US3668568A - Signal processing apparatus - Google Patents

Signal processing apparatus Download PDF

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Publication number
US3668568A
US3668568A US870478A US3668568DA US3668568A US 3668568 A US3668568 A US 3668568A US 870478 A US870478 A US 870478A US 3668568D A US3668568D A US 3668568DA US 3668568 A US3668568 A US 3668568A
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elastic
electric
impulses
wave
waves
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Frederic R Morgenthaler
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CHU ASSOCIATES
CHU ASSOCIATES Inc
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CHU ASSOCIATES
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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/30—Time-delay networks
    • H03H9/40—Frequency dependent delay lines, e.g. dispersive delay lines

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  • This disclosure involves a novel and compact pulse compression filter and the like, employing elastic shear-wave, spin- [56] Reerences Cited wave, longitudinal-wave transduction by means of a timevarying magnetic bias field, providing increased power han- UNITED STATES PATENTS dling capability and greater compression ratios than presentday filters. 3,249,882 5/1966 Stern ..330/56 X 3,353,118 11/1967 Olson et al ..333/30 19 Claims, 1 Drawing Figure OUTPUT IN PUT PATEMTEDJUH s :972
  • the present invention relates to signal-processing apparatu's, being more particularly, though not exclusively, directed to producing controlled frequency-dispersive time delay including time compression, expansion, inversion or other delay of electric impulses preferably of the type involving frequency-modulated impulses, such as so-called chirp pulses and the like useful in radar and similar applications, as described, for example, in'the Proceedings of the'IEEE, Vol. 56, No. 3, March, 1968, pages 273-285.
  • the present invention is primarily directed; it being an object of the invention to provide a new and improved signal-processing apparatus of this character that has vastly increased powerhandling, pulse-compression ratio, and wideband capabilities.
  • a further object is to provide a new and improved time signal-processing filter apparatus of more general utility, also, as well as a novel method or signal processing.
  • An additional object is to provide new and improved signaldelay apparatus.
  • the invention contemplates an electric-impulse signal-processing apparatus having, in combination, an elastic-wave-supporting device, input and output transducer means disposed at the device for respectively coupling electric impulses thereto to generate and propagate elastic waves therein and for transducing such waves into electric output impulses, and means for applying a time-varying energy field to the device during the coupling of said electric impulses into the device by the input transducer means in order to cause different frequencies in said waves to be advanced or delayed in time by different amounts, thereby to introduce time signal-processing into the output impulses.
  • Preferred details are hereinafter set forth.
  • FIGURE is a combined longitudinal section and schematic circuit diagram of a preferred embodiment.
  • microwave elastic waves (phonons)v can. be converted into spin waves (magnons), and vice versa, by means of a spatially uniform but time-varying magnetic bias field in a single crystal yttrium iron garnet (YIG), as described in my article entitled ,Phase-Velocity- Modulated Magnetoelastic Waves" appearing in the Journal of Applied Physics, Vol. 37, No. 8, July 1966, pages 3,326-7.
  • YIG yttrium iron garnet
  • Experiments have verified the theoretical prediction that such conversion occurs at constant wave number and momentum but with variable frequency, energy and power flux.
  • Advantage is taken of this phenomenon, when modified in accordance with the present invention, to provide, among other things, a novel pulse compression or delay filter that is compact, versatile, affords greater compression ratios than conventional filter, and is suitable for wideband microwave radar systems and the like.
  • the filter consists of a single crystal fem'm'agnetic rod (such as YIG) capable of supporting elastic waves and provided with piezoelectric shear and iongitudinal elastic wave transducers deposited respectively on the input and output end regions of the rod.
  • a coil wound around the crystal is used to produce a transient or time-varying magnetic energy field bias. If the bias is a ramp function, turned on after an input electric chirp signal is introduced or coupled to the rod, it can serve to convert each frequency component of the input shear elastic wave, first to a magnetic spin wave and then to a longitudinal elastic wave of relatively fast.
  • the pulse compression factor is increased by a factor that is the ratio of the longitudinal to shear wave velocities V,/V, normally a factor of about 2.
  • Such a filter is flexible because the bias current ramp can be altered to match a variety of chirp input impulses; and it is compact because for input pulses of microsecond duration, the crystal may be about 1 centimeter long.
  • Such a filter is potentially wide band (within the limits of the transducers), moreover, because the linearity of the filter is as good as that of the bias ramp function. In principle, indeed, microsecond to nanosecond compression is possible.
  • the peak bias energy required to filterone such pulse is typically a few millijoules.
  • a preferred version of such a filter is shown in section comprising a sphere of polycrystalline YIG 1, for example, diametrically cored and provided with a high quality single-crystal cylindrical rod 1', as of YIG, disposed within the core.
  • Shear-wave (of the appropriate polarization) and longitudinal-wave electric-to-elastic wave transducers (such as CdS or ZnO) are deposited on the parallel and optically flat end faces at 2 and 4, respectively.
  • a solenoid coil 3 is wound about the sphere 1 such that the number of turns per unit length as projected along the sphere axis is a constant.
  • the entire structure is magnetized to saturation either by a permanent magnet or an electromagnet.
  • the dispersion relation ((0 vs k curve) has the form of a first rising curve, followed by a horizontal plateau, as disclosed in my said article, and then by a continuing or second rising curve.
  • the plateau region can be moved up and down by varying the magnetic field at 5-3, such that, in effect, the spin waves serve as a magnon elevator," elevating the frequency w from the first rising curve to the second curve where the frequency is thus increased, (or, on the removal of the ramp, causing the magnon elevator" to drop back again or reverse).
  • time signal-processing is effected, in accordance with the invention, by both the conversion between the types of elastic waves (through the spin-wave conversion) and by the differences in velocity therebetween.
  • the critical time gradients for longitudinal wave conversion will range linearly with frequency from about 157 oe./p.sec. at 1.85 Gl-iz to 235 oe./p.sec. at 2.77 Gl-lz.
  • the corresponding values of the conversion efficiencies range from 0.324 (-4.89 db) at 1.85 GHz, to 0.444 (-3.53 db) at 2.77 Gl-lz.
  • the average conversion loss for the signal pulse is approximately 4 db.
  • the shear elastic wave transducer 2 should be flat over the frequency range l-l.5 GHz; and the longitudinal transducer 4, over the frequency range l.85 2.77'GHz.
  • a novel and compact pulse compression filter employing elastic shear wave-spin wave/elastic longitudinal wave transduction by means of a time-varying magnetic field bias has been produced.
  • the linearity of the filter is as good as the current ramp function can be made; and the bandwidth as wide as that of the input and output transducers.
  • Sub-microsecond to microsecond input pulses can be accommodated. For 500 MHz. chirp bandwidths, compression into the nanosecond range is attainable. Compression is increased by the factor V,/V, over conventional filters.
  • Another outstanding advantage is the ease and rapidity with which the filter may be matched to various input pulses by merely altering the bias waveform.
  • the peak bias energy required to filter one pulse is typically a few millijoules; and while other ferrimagnetic and similar devices may be used, the single crystal YIG appears to be a most suitable device for these purposes. While the spatial gradient of the magnetic field has been described as uniform, moreover, it may also be varied or nonuniform along the crystal device; and other fields besides magnetic fields may, in certain instances, be employed to create the non-uniform time-varying conversion process.
  • An electric-impulse signal-processing apparatus having, in combination, an elastic-wave-supporting device, input and output transducer means disposed at the device for respectively coupling electric impulses thereto to generate and propagate elastic waves therein and for transducing such waves into electric output impulses, and means for applying a transient time-varying energy field to the device during the coupling of said electric impulses into the device by the input transducer means, and which varies substantially during the transit of an impulse in said device, in order to cause different frequencies in said waves to be advanced or delayed in time by difierent amounts, thereby to introduce time signal-processing into the output impulses.
  • An electric-impulse signal-processing apparatus as claimed in claim 2 and in which means is provided for converting said spin waves to elastic waves for transducing into said electric output impulses.
  • An electric-impulse signal-processing apparatus having, in combination, an elastic-wave-supporting device capable of supporting relatively slow and fast elastic waves, input and output transducer means disposed at the device for respectively coupling electric impulses thereto in order to generate and propagate therein one of the said elastic waves and for transducing the other of said elastic waves into electric output impulses, and means for applying a transient time-varying energy field to the device during the coupling of said electric impulses into the device by the input transducer means, and which varies substantially during the transit of an impulse in said device, in order to cause the said one elastic waves propagating in said device to become converted into the said other elastic waves, thereby to introduce time signal-processing into the output impulses caused both by the conversion from the said one to the said other elastic waves and by the difference in velocity therebetween.
  • An electric-impulse signal-processing apparatus comprising a magnetic crystal including YIG, and a magneticfield-producing means oriented to set up its field at one of a substantially 22.5 and a 25.52 angle with respect to the 100 axis in the respective 100 and 1 l0 planes.
  • a method of changing the transit time of relatively low and high frequency components of elastic impulses that comprises, propagating such impulses in an elastic-wave-supporting medium, and, during the propagating, subjecting the medium to a transient time-varying energy field apart from said impulses which varies substantially during the transit of an impulse in said medium.

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  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Control Of Motors That Do Not Use Commutators (AREA)
  • Radar Systems Or Details Thereof (AREA)
  • Geophysics And Detection Of Objects (AREA)
US870478A 1969-10-06 1969-10-06 Signal processing apparatus Expired - Lifetime US3668568A (en)

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US87047869A 1969-10-06 1969-10-06

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US (1) US3668568A (fr)
JP (1) JPS4942279B1 (fr)
BE (1) BE747570A (fr)
BR (1) BR7019227D0 (fr)
CA (1) CA925964A (fr)
DE (1) DE2045502A1 (fr)
FR (1) FR2065851A5 (fr)
GB (1) GB1262611A (fr)
IL (1) IL33964A (fr)
SE (1) SE357832B (fr)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3753163A (en) * 1971-12-27 1973-08-14 Chu Associates Electromagnetic wave-elastic wave transducer and method
US3753165A (en) * 1971-12-27 1973-08-14 Chu Associates Tunable variable bandwidth magneto-elastic filter and method
US4017751A (en) * 1974-12-17 1977-04-12 Thomson-Csf Elastic volume wave convolution device
US4096461A (en) * 1974-08-23 1978-06-20 U.S. Philips Corporation Magnet system for tunable YIG oscillator and tunable YIG filter
US4758795A (en) * 1986-07-01 1988-07-19 The United States Of America As Represented By The Secretary Of The Navy Microwave pulse compression in dispersive plasmas

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS52576U (fr) * 1975-06-16 1977-01-05
JPS5399748A (en) * 1977-02-10 1978-08-31 Sony Corp Variable delay line

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3249882A (en) * 1962-12-17 1966-05-03 Gen Electric Spin and phonon spin traveling wave parametric amplifiers and spin wave delay lines
US3353118A (en) * 1964-05-19 1967-11-14 Teledyne Inc Magnetostatic wave variable delay apparatus
US3425002A (en) * 1963-11-07 1969-01-28 Shiro Okamura Variable delay device
US3444484A (en) * 1967-04-03 1969-05-13 Raytheon Co Solid state delay line for propagation of microwave frequency energy in spin wave mode

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3249882A (en) * 1962-12-17 1966-05-03 Gen Electric Spin and phonon spin traveling wave parametric amplifiers and spin wave delay lines
US3425002A (en) * 1963-11-07 1969-01-28 Shiro Okamura Variable delay device
US3353118A (en) * 1964-05-19 1967-11-14 Teledyne Inc Magnetostatic wave variable delay apparatus
US3444484A (en) * 1967-04-03 1969-05-13 Raytheon Co Solid state delay line for propagation of microwave frequency energy in spin wave mode

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
Pulse Compression Using X-Band Magnetoelastic Wave in Yig Rods by De Vaart, Proceedings of the IEEE, April 1966, page 1,007 *

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3753163A (en) * 1971-12-27 1973-08-14 Chu Associates Electromagnetic wave-elastic wave transducer and method
US3753165A (en) * 1971-12-27 1973-08-14 Chu Associates Tunable variable bandwidth magneto-elastic filter and method
US4096461A (en) * 1974-08-23 1978-06-20 U.S. Philips Corporation Magnet system for tunable YIG oscillator and tunable YIG filter
US4017751A (en) * 1974-12-17 1977-04-12 Thomson-Csf Elastic volume wave convolution device
US4758795A (en) * 1986-07-01 1988-07-19 The United States Of America As Represented By The Secretary Of The Navy Microwave pulse compression in dispersive plasmas

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Publication number Publication date
SE357832B (fr) 1973-07-09
JPS4942279B1 (fr) 1974-11-14
FR2065851A5 (fr) 1971-08-06
BR7019227D0 (pt) 1973-03-15
GB1262611A (en) 1972-02-02
DE2045502A1 (de) 1971-04-15
BE747570A (fr) 1970-08-31
CA925964A (en) 1973-05-08
IL33964A0 (en) 1970-04-20
IL33964A (en) 1973-08-29

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