US2441954A - Pulse modulation communication systems - Google Patents

Pulse modulation communication systems Download PDF

Info

Publication number
US2441954A
US2441954A US594871A US59487145A US2441954A US 2441954 A US2441954 A US 2441954A US 594871 A US594871 A US 594871A US 59487145 A US59487145 A US 59487145A US 2441954 A US2441954 A US 2441954A
Authority
US
United States
Prior art keywords
anode
voltage
valve
cathode
resistance
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
US594871A
Other languages
English (en)
Inventor
Chatterjea Prafulla Kumar
Beney James Kinloch
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.)
STC PLC
Original Assignee
Standard Telephone and Cables PLC
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 claimed from GB2559344A external-priority patent/GB596654A/en
Application filed by Standard Telephone and Cables PLC filed Critical Standard Telephone and Cables PLC
Application granted granted Critical
Publication of US2441954A publication Critical patent/US2441954A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B14/00—Transmission systems not characterised by the medium used for transmission
    • H04B14/02—Transmission systems not characterised by the medium used for transmission characterised by the use of pulse modulation
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03K—PULSE TECHNIQUE
    • H03K7/00—Modulating pulses with a continuously-variable modulating signal
    • H03K7/08—Duration or width modulation ; Duty cycle modulation

Definitions

  • the present invention relates to arrangements for generating rectangular electrical pulses of adjustable, duration.
  • the invention provides an arrangement for generating periodic electrical waves comprising two thermionic valves each having at least a cathode, a control grid and an anode, a source of anode current for the said valves, meansrfor coupling the anode of the first valve to the control grid of the second valve, means for applying saw-tooth waves to the control grid of the first valve, means for feeding back the output variations of the second valve in positive phase to the input of the first valve, andmeans for deriving periodic waves from either of the said anodes.
  • the two valves are replaced by a double triode having a single cathode common to both triode portions.
  • FIG. 1 shows a schematic circuit diagram of an arrangement according to the invention
  • Fig. 2 shows a valve characteristic
  • Fig. 3 shows wave form curves employed to explain the action of Fig. 1.
  • a double triode vacuum valve i has a cathode 2 common to both sections.
  • the two separate control grids are designated 3 and 4, and the corresponding separate anodes are 5 and 6, respectively.
  • the cathode 2 is connected to the grounded negative terminal "l of the high tension source through a load resistance 8.
  • the two anodes 5 and 6 are connected to the positive high tension terminal 9 through individual anode resistanceslfl and H, and a common resistance 12, a bypasscondenser l3, being provided.
  • An arrangement for biassing the control grids 3 and 4 either positively or negatively comprises two equal resistances l4 and [5 connected in series across a direct current source intended to be connected to the terminals l6 and IT. The junction point of these resistances is connected to ground, and the terminals 16 and I1 arefurther shunted by two potentiometers l8 and IS.-
  • the control grids 3 and 4 are respectively con-J nected to the movable contacts of potentiometers l8 and I9 through resistances 20 and 2
  • the anode 5 is connected to the control grid 4- by a blocking condenser 24.
  • a saw-tooth wave generator (not shown) of any suitable typeis intended to be connected to the input terminals 25 and 26, and supplies waves through a resistance 21 to the control grid 3. This resistance forms a reducing potentiometer with the resistance 20, so that a suitable .iraction of the sawtooth voltage is applied to the control grid 3.
  • the resistance 21 is shunted by a-condenser 28, which compensates, in known manner for the frequency distortion introduced by the stray capacity shunting the resistance 20.
  • the anode 6 is connected to the output terminal 29 through a condenser 30.
  • A'resistance 31 is provided to shunt the terminals 1 and 29, andforms with the condenser 30 a pulse differentiating circuit.
  • Modulating voltages maybe applied to the control grid 3 from the input terminal 32 through the blocking condenser 33 and resistance 34; or alternatively, they may be applied to the other control grid 4 from the input terminal 35 through the blocking condenser 36 and resistance 31.
  • Element gig g The two triode portions of the valve l'ares'up posed to be similar, a typical characteristic curve for either being shown in Fig. 2. This shows the relation between the anode current Ia and the control grid voltage Vg with respect to the cathode.
  • the grid bias of the left hand portion of the valve is adjusted by means of the potentiometer I8 to a value such that whena driving voltage is applied: at the terminal 25, the anode; current Ia varies between a value given by the point 33 on the lower band, a little above the cut-oil point; e g and a value given by a point 39 somewhere below the saturation point of the valve, so that the worlring point varies over the portion of the charac'- teristic curve between the points-38-and"39, and a the grid voltage swings between the correspondj ing values OM and ON.
  • the grid bias of the right hand half .of the valve is adjusted by the potentiometer Hi to a relatively large positive value Q, when the left handhalfgisinxthe con+- dition represented by the point 38'; This value feedbackithrou'ghthe cathode resistance 8 acting to accelerate the change.
  • representing the same as behand' half of the valveis small, so-that" the potential of the anode" 5 will be a little below the voltage of the dotted line 41, as represented by thepoints 43.
  • the anode current in the'righthand half of .the valve is a maximum and the corresponding anode voltage is' a minimum as indicated by the points 44'. .As the' saw-tooth voltage'increases from zero, the anode current of the left-hand half increases and theivoltageof the corresponding anode falls. This change will, however, be small due to the action of the cathode resistance 8.
  • Thesudd'en decrease in cathode potential produces a sudden increase "in the left-hand anode current and a corresponding left hand anode current rises.
  • thefly-back strokeoccurs thereis'a relatively rapid fall in cathode voltagefollowed by a sudden rise atthemoment of saturationof the right-hand portion;of the valve.
  • the'trailing'edges of the pulses from the anode 6 may be time modulated.
  • time duration modulated pulses may be obtained ⁇ direct from the anode 6, or pairs of short marking'pulse's one of which in each'pair in time-phase-mo'dulated may be'obtained from terminaLZQafterdifferentiation by theelements 30 and 3!.
  • the doubletrio'de l with its associated circuits operates practically in the same way as a gridcont'rolled gas filled triode of which the; cathode, control grid and anode are represented by theelements. 2; 3 and 6' respectively.
  • Fig. l can be regarded as a two-stage amplifier in' which the cathode resistance 8 acts to feed back the output variations to the input in positivephase- It also acts to introduce localnegativefeedback in each stage separately. It will be understood that the desired results according to the invention can be obtained by introducing the positive feedb ways. 7 V
  • An arrangement according to claim 1 further including means for difierentiating the variable duration pulses to produce variable time displaced pulses.
  • An arrangement according to claim 1 further including means for adjusting the durations of the derived pulses.
  • An arrangement according to claim 1 fur- 5 ther including means for adjusting the durations of the derived pulses including means for adjusting the bias of one of said control grids.

Landscapes

  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Electrotherapy Devices (AREA)
US594871A 1944-12-20 1945-05-21 Pulse modulation communication systems Expired - Lifetime US2441954A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB2559344A GB596654A (en) 1944-12-20 Improvements in or relating to pulse modulation communication systems

Publications (1)

Publication Number Publication Date
US2441954A true US2441954A (en) 1948-05-25

Family

ID=10230194

Family Applications (1)

Application Number Title Priority Date Filing Date
US594871A Expired - Lifetime US2441954A (en) 1944-12-20 1945-05-21 Pulse modulation communication systems

Country Status (3)

Country Link
US (1) US2441954A (enrdf_load_stackoverflow)
BE (1) BE476259A (enrdf_load_stackoverflow)
FR (1) FR939273A (enrdf_load_stackoverflow)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2519030A (en) * 1946-10-29 1950-08-15 Gen Electric Mixer circuit

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2061734A (en) * 1934-09-29 1936-11-24 Rca Corp Signaling system
US2086918A (en) * 1935-08-22 1937-07-13 Rca Corp Method of frequency or phase modulation
US2211750A (en) * 1937-03-09 1940-08-20 Cable & Wireless Ltd Wireless telegraph system
US2338395A (en) * 1940-06-25 1944-01-04 Gen Electric Signal transmission system
US2338512A (en) * 1942-10-22 1944-01-04 Westinghouse Electric & Mfg Co Telephone transmitter circuit

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2061734A (en) * 1934-09-29 1936-11-24 Rca Corp Signaling system
US2086918A (en) * 1935-08-22 1937-07-13 Rca Corp Method of frequency or phase modulation
US2211750A (en) * 1937-03-09 1940-08-20 Cable & Wireless Ltd Wireless telegraph system
US2338395A (en) * 1940-06-25 1944-01-04 Gen Electric Signal transmission system
US2338512A (en) * 1942-10-22 1944-01-04 Westinghouse Electric & Mfg Co Telephone transmitter circuit

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2519030A (en) * 1946-10-29 1950-08-15 Gen Electric Mixer circuit

Also Published As

Publication number Publication date
BE476259A (enrdf_load_stackoverflow)
FR939273A (fr) 1948-11-09

Similar Documents

Publication Publication Date Title
US2462111A (en) Multichannel pulse distributor system
US2313906A (en) Electrical delay circuit
US2641698A (en) Delay line decoder
US2560434A (en) Device for translating duration or time modulated pulses into coded pulses
GB635474A (en) Improvements in or relating to thermionic multivibrators for use in multi-channel electrical pulse communication systems
US2692334A (en) Electrical circuit arrangement for effecting integration and applications thereof
US2633528A (en) Electronic pulse modulator switch
US2540923A (en) Electron-discharge tube circuit arrangement
US2597322A (en) Pulse generator circuit
US2730575A (en) Sync pulse-emphasizing amplifier
US2441954A (en) Pulse modulation communication systems
US3074020A (en) Bistable multivibrator which changes states in response to a single limited range, variable input signal
US2569164A (en) Variable sweep circuit
US2537843A (en) Pulse regeneration apparatus
US2572792A (en) Thermionic valve circuits
US2662178A (en) Voltage generating circuit
US2564000A (en) Pulse generator system
US2416292A (en) Saw-tooth wave generation
US2471413A (en) Pulse code-signaling system
US2419606A (en) Linear saw-tooth generator
US3177431A (en) Predistorting modulating circuit for pulse generator
GB592792A (en) Single pulse electronic relay
US2975366A (en) Pulse width discriminator
US2549874A (en) Electronic relay circuit arrangement
US2518341A (en) Pulse modulation system