Патент USA US2404333код для вставки
July 16, 1946. 2,404,333 - HARRY WHALLEY ' CHARLES WALTER MILLER ATT ORNEYS Patented July 16, 1946 2,404,333 UNITEDy STATES lPATENT OFFICE RADIO REoEIvER Harry Whalley, Darwen, and CharlesV Walter ,Millen Sale, England, _assignors .to Metro politan-Vickers Electrical Company Limited, London, England, a company of `-Great Britain Application December 16, 1943, Serial No. 514,478 l In England August» 8, ‘1941. 1 claim. (c1. 25o-¿20) t ' 1 ` This invention relates >specifically to so-cv'alled f far as possible from the wavebands covered by the receiver. The invention is based on the above consider ations which are given in greater detail in the following statement which includes further con panoramic radio receivers the nature of which was described in “Electronics,” June, 1940 `and wherein, inbrief,._a waveband `or it may be any selected one vof av plurality rof wavebands, is scanned from end. to end by the `automatic vari siderations. ation of a tuning parameter at arate comparable , In general a satisfactory panoramic receiver shouldhave a high sensitivity to enable- the maxi mum number of signals to be observed, b the ’ with. thefrequency 'of .the persistence, of vision, the output or outputs due to any received >radio trans missionsA which’may-v be taking place within the waveband being indicated as resonance or peak components perpendicular to atime base wave selectivity should be high to give adequate disn crimination between adjacent signals, consistent with thetuned circuits being kable to respond at band component on the screen of a cathode ray the rate of time base sweep and of scanning syn tubeî the time base component being provided syn chronously with the scanning such as by means of a saw-toothtype of oscillation generator. Pro vision can-be madewhereby _any selected one of the `,thus indicated transmissions can be tuned into manually and its modulation listened to or recorded or` otherwise indicated, that is to say, 20 the scanningr of _the waveband can be effected solely by hand such as through the turning .of a chronously therewith, cit is desirable at thesame time thatsecond channel interference’should be absent or substantially absent; d the process of scanning should involve the smallest number‘oi tuning parameters as possible; and e tuning can be conveniently carried out by electronicrather than mechanical means. Y „ Regarding a above, this involves high overall gainjwhich isconveniently obtainable by the use . of an ,îampliñer of standard design operated at, . for example, 1.6 Irnc. per second or 465 kc. pe-r sec knob about an associateddial indicating the wave length. In such a panoramic receiver it has been convenient for the purpose _of therapidscanning oiï‘the waveband to‘fffwobble” the'value of cer tain ltuning components -of the oscillatorsection. 25 ond. VThis will also satisfy requirement b above while the consequent use of a superheterodyne cir cuit simpliñes the requirement d above but it in of, vafrequency changer valve in ~a superhetero- s vdyne„circuit„which superheterodyne circuit pref troduces the difficulty of second. channel interfer withcorresponding intermediate frequency cir ence c above'. As an example, a particular re ceiver may be quoted which was required to cover , afrequency range of fromfifteen to thirty mega cuitsi land ,preferably 5 the ,scanning is `effected by cyclesper second in thirty consecutive bands’each erably4 has 4¿three stages of `frequency ` changing aireact‘or valveassociated with the second ofthe of five hundred kilocycles per secondwidth; such receiver therefore had to be capable of tuning oscillators through'lan amplifier as described in UnitldïStates application _Serial No. 503,277, -ñled September, 21; «1943- . Y ‘ '- 03 Ur automatically through five hundred kilocycles per ' second on each of the bands at a recurrence fre - »what heejëeée .Celledthe “Single-Span”, «tuning guency of the order ofrtwenty-iive per second. To principle in domestic and otherfradio receivers "achieve _this mechanically with normal input cir has been proposed but has not apparently come into cominercialuse. ¿ __ , . y ^ The general- advantages ¿offthesuperheterodyne receiver over other types are also well known and its use in a panoramic receiver is highly desir cuits Wouid haye involved >the use of at least two.~ _ 40 continuously variable timingïdevices such as au tomatically rotating condensers, as wellgascom plicated band switching means to cover the neces sary >number of bands. If the tuning Were to be f effected electronically such as by means of a re able, and when panoramic receivers are required to scan a relativelyvlarge number of wavebands, 45 actor valve, the switching would not be simpli for instance twenty or thirty, there may be great fied; therefore a preliminary frequency changing complexity and expense unless provision is made stage (it is preceded by a signal’frequency ampli-v for reducing the number of preset tuning circuits ñer) was proposed for converting allsignals to a which have to be changed when the waveband to frequency band of ñve hundred kilocycles persec be scanned is altered. In order that the received 50 ond in Width vso that a single automatically var signals shall have sufficient amplitude at the first iable oscillator and its associated frequency frequency changer to override valve noise in the changer would suflice to produce the panoramic mixer some signal frequency amplification is gen sweeps, irrespective of the band to which the erally desirable. It is, however, also desirable kthat “image" frequency signals fare removed as receiver was adjusted. According to the present invention a panoramic 2,404,333 3 I . „1 ,i :ff ;. ifi; 4 „ receiver has at least ‘two and preferably three frequency>r changer stages with aperiodic signal frequency amplification prior to- the first stage, radio frequency amplifier stage which is aperi-V any signal 'frequencyr so that the-"tuned Ycircuitv elements, preferably condensers only, which have to be selectively switched to the fixed element of Acycles* per 'second plusl the'g mid-frequency of the ity to deal with such high frequencieahelpSJlo. quency amplifier, sharply tuned to 1.6 mc./sec. odic, at least Within the band to be scanned. M. I is the ñrst mixer stage supplied from A_R. F. A. and from the first oscillator '0.I having a fre >whilst the first oscillator frequency is high for giving a first intermediate frequency higher than 5 quency, _in the particular example„o=f 33 mega band of signals being- scanned.>>y #It'ï . that the scanning is over a band of one-,half'megacycle I. F. A, I is the first intermediate the receiver for frequency >band changing are re duced, namely to- those of the oscillator circuit l0Y frequency amplifier, which may include a filter which responds uniformly over the band, in the because the image frequency is so high/that it can " example 33 .mc.i250 kc./sec. and attenuates out easily be filtered out, or is even inherently elim inated. The aperiodic signal frequency amplifier 4 .j side it.- M. 2l is the second mixer stage suppliedj from I,~ F._ A; l Aand from the second oscillator 0.2 does not increase the selectivity and gives only aY small gain, but it has been’found in the com- l5 the frequency of which, in the example, is lWob- Y bination above set forth toV give satisfactory per-¿ Y bled between ‘theîlimits of 34.35 and 34.85 mc./ formance in practice and also, due tojits'inabil-> , ' .'isec. „L F. A. 2 is the second intermediate fre M. 3 is'the third- mixer stage, supplied from I. F. A. mediate frequency amplifier circuit` preferably 20 2 and from the third oscillator 0.3, the frequency of which is 2.065 mc./sec. The mixer M.' 3 feeds ' has a' band-pass characteri'sticrcfv adequate ifre to> they third intermediate .frequency amplifier quency width which may be, for example,' five I. F. A. 3 tuned to 465 kc./sec., this amplifier feed hundred kilocycles per second'so' that the fre ing to the detector Dwhich is preferably asso quency wobbling can be done' at the second os-` iilterout the image frequencies. The first inter-` - cillator, ’thus enabling all bands Vselected to have 25 ciated with a limiter L in accordance with UnitedV States Application Serial No.' l503,280,7‘iiled .Sep i tember- 21, 1943.1y The rectangleB. F. O. Vrepre In an example olf panoramic receiverîinac an equal Width. sents the beat frequency oscillatorfwhich may be ' used for heterodyning a continuous wave signal; quency rangeof fifteen' to thirty megacycles in steps of five hundred kilocycles-per second, the 30 in order to obtain an audible beatnote if desired cordance withV the invention for a signal Vfre-` The output from theV detector goes, on the one . first oscillator frequency is `from forty-eight to hand, to the audio frequency amplifier A. A. su "-` plying the phones VVlë’h. or loud speaker or otherÍ sixty-three megacycles per second and the míd-` frequencyv to Vwhich Ythe intermediate frequency amplifier is tuned is thirty-three megacycles per indicating device, and,von the otherhand, to the second, »the image 'frequency 1 beingV from' eighty-' 35 video’ampliiier V. A., the output of which is taken to the cathode raytube _represented by the rec one toninety~six mega'cycles per second. i tangle C.'R_ T. The'time base of the latter is 'Thus fthe' present invention employsr the '_per seknovrnfsingle span principle in a panoramic »Y . fed from the timeY base generator represented by the rectangle T. Vl2». G.,ìthe„output of'which is also receiven'particularly in cases where the frequen-` cies are s_o chosen that aperiodic signal frequency 40 applied to the second- o'scillaltorl)¿_.2` to wobble the normally iixedfrequency ó-f the latter in synchro ` ' circuits are permissible and yet second 'channel nism with-the timebase of the cathode ray'tube interference is avoided, Whilst the choice of ’band overa band of 500 kilocycles'. ' ' ' ' Í i ~ to be observed is decided'fmerely by the tuning of the first oscillator. _The use of )this arrange-` In _a panoramic receiver, an _input radiofre ment in conjunction with aïmain'intermediate 45 quency ampliñerstage-aperiodic over the 'range f Y frequency amplifierV with»_V its .frequencies i chosen We wide frequency band passed Y‘by the »fìr'stinter-à I ' l ‘ Aof signals to »be received, a first frequency changer stage variable to select a band of frequencies of Í appropriately, enables'adequate selectivity, sensi-` tivity and freedom from second channel inter-` ference to be obtained,~in-spite of .fthe simple nature of >the input circuits and the necessarily claim': substantiallyA constant' Width to be- scanned p and arranged to convert the selected band to an in e termediatefrequency -higher than that ofthe re-'v mediate frequency amplifier.' >It is to be under-` Vst'oo'd'that wev do' notherein claim per se auto ceived signal, an intermediate frequency» ampli-‘ fier, a second frequency changer'stage for 'scan-A ning the band selectedv byY the'ñrst frequency matically varying the tuning of the> second- osY>-Ã cillator instead of the first, in a panoramic re'-` 55 changer stage', means for varying the oscillator ceiver,» '- Í , » ‘f ï ~ ' The :accompanying drawing is a block diagramùLA _indicating a particular panoramic radio receivern in accordance with the presentïinvention." fÍ _ Starting from the left-hand end of the'diagram 60 the rectangle A. l2.. F.’ AL represents the desirable frequency of _said secpndïfrequency changer stage to Veffect panoramic scanning,` and adetector _stage forthescannedsignalsl'r >HARRY j; " ' ` ' -'