US1935776A - Side band reversal transmission system - Google Patents

Side band reversal transmission system Download PDF

Info

Publication number
US1935776A
US1935776A US364105A US36410529A US1935776A US 1935776 A US1935776 A US 1935776A US 364105 A US364105 A US 364105A US 36410529 A US36410529 A US 36410529A US 1935776 A US1935776 A US 1935776A
Authority
US
United States
Prior art keywords
frequency
carrier
phase
circuit
wave
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
US364105A
Other languages
English (en)
Inventor
Jr John Hays Hammond
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.)
Individual
Original Assignee
Individual
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 Individual filed Critical Individual
Priority to US364105A priority Critical patent/US1935776A/en
Priority to GB3224429A priority patent/GB343538A/en
Priority claimed from GB3224429A external-priority patent/GB343538A/en
Priority to FR684214D priority patent/FR684214A/fr
Priority to US580520A priority patent/US1976393A/en
Application granted granted Critical
Publication of US1935776A publication Critical patent/US1935776A/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
    • H04B14/002—Transmission systems not characterised by the medium used for transmission characterised by the use of a carrier modulation
    • H04B14/006—Angle modulation

Definitions

  • the object of this invention is to provide a system of radio communication by which intelligence can be transmitted subject to little or no interference from other radio signals or from atmospheric conditions.
  • Another object of this invention is to provide a system of telegraphy and telephony which will produce a small amount of interference with respect to nearby receivers of the usual type, without, however, preventing strong signals from being received by special types of receivers.
  • This invention relates to transmission by modulation methods or by a wave which may be compounded from a plurality of continuous waves. More particularly, this invention relates to the special feature that the signalling is accomplished by the reversal or other alteration of the phase of any of the constituents of the composite wave.
  • Figs. 1, 2, 3, 4, and 5 are each diagrams indicating the envelope of different synthetic waves.
  • Fig. 6 is a circuit diagram of a transmitter for carrying out the objects of my invention.
  • Fig. '7 is a circuit diagram of a receiver for cooperation with the transmitter of Fig. 6.
  • Fig. 8 is a circuit diagram of an alternative form of transmitter for carrying out the principles of my invention.
  • Fig. 9 is a circuit diagram of an alternative form of receiver for cooperation with the transmitter of Fig. 8.
  • a modulated sine wave is in all respects equivalent to a plurality of waves.
  • these waves are termed the carrier frequency and the side frequencies.
  • An additional characteristic of these three constituent waves when arranged as in amplitude modulation, is shown by representing them in a vectorial sense, withone vector for each wave.
  • the angle between the vector representing the carrier C and the vector S+ representing the upper side frequency must be equal to the angle between same carrier vector C and the vector 3- representing the lower side frequency.
  • the waves C and 8+ are 'at their maximum positive value
  • the wave S- must be at its maximum positive value. Consequently a sinusoidally amplitude modulated wave cannot be produced synthetically from three sinusoidal waves unless the following conditions are met.
  • the amplitudes of the side waves must be equal and not more than half the carrier wave.
  • the difference between the frequencies of the carrier wave and the upper side frequency must be exactly the same as the difference 'between the carrier frequency and the lower side frequency.
  • the envelope shown in Fig. 1 is that of composite wave made up of three waves suitably related to produce a sine modulated wave in accordance with the above rules.
  • the envelope shown in Fig. 2 is that which would be produced, if, for example, the upper side wave were altered in phase by 180 from that which would be proper in conjunction with the other constituents to produce the sine modulated form posite form shown in Fig. 1 is an audio modulated form of 1,000 cycle modulation, then a non-oscillating detector operated by a voltage of such wave form will produce chiefly a 1,000 cycle tone, whereas if actuated by a wave as shown in Fig. 2, it will produce substantially a 2,000 cycle tone, or if by a wave as shown in Fig. 3, a resultant of both 1,000 cycle and 2,000 cycle tones.
  • three audio signals result.
  • the first is produced by the beat action between the carrier and the upper side frequency.
  • the second is produced by the beat action between the carrier and the lower side frequency.
  • the third is produced by the beat action between the upper and the lower side frequencies.
  • the resultant 2,000 cycle current is the same, whether the form of envelope transmitted is that of Fig. 1, Fig. 2, or Fig. 3, since it arises from the beat action between the two side waves.
  • the net 1,000 cycle current produced is the same, whether the form of envelope transmitted is that of Fig. 1, Fig. 2, or Fig. 3, since it arises from the beat action between the two side waves.
  • cycle detected currents, due to the carrier and the individual side frequency constituents are related as to phase.
  • they In the case they are in the phase relationship which would give the envelope as indicated in Fig. 1, they give the maximum net value.
  • they are in such phase relation as to give the form of envelope shown in Fig. 2 they are in phase opposition and give minimum net value, and in the case they are in such phase relation as to give the form of envelope shown in Fig. 3, they are in phase quadrature to give an intermediate value.
  • the common problem of transmitters constructed in accordance with this invention is to produce three or more waves, related in frequency and amplitude and to control the phase of one or more of the constituent waves.
  • the upper and lower side frequencies are to be replaced by upper and lower side bands, and that one band can be operated upon as a group to give 180 phase reversal to all of the constituent frequencies of the group.
  • a common feature of the receiver for cooperation with such a transmitter is the selective tuning circuits by which the energy of the carrier and of one side band may be directly or indirectly diverted to one detector, and energy of the carrier and of the other side band may be diverted to another detector. By these circuits the two detected currents can be separated.
  • the ordinary type tuner however, with, but one detector, cannot segregate out the constituent waves and the constituent currents. Thus, if a wave, the envelope of which is represented in Fig.
  • Fig. 4 shows the envelope of the composite wave, composed of half the energy of the carrier and all of the energy of the lower side frequency of the composite wave, the envelope of which is shown in Fig. 2, and Fig. 5 shows the envelope of the composite wave composed of half the energyof the carrier and all of the energy of the upper side frequency of the same wave.
  • the difference between the carrier frequency and the side frequency will be a high frequency, say of the order of 20,000 cycles.
  • the transmitter arrangement for producing the composite waves in case the ratio of the carrier frequency to difference frequency is not too high, for example is shown in Fig. 6.
  • the difference frequency between the carrier frequency and the side frequencies is produced and determined by the frequency of the tube 1 and its associated circuits.
  • the frequency of the oscillation circuits is determined principally by the values of the inductances 6 and '7 and the condenser 8.
  • the carrier frequency is produced and its-frequency determined by the thermionic device 4 and its associated circuits, the frequency of the oscillations produced being principally determined by the value of the inductance 9 and the capacity 10.
  • the method of and circuit for producing these oscillations is well known in the art and need not be described here in detail.
  • Tubes 2 and 3 are high frequency amplifiers.
  • the plate power for these amplifiers is supplied in part by the battery 11 and in part by the voltage developed across the inductances 6 and '7 of the difference frequency oscillator circuit.
  • the grid circuits of the tubes 2 and 3 are actuated in phase by their parallel coupling to the high frequency circuit of tube 4. In consequence high frequency modulated currents appear in the plate circuits of tubes 2 and 3.
  • the modulation thus caused will be nearly sinusoidal if the proper relation exists between the direct voltage and the alternating low frequency voltage. Moreover, the modulations will be out of phase with the result, which can readily be shown that with a symmetrical arrangement, the carrier currents are in phase but the side frequencies are out of phase in the two plate circuits. This is indicated by the arrows C, 8+, and S in each plate circuit which show the instantaneous directions of carrier and side frequency currents.
  • the coupling coil 16 is substantially free of currents of the side frequencies so that a pure carrier frequency current isdeveloped in the tuned circuit 17. Furthermore, due to the phase difference of the side frequencies in coils 12 and 14, a reversed coupling winding used on one side will cause the carrier I frequency to .be substantially balanced out with respect to circuit 18, whereas it will cause the frequency desired to be accepted. This circuit need be sharp enough only to discriminate against the lower side band frequencies. Similarly, the carrier frequency is substantially balanced out from circuit 19 which would be tuned only to discriminate against the upper side band.
  • This process therefore, provides a means for separating out the three constituent frequencies arising by modulation of the carrier by the difference frequency.
  • the three constituent frequencies are combined in the grid circuit of the tube 5 by means of the resistance couplings 22, 23, 24, and 25 and means are provided by switches 20 and 21' for reversing the phase of either side frequency current for the purposes of keying.
  • the tube 5 is a radio frequency power amplifier tube delivering its output plate power into an antenna 26 or any other appropriate radiating system.
  • a composite wave form may be radiated from the antenna, the envelope of which wave is as shown in either Fig. 1 or 2 depending upon the throw of the reversing switches.
  • the condition of the current in the antenna may be examined for purposes of making adjustment of the coils and condensers, and for monitory purposes by means of an aperiodic detector circuit including the tube 28 and its associated circuits.
  • the tube 28 is preferably of the three electrode type and hasits grid connected through the resistance 30 and battery 29 to the plate, in order to give it very nearly a straight line rectification characteristic.
  • radio voltage is induced upon the tube circuit'through the coil 27, there will appear in the coil 31 a direct current and also a current of the frequency determined by the envelope of the composite wave being radiated by the antenna 26.
  • This current may be investigated by the tuned circuit comprising the coil 32, the meter 33, condensers 34 and 35, and the switch 36.
  • a receiver may be employed as shown in Fig. 7. This comprises a receiving antenna or other receiving system 37, a radio frequency amplifier 38, carrying in its plate circuit a pair of coils 39 and 40.
  • the wave form of the plate circuit of the amplifier tube will be reproduced the wave form similar to that radiated by the transmitter antenna, say of Fig. 2 when in signalling condition.
  • coupled circuit systems 41 and 42, associated with detector tube 45, and coupled circuits 43 and 44, associated with detector tube 46 the energy delivered from the plate circuit is divided, with half of the carrier and all of the lower side frequency energy diverted to detector 45, and half of the carrier and all of the higher side frequency energy diverted to detector 46.
  • the wave forms of envelopes across grids of detectors 45 and 46 are
  • the detected currents in the plate circuits will also be out of phase.
  • the output detected currents are to be combined by a differential transformer, with windings 4'7 and 48 differently related than 49 and 50.
  • the opposingly phased currents in plate circuits of tubes 45 and 46 will produce an additive effect in the tuned system 48, 50, 51, and 52 which is tuned to the difference frequency employed.
  • the current of difference frequency then may be detected by means of a separate heterodyne oscillator 53, and detector 54, and indicated by telephones 55.
  • Amplifiers may be inserted wherever desired for building up the difference frequency which may be of audio frequency tone. It is understood, of course, that in case the difference frequency is of audio frequency, no second detection will be required.
  • the side frequencies may be so close to the carrier wave that it is not feasible to separate them out by filtering.
  • the upper 5 The transmitter this will increase the phase of modulation with respect to one side frequency by 90, but de-, crease the phase of modulation with respect to the other side frequency by 90, giving a total phase displacement by the two channels of 180.
  • a transmitter for voice modulation in accord- .ance with this plan may be constructed as indicated in Fig. 8.
  • tube 56 and its associated circuits, particularly the circuit 5'1 produce and determine the frequency of the carrier frequency oscillations.
  • the output of this tube is capacitively coupled by the condenser 58 to a phase shifting circuit, comprising resistance 59 and coil 60 in series, paralleled by resistance 61, condenser 62 and coil 63 in series. Constants of these impedances are so chosen that the phase of the current in coil 60 differs from that in coil 63 by 90.
  • Coils 60 and 63 are the primaries of two transformers, the secondaries of which are coils 64 and 65 respectively.
  • the coil 64 supplies power for exciting the grid circuit of tubes 66 and 67, which in conjunction with other apparatus produces the radiated side band energy
  • coil 65 supplies power to radio amplifier tube 68 which in conjunction with other apparatus amplifies and radiates the carrier frequency energy.
  • Tubes 69 and 70 are push-pull modulators of the plate modulation type, arranged in a balanced manner, with both grids actuated from a common speech or other audio frequency source, as indicated, by the microphone circuit, 71, 72.
  • the grid of the tube 69 becomes most positive when the grid of tube '70 becomes most negative, and consequently the speech or other audio power is maximum for tube 66 when it is minimum for tube 6'7.
  • the output circuits of these tubes have opposite couplings, 73 and '74, to the common output circuit. 1
  • circuit 75-76 tuned to a frequency intermediate between the two side bands, has currents of only .the side band frequencies and no carrier frequency current.
  • the voltage due to the side frequency currents in coil '75 supplies the grid of the radio frequency amplifier 80, and the amplified signals are impressed through coupling 82 upon the antenna circuit 84.
  • the voltage due to the carrier frequency current in coil 78 is impressed upon the grid of the amplifier tube 81, and the amplified signals are impressed upon the antenna circuit through coupling 83.
  • the antenna current of 84 has the same components and is the same as would have been produced by the usualtype modulation, except that the phase of the carrier has been changed by 90.
  • the effect of this alteration of carrier is precisely the same as if the phase of one of the side bands of the ordinarily modulated signal had been altered by 180, or completely reversed.
  • this type of transmission has the especial property of producing little effect upon ordinary type receivers, because the detected currents produced by the carrier and one side band are neutralized by the detected currents produced by the carrier and the other side band.
  • the noise produced by beating between side bands themselves is small and of poor quality, and often unintelligible.
  • a receiver for reception of signals produced by the transmitter of-Fig. 8 is shown in Fig. 9.
  • This receiver is of the superheterodyne type, employing two detectors in the intermediate frequency.
  • This circuit is preferred for audio modulated signals, since it permits the reconstruction of the audio wave by circuits of a comparatively low frequency and by fixed filter systems, rather than by variable high frquency circuits as shown in the receiver of Fig. 7. It is to be understood that this receiver will receive the signals trans mitted by the transmitter of Fig. 6.
  • the incoming signals are picked up and tuned in by circuit 86 and combined on the input side of the first detector 88 with a local heterodyne frequency supplied by the oscillator 8'7.
  • a local heterodyne frequency supplied by the oscillator 8'7.
  • This intermediate frequency of say 30 kc. is modulated with the side bands in the same relation as they exist in the incoming signal, so that the result of first detection is merely to reduce the frequency of the modulated signals without changing their general nature.
  • the energy of this reduced frequency modulated wave is segregated out by means of filters 89 and 90.
  • the method of radio transmission and reception which comprises producing and transmitting a complex wave form compounded of a 150 carrier and two side bands, sending a signal by varying the phase of one of the three constituents, from that which is necessary in conjunction with the others to produce a simple modulated wave form, receiving and independently detecting the two side bands and combining the resultant frequencies in the proper phase relationship to reproduce the original modulating wave.
  • the method of radio transmission and reception which includes producing a carrier frequency, producing an audio frequency to be transmitted, modulating said carrier frequency by said audio frequency, sending a message by altering the phase of one of the three components thus produced to cause the two side bands to be in opposition, radiating the three constituent frequencies thus altered, receiving and independently detecting the two side bands and combining the resultant frequencies in the proper phase relationship to reproduce the original modulating wave.
  • the method of radio transmission and reception which includes producing a carrier frequency, modulating a portion of said generated carrier frequency by an audio frequency to be transmitted, suppressing the carrier frequency from the resultant of said modulation, transmitting the side bands produced by said modulation, independently altering the phase of another portion of said carrier frequency as generated and transmitting it so that the transmitted side bands taken in conjunction with the transmitted carrier frequency are in opposition, receiving and independently detecting the two side bands and combining the resultant frequencies in the proper phase relationship to reproduce the original modulating Wave.
  • Apparatus for the transmission and reception of radiant energy which comprises means 3 for producing a carrier frequency, means for producing an audio frequency, push-pull means for modulating said carrier frequency by said audio frequency and eliminating from the output thereof said carrier frequency, means for radiating the side bands produced by said modulation, means for altering the phase of the carrier frequency 90 electrical degrees, means for radiating the carrier frequency, the phase of which has been thus altered, means for receiving the said transmissions including a heterodyne means for detecting the incoming energy, filter means for separating the side components caused by said first detection, means for independently detecting each of said side components and means for combining the detected audio frequency in the proper phase relationship.
  • Means for the transmission and reception of radiant energy which comprises means for modulating a carrier frequencyby an audio frequency, and signaling means for altering one of the three constituents produced by said modulation from that which is necessary in conjunction with others to produce a simple modulated wave, means for transmitting the three frequencies thus produced, means for independently detecting part of the carrier frequency energy and reach of the side band frequency energies, and means for combining the energy thus detected in the proper phase relationship to reproduce the modulating frequency.
  • Means for the transmission and reception of radiant energy which comprises means for modulating a carrier frequency, signaling means for v said transmitter.
  • Means for the transmission and reception of radiant energy which ⁇ comprises signaling means for altering one of the three constituents of a modulated carrier frequency transmission from that which is necessary in conjunction with the others to produce a simple modulated wave form to send a message and means for receiving the transmission thus produced comprising means for diverting part of the carrier energy and one side bandto one detector and part of the carrier frequency and the other side band to the other detector, means for combining the output energy of the two detectors in such a way that the detected energy due tothe signal will be additive but detected energies due to the stray disturbances will be subtractive.
  • a telegraphic signalling system comprising, means for producing a carrier and two related side bands, means including a key circuit for changing the phase ofsat least one side band with respect to the other for sending code messages in accordance with said changes, means for receiving said radiations comprising a split channel receiver, each channel thereof including detecting means, one of said detecting means being operated by the carrier and one side band and v the other detecting means being operated by the carrier and the other side band, a combining circuit connected to the outputs of both channels in such-a way that the current flowing in said combining circuit varies in accordance with said changes in phase caused by said key circuit at J OHN HAYS HAMIWOND. JR.

Landscapes

  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Transmitters (AREA)
US364105A 1929-05-18 1929-05-18 Side band reversal transmission system Expired - Lifetime US1935776A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
US364105A US1935776A (en) 1929-05-18 1929-05-18 Side band reversal transmission system
GB3224429A GB343538A (en) 1929-05-18 1929-10-23 Improvements in or relating to a method of and apparatus for wireless signalling
FR684214D FR684214A (fr) 1929-05-18 1929-10-30 Perfectionnement aux procédés de transmission de signaux, de paroles, d'images, etc.
US580520A US1976393A (en) 1929-05-18 1931-12-12 Side band reversal transmission system

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
US364105A US1935776A (en) 1929-05-18 1929-05-18 Side band reversal transmission system
GB3224429A GB343538A (en) 1929-05-18 1929-10-23 Improvements in or relating to a method of and apparatus for wireless signalling
US580520A US1976393A (en) 1929-05-18 1931-12-12 Side band reversal transmission system

Publications (1)

Publication Number Publication Date
US1935776A true US1935776A (en) 1933-11-21

Family

ID=27259035

Family Applications (2)

Application Number Title Priority Date Filing Date
US364105A Expired - Lifetime US1935776A (en) 1929-05-18 1929-05-18 Side band reversal transmission system
US580520A Expired - Lifetime US1976393A (en) 1929-05-18 1931-12-12 Side band reversal transmission system

Family Applications After (1)

Application Number Title Priority Date Filing Date
US580520A Expired - Lifetime US1976393A (en) 1929-05-18 1931-12-12 Side band reversal transmission system

Country Status (2)

Country Link
US (2) US1935776A (fr)
FR (1) FR684214A (fr)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2429787A (en) * 1943-04-24 1947-10-28 Standard Telephones Cables Ltd Duplicate transmission
US2645710A (en) * 1948-03-12 1953-07-14 Hartz Julius Radio transmission and carrier wave modulation
US3114106A (en) * 1960-11-23 1963-12-10 Mcmauus Robert Paul Frequency diversity system
US3308466A (en) * 1963-09-13 1967-03-07 Benjamin John Receivers for an aircraft landing system
US3353099A (en) * 1963-08-16 1967-11-14 Tokyo Shibaura Electric Co Double-sideband communication system
US3508154A (en) * 1967-02-20 1970-04-21 David W Kermode Means for suppressing interference in radio circuits
US4034402A (en) * 1974-07-01 1977-07-05 Hughes Aircraft Company Video scrambling system

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR957756A (fr) * 1944-07-21 1950-02-25
US2836657A (en) * 1944-11-20 1958-05-27 Gen Electric Secrecy communication system

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2429787A (en) * 1943-04-24 1947-10-28 Standard Telephones Cables Ltd Duplicate transmission
US2645710A (en) * 1948-03-12 1953-07-14 Hartz Julius Radio transmission and carrier wave modulation
US3114106A (en) * 1960-11-23 1963-12-10 Mcmauus Robert Paul Frequency diversity system
US3353099A (en) * 1963-08-16 1967-11-14 Tokyo Shibaura Electric Co Double-sideband communication system
US3308466A (en) * 1963-09-13 1967-03-07 Benjamin John Receivers for an aircraft landing system
US3508154A (en) * 1967-02-20 1970-04-21 David W Kermode Means for suppressing interference in radio circuits
US4034402A (en) * 1974-07-01 1977-07-05 Hughes Aircraft Company Video scrambling system

Also Published As

Publication number Publication date
US1976393A (en) 1934-10-09
FR684214A (fr) 1930-06-23

Similar Documents

Publication Publication Date Title
US2269594A (en) Modulation of wire and radio transmission by frequency variation
US1794932A (en) Frequency modulation
US2341649A (en) Frequency control
US1935776A (en) Side band reversal transmission system
US2410983A (en) Discriminator-rectifier circuit
US2044745A (en) Receiving circuits
US2303493A (en) Diversity signaling system
US2288575A (en) Frequency modulation
US1941068A (en) Radiosignaling
US2104012A (en) Multiplex radio signaling system
US2288802A (en) Signaling system
US2272840A (en) Selectivity by phase quadrature method
US2081577A (en) Phase modulation
US1816579A (en) Radio communication system
US2186146A (en) Side band suppression system
US1807510A (en) Silent wave radio transmission system
US1758940A (en) Means for separating undesired from desired electric currents
US2404062A (en) Selectivity by phase quadrature using triple selectivity circuits
US1420055A (en) Selective receiving system
US2280569A (en) Frequency modulation receiver
US2123221A (en) Radio circuit for channel reception
US2118161A (en) Receiving system for frequency modulated waves
US2413348A (en) Signaling system
US1838762A (en) System and apparatus for secret radio communication
US1958954A (en) High frequency transmission