US2472531A - Panoramic receiver with pulse narrowing systems - Google Patents

Description

June 7, 1949. J. l. HELLER 2,472,531

PANORAMIC RECEIVER WITH PULSE NARRWING SYSTEMS Filed May 7, 1946 grvue/wto'v kseplz [.Hellez Patented June 7, 1949 PANORAMIC RECEIVERWITHTUUSE NARROWING SYSTEMS Josepha-I. HellennNew-York N. .1 1, assignontto- Panoramic'Radio Corporation NewYork,.N.lY.; a corporation of New .York' Application Maw; 1946, Serial Nb.- 667;847 3 Claims. (Cl. 250.-20 )i This :invention; relates generally topulse narrowing; and esharpening, having particular.v but notvexclusive application to panoramic equip-- ment.

In displaying. pulses. On'i oscilloscopes and the I like, the-vindication providedin response to a peaked? signal possesses an outline determined only in part by the character of the-signal, a

charact'eristic-of-the intermediate frequency amstud-y. r of- J the afollowing detailed descriptiomof at: specific embodiment of zthe invention,whenataken-v inacon-junctiom with the accompanying-drawings, wherein:

Figure-:1 .ais: atblock :circuit diagram-of an emr' bodiment" of any invention and a Fi'glllerz is an iillustratiomof certaintirequency characteristics associated with: thetembodimentof Figure 1, and indicating the characterioftresponses =availabletin-iapparatusvutilizing;myinvention-.

Referring; nowv. to the idrawingaw the enumerat I denotes-r anwantenna for: providing signa1s':-.. toa: thetwide band-/R.-- 1 amplifier 2,-.' the amplified? RrFa signalsr-beinggapplied to a mixer-'3 for-con-- versiomto a.suitab1e.'I. F. frequency; in the mana her well know-n per -.se:-inttheradio art,- by1app1y+ ing-atozthe -mixer. 3 .a signal derivable-from; thee localnosciliator .ot ithe rfrequencyiof: the *locala .os-v

plifienof theepanoramictdevice,sincerthe signal- 2 cillator-illm The-:frequencyrofrtheelocal:oscillatorvr is ifrequency swept during its translation :imthe panoramic zdevicas through the pass band 70f 1a", translating-channel.

It .is ;-desirab1e,;in connection :withpanoramic 4 .is*?sweptr'-.throughi aapredetermined frequency" spectrum by means ofiareactance tube- 5;:towhich may bevsupplied COIItEOlrFDOtGHti-QJS; preferably; 0f: sawtooth character; 'andrprovided. by the sawtooth techniqueimparticuIar; and inoscilloscopedesign oscillator :6".

generally; toprovidewmeans -f0r sharpening; or narrowingii indicated: pulses in order: to enable: discrimination betweerr adjacent pulses,-=to -enab1e-- accurate interpretation oftthe indications and of their location onthewface-of the indicator.

I czprovide meansfor narrowingPulses, in accordance with a novel principle, to=-wit,by'passin'g eachzpulse inparallel through a'pair of IE. channels;-.onexof :which .has .lowv Q and the other: of

which'has high Q,vand detecting the-outputs otthe -"No. 2,381,Q;-issued: August --14; 1945; 1; basis I. .F-.-wchannels impolarityn opposing ;relation', to-

provide ar narrowed pulse; .the rationale of the v method involving-the wellknown property) of; tuned-circuits; that suchrcircuit's ofi'adicallydif Itris 'asfurther'object of my inventionxto provides;

panoramic displays a: providing pulses: which "are narrower (and; sharper *thanr has: hitherto been? the. "case;

Itsiszstill; another object; oimyinventionto @1'0-3 vide. s-for narrowingapulses vby a 2 comparison: me-e The circuit arrangement-above described :in P

detailcis'iolot @and-.- we1-l-.- known perse, in. :thewart relating stow panoramic receiving and analyzing devices;-and. sis intended tow-beexemplary only 30 of vmany; similar devices,- toawhichl my invention may apply. The above described circuit, andtstill.

further rcircuitsvfor -the-:same :purpose; andto which: [my invention. is applicable; have: been: described in the .-U.1-srpatentito wallace et alaa of I an: application:serial No:-402 822,rfiled 31115 5717; 1941, and in the U. S-.:pa-tent1to1Marcel:Wallace: No.2,367,907,:issued-January- 23, 1945, on the basis 1of.:anaapplication:Serial-1No; 420,014, dated 40" November-21, 1941.

The signal: derivedcirom =the-mixer3 may be:- applied to ta pair-of I; F; channels :7 and- 8,: com

nected-a-inwparallelgl the :channel I :being: arranged and adapted: to -have relatively low Q, and the e channel 8vto have'relativelyhi'ghfQ. The outputs:

thod; theepulsesibeingrpassedcin parallelnthrougha a pair ofiresistors Mvandwl5';=the:midpointifi'zof "translating? circuits: having?v radically different:

gains'at the centertandasubstantially similar: gains:

adj aeent the edges of atheir characteristicsi Thez'above' and'still further :objects andadvan-t whichiimaygbe grounded. The algebraic I sum of; the' :IECfifiB'dvVOltflEBS provided :across; each of; theresistorsi band-1 5 is vavailable at the cathodes 1 l 2 *anda. l 3, which: mam-accordingly be. rconneetedi tages not my: invention willzlbecomec clearxiuponzz -="=tol-.the--iverticala platesl 1 of. .a cathode- -ray.,--0sciL- locope l 8, a horizontal plate I 9 of which is grounded, and the other horizontal plate of which may be connected to the sawtooth generator 6 which provides sweep voltage for the indicator 18.

As the local oscillator 6 is swept through its assigned frequency spectrum, signals available in the wide band B. F. amplifier 2 are brought successively to edges of the pass bands of the channels 7 and 8, and then swept through the said pass bands, producing thereby signals of varying amplitude corresponding with the transfer impedance characteristics of the channels and 8, respectively, and which are illustrated at 20 and 2t, respectively, in Figure 2 of the accompanying drawings. The curve 20 represents the characteristic of a heavily loaded tuned circuit, of low Q. and the curve 2! that of a lightly loaded, or high Q tuned circuit.

The signal appearing across the deflection plates 1 I of the indicator l8 has ordinates corresponding with the difference between the ordinates of the curves 2!? and 2|, for each point on the frequency or time axis. The signal 22 may be amplified, if desired, prior to application to the plates ll. Since the above described action takes place for weak as well as for strong signals, small signals are not differentiated against by my novel method of narrowing the visible width of signal indications.

It will be clear that my invention may be applied to double conversion panoramic devices, such as is illustrated in Figure l of Wallace et al., #2381340, referred to supra, by utilized two parallel 2nd I. F. channels, each having a different relative Q. It will further be clear that my invention may be applied to panoramic devices comprising no conversion step, and no I. F. channels, and which may be of the character illustrated in Figures 1 or 4 of the patent to Wallace, No. 2,367,907, referred to supra, by utilizing a pair of video amplifiers in parallel, each having a different relative gain at the center of its pass band and similar gains at the edges of its pass band.

I do not, however, intend to limit my invention to application in any of the above panoramic devices, since it will find application to devices of various character in which panoramic principles are employed, or in which frequenc modulated signals are visually indicated, or in which signals generally are indicated in the face of an oscilloscopic indicator.

Having described various specific embodiments of my invention, I desire to point out that various modifications thereof may be resorted to without departing fro-m the spirit of the invention.

What I claim and. desire to secure by Letters Patent of the United States is:

1. In a panoramic receiving system for analyzing signals occupying a first predetermined frequency spectrum, means for converting said signals to further signals occupying a second predetermined frequency spectrum, said last named means comprising a local oscillator for generating a hetrodyning frequency, means for periodically varying said heterodyning frequency, a first narrow band intermediate frequency tuned channel coupled with said means for converting said signals to translate succeeding selected portions of said second predetermined frequency spectrum in time sequence during periodic variation of said heterodyning frequency, said first intermediate frequency channel having a predetermined high ratio of peak response to response at high energy points of the selectivity characteristic thereof, means comprising a further tuned intermediate frequency channel coupled with said means for converting said signals to translate selected portions of said second predetermined frequency spectrum in time sequence during periodic variation of said heterodyning frequency, said further intermediate frequency channel having a predetermined low ratio of peak response to response at half energy points of the selectivity characteristics thereof, said first and further intermediate frequency channels being tuned to the same center frequency, and having substantially identical responses at a plurality of points below said first mentioned half energy points, means for separately detecting signals translated by said first and further intermediate frequency channels, means for differentially combining the outputs of said means for separately detecting, a cathode ray tube indicator having a cathode ray beam and means for deflecting said cathode ray beam in a first and a second coordinate direction, for controlling said means for deflecting to deflect said cathode ray beam in said first coordinate direction in synchronism with variations of said heterodyning frequency and means responsive to said means for differentially combining for controlling said means for deflecting to deflect said cathode ray beam in said second coordinate direction.

2. A spectrum analyzer for analyzing a band of discrete signals occupying a predetermined wide frequency spectrum, a first relatively narrow band frequency amplifier having a relatively great selectivity, a second relatively narrow band frequency amplifier having a relatively low selectivity, means for applying said band of discrete signals to said first and second amplifiers in parallel, means for periodically and continuously frequency scanning said band of discrete frequencies with respect to said first and second amplifiers, whereby each signal of said band of signals scans periodically through the selectivity characteristics of said first and second amplifiers, means for detecting the amplified output of said first amplifier, means for detecting the amplified output of said second amplifier, means for differentially combining said detected outputs, a visua1 indicator for displaying the frequency content of said band of discrete signals, and means responsive to said means for differentially combining for activating said visua1 indicator to provide a distinctive visual response for each signal of said band of discrete signals.

3. In combination, in a system for analyzing a band of signals distributed within a predetermined frequency spectrum, a local oscillator for providing heterodyning signals, a mixer for converting said frequency spectrum to a further frequency spectrum by combining said signals with said heterodyning signals, means for amplifying a selected portion only of said further frequency spectrum, means for periodically varying the frequency of said local oscillator to vary periodically said selected portion of said further frequency spectrum, said means for amplifying comprising a pair of tuned circuits connected with their inputs in parallel, said tuned circuits having one a high Q and the other a low Q and being both tuned to the same resonant frequency, Q meaning the ratio of reactance to resistance of the tuned circuit at resonant frequency, separate means for detecting the responses of said tuned circuits to signals applied thereto, means for differentially combining said detected responses, and means responsive to said means for differentially com- 'bining for visually plotting said responses for all 5 signals of said band of signals simultaneously against a frequency baseline.

file of this patent:

UNITED STATES PATENTS JOSEPH I. HELLER. Number Name Date 1,622,000 Round Mar. 22, 1927 REFERENCES CITED 5 2,250,132 Parr Jul 22, 1941 2,262,218 Andrews Nov. 11, 1941 The followmg references are of record 1n the 2,381,940 Wallace et a1 Aug. 14 1945

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