US2566876A - Phase shift system - Google Patents

Phase shift system Download PDF

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Publication number
US2566876A
US2566876A US662665A US66266546A US2566876A US 2566876 A US2566876 A US 2566876A US 662665 A US662665 A US 662665A US 66266546 A US66266546 A US 66266546A US 2566876 A US2566876 A US 2566876A
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phase
frequency
resistance
voltage
network
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US662665A
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Robert B Dome
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General Electric Co
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General Electric Co
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Priority to BE482632D priority Critical patent/BE482632A/xx
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Priority to FR982984D priority patent/FR982984A/fr
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    • 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
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H11/00—Networks using active elements
    • H03H11/02—Multiple-port networks
    • H03H11/16—Networks for phase shifting
    • H03H11/18—Two-port phase shifters providing a predetermined phase shift, e.g. "all-pass" filters
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H11/00—Networks using active elements
    • H03H11/02—Multiple-port networks
    • H03H11/16—Networks for phase shifting
    • H03H11/22—Networks for phase shifting providing two or more phase shifted output signals, e.g. n-phase output

Definitions

  • My invention relates to electrical phase shift systems and it has for its object to provide new and improved means for obtaining from a single source of voltage two resultant voltages which are constant in amplitude, but which difler in phase by a substantially constant phase angle.
  • each derived voltage would have an amplitude characteristic linearly variable with the input amplitude and the ratio of the amplitude of either of the derived voltages to the amplitude of the input voltage should be independent of frequency.
  • phase shift system is extremely useful, for example, as in a single side band telephone system in which the output voltage at the final side band frequencies is obtained directly without the usual necessity for double or triple modulation methods and without the necessity for very sharp cut-oil band pass filters.
  • Fig. 1 is a circuit diagram of one channel of a phase shifting system embodying my invention
  • Fig. 2 is a modification of the system of Fig. 1 including an additional network
  • Fig. 3 illustrates still another modification of the circuit of Fig. 1
  • Fig. 4 is a block diagram of a single side band transmitter utilizin the phase shifting system of Fig. 1
  • Figs. 5 and 6 are curves illustrating, respectively, the phase shift and the difference angle between the output voltages of the system of Fig. 4;
  • Fig. 1 is a circuit diagram of one channel of a phase shifting system embodying my invention
  • Fig. 2 is a modification of the system of Fig. 1 including an additional network
  • Fig. 3 illustrates still another modification of the circuit of Fig. 1
  • Fig. 4 is a block diagram of a single side band transmitter utilizin the phase shifting system of Fig. 1
  • Figs. 5 and 6 are curves illustrating, respectively, the phase shift and the difference angle between the output voltage
  • Fig. 8 includes a block diagram of a single side band transmitting system in which the phase shifting system of my invention is combined with electric wave filters and graphs illustrating the operational characteristics It is still another object of my invention to I provide a new and improved phase shifting system which employs dissipative impedance elements.
  • One of the features of my invention consists in shifting the phase of the two derived voltages with respect to the source in two independent channels by choosing suitable circuit constants in the two channels so that the phase diflerence of the derived voltages at any frequency is maintained substantially constant at as the input voltage is varied over a wide range of frequencies.
  • Another feature of my invention consists in employing filter sections of a semi-lattice form so that the change in phase is obtained without any distortion in the amplitudes of the resultant voltages. Furthermore, the phase angle in any one channel is shifted progressively according to the logarithm of the product of a numerical of this system.
  • a source I of voltage which may be, for example, a source of audio frequency voltages having an outputterminal 2 connected to the control electrode 3 of an electron discharge device 4.
  • the opposite terminal of the source I may be grounded and the discharge device I has a cathode 5 connected to ground through a resistor 6.
  • the anode I of the device I is connected through the resistor I to the positive terminal of a source of anode voltage illustrated here as the battery 9.
  • the negative terminal of the battery 9 lsillustrated as grounded.
  • The. circuit thus far described is a conventional phase inverter circuit.
  • a phase-shifting network is connected across the anode and cathode terminals of the device 4 and comprises a capacitor Ill connected in series with a resistor ll.
  • the capacitor is connected to the anode so that it likewise functions to block the flow of unidirectional currents.
  • a voltage shifted in phase with respect to the source I may then be obtained by connection between conductor l2, connected to the junction of the elements It and II, and ground.
  • the circuit of Fig. 1 illustrates only one channel of a phase shifting network. If a second channel consisting of a network of, for example, six stages identical in all respects to the channel illustrated in part in Fig. 1 is set up, and if a slightly different value of m0 is employed for the first stage or circuit of the channel and each stage of the network with its RuCin product is equal successively to 5.3 times the RuCm product of'the next succeedim stage, another phase angle curve will result which again increases 73.5 for each doubling of frequency. At any frequency, however, there is maintained, within 12.2% a fixed phase angle -'diiference with the output voltage of the first channel. By suitably choosing the correct value of too for the second channel, the phase angle differences between the output voltage of the two fv'ersus frequency curve may be obtained for any 10,000 cycles 900, and
  • the circuit may be operated with this phase linearity to translate frequenciesvarying over "the range of 3045.000 cycles.
  • 3 earity with variations of :l.l is available over Phase angle lin-' a range of frequencies of 60:1, such as the range from 100 cycles to 6000 cycles.
  • the value of 1.1 refers to maximum deviations from a straight line in. the range specified.
  • phase shift angle at 10 cycles may ,be made equal to 210;-at 100 cycles, 410; at
  • Th'us,' in this channel also the phase angle shifts progressively according to the logarithm of the frequency.
  • v The angle advances 200 for frequency changes of 10 to 1. It is to be noted, however, that, at any frequency, the phase angle difference between the two channels is In the circuit of Fig. 2 I have illustrated another resistance-capacitance network which does not require the isolation tube I, shown in Fig. 1
  • the derived voltage has constant amplitude over the entire frequency range, that is, the output voltage is a constant fraction of the input voltage of the network regardless of frequency.
  • Fig. 3 shows a circuit arrangement similar to that illustrated in Fig.2 and which likewise is arranged to produce a total phase shift of 360 when the input frequency is varied from zero frequency to infinite-frequency.
  • I instead of using an electron discharge device to obtain the two 180 displaced source voltagw, I have shown here a transformer It for accomplishing this result.
  • the signal source I isconnected to the primary winding iii of the transformer, while the secondary winding 20 is provided with a centertap 2
  • which is connected to iu n CHR13 IB lS R" 40.12 5 f a 1-4a.
  • Fig. 4 I have shown a block diagram of a single side band transmitter utilizing the principle of the phase shifting circuits disclosed in Figs. 1-3.
  • a. source of audio voltages which is illustrated as a microphone 22, is connected through a band pass filter 23 to a. push-pull device 24.
  • the push-pull device may take the form of either the electron discharge device. 4 of the'transformer l8 and is arranged to provide voltages across the output terminals 25, 26 which have a phase difference of 180.
  • the terminals 25, 2i are each connected to networks 21, 28.
  • the network 21 preferably comprises a phase shifting channel which may consist of the impedance elements III, II, l3-I6.
  • the network 28 comprises a second phase-shifting channel of similar impedance elements which is arranged so that the phase difference between the two channels can be maintained substantially constant at over a wide range of frequencies.
  • the output voltages of the networks 21, 28 are supplied assume respectively to balanced modulators II, 80.
  • is directly connected by means of conductor 32 to modulator 29 to supply carrier frequency thereto to be modulated by the output of the network 21.
  • is likewise supplied through a 90 phase shifting device 33 to the modulator 30.
  • the outputs of the two modulators 29, 30 are supplied to a mixer and ampliiler circuit 34 to produce a single side band radio frequency. This output frequency may be supplied to an antenna 35 or any other suitable transmitting device.
  • the value of In of the second network 28 may be found to be cycles per second. With these values of In for the two networks, the values of the resistance and capacitance required may easily be calculated.
  • the phase shift curves for the two networks 21, 2B, calculated in the manner described, are shown in Fig. in which the phase angle in degrees is plotted as ordinate and the logarithm of the frequency in cycles per second is plotted as abscissa.
  • the difference angle for the phase shifts in the two networks is shown plotted in Fig.
  • a single side band carrier wave is obtained without the requirement of auxiliary filters to aid in reducing the unwanted side band. Furthermore, I have found that the weaker side band is maintained at a value which is less than 5% of the stronger side band when the deviation from a 90 phase shift is less than 6. As a result, it is quite evident that, from a study .of the curves of Figs. 5 and 6, most satisfactory operation of the single side band is obtained by the use of my improved phase-shifting system.
  • the elements I, II. II and II of this circuit operate in the same manner as the corresponding elements of Figs. 2 and 3 to produce the first three hundred and sixty degrees of phase shift.
  • the elements 38 and 39 are added to produce a further phase shift of one hundred and eighty degrees making a total phase shift of five hundred and forty degrees.
  • condenser ID has high impedance and the oscillations are passed by resistance l3 having the phase of the lower winding of the transformer.
  • the impedance of condenser l0 becomes low and it passes the oscillations through resistance II which becomes increasingly effective as the reactance of condenser l0 reduces. This produces the first one hundred and eighty degrees of phase shift.
  • condenser ll passes the oscillations through resistance 39 more readily than resistance ll thereby producing the next one hundred and eighty degrees of phase shift.
  • condenser 38 passes oscillations more freely than resistance 39 thereby again producing a one hundred and eighty degree phase shift making a total of five hundred and forty degrees. Obviously the system may be still further extended to produce additional shift of phase.
  • each phase shift of one hundred and'eighty degrees being brought about by a single RC circuit, or combination, having a resistance arm and a capacity arm to one of which voltage of one phase is applied and to the other of which voltage of opposite phase is applied.
  • a single RC circuit, or combination having a resistance arm and a capacity arm to one of which voltage of one phase is applied and to the other of which voltage of opposite phase is applied.
  • FIG. 8 I have shown another transmitting system of the single side band type which employs conventional filters and which likewise permits the utilization of audio frequencies which approach zero frequency.
  • the source of audio frequency indicated as the microphone 22, is connected through a high pass filter ll to a push-pull device 21.
  • the device ad is similar to that described in connection with the system of Fig. 4 and is arranged to provide outputvoltages which are displaced in phase by 180.
  • the output voltages of the device 24 are supplied to the networks 21, 28 which are constructed in a manner similar to that described in connection with Fig. 4.
  • is directly connected to a modulator 28 where the carrier frequency is modulated by the output of the network 21.
  • the voltage of the generator Si is shifted in phase by 90 by th phase-shifting device 33 and supplied to the balanced'modulator 80 where it is combined with the output of the network 28.
  • pass fllter 42 which may be, for example, of the quartz crystal type.
  • the voltages translated by the filter 42 are amplified by an amplifier l3 and supplied to an antenna (r other type of radiating element 85.
  • curve 46 illustrates the range of frequencies which are present at the output of the mixer 84. It will be observed that one side band is suppressed in the region of 27-600 cycles per second spaced from the carrier.
  • the characteristic of band pass crystal filter 42 is denoted by the curve 41.
  • the composite characteristic of the system is therefore denoted by the curve 48 which shows that the signal radiated contains single side band components corresponding to an audio frequency range of 2'7 to 8000 cycles per second. Th additional range from 27 to 600 cycles per second adds considerably to the naturalness of speech and the low frequency notes of music.
  • my improved phase-shifting system permits a shifting of the output voltage relativ to the input voltage through a phase angle which is substantially linearly proportional to the logarithm of the input frequency.
  • the amplitude of the output voltage with respect to the input is independent of frequency.
  • Two such networks may be employed to obtain two voltages displaced 90 for single side band generation as described previously.
  • Such voltages may be useful in operating a three-phase motor, for example, from a sin le phase source of frequencies.
  • phaseshifting system does not employ inductances in the filter circuits required with their attendant and inevitable series resistance and shunt capacitance. In this way, this system is relatively free from any objectionable pick up of unwanted signals from stray magnetic fields. At the same time, the system is relatively low in cost, size, and weight.
  • a single side band transmitter comprising a source of audio frequency voltage, means for pro-' ducing two audio frequency voltages displaced in phase by 180", a pair of independent channels, each comprising a plurality of resistances and capacitances, means supplying said two voltages to each of said channels to shift the phase thereof, the value of the resistances and capacitances in said two channels being such that the difference of the phase shift angles in said two channels is maintained substantially constant at a value of as the frequency of said audio voltage is varied from a value close to zero to an intermediate frequency in the audio range, a source of rad o frequency voltage.
  • means for modulating said radio frequency voltage with the output of a first of said channels means for shifting the phase of said radio frequency voltage by 90, means for modulating said shifted radio frequency voltage with the output of the other of said channels, and means for mixing said two modulated radio frequency voltages to produce a radio frequency voltage having a single side band for frequencies below said intermediate frequency and two side bands for frequencies above said intermediate frequency, and means to suppress the narrower of said two side bands.
  • a wide band phase shifting system comprising a pair of input terminals, means for producing at said terminals voltages balanced with respect to ground, a pair of resistances connected in series between said terminals, a first capacitance connected in series with a first of said resistances and a second capacitance connected in shunt to the second of said resistances, said resistances having a common point, and a third resistance and a third capacitance connected in parallel between said point and ground, the products of corresponding of said resistances and capacitances being equal.
  • a wide band phase shifting system com prising a pair of input terminals across which voltages balanced with respect to ground are provided, a pair of resistances connected in series 11 between said terminals, a first capacitance 01 being connected in series with a first of said resistances R1 and a second capacitance being connected in shunt with the second of said resistances R2, said resistances having acommon point, and a third resistance R: and a third capacitance C: being connected in parallel between said point and ground, R1 being equal' to an: where a is a constant, and Re being equal to the productsof clRl, C2Rc, CsR: all being equal.
  • a single side band transmitter comprising a source of audio frequency voltage, means for producing two audio frequency voltages displaced f in phase by 180', a pair of independent channels,
  • each consisting of a plurality of resistances and capacitances means for supplying said two volt- 1 ages to each of said channels to shift the phase thereof, the value of the resistances and capacitances in said two channels being such that the difference of, the phase shift angles in said two range and each capacitance having higher impedance to the oscillations of the lower frequency in the respective portion than the resistance of the' same combination, and each resistance having higher impedance than the corresponding capacity to oscillations of higher frequency in o the respective portions, and the time constants of the different combinations being diilferent and so related that the phase shifts in the different portions are cumulative and produce a total phase shift over the total frequency range that is sub-'- stantially linear with the logarithm of frequency.
  • a phase shift network comprising two capacities and two resistances, and a pair of'output terminals, said network having two input arms one including one of said capacities and the otherfincluding one of said resistances, means to convert single phase oscillations to oscillations of opposite phase balanced channels is maintained substantially constant by a predetermined value as the frequency of said audio voltage is varied over a wide range offrequencies, a source of radio frequency voltage, means for modulating said radio frequency voltage with the output of a first of said channels,
  • phase shift network adapted tohave applied thereto alternating voltages having freque'ncies extending over'a wide range, means to convert said voltage to balanced voltages of o osite phase, and means to derive from said balanced voltages an output voltage varying in phase from a predetermined phase relation to said applied voltage at a median fre-- quencydetermined by the constants of the nettransmitted more readilyby the resistance andthose of higherfrequency in the respectiverange more readily bythe capacity whereby each combination produces a one. hundred .and eighty deare cumulative over the total ranges.
  • the combination in a phase shiftnetwork, a pair of output terminals, means toproduce oscillations with respect to one of said output termi capacitance combinations each comprising a'resistance element and a capacity element, means on; gree phase shift of oscillations between said terminals and the different combinations having different time constants whereby said phase shifts of said frequency.
  • a phase shift network adapted to have applied thereto alternating voltages having frequencies extending over a wide range, means to convert said voltage to balanced voltages of opposite phase, and means to'derive from sad balanced voltages an output voltage varying in phase from a predetermined phase relation in. said applied voltage at a median frequency determined by the constants of the network in either direction to an extent greater than ninety degrees, said last means comprising a plurality of resistance capacitance combinations connected to produce said phase shift, each resistance capacitance combination having a fixed time constant, and the time constants of the different resistance capacitance combinations being related to maintain the phase relationship between the output and applied voltage substantially linear with the logarithm of the frequen-' cies in said range.
  • phase shift networks in cascade. each comprising means to produce balanced voltages of opposite phase and means to derive therefrom a voltage variable in phase in either direction from a fixed phase relation corresponding to a median frequency determined by the time constant of the respective network, the time constant of each network being different from the time constant of the preceding of frequency over said range of frequencies.
  • a phase shift network connected between a pair of input terminals and a pair of output terminals, said input terminals having impressed between them a signal voltage having frequencies extending over a wide range, said network comprising a plurality of electron discharge devices, each having an input electrode and a pair of output electrodes and having an operating circuit connection in which the voltage applied to the input electrode is reproduced with opposite phase on one of said output electrodes, a series combination of resistance and capacity connected between said output electrodes of each device, the.
  • the diii'erent series connetwork by anamount such that the output voltage of the last network has a phase relation with respect to the input voltage of the first network varying linearly with the logarithm of the frequency over the range of frequencies applied to the first network.
  • each network comprising means to produce balanced voltages of opposite phase and means to derive therefrom a voltage variable in either direction from a fixed phase relation corresponding to a median frequency determined by the time constant of the network, the time constants of the different networks being different and said networks having resistance and capacitance proportioned to produce substantial linearity between the logarithm of frequency and the phase shift produced.
  • phase shift networks in cascade each comprising means to produce balanced voltages of opposite phase and means to derive therefrom a voltage variable in either direction from a fixed phase relation corresponding to a median frequency determined by the time constant of the network the time constant of each network in the cascade having a ratio of substantially 5.3 to the time constant of a different network in the cascade.
  • a phase shift network connected between a pair of input terminals and a pair of output terminals. said input terminals having impressed between them a signal voltage having frequencies extending over a wide range, said network comprising a plurality of electron discharge devices, each having an input electrode and a pair of output electrodes an having an operating circuit connection in which the voltage applied to the input electrode is reproduced with opposite phase on one of said output electrodes, a series combination of resistance and capacity connected between said output electrodes of each device,
  • a network having a pair of output terminals, and having a pair of input terminals to which may be applied voltages oi opposite phase with respect to the voltage at one of said output terminals, a connection between the other output terminal and each of said input terminals, impedance elements in each of said connections so proportioned relative to each other that as the frequency increases said oscillations are passed more freely first by one, then the other, then again by said one of said connections whereby a phase shift of three hundred and sixty degrees occurs in oscillations between said output terminals.
  • a phase shift network having a pair of output terminals, means to produce two oscillatory voltages with respect to one of said output terminals having opposite phase, two branch paths to the other output terminal. means to supply one of said voltagm through one of said paths and the other through the other path to said other of said output terminal, and

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Application Number Priority Date Filing Date Title
BE482632D BE482632A (en, 2012) 1946-04-17
US662665A US2566876A (en) 1946-04-17 1946-04-17 Phase shift system
FR982984D FR982984A (fr) 1946-04-17 1947-04-17 Système déphaseur pour émetteur à bande latérale unique

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Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2676308A (en) * 1947-12-05 1954-04-20 Hartford Nat Bank & Trust Co Device for deriving phase-shifted voltages from an input voltage of varying frequency
US2901599A (en) * 1954-07-16 1959-08-25 Rca Corp Amplitude-modulated radio transmitter combining two constant amplitude phase modulated signals
US2927272A (en) * 1958-01-06 1960-03-01 Itt Wave analyzer
US2991425A (en) * 1959-10-26 1961-07-04 Bell Telephone Labor Inc Delay network
US3004460A (en) * 1956-12-31 1961-10-17 Baldwin Piano Co Audio modulation system
US3004459A (en) * 1956-12-31 1961-10-17 Baldwin Piano Co Modulation system
US3007361A (en) * 1956-12-31 1961-11-07 Baldwin Piano Co Multiple vibrato system
US3013209A (en) * 1958-06-09 1961-12-12 Henry J Bickel Coherent memory filter
US3083606A (en) * 1959-03-02 1963-04-02 Don L Bonham Electrical music system
US3109991A (en) * 1955-12-15 1963-11-05 Gen Electric Audio limiter for phase modulation circuits
US3123769A (en) * 1964-03-03 Phase
US3252094A (en) * 1962-05-28 1966-05-17 Univ Oklahoma State Method of providing double side band suppressed carrier transmission signal
US3798573A (en) * 1973-03-16 1974-03-19 Bell Telephone Labor Inc Phase modulator using a frequency mixing process
US4403614A (en) * 1979-07-19 1983-09-13 Medtronic, Inc. Implantable cardioverter
US4654608A (en) * 1986-02-03 1987-03-31 The United States Of America As Represented By The Secretary Of The Air Force Double sideband generation with serrodyne modulators

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1719052A (en) * 1926-09-20 1929-07-02 American Telephone & Telegraph Single-side-band carrier system
US2048900A (en) * 1932-07-20 1936-07-28 Rca Corp Modulation
US2376392A (en) * 1943-02-23 1945-05-22 Sperry Gyroscope Co Inc Phase shifter
US2397992A (en) * 1942-11-17 1946-04-09 Edwin K Stodola Electrical network
US2431569A (en) * 1942-10-14 1947-11-25 Hartford Nat Bank & Trust Co Frequency modulation

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1719052A (en) * 1926-09-20 1929-07-02 American Telephone & Telegraph Single-side-band carrier system
US2048900A (en) * 1932-07-20 1936-07-28 Rca Corp Modulation
US2431569A (en) * 1942-10-14 1947-11-25 Hartford Nat Bank & Trust Co Frequency modulation
US2397992A (en) * 1942-11-17 1946-04-09 Edwin K Stodola Electrical network
US2376392A (en) * 1943-02-23 1945-05-22 Sperry Gyroscope Co Inc Phase shifter

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3123769A (en) * 1964-03-03 Phase
US2676308A (en) * 1947-12-05 1954-04-20 Hartford Nat Bank & Trust Co Device for deriving phase-shifted voltages from an input voltage of varying frequency
US2901599A (en) * 1954-07-16 1959-08-25 Rca Corp Amplitude-modulated radio transmitter combining two constant amplitude phase modulated signals
US3109991A (en) * 1955-12-15 1963-11-05 Gen Electric Audio limiter for phase modulation circuits
US3007361A (en) * 1956-12-31 1961-11-07 Baldwin Piano Co Multiple vibrato system
US3004459A (en) * 1956-12-31 1961-10-17 Baldwin Piano Co Modulation system
US3004460A (en) * 1956-12-31 1961-10-17 Baldwin Piano Co Audio modulation system
US2927272A (en) * 1958-01-06 1960-03-01 Itt Wave analyzer
US3013209A (en) * 1958-06-09 1961-12-12 Henry J Bickel Coherent memory filter
US3083606A (en) * 1959-03-02 1963-04-02 Don L Bonham Electrical music system
US2991425A (en) * 1959-10-26 1961-07-04 Bell Telephone Labor Inc Delay network
US3252094A (en) * 1962-05-28 1966-05-17 Univ Oklahoma State Method of providing double side band suppressed carrier transmission signal
US3798573A (en) * 1973-03-16 1974-03-19 Bell Telephone Labor Inc Phase modulator using a frequency mixing process
US4403614A (en) * 1979-07-19 1983-09-13 Medtronic, Inc. Implantable cardioverter
US4654608A (en) * 1986-02-03 1987-03-31 The United States Of America As Represented By The Secretary Of The Air Force Double sideband generation with serrodyne modulators

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BE482632A (en, 2012)
FR982984A (fr) 1951-06-18

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