitude of the impulse is not in this case alinear function of the modulating voltage, chiefly because the characteristic curve of a pentode is not linear when the anode current approaches zero; as a matter of fact, said characteristic curve is such that the anode current is a function of the voltage of the suppressor grid when the other electrodes are submitted to unvarying voltages. Moreover this methodimplies the necessity of providing a negative bias to the suppressor grid, which is a drawback in many cases. g,
  • a multi-grid tube such as a hexode or a tube having a number of grids higher than that generally used in frequency changing'tubes.
  • the unmodulatedj impulse is applied to one of the control grids, say the first grid while the modulating voltage is applied to the second or control grid.
  • the source of unmodulated impulses is shown at 2 and the impulses are fed to the first grid through the condenser 3, said grid being grounded through the The impulses are applied, here resistance 4 again in their positive direction.
  • Their amplitude is at least equal tothe cut off voltage of the tube that is to the absolute value of the negative voltage that it is necessary to apply to said grid for cutting off the anode current of the tube.
  • the actionof "the grid cathode current is such that during the interval separating two impulses, the grid of the tube is brought to a value less than the cut gff value, said grid assuming a potential practically equal to that of the cathode at the moment of the passage of the impulses, this being the usual well known effect of peak'detectors.
  • the tube is locked between the impulses as the grid is brought to the potential of the cathode onlyat the moment of the passage of the impulses so as to release the tube at this moment and only at this moment.
  • the modulating voltage pro-vided by the source of positive voltage 5 which varies slightly as a function of time and that may reach the value zero, is applied to the second controlling grid of the tube I so as to amplitude modulate the impulses produced by said tube as a function of the instantaneous voltage of said supply 5.
  • an improved linearity of the impulses is obtained through a feedback system inserted between the supply 5 and the second controlling grid 6.
  • This feedback includes a resistance I inserted between the source 5 and the grid 6 and a condenser 8 inserted between the anode 9 of the tube l and the point connecting the grid 6 with the resistance l.
  • H designates the loadresistance inserted in the anode circuit, said resistance being connected through its end opposed to the anode with a high voltage source that is not illustrated.
  • the impulses provided at the output of the tube l are supplied to the output circuit connected at a point between the anode 9 and the resistance II], to the terminals l! and I2.
  • the above disclosure shows that the tube is locked during the intervals between the successive impulses and is capable of feeding current only at the moment of the passage of the latter.
  • the condenser 8 is given a sufficient capacity for the time constant of the system I8 to be high with reference to the duration of said impulse.
  • An important application of the invention is that wherein several systems of the type illustrated in Fig. l are used, for providing a multiplex communication.
  • the simplest manner of proceeding in this case consists in inserting several tubes in parallel with the common anodic resistance I0, said tubes receiving unmodulated impulses that are staggered as to time and separated modulating voltages, whereby there is collected across the terminals II---I2 the desired train of impulses, while a supplementary member may provide the synchronising impulse.
  • the following drawback appears sage of an impulse through the tube considered,
  • the voltage of the grid 6 is not exactly that of the source 5 which leads to cross-talk or interaction between the diil'erent channels of the multiplex communication system.
  • Fig. 2 shows a modification of the arrangement that removes this drawback.
  • the elements already shown in Fig. 1 play the same part and have received the same reference number.
  • the anodes of all the tubes such as I are connected in parallel with the lower end of the resistance I0.
  • diode I3 may be replaced by rectifiers and many other details may also be changed without widening unduly the scope of our present invention as defined in accompanying claims.
  • Our invention is applicable in particular to advantage to different measuring systems operating through impulses.
  • a mixing tube circuit adapted to provide amplitude modulation impulses in linear relationship with modulating voltages, comprising a mixing tube having a plurality of grids, means for feeding unmodulated impulses to one of said grids, means for feeding a modulating voltage to a second one of said grids and a feedback system coupling said secondgrid with the anode of said tube to produce the aforesaid linear relationship.
  • a mixing tube circuit adapted to provide amplitude modulated impulses in linear relationship with modulating voltages, comprising a tube having a plurality of grids, means for feeding unmodulated impulses to one of said grids, means for feeding a modulating voltage to a second one of said grids and a feedback system coupling said second rid with the anode of said tube, said feedback system including a resistance in series with said last mentioned grid and a capacitor connected to provide a connection between said last mentioned grid and said anode to produce the aforesaid linear relationship.
  • a mixing tub circuit adapted to provide amplitude modulated impulses in linear relationship with modulating voltages, comprising a mixing tube having a first grid and a second grid and an anode, a source of unmodulated impulses, connections for connecting said source to said first grid, said tube being biased to cutoff and the amplitude of said impulses being such as to overcome said bias and permit current to flow through said tube, a source of modulated impulses connected to said second grid and a feedback system connected to the anode of said tube and to said second grid, said feedback system comprising a resistor-capacitor circuithaving a time constant that is high compared to the duration of the individual impulses of said second source, said feedback system functioning to produce a linear relationship between the amplitude modulated impulses in the output of said tube and the voltage of said modulated impulse source.
  • a mixing tube circuit adapted to provide amplitude modulated impulses in linear relationship with modulating voltages, comprising a mixing tube having a first grid and a second grid and an anode, a source of unmodulated impulses, a resistor-capacitor circuit having a time constant considerably greater than the duration separating two consecutive impulses of said source, connections for connectin said resistor-capacitor circuit between said source and said first grid, said tube being biased to cutoff and the amplitude of said impulses being such as to overcome said bias and permit current to flow through said tube, a source of modulated impulses connected to said second grid and a feedback system connected to the anode of said tube and to said second grid, said feedback system functioning to produce linear relationship between the amplitude modulated impulses in the output of said tube and the voltage of said modulated impulse source.
  • a mixing tube circuit adapted to provide amplitude modulated impulses in linear relationship with modulating voltages, comprising a mixing tube having a first grid and a second grid and an anode, a source of unmodulated impulses, a resistor-capacitor circuit havin a time constant considerably greater than the duration separating two consecutive impulses of said source, connections for connecting said resistor-capacitor circuit between said source and said first grid, said tube being biased to cutoff and the amplitude of said impulses being such as to overcome said bias and permit current to flow through said tube, a source of modulated impulses connected to said second grid and a feedback system connected to the anode of said tube and to said second grid,
  • said feedback system comprising a resistor-capacitor circuit having a time constant that is high compared to the duration of the individual impulses of said second source, said feedback system functioning to produce a linear relationship between the amplitude modulated impulses in the output of said tube and the voltage of said modulated impulse source.

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  • Amplifiers (AREA)
  • Amplitude Modulation (AREA)
US66644A 1947-12-26 1948-12-22 Pulse modulating system Expired - Lifetime US2614247A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR654618X 1947-12-26

Publications (1)

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US2614247A true US2614247A (en) 1952-10-14

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US (1) US2614247A (enrdf_load_stackoverflow)
FR (1) FR959234A (enrdf_load_stackoverflow)
GB (1) GB654618A (enrdf_load_stackoverflow)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2682624A (en) * 1952-12-19 1954-06-29 Tung Sol Electric Inc Light-sensitive circuit
US2728891A (en) * 1950-04-15 1955-12-27 Emi Ltd Modulation circuit arrangements
US2774040A (en) * 1953-08-28 1956-12-11 Alan A Meyerhoff Phase modulation systems
US3015802A (en) * 1953-04-07 1962-01-02 Roy R Newsom Remote control of traffic signals

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3002158A (en) * 1956-12-31 1961-09-26 North American Aviation Inc Time modulation circuit

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB388756A (en) * 1931-08-29 1933-02-28 Marconi Wireless Telegraph Co Improvements in or relating to modulation systems suitable for use in wireless signalling and like transmission systems
US2248549A (en) * 1936-09-05 1941-07-08 Loewe Radio Inc Television transmitter
US2278159A (en) * 1933-07-12 1942-03-31 Hazeltine Corp Oscillator-modulator system
US2462111A (en) * 1944-05-26 1949-02-22 Int Standard Electric Corp Multichannel pulse distributor system

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB388756A (en) * 1931-08-29 1933-02-28 Marconi Wireless Telegraph Co Improvements in or relating to modulation systems suitable for use in wireless signalling and like transmission systems
US2278159A (en) * 1933-07-12 1942-03-31 Hazeltine Corp Oscillator-modulator system
US2248549A (en) * 1936-09-05 1941-07-08 Loewe Radio Inc Television transmitter
US2462111A (en) * 1944-05-26 1949-02-22 Int Standard Electric Corp Multichannel pulse distributor system

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2728891A (en) * 1950-04-15 1955-12-27 Emi Ltd Modulation circuit arrangements
US2682624A (en) * 1952-12-19 1954-06-29 Tung Sol Electric Inc Light-sensitive circuit
US3015802A (en) * 1953-04-07 1962-01-02 Roy R Newsom Remote control of traffic signals
US2774040A (en) * 1953-08-28 1956-12-11 Alan A Meyerhoff Phase modulation systems

Also Published As

Publication number Publication date
GB654618A (en) 1951-06-20
FR959234A (enrdf_load_stackoverflow) 1950-03-25

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