DK162000B - NOISE REDUCTION SYSTEM, FOR FM RADIO RECEIVERS, AT LOW SIGNAL LEVELS. - Google Patents

NOISE REDUCTION SYSTEM, FOR FM RADIO RECEIVERS, AT LOW SIGNAL LEVELS. Download PDF

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Publication number
DK162000B
DK162000B DK200886A DK200886A DK162000B DK 162000 B DK162000 B DK 162000B DK 200886 A DK200886 A DK 200886A DK 200886 A DK200886 A DK 200886A DK 162000 B DK162000 B DK 162000B
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Prior art keywords
intermediate frequency
oscillator
pll loop
frequency
band
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DK200886A
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Danish (da)
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DK200886D0 (en
DK162000C (en
DK200886A (en
Inventor
Bernhard-Michael Katzy
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Bosch Gmbh Robert
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Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03D—DEMODULATION OR TRANSFERENCE OF MODULATION FROM ONE CARRIER TO ANOTHER
    • H03D3/00—Demodulation of angle-, frequency- or phase- modulated oscillations
    • H03D3/001—Details of arrangements applicable to more than one type of frequency demodulator
    • H03D3/003—Arrangements for reducing frequency deviation, e.g. by negative frequency feedback
    • H03D3/004—Arrangements for reducing frequency deviation, e.g. by negative frequency feedback wherein the demodulated signal is used for controlling an oscillator, e.g. the local oscillator
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03J—TUNING RESONANT CIRCUITS; SELECTING RESONANT CIRCUITS
    • H03J7/00—Automatic frequency control; Automatic scanning over a band of frequencies
    • H03J7/02—Automatic frequency control
    • H03J7/04—Automatic frequency control where the frequency control is accomplished by varying the electrical characteristics of a non-mechanically adjustable element or where the nature of the frequency controlling element is not significant
    • H03J7/06—Automatic frequency control where the frequency control is accomplished by varying the electrical characteristics of a non-mechanically adjustable element or where the nature of the frequency controlling element is not significant using counters or frequency dividers
    • H03J7/065—Automatic frequency control where the frequency control is accomplished by varying the electrical characteristics of a non-mechanically adjustable element or where the nature of the frequency controlling element is not significant using counters or frequency dividers the counter or frequency divider being used in a phase locked loop

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Superheterodyne Receivers (AREA)
  • Input Circuits Of Receivers And Coupling Of Receivers And Audio Equipment (AREA)
  • Circuits Of Receivers In General (AREA)
  • Noise Elimination (AREA)

Abstract

1. An FM radio receiver having a mixing- and oscillator circuit for forming an intermediate frequency, an intermediate frequency band-pass filter (12), an intermediate frequency amplifier (13), a demodulator (13) for demodulating the intermediate frequency and a first (17) and second phase-locked loop (33), wherein a voltage-controlled oscillator (38) of the second phase-locked loop forms the oscillator of the mixing- and oscillator circuit, characterised in that the first phase-locked loop (17) between the intermediate frequency band-pass filter (12) and the intermediate frequency amplifier (13) is connected in series with a second band-pass filter (26) which is a narrow band filter compared with the first intermediate frequency signal, wherein the first phase-locked loop contributing to the reduction of the noise level of the intermediate frequency signal supplies its output signal to a first input (31) of a phase detector (32) which forms part of the second phase-locked loop (33) and the second input (34) of which carries a reference frequency signal, and that the second phase-locked loop readjusts the intermediate frequency to the midband of the narrow band filter.

Description

DK 162000 BDK 162000 B

Opfindelsen tager udgangspunkt i et støjreduktionssystem, til PM-radiomodtager, ved lave signalniveauer som omhandlet i indledningen til krav l.The invention is based on a noise reduction system, for PM radio receivers, at low signal levels as defined in the preamble of claim 1.

Der kendes et filter- og demodulationskredsløb 5 til PM-radiomodtagere, jf. tysk offentliggørelsesskrift nr. 32 31 708, hvis følsomhed ved lave modtagefeltstyrker trænger til forbedring. Hvis nemlig modtagefeltstyrken underskrider en bestemt værdi, bliver nyttesignalet overdøvet af modtagerstøj.A filter and demodulation circuit 5 is known to PM radio receivers, cf. German Publication No. 32 31 708, whose sensitivity at low receive field strengths needs improvement. If the receive field strength falls below a certain value, the utility signal is dimmed by receiver noise.

10 Fordele ved opfindelsen.10 Advantages of the Invention.

FM-radiomodtageren ifølge opfindelsen med de karakteristiske træk, der er angivet i krav 1, har den fordel, at støjniveauet reduceres ved små modtagefeltstyrker, idet båndbredden ved selektionen reduceres.The FM radio receiver according to the invention, with the characteristic features of claim 1, has the advantage of reducing the noise level at small receiving field strengths, as the bandwidth of the selection is reduced.

15 Med de i underkravene angivne træk muliggøres fordelagtige videreudviklinger og forbedringer af den i krav 1 angivne PM-radiomodtager. Særlig fordelagtig er en FM-radiomodtager ifølge opfindelsen, hvor der mellem mellemfrekvensbåndfiltret og den første PLL-sløjfe lig-20 ger en omskifter, som i en første kontaktstilling forbinder mellemfrekvensbåndfiltret umiddelbart med mellemfrekvensforstærkeren og i en anden kontaktstilling forbinder mellemfrekvensbåndfiltret med mellemfrekvensforstærkeren over en forstærker, en tærskelkobler og 25 den første PLL-sløjfe. En FM-radiomodtager med de forannævnte træk har den fordel, at der altid, hvis den øjeblikkelige modtagefeltstyrke er forholdsvis ringe, ved betjening af en omskifter manuelt eller automatisk i afhængighed af mellemfrekvenssignalniveauet opnås en 30 betydelig forøgelse af følsomheden. Dermed indskrænkes samtidigt støj båndbredden, og også modtagelsen ved fremmedstøj forbedres. Opfindelsen kan i øvrigt også med fordel anvendes i en modtager til fasemodulation, dvs. en PM-modtager.With the features specified in the subclaims, advantageous further developments and improvements to the PM radio receiver as claimed in claim 1 are possible. Particularly advantageous is an FM radio receiver according to the invention, where between the intermediate frequency band filter and the first PLL loop lies a switch which in a first contact position connects the intermediate frequency band directly to the intermediate frequency amplifier and in a second contact position an intermediate frequency band amplifier connects to the intermediate frequency amplifier filter. a threshold coupler and 25 the first PLL loop. An FM radio receiver having the aforementioned features has the advantage that, if the current receiving field strength is relatively low, when operating a switch manually or automatically depending on the medium frequency signal level, a considerable increase in sensitivity is achieved. This simultaneously reduces the bandwidth noise and also the reception of foreign noise improves. The invention can also advantageously be used in a phase modulation receiver, i.e. a PM receiver.

35 Tegningen.35 The drawing.

To udførelseseksempler ifølge opfindelsen er i det følgende forklaret nærmere med henvisning til tegningen, hvor 2Two embodiments of the invention are explained in more detail below with reference to the drawing, in which 2

DK 162000 BDK 162000 B

fig. 1 viser et blokdiagram over en mellemfrekvensdel og en demodulator i en FM-radiomodtager ifølge opfindelsen, og fig. 2 et blokdiagram over en omskifterautomatik 5 til en FM-radiomodtager ifølge opfindelsen.FIG. 1 is a block diagram of an intermediate frequency portion and a demodulator of an FM radio receiver according to the invention; and FIG. 2 is a block diagram of an automatic switch 5 for an FM radio receiver according to the invention.

Beskrivelse af opfindelsen.Description of the Invention

I det i fig. 1 viste blokdiagram over en FM-ra-diomodtagerkobling betegner 10 en indgang, som får tilført en modtagefrekvens fE eller en af modtage-10 frekvensen afledet første mellemfrekvens fzl. i det følgende gås der ud fra, at frekvensen på indgangen 10 er en første mellemfrekvens fzl. Efter indgangen 10 følger et blandingstrin 11, som efterfølges af et mellemfrekvensbåndfilter 12, der fortrinsvis er et på 15 en anden mellemfrekvens fZ2 på f.eks. 455 kHz afstemt keramisk filter med en forholdsvis stor båndbredde på f.eks. 14 kHz. Mellem mellemfrekvensbåndfiltret 12 og en mellemfrekvenskomponent 13, som omfatter en mellemfrekvensforstærker, en mellemfrekvensbegrænser og en 20 demodulator, ligger der en manuelt betjenelig omskifter 14, som i den ene kontaktstilling forbinder mellemfrek-vensbåndfiltret 12 med mellemfrekvenskomponenten 13 og i den anden kontaktstilling forbinder mellemfrekvensbånd filtret 12 over en forstærker 15 og en 25 tærskelkobler 16, der fortrinsvis er en Schmidt-trigger, med en første PLL(Phase-locked loop)-sløjfe 17. Den første PLL-sløjfe har en fasedetektor 18, hvis første indgang 19 (referencefrekvensindgang) er forbundet med tærskelkobleren, og hvis anden indgang 20 30 er forbundet med en første udgang 21 på en første spændingsstyret oscillator 22. En udgang på fasedetektoren 18 står over et lavpasfilter 23 i forbindelse med den spændingsstyrede oscillator 22*s indgang. En anden udgang 24 på den spændingsstyrede os-35 cillator 22 er over et båndfilter 26, der fortrinsvis er et på en frekvens fBF på 455 kHz afstemt kera-In the embodiment of FIG. 1 is a block diagram of an FM radio receiver coupler 10 denotes an input which is supplied with a receive frequency fE or a first intermediate frequency fz1 derived from the receive-10 frequency. in the following, it is assumed that the frequency of the input 10 is a first intermediate frequency fz1. Following the input 10 is a mixing step 11 followed by an intermediate frequency band filter 12, which is preferably one of 15 another intermediate frequency fZ2 of e.g. 455 kHz tuned ceramic filter with a relatively large bandwidth of e.g. 14 kHz. Between the intermediate frequency band filter 12 and an intermediate frequency component 13 which comprises an intermediate frequency amplifier, an intermediate frequency limiter and a demodulator, there is a manually operated switch 14 which in one contact position connects the intermediate frequency band filter 12 with the intermediate frequency component 12 and the other frequency component 13 and in the other frequency component over an amplifier 15 and a threshold coupler 16, which is preferably a Schmidt trigger, with a first PLL (Phase-locked loop) loop 17. The first PLL loop has a phase detector 18 whose first input 19 (reference frequency input) is connected to the threshold coupler, and whose second input 20 30 is connected to a first output 21 of a first voltage controlled oscillator 22. An output of the phase detector 18 faces a low pass filter 23 in connection with the input of the voltage controlled oscillator 22 *. Another output 24 of the voltage controlled oscillator 22 is over a band filter 26, which is preferably a 455 kHz frequency tuned to a frequency fBF of 455 kHz.

DK 162000 BDK 162000 B

3 mikfilter med en forholdsvis lille båndbredde på f.eks. kun 4 kHz, forbundet med indgangen på mellemfrekvenskomponenten 13, som efterfølges af en lavfrekvensforforstærker 27 og et lavfrekvens-båndpasfilter 28.3 microfilters with a relatively small bandwidth of e.g. only 4 kHz, connected to the input of the intermediate frequency component 13, which is followed by a low frequency amplifier 27 and a low frequency bandpass filter 28.

5 Den første spændingsstyrede oscillator 22 i den første PLL-sløjfe 17 er over en første frekvensdeler 30 forbundet med en første indgang 31 på en fasedetektor 32, som hører til en anden PLL-sløjfe 33, der omfatter den første PLL-sløjfe 17. På en an-10 den indgang 34 på fasedetektoren 32 ligger der en referencefrekvens fR2 på f.eks. 5 kHz, som afledes fra en frekvens fg på f.eks. 6,4 MHz fra en krystalstabiliseret oscillator 35 ved hjælp af en anden frekvensdeler 36, der f.eks. har et deleforhold på 15 1:1280. En udgang på fasedetektoren 32 står over et lavpasfilter 37 i forbindelse med en reguleringsspændingsindgang 38 på en spændingsstyret oscillator 39, hvis oscillatorfrekvens f0 på f.eks. 21,855 kHz tilføres en oscillatorfrekvensindgang 40 på blandings-20 trinnet 11.The first voltage controlled oscillator 22 of the first PLL loop 17 is connected over a first frequency divider 30 to a first input 31 of a phase detector 32 belonging to a second PLL loop 33 comprising the first PLL loop 17. a second input 34 of the phase detector 32 has a reference frequency fR2 of e.g. 5 kHz, which is derived from a frequency fg of e.g. 6.4 MHz from a crystal stabilized oscillator 35 by means of a second frequency divider 36, e.g. has a pitch ratio of 15 1: 1280. An output of phase detector 32 faces a low-pass filter 37 in conjunction with a regulating voltage input 38 of a voltage controlled oscillator 39, whose oscillator frequency f0 of e.g. At 21.855 kHz, an oscillator frequency input 40 is applied to the mixer stage 11.

Den i det foranstående beskrevne koblings virkemåde er følgende.The operation of the coupling described above is as follows.

Ud fra den første mellemfrekvens fzl danner blandingstrinnet 11 i forbindelse med den spændings-25 styrede oscillator 39 den anden mellemfrekvens fZ2/ som ved den i fig. 1 viste kontaktstilling af omskifteren 14 på sædvanlig måde i mellemfrekvenskomponenten 13 bliver forstærket, begrænset og demoduleret. Det ved demodulationen opnåede lavfrekvenssignal forstærkes 30 i lavfrekvensforstærkeren 27 og selekteres ved hjælp af lavfrekvens-båndpasfiltret 28. Efter båndpasfilt-ret følger på kendt måde en lavfrekvens-udgangsforstærker og en højttaler. Ved den i det foranstående beskrevne kontaktstilling af omskifteren 14 har FM-ra-35 diomodtageren en normal følsomhed, der ved en tilstrækkelig modtagefeltstyrke fører til en tilfredsstillende modtagekvalitet.From the first intermediate frequency fz1, the mixing stage 11 in conjunction with the voltage controlled oscillator 39 forms the second intermediate frequency fZ2 / as in the case of FIG. 1, the switching position 14 of the switch 14 in the usual way in the intermediate frequency component 13 is amplified, limited and demodulated. The low-frequency signal obtained by demodulation is amplified 30 in the low-frequency amplifier 27 and selected by the low-frequency band-pass filter 28. Following the band-pass filter, a low-frequency output amplifier and a speaker are known in the known manner. At the above described switching position of switch 14, the FM radio receiver has a normal sensitivity which at a sufficient reception field strength leads to a satisfactory reception quality.

44

DK 162000 BDK 162000 B

Hvis omskifteren 14 ved en kun ringe modtagefeltstyrke omskiftes til sin anden kontaktstilling, afbrydes den umiddelbare forbindelse mellem mellemfrek-vensbåndfiltret 12 og mellemfrekvenskomponenten 13.If the switch 14 is switched to its second contact position at only a low receiving field strength, the immediate connection between the intermediate frequency band filter 12 and the intermediate frequency component 13 is interrupted.

5 Den anden mellemfrekvens fz2 bliver over omskifteren 14 efter forstærkning i forstærkeren 15 tilført tærskelkobleren 16, som ud fra det tilnærmelsesvis sinusformede mellemfrekvenssignal med frekvensen fZ2 danner et firkantformet signal, der som referencesignal 10 med referencefrekvensen fR1 tilføres den første indgang 19 på fasedetektoren 18 i den første PLL-sløj-fe 17. Den første PLL-sløjfe sørger for, at den spændingsstyrede oscillator 22 over sine udgange 21 og 24 afgiver en oscillatorfrekvens, som er fast koblet 15 med den første referencefrekvens fRl* Den første PLL-sløjfe bevirker, at den af den spændingsstyrede oscillator 22 afgivne oscillatorfrekvens moduleres med lavfrekvenssignalet. Den modulerede oscillatorfrekvens fRl tilføres det smalbåndede båndfilter 26. Det med 20 hensyn til båndbredden begrænsede signal når da frem til indgangen på mellemfrekvenskomponenten 13. Den spændingsstyrede oscillator 22's oscillatorfrekvens bliver samtidigt over den første frekvensdeler 30 tilført den første indgang 31 på fasedetektoren 32 i 25 den anden PLLsløjfe 33. Den anden PLL-sløjfe skal bevirke, at mellemfrekvenssignalet med frekvensen fz2 trækkes til båndmidten af det smalbåndede båndfilter 26. Den anden fasedetektor 32 sammenligner den delte oscillatorfrekvens fra den spændingsstyrede oscillator 30 22 med den krystalstabiliserede anden referencefrek vens fR2. Den af den anden fasedetektor 32 afgivne reguleringssignalspænding UR bliver over lavpasfilt-ret 37 tilført den spændingsstyrede oscillator 39, der fortrinsvis er en ved hjælp af en kapacitetsdiode 35 styrbar krystaloscillator, som leverer oscillatorfre-kvensen fQ. Den anden PLL-sløjfe 33 holder mellem-5 The second intermediate frequency fz2 is applied to the switch coupler 16 over the switch 14 after amplification in the amplifier 15, which, from the approximately sinusoidal intermediate frequency signal with the frequency fZ2, generates a square-shaped signal which is applied to the first input 19 as the reference signal 10 with the reference frequency fR1. first PLL loop 17. The first PLL loop causes the voltage controlled oscillator 22 to output over its outputs 21 and 24 an oscillator frequency which is permanently coupled 15 with the first reference frequency fRl * The first PLL loop causes the oscillator frequency delivered by the voltage controlled oscillator 22 is modulated by the low frequency signal. The modulated oscillator frequency fR1 is applied to the narrow band band filter 26. The signal limited to 20 in the bandwidth then reaches the input of the intermediate frequency component 13. The oscillator frequency of the voltage controlled oscillator 22 is simultaneously applied to the first input 31 of the phase detector over the first frequency divider 30 second PLL loop 33. The second PLL loop must cause the intermediate frequency signal of frequency fz2 to be drawn to the band center of the narrow band band filter 26. The second phase detector 32 compares the split oscillator frequency of the voltage controlled oscillator 30 22 with the crystal stabilized f2. The regulating signal voltage UR delivered by the second phase detector 32 is applied to the low-pass filter 37 to the voltage controlled oscillator 39, which is preferably a crystal oscillator controllable by a capacitance diode 35, which supplies the oscillator frequency fQ. The second PLL loop 33 holds intermediate

Claims (6)

1. Støjreduktionssystem, til FM-radiomodta-25 ger, ved lave signalniveauer med en blandings- og oscillatorkobling til dannelse af en mellemfrekvens, med en mellemfrekvensforstærker og en demodulator til demodulering af mellemfrekvensen, kendetegnet ved, at der mellem et mellemfrekvensbåndfilter (12), 30 som slutter sig til blandings- og oscillatorkoblingens (11,39) udgang, og mellemfrekvensforstærkeren (13) ligger en første PLL-sløjfe (17) og et i sammenligning med mellemfrekvenssignalet smalbåndet båndfilter (26) i serie, og ved, at den til reduktion af mellemfrekvenssig-35 nalets støj andel bidragende første PLL-sløjfe afgiver sit udgangssignal til fasedetektoren (32) i en anden DK 162000 B PLL-sløjfe (33), som efterregulerer mellemfrekvensen til det smalbåndede båndfilters (26) båndmidte, og at en spændingsstyret oscillator (39) i den anden PLL-sløjfe udgør blandings- og oscillatorkredsløbets oscil-5 lator.1. Noise reduction system, for FM radio receivers, at low signal levels with a mixing and oscillator coupling to form an intermediate frequency, with an intermediate frequency amplifier and a demodulator for demodulation of the intermediate frequency, characterized in that between an intermediate frequency band filter (12), 30, which joins the output of the mixer and oscillator coupling (11,39), and the intermediate frequency amplifier (13) provides a first PLL loop (17) and a narrow band narrowband filter (26) in series, and reduction of the mid-frequency signal noise's proportion of contributing first PLL loop outputs its output to the phase detector (32) in a second DK 162000 B PLL loop (33), which regulates the intermediate frequency of the narrow band band filter (26) and that a voltage controlled oscillator (39) in the second PLL loop constitutes the oscillator of the mixing and oscillator circuit. 2. Modtager ifølge krav 1, kendetegnet ved, at der mellem mellemfrekvensbåndfiltret (12) og den første PLL-sløjfe (17) ligger en omskifter (14), som i en første koblestilling forbinder mellemfrekvens-10 båndfiltret umiddelbart med mellemfrekvensforstærkeren og i en anden koblestilling forbinder mellemfrekvens-båndfiltret med mellemfrekvensforstærkeren over en forstærker (15), en tærskelkobler (16), den første PLL-sløjfe (17) og det smalbåndede båndfilter (26).Receiver according to claim 1, characterized in that between the intermediate frequency band filter (12) and the first PLL loop (17) lies a switch (14) which in a first switching position connects the intermediate frequency band filter directly with the intermediate frequency amplifier and in a second one. switching position connects the medium frequency band filter to the medium frequency amplifier over an amplifier (15), a threshold coupler (16), the first PLL loop (17) and the narrow band band filter (26). 3. Modtager ifølge krav 1 eller 2, kende tegnet ved, at referencefrekvensindgangen (34) på fasedetektoren (32) i den anden PLL-sløjfe (33) får påtrykt en krystalstabiliseret referencefrekvens (fR2).Receiver according to claim 1 or 2, characterized in that a crystal stabilized reference frequency (fR2) is applied to the reference frequency input (34) of the phase detector (32) in the second PLL loop (33). 4. Modtager ifølge krav 1 eller 2, kende-20 tegnet ved, at båndfiltrene (12, 26) er keramiske filtre.Receiver according to claim 1 or 2, characterized in that the band filters (12, 26) are ceramic filters. 5. Modtager ifølge krav 1, kendetegnet ved, at den til blandingstrinnet (11) hørende spændingsstyrede oscillator (39) er en krystaloscillator.Receiver according to claim 1, characterized in that the voltage controlled oscillator (39) of the mixing stage (11) is a crystal oscillator. 6. Modtager ifølge krav 1, kendeteg net ved, at omskifteren er en i afhængighed af mellemfrekvenssignalets niveau styret omskifter (51, 52).Receiver according to claim 1, characterized in that the switch is a switch (51, 52) controlled according to the level of the intermediate frequency signal.
DK200886A 1985-05-02 1986-05-01 NOISE REDUCTION SYSTEM, FOR FM RADIO RECEIVERS, AT LOW SIGNAL LEVELS. DK162000C (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19853515746 DE3515746A1 (en) 1985-05-02 1985-05-02 FM RADIO RECEIVER
DE3515746 1985-05-02

Publications (4)

Publication Number Publication Date
DK200886D0 DK200886D0 (en) 1986-05-01
DK200886A DK200886A (en) 1986-11-03
DK162000B true DK162000B (en) 1991-09-02
DK162000C DK162000C (en) 1992-02-10

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ID=6269616

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Application Number Title Priority Date Filing Date
DK200886A DK162000C (en) 1985-05-02 1986-05-01 NOISE REDUCTION SYSTEM, FOR FM RADIO RECEIVERS, AT LOW SIGNAL LEVELS.

Country Status (4)

Country Link
EP (1) EP0199887B1 (en)
AT (1) ATE45450T1 (en)
DE (2) DE3515746A1 (en)
DK (1) DK162000C (en)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2596220A1 (en) * 1986-03-21 1987-09-25 Portenseigne FREQUENCY DEMODULATOR
EP0276144B1 (en) * 1987-01-20 1993-11-18 Matsushita Electric Industrial Co., Ltd. Signal receiver for terrestrial and satellite broadcastings
CA2071421C (en) * 1991-06-19 2000-08-08 Yoshiaki Kumagai Automatic frequency control circuit
CH702685B1 (en) * 1999-10-06 2011-08-31 Richemont Int Sa frequency modulation receiver, particularly an RDS application.

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3530383A (en) * 1966-11-18 1970-09-22 Itt Ultra-sensitive receiver
JPS5643809A (en) * 1979-09-19 1981-04-22 Hitachi Ltd Automatic gain controller
GB2079552B (en) * 1980-07-02 1984-02-01 Philips Electronic Associated Double phase lock loop
DE3231708A1 (en) * 1982-08-26 1984-03-01 Robert Bosch Gmbh, 7000 Stuttgart Filter and demodulation circuit

Also Published As

Publication number Publication date
DK200886D0 (en) 1986-05-01
DE3664990D1 (en) 1989-09-14
EP0199887A3 (en) 1987-12-23
DK162000C (en) 1992-02-10
DE3515746A1 (en) 1986-11-06
EP0199887B1 (en) 1989-08-09
ATE45450T1 (en) 1989-08-15
DK200886A (en) 1986-11-03
EP0199887A2 (en) 1986-11-05

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