US2472798A - Low-pass filter system - Google Patents
Low-pass filter system Download PDFInfo
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- US2472798A US2472798A US512115A US51211543A US2472798A US 2472798 A US2472798 A US 2472798A US 512115 A US512115 A US 512115A US 51211543 A US51211543 A US 51211543A US 2472798 A US2472798 A US 2472798A
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H7/00—Multiple-port networks comprising only passive electrical elements as network components
- H03H7/01—Frequency selective two-port networks
- H03H7/17—Structural details of sub-circuits of frequency selective networks
- H03H7/1741—Comprising typical LC combinations, irrespective of presence and location of additional resistors
- H03H7/1775—Parallel LC in shunt or branch path
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H7/00—Multiple-port networks comprising only passive electrical elements as network components
- H03H7/01—Frequency selective two-port networks
- H03H7/0115—Frequency selective two-port networks comprising only inductors and capacitors
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04J—MULTIPLEX COMMUNICATION
- H04J1/00—Frequency-division multiplex systems
- H04J1/02—Details
- H04J1/04—Frequency-transposition arrangements
- H04J1/045—Filters applied to frequency transposition
Definitions
- This invention relates generally to wave transmission networks and more particularly to adjustable low-pass networks employing a plurality of fixed lter circuits.
- adjustable low-pass filters having a continuously variable cut-off frequency have included a plurality of individually adjustable reactive filter components.
- Adjustable reactive elements suitable for low-pass networks, are costly and cumbersome. It also is costly and inconvenient to gang a large number of adjustable reactive elements for convenient unitary adjust-V ment of the cut-off frequency.
- the instant invention contemplates broadly converting the currents of one frequency into currents of a higher frequency.
- the higher frequency currents are applied to a low-pass network employing only two fixed reactive filter networks in combination with two fixed modulators and two adjustable carrier frequency sources such as, for example, thermionic tube oscillators.
- the two fixed filter networks have frequency band pass characteristics at frequencies related to but appreciably higher than the desired low-pass cutoff frequency. The conversion to higher frequencies reduces the physical size and cost of the filter components.
- the signal frequency currents which are to be attenuated are applied to a first carrier frequency from one of the oscillator circuits to provide two equal side bands.
- the two side bands and the rst carrier frequency are applied to the first filter network to attenuate only the upper side band to the desired low-pass band width.
- the unequally attenuated side bands and the first carrier are then applied to the second carrier frequency which is selected to be substantially higher than the first carrier frequency.
- the second fixed filter network has a pass band which attenuates the lower part of the upper band side band to a value substantially equal to the upper part of the upper band side band, thereby providing a high frequency carrier having two side bands each having widths equivalent to the desired low-pass hand.
- the high frequency modulated carrier is applied to a demodulator or envelope detector to derive the low-pass frequency band desired.
- Among the objects of the invention are to provide an improved method of and means for transmitting a predetermined low-pass frequency band. Another object of the invention is to provide an improved low-pass transmission network employing relatively high frequency band-pass filter netlator will include a works. An additional object of the invention is to provide an improved adjustable low-pass transmission network employing a plurality of fixed band-pass filter networks.
- a further object of the invention is to provide an improved adjustable low-pass transmission network employing in combination a plurality of xed filter networks, a plurality of adjustable carrier frequency sources and means for modulating the signal frequencies with the carrier frequency sources to provide the desired low-pass frequency transmission band.
- Figure 1 is a schematic circuit block diagram of a preferred embodiment
- Figure 2 is a family of graphs indicating the operation of the circuit of Figure 1
- Figure 3 is a schematic circuit diagram of a typical fixed band-pass filter network forming one of the elements of the circuit of Figure 1
- Figure 4 is a graph illustrative of the frequency band-pass characteristics of filter networks of the type described in Figure 3. Similar reference characters are applied to similar elements throughout the drawing.
- a source of signals occupying a frequency band from zero to a frequency f1 is applied to the input circuit of a first thermionic tube modulator 3.
- a source of carrier frequency currents such as, for example, a thermionic tube oscillator 5 also is connected to the input circuit of the first modulator 3 to provide modulated carrier currents in the output circuit of the modulator 3.
- the frequency ,fcl of the first carrier frequency oscillator 5 is appreciably higher than the highest signal frequency f1, the currents derived from the first moducarrier and sidebands covering a frequency spectrum from (fcl-fD to (fcl-i-fl).
- This frequency spectrum is applied to the input of a fixed band-pass filter network having a pass band (fc1-,1-A) to (icl-H2). It will be seen that the lower sideband (fel-f1) will not be attenuated by the band-pass filter l while the upper sideband (fel-H1) will be attenuated to a value (icl-H2)
- the currents derived from the first band-pass filter 'l are applied to the input circuit of a second thermionic tube modulator 9.
- the output of a second carrier frequency source such as, for example, a thermionic tube oscillator ll having a carrier frequency fc2, is also applied to the input of the second modulator Si.
- the modulated carrier derived from the second modulator 9 will include carrier and sidebands covering the spectra (fcZ-fcl) f2 to (fc2-fc1) +f1 and (fc2+fc1) -fl to (fc2- ⁇ -fc1)f-f2.
- the output of the second bandpass filter I3 will comprise'ff'requencies covering4 the spectrum (fc2-l-fc1) -f2 to (fc2-l-fc1) -l-f2 or, in other words, a carrier (jez-Hol) having equal upper and lower sidebands f2;
- the output of the second band-pass filter I3. is applied to a demodulator I5 such as, for example, a diode thermionic. tubi-' ,eto,derive ⁇ currents covering; thefrequencygspectrum from zero to f2, which isthe, desired'lo'w frequency spectrum4 from z'er'o'to f2, which'is the diesiredlow frequency pass baud yIf ⁇ it isA desired to lc lerivea ⁇ v ⁇ pass band from zero to a.frequencyf3.;fwh'ee f3 f2: f1, it merely is necessary"to'increase'the frequency of the rst Crlier frquencv'fci to ,ayalue (fc1-l-f2*f3) and s1' ,n1'i ⁇ J.lta Iitliya5indifaledbyV the dash line 33 of Fig; 1, tofdecfraserthesecondcarrier frequency f
- the .rst carrier fcl ⁇ will lie/decreased in'frequencyand the second carrier f ⁇ c 2 ⁇ , ⁇ w il1flbe increasedgin 'frequency in the same manner 'asdescribed heretofore.
- Inrtigurez. eraphaindieates the. Original, Signal frequency,,bandy '0tol ⁇ )"land the desired low-pass bandlj to f2.
- the rstcarrierfrequency isindicatdb'y, thedasljifline fol andthe output currents derivedlfrom therst modulator are indicated by thefrequeney spptrunr (fai-fai) to fc1+f1 Graph'bindicates' the parie-pass characteristics of the Afirst and second 'band-pass lters.
- olii-the .upper -portionmof the upper sidebandwhereby two equall sidebands having a band widthfZ and-acarried (fc2-l-fcl) are .obtained .frnmmhesecondflten network.L
- the ⁇ currents illustrated, by the graph. e are applied :to ,the .demodulatorl5 to, derive the desired low frequencypass band.
- the fixed band-pass lter networks I,- I3 - may beof any conventionaligtype known ⁇ inf the art which. Willygprevide ftheLdeSirei-.fliequeeey bendf, passrspectra and permissible phase. distortion.
- A4 typical bandeplass filter Vneetvvork I is illustrated schematically. in Figure andv includes a first resonant.
- ⁇ circuit I 1 -Y comprising a .parallel-con,- nected .inductor., ⁇ V I 9,.,an1l cai'oacitor 2L.
- 1, .Z'L may bevtuned to the same orislighltly diierentrespnant frequencies, and, if desired, the.,inclluctorsl ,I9, 29, may be inductively aswell Aas icapacitively coupled. Likewise, the
- Figure 4 illustrates a typical response curve for a band-pass filter of the type described in Figure 3 wherein substantially uniform lattenuation is provided at all frequencies except those within a predetermined frequency band wherein extremely low attenuation; i. e., good-transmission is provided for the desired 'applied signal currents.
- any other known types of band-pass lte'r networks may be substituted for the type described in Figure 3J and that phase distortion of the signal may be minimized to. any desired extent by applying Bodes theory tothe design of linear phase shift filters in each of the band-pass filter networks.
- the advantages ofthe low-pass network thus described areV particularly outstanding if an adjustable network providing low phase distortion of the signal is desired.
- said-j secondi currents g thirdncurrents.V having a, second,-gcarrier -andfzztwo equals-second 'sidebands each having the zdesiredifrequencyzband:.widthi and detectionrand tilterrmeans forlde'modulating; said third currentsz'to denve-Afourtl'ilcurrents hav#- irigsubstantiallyonlyrfrequencieszfwithimsaid 'dei sired lowpassbandn.
- An adjustable low band pass network for a source of signal frequency currents including a pair of modulators, a pair of carrier current sources having adjustabie different carrier frequencies, a pair of filter networks each capable of transmitting a band of frequencies including a different one of said carrier frequencies, means including one of said modulators responsive to said signal source and to one of said carrier current sources for deriving from one of said filter networks said one carrier and two sidebands, one of said sidebands having the desired low pass band width, means including said other modulator and said other filter network responsive to said frequencies derived from said one filter and said other carrier source for deriving currents of said other carrier and two equal second sidebands each having said desired low pass band width, means for adjusting the frequencies of said carrier current sources, and means for detecting said last mentioned equal sidebands to derive currents having. substantially only Afrefquencies within said desired low pass band.
- An adjustable. low band pass network for a source of signal frequency currents including a pair of modulators, a pair of carrier current sources having adjustable ldifferent carrier frequencies, a pair of filter networks each capable of transmitting a band of frequencies including a different one of said carrier frequencies, means including one of said modulators responsive to said signal source and to one of said carriercurrent sources for deriving from one of said filter networks said one carrier and twor sidebands,
- a low band pass network for a source of signal frequency currents including a first modulator, a first carrier frequency current source, a
- - ⁇ first band pass filter network means for applying rcurrents including currents of frequencies to be transmitted and said first carrier currents to said first modulator to derive said first carrier and equal sideband currents, means for applying said equal sideband currents to said first filter to pass said first carrier, a complete one of said sidebands and only the desired low frequency portion of the other of said sidebands, a second carrier frequency current source, a second modulator,
- An adjustable low band pass network for a, source of signal frequency currents including a .nrst modulator, a first adjustable carrier frequency current source, a first band pass filter network, means for applying currents including currents of frequencies to be transmitted and said first carrier ,currents to said first modulator to derive said first carrier and equal sideband currents, means for'applying said equal sideband currents to said first filter to pass said first carrier, a complete one of said sidebands and only the desired low frequency portion of the other of said sidebands, a second adjustable carrier frequency current source, a second modulator, means for applying said second carrier currents and said first carrier and sideband currents derived from said first filter to said second moduand second equal sideband currents, a secondhand pass filter network, means for applying said second carrier and second equal sideband currents to said second filter to derive two equal sidebands each having widths corresponding to said desired low frequency portion of said other of said first sidebands, means for adjusting the frequencies of said'carrier current sources,
- An adjustablelow band pass network for a source'of signal frequency currents including a first modulator, a first adjustable' carrier frev quency current source, a first band pass filter network, means for applying currents including currents of frequencies to be transmitted and 'said first carrier currents to said first modulator to derive said first carrier and equal sideband currents, means for applying said equal sideband currents to said first filter to pass said first carrier, a complete one of said sidebands and only the desired low frequency portion of the other of said sidebands, a second adjustable carrier frequency current source, a vsecond modulator.
- the method of providing low band pass transmission of signal frequency currents comprising generating first carrier currents, moda-e '.-t-lating said 'mrst carrier .currents by. applying artheretoisaidfsignal. currents, selecting apredetervi'.rn'iinedsirequency. portiomincludingfthe'carrier and eatrleastportions*ofsbothzsidebandsrof saidzmodu- ⁇ dated-carrier currents; generatngseconmcarrier ⁇ currents.
- modulated carrier. currents,.selecting a.predeter 'mined portion ofsaid-.lastwmentioned .carrier cur- .'rents, adjusting 'the frequencies of .said :,rst and pfaid ⁇ second carrier currents, and :detecting-@said fselected portion of said :last mentioned.. ⁇ carrier- .:currents' Ato .-derive signal .currents lhaving sub- ..stantially vonly ,frequencies .withinl said desired I dow .passband 111.*51hemethod.
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Description
Patented June 14, 1949 'time LOW-PASS FILTER SYSTEM Gordon L. Fredendall, Feasterville, to Radio Corporation of America,
of Delaware Pa., assignor a corporation Application November 29, 1943, Serial No. 512,115
(Cl. ri-44) 13 Claims.
This invention relates generally to wave transmission networks and more particularly to adjustable low-pass networks employing a plurality of fixed lter circuits.
l Heretofore, adjustable low-pass filters having a continuously variable cut-off frequency have included a plurality of individually adjustable reactive filter components. Adjustable reactive elements, suitable for low-pass networks, are costly and cumbersome. It also is costly and inconvenient to gang a large number of adjustable reactive elements for convenient unitary adjust-V ment of the cut-off frequency.
The instant invention contemplates broadly converting the currents of one frequency into currents of a higher frequency. The higher frequency currents are applied to a low-pass network employing only two fixed reactive filter networks in combination with two fixed modulators and two adjustable carrier frequency sources such as, for example, thermionic tube oscillators. The two fixed filter networks have frequency band pass characteristics at frequencies related to but appreciably higher than the desired low-pass cutoff frequency. The conversion to higher frequencies reduces the physical size and cost of the filter components.
The signal frequency currents which are to be attenuated are applied to a first carrier frequency from one of the oscillator circuits to provide two equal side bands. The two side bands and the rst carrier frequency are applied to the first filter network to attenuate only the upper side band to the desired low-pass band width. The unequally attenuated side bands and the first carrier are then applied to the second carrier frequency which is selected to be substantially higher than the first carrier frequency. The second fixed filter network has a pass band which attenuates the lower part of the upper band side band to a value substantially equal to the upper part of the upper band side band, thereby providinga high frequency carrier having two side bands each having widths equivalent to the desired low-pass hand. The high frequency modulated carrier is applied to a demodulator or envelope detector to derive the low-pass frequency band desired.
, Among the objects of the invention are to provide an improved method of and means for transmitting a predetermined low-pass frequency band. Another object of the invention is to provide an improved low-pass transmission network employing relatively high frequency band-pass filter netlator will include a works. An additional object of the invention is to provide an improved adjustable low-pass transmission network employing a plurality of fixed band-pass filter networks.
A further object of the invention is to provide an improved adjustable low-pass transmission network employing in combination a plurality of xed filter networks, a plurality of adjustable carrier frequency sources and means for modulating the signal frequencies with the carrier frequency sources to provide the desired low-pass frequency transmission band.
The invention will be further described by reference to the accompanying drawing of which Figure 1 is a schematic circuit block diagram of a preferred embodiment, Figure 2 is a family of graphs indicating the operation of the circuit of Figure 1, Figure 3 is a schematic circuit diagram of a typical fixed band-pass filter network forming one of the elements of the circuit of Figure 1 and Figure 4 is a graph illustrative of the frequency band-pass characteristics of filter networks of the type described in Figure 3. Similar reference characters are applied to similar elements throughout the drawing.
Referring to Figure l of the drawing, a source of signals occupying a frequency band from zero to a frequency f1 is applied to the input circuit of a first thermionic tube modulator 3. A source of carrier frequency currents such as, for example, a thermionic tube oscillator 5 also is connected to the input circuit of the first modulator 3 to provide modulated carrier currents in the output circuit of the modulator 3. if the frequency ,fcl of the first carrier frequency oscillator 5 is appreciably higher than the highest signal frequency f1, the currents derived from the first moducarrier and sidebands covering a frequency spectrum from (fcl-fD to (fcl-i-fl).
This frequency spectrum is applied to the input of a fixed band-pass filter network having a pass band (fc1-,1-A) to (icl-H2). It will be seen that the lower sideband (fel-f1) will not be attenuated by the band-pass filter l while the upper sideband (fel-H1) will be attenuated to a value (icl-H2) The currents derived from the first band-pass filter 'l are applied to the input circuit of a second thermionic tube modulator 9. The output of a second carrier frequency source such as, for example, a thermionic tube oscillator ll having a carrier frequency fc2, is also applied to the input of the second modulator Si. The modulated carrier derived from the second modulator 9 will include carrier and sidebands covering the spectra (fcZ-fcl) f2 to (fc2-fc1) +f1 and (fc2+fc1) -fl to (fc2-{-fc1)f-f2. These two sidebands and the second carrier frequency fc2 are applied to the input of a second bandpass lterl network having a pass band covering the spec; trum fc2+fc41-f2 to f2+f1+f2+nf It will be seen that the second band-pass filter will at` tenuate the lower portion of the upper sideband to a band width equivalent to f2, and will not affect the transmission of the upper portion of the upper sideband which already has a band width of f2. Therefore, the output of the second bandpass filter I3 will comprise'ff'requencies covering4 the spectrum (fc2-l-fc1) -f2 to (fc2-l-fc1) -l-f2 or, in other words, a carrier (jez-Hol) having equal upper and lower sidebands f2;
The output of the second band-pass filter I3. is applied to a demodulator I5 such as, for example, a diode thermionic. tubi-' ,eto,derive` currents covering; thefrequencygspectrum from zero to f2, which isthe, desired'lo'w frequency spectrum4 from z'er'o'to f2, which'is the diesiredlow frequency pass baud yIf`it isA desired to lc lerivea`v` pass band from zero to a.frequencyf3.;fwh'ee f3 f2: f1, it merely is necessary"to'increase'the frequency of the rst Crlier frquencv'fci to ,ayalue (fc1-l-f2*f3) and s1' ,n1'i`J.lta Iitliya5indifaledbyV the dash line 33 of Fig; 1, tofdecfraserthesecondcarrier frequency f'c2 toA`[fc2-'-2f(f2'-f3 l. Similarly, if it is desired toincrease` thepass band, the .rst carrier fcl `will lie/decreased in'frequencyand the second carrier f`c 2`,`w il1flbe increasedgin 'frequency in the same manner 'asdescribed heretofore.
Inrtigurez. eraphaindieates the. Original, Signal frequency,,bandy '0tol `)"land the desired low-pass bandlj to f2. The rstcarrierfrequency isindicatdb'y, thedasljifline fol andthe output currents derivedlfrom therst modulator are indicated by thefrequeney spptrunr (fai-fai) to fc1+f1 Graph'bindicates' the parie-pass characteristics of the Afirst and second 'band-pass lters.- Graph c'indicat'es'th'e output-currents derived from the rst lter networkfshowing theattenuation of the upper 4sideband v(fcl-l-Jl) 5to a value f2.
Graph d'illustrates thesecond carrier frequency, indicatedfby thedash line fc2, and the upper and lower sidebands provided-byA the modulation of `the second carrier bywthe modulated. rst carrier..V Graph fe .illustratestheattenuation: of `the lower portion .offthe `upper..sideband and t -e..lack. of attenuation; olii-the .upper -portionmof the upper sidebandwhereby two equall sidebands having a band widthfZ and-acarried (fc2-l-fcl) are .obtained .frnmmhesecondflten network.L As; explained heretofore., the `currents illustrated, by the graph. e are applied :to ,the .demodulatorl5 to, derive the desired low frequencypass band.
The fixed band-pass lter networks I,- I3 -may beof any conventionaligtype known `inf the art which. Willygprevide ftheLdeSirei-.fliequeeey bendf, passrspectra and permissible phase. distortion. A4 typical bandeplass filter Vneetvvork Iis illustrated schematically. inFigure andv includes a first resonant. `circuit I 1 -Y comprising a .parallel-con,- nected .inductor.,`V I 9,.,an1l cai'oacitor 2L. coupled throughcou'pling .capacitors 4v23, -25 to a second resonant .circitfll comprising a `parallel-con,-v nected in'ductor 29and ,capacitor 3|., Theparallel. resonant circuits 4| 1, .Z'Lmay bevtuned to the same orislighltly diierentrespnant frequencies, and, if desired, the.,inclluctorsl ,I9, 29, may be inductively aswell Aas icapacitively coupled. Likewise, the
coupling between'th'e resonant circuits I'I, 21 may" 75 be entirelyy inductive and the coupling capacitors 23, 25 omitted.
Figure 4 illustrates a typical response curve for a band-pass filter of the type described in Figure 3 wherein substantially uniform lattenuation is provided at all frequencies except those within a predetermined frequency band wherein extremely low attenuation; i. e., good-transmission is provided for the desired 'applied signal currents.
It should be understood that any other known types of band-pass lte'r networks may be substituted for the type described in Figure 3J and that phase distortion of the signal may be minimized to. any desired extent by applying Bodes theory tothe design of linear phase shift filters in each of the band-pass filter networks. The advantages ofthe low-pass network thus described areV particularly outstanding if an adjustable network providing low phase distortion of the signal is desired. Adjustable low-pass filters, having a variable cut=oit frequency, designed according tojBodes theory; would require'the gauging of numerous variable capacitorsand inductors;
Thus the invention described'compris'es van im# proved means for and method of securing low band-pass -1 transmission of* signal" frequency' cur'i rentsby' conversions of* low frequencies l to higher frequencies-and-byemployingrelativelyhigh"fre= quencyvband-'pass filters infcombination' withV conventionalL th'ermionicf tubemodulators and adjustable'fthermionic tube oscillatorsl After the required frequency-conversions andattenuations,v the original signal frequencies; lessfthe'undesired frequencies, are obtainedly by' demodl'lltion.` In the; described vsystem `relatively simple frequency ChangeSbring; about @thea desired tb'and-'pass' lcharacteristics instead'4 of :changing Ythe freactive' char'- acteristic of band-pass filters; which reactive changes yarezusually accompaniedK withuundesired 40 phase/shifts.
I `claim ,as-my: invention:
1'.4 Apparatuszfor providinglombandpass transmission` vofgfsgnal, `frequency fcurrents z including means,... forpderiving; from'` said;A signal .1 currents second-' currents having aa;v carrier andstwol side bands; one` Ofatsaidfsidebands. having .the desired. frequency band width, means for derivingifrom; said-j secondi currents g thirdncurrents.V having a, second,-gcarrier -andfzztwo equals-second 'sidebands each having the zdesiredifrequencyzband:.widthi and detectionrand tilterrmeans forlde'modulating; said third currentsz'to denve-Afourtl'ilcurrents hav#- irigsubstantiallyonlyrfrequencieszfwithimsaid 'dei sired lowpassbandn.
2:, Apparatusonprovidingfadi ustableiow band pass transmissionnoffsignalj.frequency? currents including .fmeans .Ii-fori.'- derivingqfrom i: said 1 signal currents-second .currents having ,a'fcarrier l and two lsidebandS.-.-,onepf saidsidebands havingthe desired f ,frequency band width; .means for deriv.- ingfr.omfsaid secondcurrentsthird currents hav-1 ingya ,second carrierand two=equali second-.sida bandseach -hayingathe desiredafrequency :bandwidth,fme'ans for,.adj ustinglfthe- .carriei` frequency upon A which each of -said:sidebandsdepend, and
detection and -Ilterz-,means fondemodulating sa-id' third currents... td derive fourth.. currentsehaving. substantially only frequencies Withinfsaiddesired 1ow.pass,.band.
3..,A low..ban d ;pass,.network forma .source fof. signal .l frequency. I currents.. including. ..a pair-.0L modulators, a pairofcarrier current sources hav ingidierent carrienfrequencies, .a pair. of. filter.` networkseach capable.of,..transmitting.,a Iband` of frequencies including a different one of said'M having substantially only e carrier frequencies-means including `one of said modulators responsive to said signal source and to one of said carrier current sources for deriving from one of said filter networks said one carrier and two sidebands, one of said sidebands having the desired ylow pass band width, means including said other modulator and said other filter network responsive to said frequencies derived from said one lter and said other carrier sourcefor yderiving currents of said other carrier and two equal second sidebands each having said desired low pass band width, and means for detectingsaid last mentioned equal sidebands to derive currents frequencies within said desired low pass band. f
4. An adjustable low band pass network for a source of signal frequency currents including a pair of modulators, a pair of carrier current sources having adjustabie different carrier frequencies, a pair of filter networks each capable of transmitting a band of frequencies including a different one of said carrier frequencies, means including one of said modulators responsive to said signal source and to one of said carrier current sources for deriving from one of said filter networks said one carrier and two sidebands, one of said sidebands having the desired low pass band width, means including said other modulator and said other filter network responsive to said frequencies derived from said one filter and said other carrier source for deriving currents of said other carrier and two equal second sidebands each having said desired low pass band width, means for adjusting the frequencies of said carrier current sources, and means for detecting said last mentioned equal sidebands to derive currents having. substantially only Afrefquencies within said desired low pass band.
5. An adjustable. low band pass network for a source of signal frequency currents including a pair of modulators, a pair of carrier current sources having adjustable ldifferent carrier frequencies, a pair of filter networks each capable of transmitting a band of frequencies including a different one of said carrier frequencies, means including one of said modulators responsive to said signal source and to one of said carriercurrent sources for deriving from one of said filter networks said one carrier and twor sidebands,
one of said sidebands having the desired low pass'v band width, means including said other modulator and said other filter network responsive to said frequencies derived from said one filter and said other` carrier source for deriving currents of said other carrier and two equal second sidebands each having said desired low pass band width, means for adjusting simultaneously the frequencies of said carrier current sources, and means for detecting said last mentioned equal sidebands to derive currents having substantially only frequencies within said desired low pass band.
6. A low band pass network for a source of signal frequency currents including a first modulator, a first carrier frequency current source, a
-`first band pass filter network, means for applying rcurrents including currents of frequencies to be transmitted and said first carrier currents to said first modulator to derive said first carrier and equal sideband currents, means for applying said equal sideband currents to said first filter to pass said first carrier, a complete one of said sidebands and only the desired low frequency portion of the other of said sidebands, a second carrier frequency current source, a second modulator,
having Asubstantially only lator to derive said second carrier :means for applying said second carrier currents and said first carrier and sideband currents derived from said first filter to said second modulator to derive said second carrier and second equal second sideband currents, a second band pass filter network, means for applying said second carrier and said second equal sideband currents to said second filter to derive two equal sidebands each having widths corresponding to said desired low frequency portion of said other of said first sidebands, and means for detecting said last mentioned equal sidebands to derive currents frequencies within the desired low pass band.
'7. An adjustable low band pass network for a, source of signal frequency currents including a .nrst modulator, a first adjustable carrier frequency current source, a first band pass filter network, means for applying currents including currents of frequencies to be transmitted and said first carrier ,currents to said first modulator to derive said first carrier and equal sideband currents, means for'applying said equal sideband currents to said first filter to pass said first carrier, a complete one of said sidebands and only the desired low frequency portion of the other of said sidebands, a second adjustable carrier frequency current source, a second modulator, means for applying said second carrier currents and said first carrier and sideband currents derived from said first filter to said second moduand second equal sideband currents, a secondhand pass filter network, means for applying said second carrier and second equal sideband currents to said second filter to derive two equal sidebands each having widths corresponding to said desired low frequency portion of said other of said first sidebands, means for adjusting the frequencies of said'carrier current sources, and means for detecting said last mentioned equal sidebands to derive currents having substantially only frequencies within the desired low pass band.
8. An adjustablelow band pass network for a source'of signal frequency currents including a first modulator, a first adjustable' carrier frev quency current source, a first band pass filter network, means for applying currents including currents of frequencies to be transmitted and 'said first carrier currents to said first modulator to derive said first carrier and equal sideband currents, means for applying said equal sideband currents to said first filter to pass said first carrier, a complete one of said sidebands and only the desired low frequency portion of the other of said sidebands, a second adjustable carrier frequency current source, a vsecond modulator. means for applying said second carrier currents and said first carrier and sideband currents derived from sald rst filter to said second modulator to derive said second carrier and second equal sideband currents, a second band pass filter network, means for applying said second carrier and second equal sideband currents to said second filter to derive two equal sidebands each having widths corresponding to said desired low frequency portion of said other of said first sidebands, means for adjusting simultaneously the frequencies of said carrier current sources, and means for detecting said last mentioned equal sidebands to derive currents having substantially only frequencies within the desired low pass band.
9. The method of providing low band pass transmission of signal frequency currents comprising generating first carrier currents, moda-e '.-t-lating said 'mrst carrier .currents by. applying artheretoisaidfsignal. currents, selecting apredetervi'.rn'iinedsirequency. portiomincludingfthe'carrier and eatrleastportions*ofsbothzsidebandsrof saidzmodu- `dated-carrier currents; generatngseconmcarrier `currents. of.a lfrequency.-liiflerent fthamsaid .':rst .carrier4 currents; emodulating `saidsecond carrier .gcurrents =byfapp1ying theretosaidlselectedimodu- 1 lated .nari-ier currents, .selecting fa a predetermined portion of said last mentionewmodulated carrier f @currents .and 4'detecting.zsaidfselected :portioni of fthe:last-mentioned. carrier. currents fto. derive :'Sg-
1f nal vcurrents zhaving substantially .only frequencies Within said desiredlow.passfband filmt-The method .-of. providing .adjustable lowt band .pass .transmissionvof::signal zfrequencynurl,rents comprising generatingfiirstfcarriencurrents, :emodulating asaid Afirst carrier. currents byfpply- AfingJtheretosaid signal fcurrents; selecting@ epredetermined-:frequency .portion including `rt-heicar- .4
:v1-ier and fatleast portions t of .both :sidebands of Vsaid .modulatec-fcarrier currents, generating esec- .ondscarrier currents oitaifrequency` diierent'than usaid riirstcarrier; currents, modulating said. second carrier currents byapplying .thereto saidiselected,v
modulated carrier. currents,.selecting a.predeter 'mined portion ofsaid-.lastwmentioned .carrier cur- .'rents, adjusting 'the frequencies of .said :,rst and pfaid `second carrier currents, and :detecting-@said fselected portion =of said :last mentioned..` carrier- .:currents' Ato .-derive signal .currents lhaving sub- ..stantially vonly ,frequencies .withinl said desired I dow .passband 111.*51hemethod. .of -providingadjustablezdow `t lband f pass transmissionl of signal'ffrequency .cur-` irentscomprising.generatlngbrst carrierfcurrents, 'f modulating-said :first Acarrier currentsbysaidsig- .nallcurrents, selecting a-predetermined frequency portion including the. carrierand.atrleastvportions rof -both .sidebands .of said modulated vcarrier/currents, generating second-.carrier currentsofadre- `quency different :than said :iirstncarrier currents, modulating. said second 'carrier cum-ents'by said .selected modulated lcarrier .-currentsf selecting a,
. :predetermined portion of :said last'mentioned-.curr
rents, .adjusting simultaneously the"=frequencies ofssaid rst and said secondcarrier currentseand detecting said selected :portion offsaid-ilast-amenl:tioned ycarrier currents .to .derivelsignal currents having substantially only :frequencies withingsaid-'f :desired V:low pass band.
L2. mheiimethodl offnproviding:adjustable low gmnd-I pass Li-,ransmissien ofisignal {frequency-.eur- ,z-rentszcomprisinafgeneratinglirst carrier, currents. f-.,modu1atingadrst fcarriemcurxents bassa-insig- 5 mal.:currents;selecting@predetermined:frequency mortionincluding fthe carrierlandiat leastmortions .cffbotnsidebands nffsaidmcdulated eurxentsfsen- L-.ferating secondV carrierncurrents of a :htenuency sminerent ithan-gsaid lrstvcarrier currents, modulozzlatinerfsaid l:secondmarriemcurrents :by saidfsa- .lectedmodulatedzcarrierlcurrents, rselesting;affpre :'detenninedn pontionzof said. last .mentoned..m1rfgrents, adjusting4 the -:frequency` j f `said {n1- st @earfrier; currents andfsaidxsecond 4carrier. currents. in 15 opposite senses, and detectingvsaid selected @por- :tion 1,oszaiidilast inelritionecarrier: currents .to de- Lrire-signalcurrents havingsubstantially only:;fre '-,;-quencies mithin :.said desired :low mass band.
13; The-method of :providing vadjustable:new .-ph .nd pass transmissionmf signal -frequencmcurfrrents comprising4 generating rstlcarrier currents, `.:siriodulatine:.said rstcarrier. currents by-said sig- 1 nal-,currentsfselecting-a predetennnedirequency fzportonfincluding :the carrier and. at least'ponticns 1 f Jof: bothsidebands of said'modulatedv currentsleneerating: Asecond f carrier currents :nf a Y .frequency :.different :than said rst zcarrier fcurrents, fmodulating'said second 'carriencurrents byfsaid selected modulated carriercurrents,` :selecting a predetermined portion of said .lastcmeritioned currents, -'.-adll1ting the frequency! .0f saidxfrst Icarrier. currents and said second carrierfcurrentsginf opposite :'senses andain different-:proportionateamounts.and detecting-.,.-saidselected:portion ofrsaid last-men- .,xtionedfcarrier; .currents to s derive. signal currents r havingsubstantially'lonlyfrequencies -within vsaid fidesired low rpassaband.
1 GQRDQN IL. 'FREDENDALL.
:BEEERENCES :CITfED UNITED, :STATES .PATENTS 4are of -record in the 45, iNumber Nam-e Date :1,861,488 Osborne Dec. 7, A19120 11;830j896 Wintringham gNov.` 10; i931 Lf1,905;714 Horton ;.Aprli25g r1933 w .'l-=;2;339,'633 Gilman .Ian2'18,*1944
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US512115A US2472798A (en) | 1943-11-29 | 1943-11-29 | Low-pass filter system |
| GB23737/44A GB584769A (en) | 1943-11-29 | 1944-11-28 | Improvement in low-pass network |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US512115A US2472798A (en) | 1943-11-29 | 1943-11-29 | Low-pass filter system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| US2472798A true US2472798A (en) | 1949-06-14 |
Family
ID=24037728
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US512115A Expired - Lifetime US2472798A (en) | 1943-11-29 | 1943-11-29 | Low-pass filter system |
Country Status (2)
| Country | Link |
|---|---|
| US (1) | US2472798A (en) |
| GB (1) | GB584769A (en) |
Cited By (45)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2635143A (en) * | 1948-02-24 | 1953-04-14 | Marconi S Wireless Telegrpah C | Variable electrical filter |
| US2923887A (en) * | 1955-11-29 | 1960-02-02 | Ross Radio Corp | Electronic circuit arrangement for the controlled amplification of a desired signal |
| US2951206A (en) * | 1957-11-15 | 1960-08-30 | Rca Corp | Variable delay line |
| US3505607A (en) * | 1966-11-19 | 1970-04-07 | Philips Corp | Arrangement for selecting in a correct phase relationship a characteristic component from a frequency spectrum |
| US6049706A (en) * | 1998-10-21 | 2000-04-11 | Parkervision, Inc. | Integrated frequency translation and selectivity |
| US6061551A (en) * | 1998-10-21 | 2000-05-09 | Parkervision, Inc. | Method and system for down-converting electromagnetic signals |
| US6061555A (en) * | 1998-10-21 | 2000-05-09 | Parkervision, Inc. | Method and system for ensuring reception of a communications signal |
| US6091940A (en) * | 1998-10-21 | 2000-07-18 | Parkervision, Inc. | Method and system for frequency up-conversion |
| US20010027561A1 (en) * | 1998-11-30 | 2001-10-04 | Microsoft Corporation | Video on demand methods and systems |
| US6370371B1 (en) | 1998-10-21 | 2002-04-09 | Parkervision, Inc. | Applications of universal frequency translation |
| US6542722B1 (en) | 1998-10-21 | 2003-04-01 | Parkervision, Inc. | Method and system for frequency up-conversion with variety of transmitter configurations |
| US6560301B1 (en) | 1998-10-21 | 2003-05-06 | Parkervision, Inc. | Integrated frequency translation and selectivity with a variety of filter embodiments |
| US20030128776A1 (en) * | 2001-11-09 | 2003-07-10 | Parkervision, Inc | Method and apparatus for reducing DC off sets in a communication system |
| US6694128B1 (en) | 1998-08-18 | 2004-02-17 | Parkervision, Inc. | Frequency synthesizer using universal frequency translation technology |
| US6704558B1 (en) | 1999-01-22 | 2004-03-09 | Parkervision, Inc. | Image-reject down-converter and embodiments thereof, such as the family radio service |
| US6704549B1 (en) | 1999-03-03 | 2004-03-09 | Parkvision, Inc. | Multi-mode, multi-band communication system |
| US6813485B2 (en) | 1998-10-21 | 2004-11-02 | Parkervision, Inc. | Method and system for down-converting and up-converting an electromagnetic signal, and transforms for same |
| US6873836B1 (en) | 1999-03-03 | 2005-03-29 | Parkervision, Inc. | Universal platform module and methods and apparatuses relating thereto enabled by universal frequency translation technology |
| US6879817B1 (en) | 1999-04-16 | 2005-04-12 | Parkervision, Inc. | DC offset, re-radiation, and I/Q solutions using universal frequency translation technology |
| US6963734B2 (en) | 1999-12-22 | 2005-11-08 | Parkervision, Inc. | Differential frequency down-conversion using techniques of universal frequency translation technology |
| US6975848B2 (en) | 2002-06-04 | 2005-12-13 | Parkervision, Inc. | Method and apparatus for DC offset removal in a radio frequency communication channel |
| US7006805B1 (en) | 1999-01-22 | 2006-02-28 | Parker Vision, Inc. | Aliasing communication system with multi-mode and multi-band functionality and embodiments thereof, such as the family radio service |
| US7010286B2 (en) | 2000-04-14 | 2006-03-07 | Parkervision, Inc. | Apparatus, system, and method for down-converting and up-converting electromagnetic signals |
| US7010559B2 (en) | 2000-11-14 | 2006-03-07 | Parkervision, Inc. | Method and apparatus for a parallel correlator and applications thereof |
| US7027786B1 (en) | 1998-10-21 | 2006-04-11 | Parkervision, Inc. | Carrier and clock recovery using universal frequency translation |
| US7039372B1 (en) | 1998-10-21 | 2006-05-02 | Parkervision, Inc. | Method and system for frequency up-conversion with modulation embodiments |
| US7054296B1 (en) | 1999-08-04 | 2006-05-30 | Parkervision, Inc. | Wireless local area network (WLAN) technology and applications including techniques of universal frequency translation |
| US7072390B1 (en) | 1999-08-04 | 2006-07-04 | Parkervision, Inc. | Wireless local area network (WLAN) using universal frequency translation technology including multi-phase embodiments |
| US7082171B1 (en) | 1999-11-24 | 2006-07-25 | Parkervision, Inc. | Phase shifting applications of universal frequency translation |
| US7085335B2 (en) | 2001-11-09 | 2006-08-01 | Parkervision, Inc. | Method and apparatus for reducing DC offsets in a communication system |
| US7110444B1 (en) | 1999-08-04 | 2006-09-19 | Parkervision, Inc. | Wireless local area network (WLAN) using universal frequency translation technology including multi-phase embodiments and circuit implementations |
| US7236754B2 (en) | 1999-08-23 | 2007-06-26 | Parkervision, Inc. | Method and system for frequency up-conversion |
| US7292835B2 (en) | 2000-01-28 | 2007-11-06 | Parkervision, Inc. | Wireless and wired cable modem applications of universal frequency translation technology |
| US7295826B1 (en) | 1998-10-21 | 2007-11-13 | Parkervision, Inc. | Integrated frequency translation and selectivity with gain control functionality, and applications thereof |
| US7321640B2 (en) | 2002-06-07 | 2008-01-22 | Parkervision, Inc. | Active polyphase inverter filter for quadrature signal generation |
| US7379883B2 (en) | 2002-07-18 | 2008-05-27 | Parkervision, Inc. | Networking methods and systems |
| US7454453B2 (en) | 2000-11-14 | 2008-11-18 | Parkervision, Inc. | Methods, systems, and computer program products for parallel correlation and applications thereof |
| US7460584B2 (en) | 2002-07-18 | 2008-12-02 | Parkervision, Inc. | Networking methods and systems |
| US7515896B1 (en) | 1998-10-21 | 2009-04-07 | Parkervision, Inc. | Method and system for down-converting an electromagnetic signal, and transforms for same, and aperture relationships |
| US7554508B2 (en) | 2000-06-09 | 2009-06-30 | Parker Vision, Inc. | Phased array antenna applications on universal frequency translation |
| US7599421B2 (en) | 1999-03-15 | 2009-10-06 | Parkervision, Inc. | Spread spectrum applications of universal frequency translation |
| US7693230B2 (en) | 1999-04-16 | 2010-04-06 | Parkervision, Inc. | Apparatus and method of differential IQ frequency up-conversion |
| US7724845B2 (en) | 1999-04-16 | 2010-05-25 | Parkervision, Inc. | Method and system for down-converting and electromagnetic signal, and transforms for same |
| US7773688B2 (en) | 1999-04-16 | 2010-08-10 | Parkervision, Inc. | Method, system, and apparatus for balanced frequency up-conversion, including circuitry to directly couple the outputs of multiple transistors |
| US8295406B1 (en) | 1999-08-04 | 2012-10-23 | Parkervision, Inc. | Universal platform module for a plurality of communication protocols |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US1361488A (en) * | 1920-03-31 | 1920-12-07 | American Telephone & Telegraph | Plural modulation system |
| US1830896A (en) * | 1928-01-19 | 1931-11-10 | American Telephone & Telegraph | Adjustable electric filter system |
| US1905714A (en) * | 1931-04-10 | 1933-04-25 | Bell Telephone Labor Inc | Signaling system |
| US2339633A (en) * | 1942-03-23 | 1944-01-18 | Bell Telephone Labor Inc | Variable selective system |
-
1943
- 1943-11-29 US US512115A patent/US2472798A/en not_active Expired - Lifetime
-
1944
- 1944-11-28 GB GB23737/44A patent/GB584769A/en not_active Expired
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US1361488A (en) * | 1920-03-31 | 1920-12-07 | American Telephone & Telegraph | Plural modulation system |
| US1830896A (en) * | 1928-01-19 | 1931-11-10 | American Telephone & Telegraph | Adjustable electric filter system |
| US1905714A (en) * | 1931-04-10 | 1933-04-25 | Bell Telephone Labor Inc | Signaling system |
| US2339633A (en) * | 1942-03-23 | 1944-01-18 | Bell Telephone Labor Inc | Variable selective system |
Cited By (108)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2635143A (en) * | 1948-02-24 | 1953-04-14 | Marconi S Wireless Telegrpah C | Variable electrical filter |
| US2923887A (en) * | 1955-11-29 | 1960-02-02 | Ross Radio Corp | Electronic circuit arrangement for the controlled amplification of a desired signal |
| US2951206A (en) * | 1957-11-15 | 1960-08-30 | Rca Corp | Variable delay line |
| US3505607A (en) * | 1966-11-19 | 1970-04-07 | Philips Corp | Arrangement for selecting in a correct phase relationship a characteristic component from a frequency spectrum |
| US6694128B1 (en) | 1998-08-18 | 2004-02-17 | Parkervision, Inc. | Frequency synthesizer using universal frequency translation technology |
| US8233855B2 (en) | 1998-10-21 | 2012-07-31 | Parkervision, Inc. | Up-conversion based on gated information signal |
| US20090221257A1 (en) * | 1998-10-21 | 2009-09-03 | Parkervision, Inc. | Method and System For Down-Converting An Electromagnetic Signal, And Transforms For Same, And Aperture Relationships |
| US6091940A (en) * | 1998-10-21 | 2000-07-18 | Parkervision, Inc. | Method and system for frequency up-conversion |
| US6266518B1 (en) | 1998-10-21 | 2001-07-24 | Parkervision, Inc. | Method and system for down-converting electromagnetic signals by sampling and integrating over apertures |
| US7376410B2 (en) | 1998-10-21 | 2008-05-20 | Parkervision, Inc. | Methods and systems for down-converting a signal using a complementary transistor structure |
| US6353735B1 (en) | 1998-10-21 | 2002-03-05 | Parkervision, Inc. | MDG method for output signal generation |
| US6370371B1 (en) | 1998-10-21 | 2002-04-09 | Parkervision, Inc. | Applications of universal frequency translation |
| US6421534B1 (en) | 1998-10-21 | 2002-07-16 | Parkervision, Inc. | Integrated frequency translation and selectivity |
| US6542722B1 (en) | 1998-10-21 | 2003-04-01 | Parkervision, Inc. | Method and system for frequency up-conversion with variety of transmitter configurations |
| US6560301B1 (en) | 1998-10-21 | 2003-05-06 | Parkervision, Inc. | Integrated frequency translation and selectivity with a variety of filter embodiments |
| US6580902B1 (en) | 1998-10-21 | 2003-06-17 | Parkervision, Inc. | Frequency translation using optimized switch structures |
| US8340618B2 (en) | 1998-10-21 | 2012-12-25 | Parkervision, Inc. | Method and system for down-converting an electromagnetic signal, and transforms for same, and aperture relationships |
| US8190108B2 (en) | 1998-10-21 | 2012-05-29 | Parkervision, Inc. | Method and system for frequency up-conversion |
| US6687493B1 (en) | 1998-10-21 | 2004-02-03 | Parkervision, Inc. | Method and circuit for down-converting a signal using a complementary FET structure for improved dynamic range |
| US6061551A (en) * | 1998-10-21 | 2000-05-09 | Parkervision, Inc. | Method and system for down-converting electromagnetic signals |
| US7308242B2 (en) | 1998-10-21 | 2007-12-11 | Parkervision, Inc. | Method and system for down-converting and up-converting an electromagnetic signal, and transforms for same |
| US7295826B1 (en) | 1998-10-21 | 2007-11-13 | Parkervision, Inc. | Integrated frequency translation and selectivity with gain control functionality, and applications thereof |
| US6798351B1 (en) | 1998-10-21 | 2004-09-28 | Parkervision, Inc. | Automated meter reader applications of universal frequency translation |
| US6813485B2 (en) | 1998-10-21 | 2004-11-02 | Parkervision, Inc. | Method and system for down-converting and up-converting an electromagnetic signal, and transforms for same |
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| US20050009494A1 (en) * | 1998-10-21 | 2005-01-13 | Parkervision, Inc. | Method and system for down-converting and up-converting an electromagnetic signal, and transforms for same |
| US7389100B2 (en) | 1998-10-21 | 2008-06-17 | Parkervision, Inc. | Method and circuit for down-converting a signal |
| US6049706A (en) * | 1998-10-21 | 2000-04-11 | Parkervision, Inc. | Integrated frequency translation and selectivity |
| US7321735B1 (en) | 1998-10-21 | 2008-01-22 | Parkervision, Inc. | Optical down-converter using universal frequency translation technology |
| US6061555A (en) * | 1998-10-21 | 2000-05-09 | Parkervision, Inc. | Method and system for ensuring reception of a communications signal |
| US8190116B2 (en) | 1998-10-21 | 2012-05-29 | Parker Vision, Inc. | Methods and systems for down-converting a signal using a complementary transistor structure |
| US6647250B1 (en) | 1998-10-21 | 2003-11-11 | Parkervision, Inc. | Method and system for ensuring reception of a communications signal |
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| US7016663B2 (en) | 1998-10-21 | 2006-03-21 | Parkervision, Inc. | Applications of universal frequency translation |
| US7027786B1 (en) | 1998-10-21 | 2006-04-11 | Parkervision, Inc. | Carrier and clock recovery using universal frequency translation |
| US7039372B1 (en) | 1998-10-21 | 2006-05-02 | Parkervision, Inc. | Method and system for frequency up-conversion with modulation embodiments |
| US7050508B2 (en) | 1998-10-21 | 2006-05-23 | Parkervision, Inc. | Method and system for frequency up-conversion with a variety of transmitter configurations |
| US8019291B2 (en) | 1998-10-21 | 2011-09-13 | Parkervision, Inc. | Method and system for frequency down-conversion and frequency up-conversion |
| US7937059B2 (en) | 1998-10-21 | 2011-05-03 | Parkervision, Inc. | Converting an electromagnetic signal via sub-sampling |
| US7936022B2 (en) | 1998-10-21 | 2011-05-03 | Parkervision, Inc. | Method and circuit for down-converting a signal |
| US7076011B2 (en) | 1998-10-21 | 2006-07-11 | Parkervision, Inc. | Integrated frequency translation and selectivity |
| US7865177B2 (en) | 1998-10-21 | 2011-01-04 | Parkervision, Inc. | Method and system for down-converting an electromagnetic signal, and transforms for same, and aperture relationships |
| US7826817B2 (en) | 1998-10-21 | 2010-11-02 | Parker Vision, Inc. | Applications of universal frequency translation |
| US7697916B2 (en) | 1998-10-21 | 2010-04-13 | Parkervision, Inc. | Applications of universal frequency translation |
| US7693502B2 (en) | 1998-10-21 | 2010-04-06 | Parkervision, Inc. | Method and system for down-converting an electromagnetic signal, transforms for same, and aperture relationships |
| US7620378B2 (en) | 1998-10-21 | 2009-11-17 | Parkervision, Inc. | Method and system for frequency up-conversion with modulation embodiments |
| US7245886B2 (en) | 1998-10-21 | 2007-07-17 | Parkervision, Inc. | Method and system for frequency up-conversion with modulation embodiments |
| US7218907B2 (en) | 1998-10-21 | 2007-05-15 | Parkervision, Inc. | Method and circuit for down-converting a signal |
| US7515896B1 (en) | 1998-10-21 | 2009-04-07 | Parkervision, Inc. | Method and system for down-converting an electromagnetic signal, and transforms for same, and aperture relationships |
| US7529522B2 (en) | 1998-10-21 | 2009-05-05 | Parkervision, Inc. | Apparatus and method for communicating an input signal in polar representation |
| US20010027561A1 (en) * | 1998-11-30 | 2001-10-04 | Microsoft Corporation | Video on demand methods and systems |
| US7006805B1 (en) | 1999-01-22 | 2006-02-28 | Parker Vision, Inc. | Aliasing communication system with multi-mode and multi-band functionality and embodiments thereof, such as the family radio service |
| US6704558B1 (en) | 1999-01-22 | 2004-03-09 | Parkervision, Inc. | Image-reject down-converter and embodiments thereof, such as the family radio service |
| US7483686B2 (en) | 1999-03-03 | 2009-01-27 | Parkervision, Inc. | Universal platform module and methods and apparatuses relating thereto enabled by universal frequency translation technology |
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| US6704549B1 (en) | 1999-03-03 | 2004-03-09 | Parkvision, Inc. | Multi-mode, multi-band communication system |
| US7599421B2 (en) | 1999-03-15 | 2009-10-06 | Parkervision, Inc. | Spread spectrum applications of universal frequency translation |
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| US7272164B2 (en) | 1999-04-16 | 2007-09-18 | Parkervision, Inc. | Reducing DC offsets using spectral spreading |
| US7724845B2 (en) | 1999-04-16 | 2010-05-25 | Parkervision, Inc. | Method and system for down-converting and electromagnetic signal, and transforms for same |
| US7693230B2 (en) | 1999-04-16 | 2010-04-06 | Parkervision, Inc. | Apparatus and method of differential IQ frequency up-conversion |
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| US7894789B2 (en) | 1999-04-16 | 2011-02-22 | Parkervision, Inc. | Down-conversion of an electromagnetic signal with feedback control |
| US7773688B2 (en) | 1999-04-16 | 2010-08-10 | Parkervision, Inc. | Method, system, and apparatus for balanced frequency up-conversion, including circuitry to directly couple the outputs of multiple transistors |
| US7072390B1 (en) | 1999-08-04 | 2006-07-04 | Parkervision, Inc. | Wireless local area network (WLAN) using universal frequency translation technology including multi-phase embodiments |
| US7054296B1 (en) | 1999-08-04 | 2006-05-30 | Parkervision, Inc. | Wireless local area network (WLAN) technology and applications including techniques of universal frequency translation |
| US8295406B1 (en) | 1999-08-04 | 2012-10-23 | Parkervision, Inc. | Universal platform module for a plurality of communication protocols |
| US7653145B2 (en) | 1999-08-04 | 2010-01-26 | Parkervision, Inc. | Wireless local area network (WLAN) using universal frequency translation technology including multi-phase embodiments and circuit implementations |
| US7110444B1 (en) | 1999-08-04 | 2006-09-19 | Parkervision, Inc. | Wireless local area network (WLAN) using universal frequency translation technology including multi-phase embodiments and circuit implementations |
| US7546096B2 (en) | 1999-08-23 | 2009-06-09 | Parkervision, Inc. | Frequency up-conversion using a harmonic generation and extraction module |
| US7236754B2 (en) | 1999-08-23 | 2007-06-26 | Parkervision, Inc. | Method and system for frequency up-conversion |
| US7379515B2 (en) | 1999-11-24 | 2008-05-27 | Parkervision, Inc. | Phased array antenna applications of universal frequency translation |
| US7082171B1 (en) | 1999-11-24 | 2006-07-25 | Parkervision, Inc. | Phase shifting applications of universal frequency translation |
| US6963734B2 (en) | 1999-12-22 | 2005-11-08 | Parkervision, Inc. | Differential frequency down-conversion using techniques of universal frequency translation technology |
| US7292835B2 (en) | 2000-01-28 | 2007-11-06 | Parkervision, Inc. | Wireless and wired cable modem applications of universal frequency translation technology |
| US7386292B2 (en) | 2000-04-14 | 2008-06-10 | Parkervision, Inc. | Apparatus, system, and method for down-converting and up-converting electromagnetic signals |
| US7822401B2 (en) | 2000-04-14 | 2010-10-26 | Parkervision, Inc. | Apparatus and method for down-converting electromagnetic signals by controlled charging and discharging of a capacitor |
| US8295800B2 (en) | 2000-04-14 | 2012-10-23 | Parkervision, Inc. | Apparatus and method for down-converting electromagnetic signals by controlled charging and discharging of a capacitor |
| US7010286B2 (en) | 2000-04-14 | 2006-03-07 | Parkervision, Inc. | Apparatus, system, and method for down-converting and up-converting electromagnetic signals |
| US7218899B2 (en) | 2000-04-14 | 2007-05-15 | Parkervision, Inc. | Apparatus, system, and method for up-converting electromagnetic signals |
| US7107028B2 (en) | 2000-04-14 | 2006-09-12 | Parkervision, Inc. | Apparatus, system, and method for up converting electromagnetic signals |
| US7496342B2 (en) | 2000-04-14 | 2009-02-24 | Parkervision, Inc. | Down-converting electromagnetic signals, including controlled discharge of capacitors |
| US7554508B2 (en) | 2000-06-09 | 2009-06-30 | Parker Vision, Inc. | Phased array antenna applications on universal frequency translation |
| US7454453B2 (en) | 2000-11-14 | 2008-11-18 | Parkervision, Inc. | Methods, systems, and computer program products for parallel correlation and applications thereof |
| US7010559B2 (en) | 2000-11-14 | 2006-03-07 | Parkervision, Inc. | Method and apparatus for a parallel correlator and applications thereof |
| US7433910B2 (en) | 2000-11-14 | 2008-10-07 | Parkervision, Inc. | Method and apparatus for the parallel correlator and applications thereof |
| US7991815B2 (en) | 2000-11-14 | 2011-08-02 | Parkervision, Inc. | Methods, systems, and computer program products for parallel correlation and applications thereof |
| US7233969B2 (en) | 2000-11-14 | 2007-06-19 | Parkervision, Inc. | Method and apparatus for a parallel correlator and applications thereof |
| US20030128776A1 (en) * | 2001-11-09 | 2003-07-10 | Parkervision, Inc | Method and apparatus for reducing DC off sets in a communication system |
| US7085335B2 (en) | 2001-11-09 | 2006-08-01 | Parkervision, Inc. | Method and apparatus for reducing DC offsets in a communication system |
| US7653158B2 (en) | 2001-11-09 | 2010-01-26 | Parkervision, Inc. | Gain control in a communication channel |
| US7072427B2 (en) | 2001-11-09 | 2006-07-04 | Parkervision, Inc. | Method and apparatus for reducing DC offsets in a communication system |
| US8446994B2 (en) | 2001-11-09 | 2013-05-21 | Parkervision, Inc. | Gain control in a communication channel |
| US6975848B2 (en) | 2002-06-04 | 2005-12-13 | Parkervision, Inc. | Method and apparatus for DC offset removal in a radio frequency communication channel |
| US7321640B2 (en) | 2002-06-07 | 2008-01-22 | Parkervision, Inc. | Active polyphase inverter filter for quadrature signal generation |
| US7460584B2 (en) | 2002-07-18 | 2008-12-02 | Parkervision, Inc. | Networking methods and systems |
| US8407061B2 (en) | 2002-07-18 | 2013-03-26 | Parkervision, Inc. | Networking methods and systems |
| US7379883B2 (en) | 2002-07-18 | 2008-05-27 | Parkervision, Inc. | Networking methods and systems |
| US8160196B2 (en) | 2002-07-18 | 2012-04-17 | Parkervision, Inc. | Networking methods and systems |
Also Published As
| Publication number | Publication date |
|---|---|
| GB584769A (en) | 1947-01-22 |
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