US2471418A - Interference reducing radio impulse receiver - Google Patents

Interference reducing radio impulse receiver Download PDF

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Publication number
US2471418A
US2471418A US457786A US45778642A US2471418A US 2471418 A US2471418 A US 2471418A US 457786 A US457786 A US 457786A US 45778642 A US45778642 A US 45778642A US 2471418 A US2471418 A US 2471418A
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United States
Prior art keywords
wave
signal
frequency
noise
phase
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Expired - Lifetime
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US457786A
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English (en)
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Earp Charles William
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International Standard Electric Corp
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International Standard Electric Corp
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Publication date
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    • 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
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S1/00—Beacons or beacon systems transmitting signals having a characteristic or characteristics capable of being detected by non-directional receivers and defining directions, positions, or position lines fixed relatively to the beacon transmitters; Receivers co-operating therewith
    • G01S1/02—Beacons or beacon systems transmitting signals having a characteristic or characteristics capable of being detected by non-directional receivers and defining directions, positions, or position lines fixed relatively to the beacon transmitters; Receivers co-operating therewith using radio waves
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/02—Systems using reflection of radio waves, e.g. primary radar systems; Analogous systems
    • G01S13/06—Systems determining position data of a target
    • G01S13/08—Systems for measuring distance only
    • G01S13/32—Systems for measuring distance only using transmission of continuous waves, whether amplitude-, frequency-, or phase-modulated, or unmodulated
    • G01S13/34—Systems for measuring distance only using transmission of continuous waves, whether amplitude-, frequency-, or phase-modulated, or unmodulated using transmission of continuous, frequency-modulated waves while heterodyning the received signal, or a signal derived therefrom, with a locally-generated signal related to the contemporaneously transmitted signal
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
    • G01S7/28—Details of pulse systems
    • G01S7/285—Receivers
    • G01S7/292—Extracting wanted echo-signals
    • G01S7/2921—Extracting wanted echo-signals based on data belonging to one radar period
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
    • G01S7/28—Details of pulse systems
    • G01S7/285—Receivers
    • G01S7/292—Extracting wanted echo-signals
    • G01S7/2923—Extracting wanted echo-signals based on data belonging to a number of consecutive radar periods
    • G01S7/2926—Extracting wanted echo-signals based on data belonging to a number of consecutive radar periods by integration
    • G—PHYSICS
    • G06—COMPUTING OR CALCULATING; COUNTING
    • G06G—ANALOGUE COMPUTERS
    • G06G7/00—Devices in which the computing operation is performed by varying electric or magnetic quantities
    • G06G7/12—Arrangements for performing computing operations, e.g. operational amplifiers
    • G06G7/19—Arrangements for performing computing operations, e.g. operational amplifiers for forming integrals of products, e.g. Fourier integrals, Laplace integrals, correlation integrals; for analysis or synthesis of functions using orthogonal functions
    • G06G7/1928—Arrangements for performing computing operations, e.g. operational amplifiers for forming integrals of products, e.g. Fourier integrals, Laplace integrals, correlation integrals; for analysis or synthesis of functions using orthogonal functions for forming correlation integrals; for forming convolution integrals
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03D—DEMODULATION OR TRANSFERENCE OF MODULATION FROM ONE CARRIER TO ANOTHER
    • H03D1/00—Demodulation of amplitude-modulated oscillations
    • H03D1/08—Demodulation of amplitude-modulated oscillations by means of non-linear two-pole elements
    • H03D1/10—Demodulation of amplitude-modulated oscillations by means of non-linear two-pole elements of diodes
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03K—PULSE TECHNIQUE
    • H03K9/00—Demodulating pulses which have been modulated with a continuously-variable signal

Definitions

  • a wave modulated such pulses are transmitted at a known rate of e by a Signal Wave-form Which iS Substantially re- 1,00o per second, for example, whereby the repetitive at a predetermined frequency.
  • the signal iiected wave from an obstacle also consists o! a Wave and a locally-derived Wave f th Same fretrain of pulses of the known periodicity or 1,000 queney and phase and preferably of the same per second.
  • a transmitted wave is varied cyclically in detector 0r balanced modulaturfrequency, at, for example 60 cycles per Secchi
  • the reflected wave from the obstacle is used to e in a System for deniodulation of signal Waves 0f interact with a portion of the transmitted wave l5 the type reieri'ed'to above the signal Wave is eli* by detecting them together, when the resuitent plied i0 e mixlng device er modulator to which is wave is, in general, of a complex nature, but is re..
  • an object of the present invention is to provide vention in e' system for demodulatlOn 0f Signal arrangements for the detection of signals sub- Waves of tile type referred to, the signal-medustantially repetitive at a predetermined frequency lated Wave 'is fed over two Paths t0 a modulator, which will discriminate against all noise which one oi ⁇ both of such Paths including a further does not conform to the characteristic envelope or modulator for combining tile signal mOdulated phase of the signal.
  • the comparison wave is obtained l by known means.
  • the timing of the wave is achieved by the phase control in a network PS of a sine-wave xof pulse periodicity generated by a source S. Amplitude limiting of this wave by a limiter L produces a square wave form.
  • Subjection to a high-pass lter F produces a ⁇ series of positive and negative pulses, which are applied to a half-wave rectier R leaving positive D. C. pulses of odicity, and timing. These pulses are passed through a transformer Tl or any other high-pass iilter, whichremoves the D. C. component, but
  • L. P. is a D. C. and low-A pass ter connected to the output of the diilerential detector D andlters out the unwanted spurious modulation of repetition frequency.
  • the directcurrent component of the output from the differential detector D is due only to identical frequency components in the two inputs, the value and sign depending upon the relative phase of the two components.
  • the total D. C. output is proportional to ei-l-ez-i-ea-I-etc.
  • Fig. 1B shows the equivalent circuit-for the frequency-sweep equipment. 'I'he signal wave and the comparison wave are applied to a differential detector as before.
  • the practical benefit is not so great, owing to the fact that the signal envelope is not so well dened, and that some of the noise is not completely random in form. If, for example, the typical signal envelope is derived from amplitude modulation caused by selective high frequency circuits, then the rectified noise tends to be synchronous with the transmitter frequency. It will be described later, how this disadvantage may be entirely eliminated.
  • Fig. lB the modulating wave from a modulator M is applied to the transmitter T to frequency modulate a carrier wave and a portion of the output T is applied to a first detector Det I in the receiver together with the received waves after reflection fromthe obstacle giving the difference between the received direct and reiiected waves.
  • Ll is an intermediate frequency amplier and Det 2 a second detector. 'Ihe Signal the correct shape, periwave output is from the secondary of the transformer T.
  • the comparison wave is derived from the modulating wav yafter passing if desired through a shaping network N.
  • the signal wave and the comparison wave are applied to a differential detector as in Fig. 1A.
  • the signal wave and the comparison wave interact to produce a direct cur- ⁇ lponents of the wave being rent output. If an alternating current output is desired, this may be easily achieved by the system shown in Fig. 2.
  • the comparison wave is modulated by a source S of frequency F in modulator M1, and the upper and/or lower sidebands of F are passed to modulator Mz -to demodulate the signal wave.
  • the ⁇ output from M2 is and bears a constant ⁇ phase relationship to the original supply at frequency F.
  • Output due to noise currents is also at frequency F, but this is composed of components which are random in phase.
  • advantage must be taken of the fact that the phase of the noise wave is random compared with the phase of the signal wave before detection. Unfortunately, both in pulse systems and frequency ysweep systems, the phase of the received wave changes rapidly according to the position of the obstacle.
  • the obstacle movesone quarter of a wavelength nearer equal to onel (or an exact multiple) period ofl repetition of the signal.
  • 'I'his delayed wave may now be utilised as the "comparison wave for demodulation of the waves in the non-delayed path in the balanced detector D.
  • the method was used for the demodulation of a single carrier wave, so that the delay network ⁇ was arranged to be a function of the band width of the transmission circuits.
  • the delay network ⁇ was arranged to be a function of the band width of the transmission circuits.
  • Such a repetitionv wave may, of course, be subjected to a Fourier analysis, when the various components will be In ⁇ at frequency F,
  • the delay network produces a linear phase distortion of the signals, this distortion being equivalent to a 5' phase rotation of 2r radians per f cycles of band width.
  • the signal wave may be represented as:
  • Noise components of indeterminate phase and frequency which can be written as EN(Sin ivi-P95) After subjecting this wr ve to a delay of f seconds, the resulting signal currents, which are rotated in phase by exact: multiples of 21r, are mathematically unchanged The noise compo- 25 nents, however, must be written down as (1) Signa1 components beating with equivalent signal components.
  • EMN2 cos 1p1
  • p1 is random, so that addition of the various components is random in amplitude and sense.
  • the total output may, of course, be zero, and is, in fact zero for the case of uniformly distributed noise over a frequency band of any multiple of f cycles, over which band p1 rotates by an exact multiple of 21r radians.
  • N1 corresponds to those particular values 75 of N which are on frequencies identical to signal frequencies.
  • the D. C. component of this series As in group 2, the various components are not all of the same sign, because both a and may be of any value. The summation Vof noise from this cause is therefore inefilcient, and may result in zero output.
  • the received wave is composed of frequency components which are exact multiples of frequency f. This assumption is, however, not necessary, the fundamental requirement for the signal being that it is composed of a multiplicity of frequency components separated by f cycles, or
  • Fig. 4 the signal-modulated wave source feeds two separate paths tothe demodulator M2 as before, and a delay network DN is inserted in one path (either path is satisfactory) as before.
  • the modulator M1 is inserted, in which the signal-modulated wave is modulated by an oscillator S at frequency F cycles.
  • a nlter F (which may also be the delay network) Yselects one of the sidebands of F produced by the signal-modulated wave.
  • the two inputs to the demodulator are now similar to those of Fig. 3, except that in the lower path all the components of the signal and noise have been raised (or lowered) in frequency by an amount F cycles.
  • the output is now selected at frequency F by lter FI. 'I'his A. C. output cannot be cancelled by a slight detuning of the signal modulated wave frequency, this detuning of the wave now only causing a phase rotation of vthe output with respect to the oscillator S. If, for example, the mean frequency of the signal-modulated wave is raised by f cycles, the phase of the output rotates through 21r radians, owing to the relative phase shift of the two paths caused by the delay network.
  • a second modulator similar to M1, may also be included in the upper path.
  • the iilter'Fl will have a mean pass frequency equal to the sum or difference frequency of the modulating oscillator S and the similar modulating oscillator of the upper path.
  • the D. C. component must be selected by a low-pass filter.
  • the bandwidth of these filters must depend upon the speed of indication of the signal required, this'being designed, for example,
  • System for the demodulation of a carrier wave present inthe form of the conveyance tion frequency and 'source is energized from further Acomprising ⁇ means for adjusting the pulsesoccurring at a given rate of repetition, said pulses being modulated in respect to one of their characteristics for to said pulses, a source for providing al comparison wave having substantially the same repeticarrier wave.
  • a second detector circuit for said signal conveying pulses, means for differentially of intelligence. comprising meansA for detecting the received carrier wave in respect phase as the pulses of said.
  • said second detector comprises an input transformer and a rectiiier in each of the secondary leads thereof, and said means for di'erentially modulating includes an input transformer and means for -balanced application of said comparison Wave pulses to said second detector.
  • V second detector and said modulating means comprise means for obtaining the arithmetical given repetitionfre- UNITED STATES' PA'I'EN'rs Number Name Datel c 1,343,308 Carson June 16, 1920 A2,036,022 Conklin- Mar. 31, 1938 2,040,221 Tubbs May 12 1936 2,067,021 Roberts Jan. 5,1937 2,108,117 Gardere et al. v.- Feb. 15,1938 2,159,493 Wright May 23, 1939 2,171,154 Wright-; Aug. 29. 1939 2,183,714 v Franke et al. Dec. 19, 1939 2,225,524 Percival Dec. 17. 1940 2,227,598 Lyman et al Jan.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • General Physics & Mathematics (AREA)
  • Mathematical Physics (AREA)
  • Theoretical Computer Science (AREA)
  • Software Systems (AREA)
  • Computer Hardware Design (AREA)
  • Nonlinear Science (AREA)
  • Power Engineering (AREA)
  • Signal Processing (AREA)
  • Radar Systems Or Details Thereof (AREA)
  • Measurement Of Velocity Or Position Using Acoustic Or Ultrasonic Waves (AREA)
US457786A 1941-01-17 1942-09-09 Interference reducing radio impulse receiver Expired - Lifetime US2471418A (en)

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Application Number Priority Date Filing Date Title
GB286896X 1941-01-17

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CH (1) CH286896A (en))
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GB (1) GB586115A (en))

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2718638A (en) * 1950-01-20 1955-09-20 Itt Signal correlation radio receiver
US2786132A (en) * 1946-11-21 1957-03-19 Rines Robert Harvey Power transmission
US2790898A (en) * 1953-05-04 1957-04-30 Bady Isidore Weak signal detector using synchronously switched rectifier bridge
US2802167A (en) * 1952-04-15 1957-08-06 Gen Electric Signal voltage amplitude limiter
US2914762A (en) * 1954-02-24 1959-11-24 Raytheon Co Dual channel noise coherence reducers
US2937273A (en) * 1957-10-31 1960-05-17 Gen Dynamics Corp Detectors
DE1237187B (de) * 1960-10-10 1967-03-23 Csf Impulsradarempfaenger mit zwei Kanaelen zur Beseitigung von unerwuenschten Empfangssignalen
US3624652A (en) * 1946-01-16 1971-11-30 Us Navy Pulse generation system

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2941202A (en) * 1951-08-04 1960-06-14 Sylvania Electric Prod Modified cross-correlation radio system and method
US2718546A (en) * 1952-11-26 1955-09-20 Motorola Inc Phase detector
USRE34004E (en) * 1953-03-30 1992-07-21 Itt Corporation Secure single sideband communication system using modulated noise subcarrier
US4176316A (en) 1953-03-30 1979-11-27 International Telephone & Telegraph Corp. Secure single sideband communication system using modulated noise subcarrier
US3112452A (en) * 1959-12-28 1963-11-26 Gen Electric Signal processing arrangement with filters in plural channels minimizing undesirableinterference to narrow and wide pass bands

Citations (19)

* Cited by examiner, † Cited by third party
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US1343308A (en) * 1916-09-05 1920-06-15 American Telephone & Telegraph Duplex translating-circuits
US2036022A (en) * 1934-01-26 1936-03-31 Rca Corp Method of and means for receiving signals
US2040221A (en) * 1933-01-04 1936-05-12 Frank C Talmadge Electrical signaling system
US2067021A (en) * 1929-12-12 1937-01-05 Rca Corp Means for converting electrical energy into acoustical energy
US2108117A (en) * 1935-06-06 1938-02-15 Int Standard Electric Corp Signaling system
US2159493A (en) * 1935-03-27 1939-05-23 Rca Corp Modulated carrier wave receiver
US2171154A (en) * 1934-06-02 1939-08-29 Rca Corp Radio receiver
US2183714A (en) * 1937-05-13 1939-12-19 Telefunken Gmbh Interference eliminator
US2225524A (en) * 1937-11-16 1940-12-17 Emi Ltd Directional wireless system employing pulses
US2227598A (en) * 1937-07-03 1941-01-07 Sperry Gyroscope Co Inc Radio absolute altimeter
US2231704A (en) * 1939-03-04 1941-02-11 Hazeltine Corp Homodyne receiver
US2233384A (en) * 1939-12-28 1941-02-25 Bell Telephone Labor Inc Radio receiver
US2266401A (en) * 1937-06-18 1941-12-16 Int Standard Electric Corp Signaling system
US2268643A (en) * 1939-10-25 1942-01-06 Rca Corp Frequency modulation distance finder
US2350702A (en) * 1940-05-21 1944-06-06 Int Standard Electric Corp System of radio communication
US2398490A (en) * 1944-03-01 1946-04-16 Rca Corp Circuit for removing noise
US2401416A (en) * 1942-09-11 1946-06-04 Rca Corp Amplifier for pulses
US2408079A (en) * 1944-06-19 1946-09-24 Standard Telephones Cables Ltd Pulse discriminator
US2410223A (en) * 1942-03-02 1946-10-29 Phillips Petroleum Co Treatment of hydrocarbons

Patent Citations (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1343308A (en) * 1916-09-05 1920-06-15 American Telephone & Telegraph Duplex translating-circuits
US2067021A (en) * 1929-12-12 1937-01-05 Rca Corp Means for converting electrical energy into acoustical energy
US2040221A (en) * 1933-01-04 1936-05-12 Frank C Talmadge Electrical signaling system
US2036022A (en) * 1934-01-26 1936-03-31 Rca Corp Method of and means for receiving signals
US2171154A (en) * 1934-06-02 1939-08-29 Rca Corp Radio receiver
US2159493A (en) * 1935-03-27 1939-05-23 Rca Corp Modulated carrier wave receiver
US2108117A (en) * 1935-06-06 1938-02-15 Int Standard Electric Corp Signaling system
US2183714A (en) * 1937-05-13 1939-12-19 Telefunken Gmbh Interference eliminator
US2266401A (en) * 1937-06-18 1941-12-16 Int Standard Electric Corp Signaling system
US2227598A (en) * 1937-07-03 1941-01-07 Sperry Gyroscope Co Inc Radio absolute altimeter
US2225524A (en) * 1937-11-16 1940-12-17 Emi Ltd Directional wireless system employing pulses
US2231704A (en) * 1939-03-04 1941-02-11 Hazeltine Corp Homodyne receiver
US2268643A (en) * 1939-10-25 1942-01-06 Rca Corp Frequency modulation distance finder
US2233384A (en) * 1939-12-28 1941-02-25 Bell Telephone Labor Inc Radio receiver
US2350702A (en) * 1940-05-21 1944-06-06 Int Standard Electric Corp System of radio communication
US2410223A (en) * 1942-03-02 1946-10-29 Phillips Petroleum Co Treatment of hydrocarbons
US2401416A (en) * 1942-09-11 1946-06-04 Rca Corp Amplifier for pulses
US2398490A (en) * 1944-03-01 1946-04-16 Rca Corp Circuit for removing noise
US2408079A (en) * 1944-06-19 1946-09-24 Standard Telephones Cables Ltd Pulse discriminator

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3624652A (en) * 1946-01-16 1971-11-30 Us Navy Pulse generation system
US2786132A (en) * 1946-11-21 1957-03-19 Rines Robert Harvey Power transmission
US2718638A (en) * 1950-01-20 1955-09-20 Itt Signal correlation radio receiver
US2802167A (en) * 1952-04-15 1957-08-06 Gen Electric Signal voltage amplitude limiter
US2790898A (en) * 1953-05-04 1957-04-30 Bady Isidore Weak signal detector using synchronously switched rectifier bridge
US2914762A (en) * 1954-02-24 1959-11-24 Raytheon Co Dual channel noise coherence reducers
US2937273A (en) * 1957-10-31 1960-05-17 Gen Dynamics Corp Detectors
DE1237187B (de) * 1960-10-10 1967-03-23 Csf Impulsradarempfaenger mit zwei Kanaelen zur Beseitigung von unerwuenschten Empfangssignalen

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Publication number Publication date
FR69134E (fr) 1958-10-01
FR939300A (fr) 1948-11-09
CH286896A (fr) 1952-11-15
GB586115A (en) 1947-03-07
BE472065A (en))
USRE23440E (en) 1951-12-18

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