DE3726181A1 - Process for the superheterodyne reception of a modulated signal - Google Patents

Process for the superheterodyne reception of a modulated signal

Info

Publication number
DE3726181A1
DE3726181A1 DE19873726181 DE3726181A DE3726181A1 DE 3726181 A1 DE3726181 A1 DE 3726181A1 DE 19873726181 DE19873726181 DE 19873726181 DE 3726181 A DE3726181 A DE 3726181A DE 3726181 A1 DE3726181 A1 DE 3726181A1
Authority
DE
Germany
Prior art keywords
frequency
local oscillator
premixer
oscillator
mixers
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
DE19873726181
Other languages
German (de)
Inventor
Walter Vollenweider
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Autophon AG
Original Assignee
Autophon AG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Autophon AG filed Critical Autophon AG
Publication of DE3726181A1 publication Critical patent/DE3726181A1/en
Withdrawn legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03D—DEMODULATION OR TRANSFERENCE OF MODULATION FROM ONE CARRIER TO ANOTHER
    • H03D7/00—Transference of modulation from one carrier to another, e.g. frequency-changing
    • H03D7/16—Multiple-frequency-changing
    • H03D7/161—Multiple-frequency-changing all the frequency changers being connected in cascade
    • H03D7/163—Multiple-frequency-changing all the frequency changers being connected in cascade the local oscillations of at least two of the frequency changers being derived from a single oscillator
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03B—GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING, BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN A NON-SWITCHING MANNER; GENERATION OF NOISE BY SUCH CIRCUITS
    • H03B1/00—Details
    • H03B1/04—Reducing undesired oscillations, e.g. harmonics
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03B—GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING, BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN A NON-SWITCHING MANNER; GENERATION OF NOISE BY SUCH CIRCUITS
    • H03B2200/00—Indexing scheme relating to details of oscillators covered by H03B
    • H03B2200/006—Functional aspects of oscillators
    • H03B2200/007—Generation of oscillations based on harmonic frequencies, e.g. overtone oscillators
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03B—GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING, BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN A NON-SWITCHING MANNER; GENERATION OF NOISE BY SUCH CIRCUITS
    • H03B2200/00—Indexing scheme relating to details of oscillators covered by H03B
    • H03B2200/006—Functional aspects of oscillators
    • H03B2200/0078—Functional aspects of oscillators generating or using signals in quadrature
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03B—GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING, BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN A NON-SWITCHING MANNER; GENERATION OF NOISE BY SUCH CIRCUITS
    • H03B2202/00—Aspects of oscillators relating to reduction of undesired oscillations
    • H03B2202/08—Reduction of undesired oscillations originated from the oscillator in circuit elements external to the oscillator by means associated with the oscillator
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03D—DEMODULATION OR TRANSFERENCE OF MODULATION FROM ONE CARRIER TO ANOTHER
    • H03D2200/00—Indexing scheme relating to details of demodulation or transference of modulation from one carrier to another covered by H03D
    • H03D2200/0041—Functional aspects of demodulators
    • H03D2200/009—Reduction of local oscillator or RF leakage
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03D—DEMODULATION OR TRANSFERENCE OF MODULATION FROM ONE CARRIER TO ANOTHER
    • H03D7/00—Transference of modulation from one carrier to another, e.g. frequency-changing
    • H03D7/16—Multiple-frequency-changing
    • H03D7/165—Multiple-frequency-changing at least two frequency changers being located in different paths, e.g. in two paths with carriers in quadrature

Landscapes

  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Superheterodyne Receivers (AREA)
  • Noise Elimination (AREA)

Abstract

In the superheterodyne receiver, the aerial 1 is followed by a prefilter 2, a preamplifier 3 and a premixer 4. The signal path then branches to the main mixers 5 and 6, which are in quadrature and the output signals of which are fed as intermediate frequency zero to the corresponding further inputs 5 and 6. These may be low-pass filters and further quadrature stages. The common local oscillator 9 supplies the three mixers 4, 5, 6 with an unmodulated signal of half the reception frequency, the phase upstream of the main mixer 5 being shifted through 90@ by the phase mixer 10. As a result, the oscillator signal cannot reradiate onto the aerial. The same isolating effect is obtained if, as a variant, different local oscillator frequencies are fed to the premixer 4 or possibly further premixers 4 on the one hand and to the main mixers 5, 6 on the other hand. A condition is that these frequencies deviate from the receiving frequency, so that interference voltages can be suppressed in the prefilter. There thus occurs a mixing down to zero in two or more stages. <IMAGE>

Description

Die Erfindung betrifft ein Verfahren zum Überlagerungs­ empfang eines modulierten Signals durch herabmischen desselben auf eine Null-Zwischenfrequenz, nach dem Oberbe­ griff des Patentanspruchs 1. Der Ausdruck "Null-Zwischen­ frequenz" wird hier verwendet um anzudeuten, daß das Mischergebnis ein mindstens die Modulation enthaltendes Signal ist, dessen Trägerfrequenz nominell Null ist, aber aus verschiedenen Gründen um einen kleinen Betrag von Null verschieden sein kann. Im folgenden soll dieser eventuelle Unterschied nicht berücksichtigt werden, d. h. es soll vereinfacht eine Zwischenfrequenz von Null angenommen werden.The invention relates to a method for superimposition receiving a modulated signal by mixing it down the same to a zero intermediate frequency, according to the Oberbe handle of claim 1. The expression "zero-intermediate frequency "is used here to indicate that the Mixing result at least containing the modulation Signal whose carrier frequency is nominally zero, but off various reasons by a small amount of zero can be different. In the following, this eventual Difference is not taken into account, d. H. it should simplified an intermediate frequency of zero will.

Solche Verfahren (Direktempfang, direct conversion, homo­ dyne, synchrodyne, Quadraturempfang) begegneten lange Zeit großen Schwierigkeiten bei der Ausführung in der Praxis, wie zum Beispiel aus dem Artikel von Saleh R. Al-Aradji und W. Gosling "A direct conversion v. h. f. receiver", The Radio and Electronic Engineer, Vol. 43, No. 7, Juli 1973, S. 442-446 hervorgeht.Such procedures (direct reception, direct conversion, homo dyne, synchrodyne, quadrature reception) met for a long time great difficulty in performing in practice, such as from the article by Saleh R. Al-Aradji and W. Gosling "A direct conversion from f. Receiver", The Radio and Electronic Engineer, Vol. 43, No. 7, July 1973, pp. 442-446 emerges.

Eines der verbliebenden Probleme war das Vermeiden uner­ wünschter Rückstrahlungen des Empfängers nach außen, bedingt durch vergleichsweise starke empfangsfrequente Lokaloszillatorsignale (LO-Signale) im Mischer.One of the remaining problems was avoiding them desired reflections of the receiver to the outside, due to comparatively strong reception frequencies  Local oscillator signals (LO signals) in the mixer.

Immerhin war man gemäß dem erwähnten Artikel soweit, daß monolytische integrierte Schaltungen für den größten Teil eines Empfängers herstellbar waren.After all, according to the article mentioned, it was so far that monolytic integrated circuits for the most part of a receiver could be produced.

In der deutschen Offenlegungsschrift 23 58 288 ist aus diesen Gründen vorgeschlagen, zwischen Antenne und Mi­ schern eine Schaltung einzusetzen, die eine geringe Durch­ laßdämpfung in Richtung von Antenne zum Empfänger, d. h. Mischer, und eine hohe Durchlaßdämpfung vom Empfänger zur Antenne aufweist. Einzelheiten dieser Schaltung fehlen in der Schrift. In German Offenlegungsschrift 23 58 288 is out these reasons suggested between antenna and Mi scher use a circuit that has a low through attenuation in the direction from antenna to receiver, d. H. Mixer, and a high transmission loss from the receiver to Has antenna. Details of this circuit are missing in the Font.

Aufgabe der Erfindung ist es, die Isolation des Empfänger­ eingangs gegen solche Störsignale auf der Empfangsfrequenz zu verbessern.The object of the invention is to isolate the receiver initially against such interference signals on the reception frequency to improve.

Dies wird durch die im Kennzeichen des Patentanspruchs 1 dargelegten Maßnahmen erreicht. Es kann dies durch wiederholtes Abwärtsmischen oder durch Kombinationen von Aufwärts- mit Abwärtsmischungen geschehen. In beiden Fällen ist jede Oszillatorfrequenz von der Empfangsfrequenz ver­ schieden und deshalb keine Rückstrahlung auf Emp­ fangsfrequenz möglich.This is indicated in the characterizing part of patent claim 1 outlined measures achieved. It can do this through repeated downmixing or by combinations of Happen upward with downward blends. In both cases is each oscillator frequency ver from the receiving frequency divorced and therefore no reflection on Emp frequency possible.

Natürlich ist mehrfaches Mischen beim Superhet bekannt, jedoch nicht bis auf eine Null-Zwischenfrequenz hinunter. Ferner ist beim Doppelsuper ein zweifaches Mischen bekannt; die LO-Frequenzen stehen aber nicht in einem konstanten, von der Eingangsfrequenz unabhängigen Verhältnis zueinan­ der. Of course, multiple mixing is known with the Superhet, but not down to a zero intermediate frequency. Furthermore, double mixing is known in the double super; but the LO frequencies are not in a constant, relationship independent of the input frequency the.  

In den weiteren Patentansprüchen sind vorteilhafte Ausfüh­ rungsarten der Erfindung angegeben. So ist im Patentan­ spruch 3 ein Überlagerungsempfänger umschrieben, bei wel­ chem der Aufwand besonders klein ist.Advantageous embodiments are in the further claims tion types of the invention. So is in the patent saying 3 an overlay recipient, at wel chem the effort is particularly small.

Durch ein entsprechend dem Patentanspruch 5 bemessenes Filter wird vermieden, daß infolge unerwünschter Misch­ produkte eine andere als die vorgesehene Frequenz empfangen wird.By a dimensioned according to claim 5 Filter is avoided due to undesirable mixing receive a different frequency than the intended frequency becomes.

Die Erfindung wird im folgenden an einem Beispiel erläutert.The invention is explained below using an example.

Fig. 1 zeigt ein Blockschema des entsprechenden Überlage­ rungsempfängers. In Richtung des Signalflusses folgen auf die Antenne 1 ein Vorfilter 2, ein Vorverstärker 3 und, gemäß der Erfindung, ein Vormischer 4. Danach wird das Signal auf die beiden in Quadratur stehenden Hauptmischer 5 und 6 verteilt, deren Ausgangssignale als Null-Zwischen­ frequenz den entsprechenden weiteren Einheiten 7 und 8 zugeführt werden. Es können dies Tiefpaßfilter und weitere Quadraturstufen sein, die als bekannt nicht einzeln darge­ stellt sind. Die Null-Zwischenfrequenz kann infolge nicht vermeidbarer Fehler bis etwa ±20% der ZF-Bandbreite von Null verschieden sein. Fig. 1 shows a block diagram of the corresponding overlay receiver. A pre-filter 2 , a pre-amplifier 3 and, according to the invention, a pre-mixer 4 follow the antenna 1 in the direction of the signal flow. Then the signal is distributed to the two main mixers 5 and 6 in quadrature, the output signals of which are fed to the corresponding further units 7 and 8 as a zero intermediate frequency. It can be low-pass filter and other quadrature stages, which are not individually known as Darge presents. As a result of unavoidable errors, the zero intermediate frequency can differ from zero up to approximately ± 20% of the IF bandwidth.

Gemäß der Erfindung ist für den Vormischer 4 und die beiden Hauptmischer 5 und 6 ein gemeinsamer Oszillator 9 vorgesehen, dessen Frequenz die Hälfte derjenigen des empfangenen Signals ist. Ein Phasenschieber 10 zwischen Oszillator 9 und Hauptmischer 5 sorgt für die Qua­ draturwirkung, d. h. eine Phasenverschiebung von 90° zwi­ schen den Oszillatoreingängen der Hauptmischer 5 und 6. According to the invention, a common oscillator 9 is provided for the premixer 4 and the two main mixers 5 and 6 , the frequency of which is half that of the received signal. A phase shifter 10 between the oscillator 9 and the main mixer 5 ensures the quadrature effect, ie a phase shift of 90 ° between the oscillator inputs of the main mixer 5 and 6 .

Dieser Empfänger eignet sich besonders für phasen- bzw. frequenzmodulierte Mobilfunknetze.This receiver is particularly suitable for phase or frequency-modulated cellular networks.

Die Erfindung kann noch auf andere Art als in der soeben beschriebenen ausgeführt werden.The invention can still be in a different way than in the just described.

Unter bestimmten Voraussetzungen, wie z. B. einer hochselek­ tiven Antenne mit hohem Gewinn, können Vorfilter 2 und/ oder Vorverstärker weggelassen werden.Under certain conditions, such as B. a highly selective antenna with high gain, pre-filter 2 and / or preamplifier can be omitted.

Für Anwendungen im Rundfunk, insbesondere Farbfernsehen kann auch die an sich bekannte Synchronempfängerschaltung entsprechend ausgestaltet werden. Das Synchronisiersignal wird dann z. B. vor dem Vormischer abgezweigt und dient zur Synchronisierung einer halb so schnell schwingenden Fre­ quenzregelschaltung (PLL) als gemeinsamen Lokaloszillator für die Vor- und Hauptmischer.For applications in broadcasting, in particular color television, the known synchronous receiver circuit can also be designed accordingly. The synchronizing signal is then z. B. branched off in front of the pre-mixer and is used to synchronize a frequency oscillating circuit (PLL) that vibrates half as fast as a common local oscillator for the pre-mixer and main mixer.

Diese und weitere mögliche Varianten sind der gebotenen Kürze halber hier nicht im einzelnen dargestellt.These and other possible variants are the ones offered For brevity not shown here in detail.

Claims (7)

1. Verfahren zum Überlagerungsempfang eines modulierten Signals durch herabmischen desselben auf eine Null-Zwi­ schenfrequenz mit Hilfe mindestens einer lokalen Oszil­ latorfrequenz, dadurch gekennzeichnet, daß das Herab­ mischen durch mindestens zwei aufeinanderfolgende Misch­ vorgänge (4; 5, 6) erreicht wird.1. A method for receiving a modulated signal by mixing it down to a zero intermediate frequency using at least one local oscillator frequency, characterized in that the mixing down is achieved by at least two successive mixing processes ( 4; 5, 6 ). 2. Verfahren nach Patentanspruch 1, dadurch gekennzeichnet, daß die zum Herabmischen verwendeten Oszillatorfrequen­ zen in einem ganzzahligen Verhältnis zueinander stehen.2. The method according to claim 1, characterized in that the oscillator frequencies used for downmixing zen stand in an integer relationship to each other. 3. Überlagerungsempfänger zur Durchführung des Verfahrens nach Patentanspruch 2, dadurch gekennzeichnet, daß er einen Vormischer (4) und zwei daran angeschlossene in Quadratur betriebene Hauptmischer (5, 6) enthält, sowie einen gemeinsamen Lokaloszillator (9), und daß die Frequenz des letzteren die Hälfte der Frequenz des empfangenen modulierten Signals ist.3. superimposed receiver for performing the method according to claim 2, characterized in that it contains a premixer ( 4 ) and two connected to it in quadrature main mixer ( 5, 6 ), and a common local oscillator ( 9 ), and that the frequency of the latter is half the frequency of the received modulated signal. 4. Überlagerungsempfänger nach den Patentansprüchen 2 oder 3 zum Empfang mehrerer Frequenzen, dadurch gekennzeichnet, daß die genannten Verhältnisse der Oszillatorfrequenzen bei jeder Empfangsfrequenz beibehal­ ten werden. 4. Superposition receiver according to patent claims 2 or 3 to receive multiple frequencies, thereby characterized in that the conditions mentioned the Maintain oscillator frequencies at every receive frequency be.   5. Überlagerungsempfänger nach Patentanspruch 3, dadurch gekennzeichnet, daß dem Vormischer (4) ein Filter (2) vorgeschaltet ist, daß so dimensioniert ist, daß am Eingang des Vormischers vorhandene Reste des Lokaloszil­ latorsignals unterdrückt werden, währenddem das Ein­ gangssignal nicht gedämpft wird.5. Superimposed receiver according to claim 3, characterized in that the premixer ( 4 ) is preceded by a filter ( 2 ) that is dimensioned such that existing residues of the local oscillator are suppressed at the input of the premixer, during which the input signal is not attenuated. 6. Überlagerungsempfänger nach Patentanspruch 5, dadurch gekennzeichnet, daß das Filter (2) ein Tiefpaß ist, dessen Grenzfrequenz zwischen dem 1- und 11/2fachen der Eingangsfrequenz liegt.6. superheterodyne receiver according to claim 5, characterized in that the filter (2) is a low-pass filter whose cutoff frequency times between 1 and 1 1/2 of the input frequency. 7. Überlagerungsempfänger nach Patentanspruch 3, dadurch gekennzeichnet, daß zum Vermeiden einer Rückstrahlung auf der Empfangsfrequenz Filter oder andere Maßnahmen zum Kleinhalten der zweiten Harmonischen der Oszillator­ frequenz im Lokaloszillator (9) und/oder in den Mischern (4, 5, 6) getroffen sind.7. Superposition receiver according to claim 3, characterized in that to avoid reflection on the reception frequency filter or other measures to keep the second harmonic of the oscillator frequency in the local oscillator ( 9 ) and / or in the mixers ( 4, 5, 6 ) are taken .
DE19873726181 1986-09-05 1987-08-06 Process for the superheterodyne reception of a modulated signal Withdrawn DE3726181A1 (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CH357286A CH671856A5 (en) 1986-09-05 1986-09-05

Publications (1)

Publication Number Publication Date
DE3726181A1 true DE3726181A1 (en) 1988-03-10

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DE19873726181 Withdrawn DE3726181A1 (en) 1986-09-05 1987-08-06 Process for the superheterodyne reception of a modulated signal

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CH (1) CH671856A5 (en)
DE (1) DE3726181A1 (en)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4125995A1 (en) * 1991-06-08 1992-12-10 Licentia Gmbh RECEIVER ARRANGEMENT
WO1998040968A2 (en) * 1997-03-12 1998-09-17 Koninklijke Philips Electronics N.V. A frequency conversion circuit
EP0932252A2 (en) * 1998-01-23 1999-07-28 Matsushita Electric Industrial Co., Ltd. Tuning demodulator for digitally modulated RF signals
EP1063767A2 (en) * 1999-06-22 2000-12-27 Alps Electric Co., Ltd. Digital television tuner having simple baseband signal processing portion
WO2001058103A2 (en) * 2000-02-02 2001-08-09 Interdigital Technology Corporation Kaskadenfrequenzumsetzer unter verwendung von phasenverschobenen signalen der lokalen oszillatoren
US6282413B1 (en) 1997-03-12 2001-08-28 U.S. Philips Corporation Multistaged frequency conversion with single local oscillator

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB9017418D0 (en) * 1990-08-08 1990-09-19 Gen Electric Co Plc Half frequency mixer

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2742578A1 (en) * 1977-09-22 1979-04-05 Hirschmann Radiotechnik Frequency converter for community antenna system - has two mixers supplied with fundamental and first harmonic from same local oscillator
DE3114063A1 (en) * 1981-04-07 1982-10-21 Licentia Patent-Verwaltungs-Gmbh, 6000 Frankfurt RECEPTION SYSTEM
JPS61171207A (en) * 1985-01-25 1986-08-01 Nec Corp Receiver

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4125995A1 (en) * 1991-06-08 1992-12-10 Licentia Gmbh RECEIVER ARRANGEMENT
US5283532A (en) * 1991-06-08 1994-02-01 Temic Telefunken Microelectronic Gmbh Receiver having a local oscillator first synchronized to a reference frequency and then to a received signal
WO1998040968A2 (en) * 1997-03-12 1998-09-17 Koninklijke Philips Electronics N.V. A frequency conversion circuit
WO1998040968A3 (en) * 1997-03-12 1999-02-18 Koninkl Philips Electronics Nv A frequency conversion circuit
US6282413B1 (en) 1997-03-12 2001-08-28 U.S. Philips Corporation Multistaged frequency conversion with single local oscillator
EP0932252A2 (en) * 1998-01-23 1999-07-28 Matsushita Electric Industrial Co., Ltd. Tuning demodulator for digitally modulated RF signals
EP0932252A3 (en) * 1998-01-23 1999-12-08 Matsushita Electric Industrial Co., Ltd. Tuning demodulator for digitally modulated RF signals
US6668025B1 (en) 1998-01-23 2003-12-23 Matsushita Electric Industrial Co., Ltd. Tuning demodulator for digitally modulated RF signals
EP1063767A2 (en) * 1999-06-22 2000-12-27 Alps Electric Co., Ltd. Digital television tuner having simple baseband signal processing portion
EP1063767A3 (en) * 1999-06-22 2003-08-20 Alps Electric Co., Ltd. Digital television tuner having simple baseband signal processing portion
WO2001058103A2 (en) * 2000-02-02 2001-08-09 Interdigital Technology Corporation Kaskadenfrequenzumsetzer unter verwendung von phasenverschobenen signalen der lokalen oszillatoren
WO2001058103A3 (en) * 2000-02-02 2002-02-14 Interdigital Tech Corp Kaskadenfrequenzumsetzer unter verwendung von phasenverschobenen signalen der lokalen oszillatoren

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