EP1864413A1 - Method for damping a high-frequency radiation of a clocked system - Google Patents

Method for damping a high-frequency radiation of a clocked system

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Publication number
EP1864413A1
EP1864413A1 EP06721180A EP06721180A EP1864413A1 EP 1864413 A1 EP1864413 A1 EP 1864413A1 EP 06721180 A EP06721180 A EP 06721180A EP 06721180 A EP06721180 A EP 06721180A EP 1864413 A1 EP1864413 A1 EP 1864413A1
Authority
EP
European Patent Office
Prior art keywords
frequency
oscillator
signal
modulation
radiation
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Withdrawn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
EP06721180A
Other languages
German (de)
French (fr)
Inventor
Rainer Gschwind-Schilling
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.)
Robert Bosch GmbH
Original Assignee
Robert Bosch GmbH
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 Robert Bosch GmbH filed Critical Robert Bosch GmbH
Publication of EP1864413A1 publication Critical patent/EP1864413A1/en
Withdrawn legal-status Critical Current

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Classifications

    • 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
    • H03B23/00—Generation of oscillations periodically swept over a predetermined frequency range
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B15/00—Suppression or limitation of noise or interference
    • H04B15/02—Reducing interference from electric apparatus by means located at or near the interfering apparatus
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B2215/00—Reducing interference at the transmission system level
    • H04B2215/064—Reduction of clock or synthesizer reference frequency harmonics
    • H04B2215/067—Reduction of clock or synthesizer reference frequency harmonics by modulation dispersion

Definitions

  • the present invention relates to a method and apparatus for attenuating high frequency radiation of a clocked system.
  • a clocked system includes an oscillator which provides a primary clock for the switching operations in the clocked system by transmitting a clock signal.
  • the switching operations within the clocked system cause spurious signals or radio frequency emissions in the frequency range of the primary clock and derived clocks, e.g. caused by internal multipliers of the system.
  • primary clocks and derived clocks are typically in the range of 10 MHz to over 1 GHz.
  • complete suppression of the interference signals or high-frequency emissions in signal lines, supply lines and over the air is not possible.
  • the high-frequency radiation also includes the interference signals which occur in a line-bound manner.
  • the high-frequency radiation can lead to interference in other circuits and cause a malfunction of these circuits.
  • problems arise in particular when the high-frequency radiation has high power in a frequency range which the further circuits use. This can lead to adverse interference effects. Therefore, maximum upper limits of the radiation power must be maintained, which must not exceed a noise emission.
  • a particularly sensitive area are the frequencies used for radio transmission, especially for radio reception.
  • the interference can lead to unwanted whistling during radio reception.
  • the invention provides a method with the features of claim 1, which reduces the power of a high-frequency radiation of a clocked system in a frequency range and a device having the features of claim 6.
  • the method according to the invention provides the following steps: determining a time-averaged maximum value which the power of the radio-frequency emission of the clocked device should not exceed in a given frequency band; Modulating an oscillation frequency of the exciting oscillator with a frequency sweep such that the average power in the predetermined frequency band is below the maximum value; Determining a bandwidth of a radio receiver; Modulating the oscillation frequency with a frequency deviation (modulation frequency / modulation), which is greater than the bandwidth of the radio receiver of the predetermined frequency band.
  • the bandwidth can be kept in a memory device, or transmitted by individual circuits and modules.
  • the underlying idea is that the power of the high frequency radiation in the predetermined, disturbed frequency ranges is distributed over a wider frequency range. This reduces the effective, ie the time-averaged performance within sensitive frequency ranges.
  • damping is to be understood. This is particularly advantageous if the other circuits are disturbed only in a certain frequency range and a fault only occurs when the interference signal permanently applied for more than a critical period with a minimum power. Since short-term disturbances can be effectively absorbed by filter and buffer devices, a disruption of further circuit by the clocked system is effectively prevented by the inventive method. Especially in radio reception, a listener does not notice short-term disturbances.
  • the inventive device for a clocked system with a stimulating oscillator wherein the exciting oscillator is set up such that its oscillation frequency is adjustable by a control signal; has a modulation oscillator, which is connected to the exciting oscillator and is adapted to output a periodic control signal for modulating an oscillation frequency of the exciting oscillator, such that the average power of a high frequency radiation in a predetermined frequency band is below a maximum value.
  • a development of the present invention provides that the modulation frequency is set to more than 400 kHz. This frequency is sufficiently high that most VHF receivers will not be disturbed.
  • a development of the present invention provides the further steps: detecting a signal corresponding to the power of the high-frequency radiation; Controlling the frequency deviation in response to the signal, such that the signal remains below a maximum signal corresponding to the maximum value.
  • a development of the present invention provides the further steps: detecting a signal corresponding to the power of the high-frequency radiation; Determining the frequency sweep based on a ratio of the maximum value to the signal;
  • a further development of the present invention provides that an amplification device is provided for amplifying the control signal between the exciting oscillator and the modulation oscillator, wherein the amplification device has an adjustable gain in order to set the frequency deviation, which is proportional to the control signal.
  • Fig. 1 is a block diagram of an embodiment of the present invention
  • Fig. 2 is a schematic representation of a frequency range used for a stereo receiver
  • Fig. 3 is a schematic representation of the frequency range of a radio receiver used
  • Fig. 5 is a schematic diagram for explaining a problem of the present invention.
  • Fig. 6 is a schematic representation of a frequency range for explaining an embodiment of the present invention.
  • FIG. 1 shows an embodiment of the present invention.
  • a clocked system 21, such as a microprocessor or a clocked voltage converter is connected to a stimulating oscillator 22 for specifying a primary clock with an oscillation frequency f ⁇ .
  • the oscillator 22 is set up such that the oscillation frequency f T can be changed by means of a control signal 30.
  • This control signal 30 is provided by a modulation oscillator 24.
  • the control signal 30 is a periodic signal, it may be sinusoidal, triangular or other. By applying the periodic control signal 30, the oscillation frequency f ⁇ is then periodically modulated with a predetermined frequency deviation between a lower and an upper limit frequency.
  • the high-frequency radiation is likewise modulated and thus its power is distributed over a frequency range corresponding to the frequency sweep.
  • a maximum permissible high-frequency radiation in individual relevant frequency ranges can be determined.
  • the frequency deviation is adjusted so that the time averaged power of the radio frequency radiation within the relevant frequency ranges is below the maximum allowable value.
  • An adjustment of the frequency deviation can be made by means of a controllable amplification device 23, which is arranged between the oscillator 22 and the modulation oscillator 24 for amplifying or damping the control signal 30.
  • an antenna device 25 which detects the high-frequency radiation of the clocked system 21.
  • the detected high-frequency radiation is supplied to a controller 26, which controls the amplifying means 23 based thereon to increase the frequency deviation.
  • a controller 26 which controls the amplifying means 23 based thereon to increase the frequency deviation.
  • This can be done, for example, by means of negative feedback, wherein the control device 26 has corresponding internal signal amplifiers and outputs the amplified signals to the amplification device 23. Since this often changes the oscillation frequency, this can lead to disturbances in the switching behavior of the clocked system 21.
  • Another embodiment therefore contemplates using a controller 26 with a suitable hysteresis or other type of memory.
  • Another embodiment determines the frequency deviation based on the product of the relevant frequency range with the quotient of the detected to the maximum permissible high frequency radiation.
  • the control device 26 has a corresponding data processing device.
  • An FM receiver detects the modulation of the oscillation frequency f ⁇ (correspondingly referred to in the radio technology as the carrier frequency) as an information signal having a frequency which corresponds to the modulation frequency f M and an amplitude which corresponds to the frequency deviation.
  • a radio handset adopts thus to a sinusoidal control signal 30 with the modulation frequency f M (in the radio technology information corresponding frequency) a pipe in a pitch true, which corresponds to the modulation frequency f M. Therefore, it is necessary to select the modulation frequency f M outside the ranges which are demodulated by an FM receiver.
  • the frequency range used is represented by a carrier frequency f T for a typical stereo signal transmission of a VHF transmitter.
  • a mono signal and two stereo signals are transmitted, also be transmitted in a band between 54.6 kHz and 59.4 kHz data signals for identification of the radio station and / or the music tracks.
  • the modulation frequency f M must be at least 59.4 kHz so as not to be converted into an audible radio signal by an FM receiver.
  • Fig. 3 the frequency range used by a single transmitter or receiver of a VHF system is shown schematically.
  • the bandwidth B is arranged symmetrically about a carrier frequency f ⁇ , where f, the information frequency and ⁇ f denote the frequency deviation. Both the information frequency f and the frequency deviation ⁇ f are within the bandwidth.
  • a signal is received by an antenna 1, supplied in the following order via an amplifier 2 to a controllable band-pass filter 3, an adjustable high-frequency amplifier 17, a second adjustable band-pass filter 4 and a mixer 5.
  • the mixer 5 is additionally supplied with the carrier frequency, which is generated by a high-frequency generator 12.
  • the high-frequency generator 12 typically has adjustable frequency elements, such as capacitance diodes, which can be adjusted by the control signal 15.
  • the signal mixed by the mixer 5 is forwarded to an intermediate circuit filter 6, which passes only signals which correspond to the bandwidth of the radio receiver.
  • the filtered signal is fed to a further amplifier 7, which communicates with a control device 8 and adapts the modulation of the high-frequency amplifier 17 by means of a control signal.
  • the intermediate frequency signal is transmitted to a second intermediate circuit filter 9.
  • a control device / demodulator 10 regulates the frequency of the high-frequency oscillator 12 by means of a control signal 15 if the demodulated carrier signal is not at 0 Hz, ie the carrier signal modulated at the frequency by the high-frequency oscillator yields the intermediate frequency. If a frequency-modulated signal with a large frequency deviation is received, then the controllable bandpass filters 3, 4 convert the frequency modulation into an amplitude modulation.
  • the amplitude modulated noise in the filter can mix with the frequency modulated signal using capacitance diodes. This new frequency-modulated signal then leads to a whistle in the radio.
  • An embodiment of the present invention makes use of the fact that the intermediate circuit filters 6, 9 filter out signals which are outside the bandwidth of the intermediate frequency filter. Signals which have a greater modulation frequency f M are considered to be signals of a transmitter with an adjacent transmission frequency and accordingly suppressed by the intermediate circuit filters 6, 9. Therefore, an oscillation signal having a modulation frequency f M which is larger than the bandwidth B of the broadcasting receiver is modulated. Then the parasitic frequency modulations do not pass through the intermediate circuit filters 6, 7 and thus do not affect the control device 10 and the high-frequency generator 12. Typically, corresponding interference suppression frequencies are above 400 kHz. Schematically, it is indicated in FIG. 6 that the modulation frequency f M must be greater than the bandwidth to be selected.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Noise Elimination (AREA)
  • Transmitters (AREA)

Abstract

The invention relates to a method for damping a high-frequency radiation of a clocked system consisting in determining an average maximum time value which is not exceedable by the power of the clocked system (21) high-frequency within a predetermined frequency band, in modulating an oscillator (22) oscillation frequency with a frequency deviation in such a way that the average power is lower than the maximum value within the predetermined frequency band and in determining a bandwidth (b) of a radio receiver and modulating an oscillation frequency (fT) with a modulation frequency (fM) which is greater than the radio receiver bandwidth.

Description

Verfahren zur Dämpfung einer Hochfrequenzabstrahlung eines getakteten SystemsMethod for attenuating a high-frequency emission of a clocked system
STAND DER TECHNIKSTATE OF THE ART
Die vorliegende Erfindung betrifft ein Verfahren und eine Vorrichtung zur Dämpfung einer Hochfrequenzabstrahlung eines getakteten Systems.The present invention relates to a method and apparatus for attenuating high frequency radiation of a clocked system.
Ein getaktetes System weist eine Oszillationseinrichtung auf, welche einen primären Takt für die Schaltvorgänge in dem getakteten System durch Übertragung eines Taktsignals vorgibt. Durch die Schaltvorgänge innerhalb des getakteten Systems werden Störsignale oder Hochfrequenzabstrahlun- gen im Frequenzbereich des primären Takts und abgeleiteter Takte z.B. durch interne Multiplikatoren des Systems verursacht. Heute typisch verwendete primäre Takte und abgeleitete Takte liegen typischer Weise im Bereich von 10 MHz bis über ein 1 GHz. Trotz teilweise aufwändiger Filtereinrichtungen ist eine vollständige Unterdrückung der Störsignale oder Hochfrequenzabstrahlungen in Signalleitungen, Versorgungsleitungen und über die Luft nicht möglich. Im nachfolgenden beinhalten zur Vereinfachung der Ausdrucksweise die Hochfrequenzabstrahlung auch die Störsignale, welche lei- tungsgebunden auftreten.A clocked system includes an oscillator which provides a primary clock for the switching operations in the clocked system by transmitting a clock signal. The switching operations within the clocked system cause spurious signals or radio frequency emissions in the frequency range of the primary clock and derived clocks, e.g. caused by internal multipliers of the system. Typically used today primary clocks and derived clocks are typically in the range of 10 MHz to over 1 GHz. Despite partially complex filter devices, complete suppression of the interference signals or high-frequency emissions in signal lines, supply lines and over the air is not possible. In the following, to simplify the expression, the high-frequency radiation also includes the interference signals which occur in a line-bound manner.
Die Hochfrequenzabstrahlung kann in weiteren Schaltkreisen zu Störungen führen und ein Fehlverhalten dieser Schaltkreise verursachen. Hierbei treten insbesondere dann Probleme auf, wenn die Hochfrequenzabstrahlung eine hohe Leistung in einem Frequenzbereich aufweist, welchen die weite- ren Schaltkreise verwenden. Dies kann zu nachteiligen Interferenzeffekten führen. Daher sind maximale Obergrenzen der Abstrahlungsleistung einzuhalten, welche eine Störabstrahlung nicht überschreiten darf.The high-frequency radiation can lead to interference in other circuits and cause a malfunction of these circuits. In this case, problems arise in particular when the high-frequency radiation has high power in a frequency range which the further circuits use. This can lead to adverse interference effects. Therefore, maximum upper limits of the radiation power must be maintained, which must not exceed a noise emission.
Ein besonders sensibler Bereich sind die für die Funkübertragung verwendeten Frequenzen, vor allem für den Radioempfang. Hierbei können die Störsignale zu unerwünschten Pfeiftönen während des Radioempfangs führen.A particularly sensitive area are the frequencies used for radio transmission, especially for radio reception. Here, the interference can lead to unwanted whistling during radio reception.
VORTEILE DER ERFINDUNGADVANTAGES OF THE INVENTION
Die Erfindung schafft ein Verfahren mit den Merkmalen des Anspruchs 1, welches die Leistung einer Hochfrequenzabstrahlung eines getakteten Systems in einem Frequenzbereich verringert und eine Vorrichtung mit den Merkmalen des Anspruchs 6. Das erfindungsgemäße Verfahren sieht die Schritte vor: Bestimmen eines zeitlich gemittelten Maximalwertes, welchen die Leistung der Hochfrequenzabstrahlung der getakteten Vorrichtung in einem vorgegebenen Frequenzband nicht überschreiten soll; Modulieren einer Oszillationsfrequenz des anregenden Oszillators mit einem Frequenzhub, derart dass die mittlere Leistung in dem vorgegebenen Frequenzband unterhalb dem Maximalwert liegt; Bestimmen einer Bandbreite eines Funkempfängers; Modulieren der Oszillationsfrequenz mit einem Frequenzhub (Modulationsfrequenz/Modulationshub), welcher größer als die Bandbreite des Funkempfängers des vorgegebenen Frequenzbandes ist. Die Bandbreite kann in einer Speichereinrichtung vorgehalten werden, oder von einzelnen Schaltkreisen und Baugruppen übermittelt werden.The invention provides a method with the features of claim 1, which reduces the power of a high-frequency radiation of a clocked system in a frequency range and a device having the features of claim 6. The method according to the invention provides the following steps: determining a time-averaged maximum value which the power of the radio-frequency emission of the clocked device should not exceed in a given frequency band; Modulating an oscillation frequency of the exciting oscillator with a frequency sweep such that the average power in the predetermined frequency band is below the maximum value; Determining a bandwidth of a radio receiver; Modulating the oscillation frequency with a frequency deviation (modulation frequency / modulation), which is greater than the bandwidth of the radio receiver of the predetermined frequency band. The bandwidth can be kept in a memory device, or transmitted by individual circuits and modules.
Die zugrundeliegende Idee ist, dass die Leistung der Hochfrequenzabstrahlung in den vorgegebenen, gestörten Frequenzbereichen über einen größeren Frequenzbereich verteilt wird. Dies reduziert die effektive, sprich die zeitlich gemittelte Leistung innerhalb sensibler Frequenzbereiche. In diesem vorgenannten Sinne ist der Begriff Dämpfung zu verstehen. Dies ist insbesondere dann von Vorteil, wenn die anderen Schaltkreise nur in einem bestimmten Frequenzbereich gestört werden und eine Störung erst auftritt, wenn das Störsignal länger als eine kritische Dauer mit einer Mindestleistung permanent anliegt. Da kurzzeitige Störungen effektiv durch Filter- und Puffereinrichtungen abgefangen werden können, wird eine Störung weiterer Schaltkreis durch das getaktete System durch das erfindungsgemäße Verfahren effektiv unterbunden. Vor allem im Radioempfang nimmt ein Hörer kurzzeitig auf- tretende Störungen nicht wahr.The underlying idea is that the power of the high frequency radiation in the predetermined, disturbed frequency ranges is distributed over a wider frequency range. This reduces the effective, ie the time-averaged performance within sensitive frequency ranges. In this aforementioned sense, the term damping is to be understood. This is particularly advantageous if the other circuits are disturbed only in a certain frequency range and a fault only occurs when the interference signal permanently applied for more than a critical period with a minimum power. Since short-term disturbances can be effectively absorbed by filter and buffer devices, a disruption of further circuit by the clocked system is effectively prevented by the inventive method. Especially in radio reception, a listener does not notice short-term disturbances.
Die erfindungsgemäße Vorrichtung für ein getakteten Systems mit einem anregenden Oszillator, wobei der anregende Oszillator derart eingerichtet ist, dass dessen Oszillationsfrequenz durch ein Steuersignal einstellbar ist; weist einen Modulationsoszillator auf, welcher mit dem anregenden Oszillator verbunden ist und eingerichtet ist ein periodisches Steuersignal zum Modulieren einer Oszillationsfrequenz des anregenden Oszillators auszugeben, derart dass die mittlere Leistung einer Hochfrequenzabstrahlung in einem vorgegebenen Frequenzband unterhalb einem Maximalwert liegt.The inventive device for a clocked system with a stimulating oscillator, wherein the exciting oscillator is set up such that its oscillation frequency is adjustable by a control signal; has a modulation oscillator, which is connected to the exciting oscillator and is adapted to output a periodic control signal for modulating an oscillation frequency of the exciting oscillator, such that the average power of a high frequency radiation in a predetermined frequency band is below a maximum value.
In den Unteransprüchen finden sich vorteilhafte Weiterbildungen und Verbesserungen des im Patent- anspruch 1 angegebenen Verfahrens und der im Patentanspruch 5 angegebenen Vorrichtung.Advantageous refinements and improvements of the method specified in patent claim 1 and the device specified in patent claim 5 can be found in the subclaims.
Eine Weiterbildung der vorliegenden Erfindung sieht vor, dass die Modulationsfrequenz auf mehr als 400 kHz eingestellt wird. Diese Frequenz ist ausreichend hoch, so dass die meisten UKW-Empfänger nicht gestört werden.A development of the present invention provides that the modulation frequency is set to more than 400 kHz. This frequency is sufficiently high that most VHF receivers will not be disturbed.
Eine Weiterbildung der vorliegenden Erfindung sieht die weiteren Schritte vor: Erfassen eines der Leistung der Hochfrequenzabstrahlung entsprechenden Signals; Steuern des Frequenzhubes anspre- chend auf das Signal, derart dass das Signal unterhalb einem dem Maximalwert entsprechenden maximalen Signal bleibt.A development of the present invention provides the further steps: detecting a signal corresponding to the power of the high-frequency radiation; Controlling the frequency deviation in response to the signal, such that the signal remains below a maximum signal corresponding to the maximum value.
Eine Weiterbildung der vorliegenden Erfindung sieht die weiteren Schritte vor: Erfassen eines der Leistung der Hochfrequenzabstrahlung entsprechenden Signals; Bestimmen des Frequenzhubs basierend auf einem Verhältnis des Maximalwertes zu dem Signal;A development of the present invention provides the further steps: detecting a signal corresponding to the power of the high-frequency radiation; Determining the frequency sweep based on a ratio of the maximum value to the signal;
Eine Weiterbildung der vorliegenden Erfindung sieht vor, dass eine Verstärkungseinrichtung zum Verstärken des Steuersignals zwischen dem anregenden Oszillator und dem Modulationsoszillator vorgesehen ist, wobei die Verstärkungseinrichtung eine einstellbare Verstärkung aufweist, um den Frequenzhub einzustellen, welcher proportional zu dem Steuersignal ist, einzustellen.A further development of the present invention provides that an amplification device is provided for amplifying the control signal between the exciting oscillator and the modulation oscillator, wherein the amplification device has an adjustable gain in order to set the frequency deviation, which is proportional to the control signal.
Ausführungsbeispiele der Erfindung sowie vorteilhafte Weiterbildungen sind in den Figuren der Zeichnungen schematisch dargestellt und in der nachfolgenden Beschreibung näher erläutert.Embodiments of the invention and advantageous developments are shown schematically in the figures of the drawings and explained in more detail in the following description.
ZEICHNUNGENDRAWINGS
In den Figuren zeigen:In the figures show:
Fig. 1 ein Blockschaltbild einer Ausführungsform der vorliegenden ErfindungFig. 1 is a block diagram of an embodiment of the present invention
Fig. 2 eine schematische Darstellung eines verwendeten Frequenzbereichs für einen Stereoempfänger;Fig. 2 is a schematic representation of a frequency range used for a stereo receiver;
Fig. 3 eine schematische Darstellung verwendeter Frequenzbereich eines Rundfunkempfängers;Fig. 3 is a schematic representation of the frequency range of a radio receiver used;
Fig. 4 eine Blockdarstellung eines Rundfunkempfängers;4 is a block diagram of a radio receiver;
Fig. 5 eine schematische Darstellung zur Erläuterung einer Problematik der vorliegenden Erfindung; undFig. 5 is a schematic diagram for explaining a problem of the present invention; and
Fig. 6 eine schematische Darstellung eines Frequenzbereiches zur Erläuterung einer Ausführungsform der vorliegenden Erfindung.Fig. 6 is a schematic representation of a frequency range for explaining an embodiment of the present invention.
BESCHREIBUNG DER AUSFÜHRUNGSBEISPIELEDESCRIPTION OF THE EMBODIMENTS
In den Figuren bezeichnen gleiche Bezugszeichen gleiche oder funktionsgleiche Komponenten, soweit nichts gegenteiliges angegeben ist. Figur 1 zeigt eine Ausführungsform der vorliegenden Erfindung. Ein getaktetes System 21, z.B. ein Mikroprozessor oder ein getakteter Spannungswandler, ist mit einem anregenden Oszillator 22 zur Vorgabe eines primären Takts mit einer Oszillationsfrequenz fτ verbunden. Der Oszillator 22 ist so eingerichtet, dass die Oszillationsfrequenz fτ mittels eines Steuersignals 30 geändert werden kann. Dieses Steuersignal 30 wird von einem Modulationsoszillator 24 bereitgestellt. Das Steuersignal 30 ist ein periodisches Signal, es kann sinusförmig, dreiecksförmig oder anderes geartet sein. Durch Anlegen des periodischen Steuersignals 30 wird dann die Oszillationsfrequenz fτ periodisch mit einem vorgegebenen Frequenzhub zwischen einer unteren und einer oberen Grenzfrequenz moduliert. Dadurch wird die Hochfrequenzabstrahlung ebenfalls moduliert und somit deren Leistung über einem dem Fre- quenzhub entsprechenden Frequenzbereich verteilt. Gemäß bekannten Spezifikationen von anderen Schaltkreises und gesetzlichen Vorgaben kann eine maximale zulässige Hochfrequenzabstrahlung in einzelnen relevanten Frequenzbereichen bestimmt werden. Daraufhin wird der Frequenzhub so eingestellt, dass die zeitlich gemittelte Leistung der Hochfrequenzabstrahlung innerhalb der relevanten Frequenzbereiche unterhalb des maximal zulässigen Wert liegt. Eine Einstellung des Frequenzhubs kann mittels einer regelbaren Verstärkungseinrichtung 23 vorgenommen werden, welche zwischen dem Oszillator 22 und dem Modulationsoszillator 24 zur Verstärkung oder Dämpfung des Steuersignals 30 angeordnet ist.In the figures, like reference numerals designate like or functionally identical components, unless otherwise indicated. Figure 1 shows an embodiment of the present invention. A clocked system 21, such as a microprocessor or a clocked voltage converter is connected to a stimulating oscillator 22 for specifying a primary clock with an oscillation frequency f τ . The oscillator 22 is set up such that the oscillation frequency f T can be changed by means of a control signal 30. This control signal 30 is provided by a modulation oscillator 24. The control signal 30 is a periodic signal, it may be sinusoidal, triangular or other. By applying the periodic control signal 30, the oscillation frequency fτ is then periodically modulated with a predetermined frequency deviation between a lower and an upper limit frequency. As a result, the high-frequency radiation is likewise modulated and thus its power is distributed over a frequency range corresponding to the frequency sweep. According to known specifications of other circuits and legal requirements, a maximum permissible high-frequency radiation in individual relevant frequency ranges can be determined. Thereafter, the frequency deviation is adjusted so that the time averaged power of the radio frequency radiation within the relevant frequency ranges is below the maximum allowable value. An adjustment of the frequency deviation can be made by means of a controllable amplification device 23, which is arranged between the oscillator 22 and the modulation oscillator 24 for amplifying or damping the control signal 30.
Es ist weiter möglich eine Antennenvorrichtung 25 vorzusehen, welche die Hochfrequenzabstrahlung des getakteten Systems 21 erfasst. Die erfasste Hochfrequenzabstrahlung wird einer Steuerungseinrichtung 26 zugeführt, welche basierend darauf die Verstärkungseinrichtung 23 steuert, um den Frequenzhub zu erhöhen. Dies kann z.B mit Hilfe einer negativen Rückkopplung erfolgen, wobei die Steuerungseinrichtung 26 entsprechende internen Signalverstärker aufweist und die verstärkten Signale an die Verstärkungseinrichtung 23 ausgibt. Da sich hierbei sehr häufig die Oszillationsfrequenz ändert, kann dies zu Störungen im Schaltverhalten des getakteten Systems 21 führen kann. Eine andere Ausführungsform sieht daher vor, eine Steuerungseinrichtung 26 mit einer geeignete Hysterese oder einem anderes gearteten Gedächtnis zu verwenden. Eine weitere Ausführungsform bestimmt den Frequenzhub basierend auf dem Produkt des relevanten Frequenzbereichs mit dem Quotienten der er- fassten zu der maximal zulässigen Hochfrequenzabstrahlung. Dazu weist die Steuerungseinrichtung 26 eine entsprechende Datenverarbeitungseinrichtung auf.It is further possible to provide an antenna device 25 which detects the high-frequency radiation of the clocked system 21. The detected high-frequency radiation is supplied to a controller 26, which controls the amplifying means 23 based thereon to increase the frequency deviation. This can be done, for example, by means of negative feedback, wherein the control device 26 has corresponding internal signal amplifiers and outputs the amplified signals to the amplification device 23. Since this often changes the oscillation frequency, this can lead to disturbances in the switching behavior of the clocked system 21. Another embodiment therefore contemplates using a controller 26 with a suitable hysteresis or other type of memory. Another embodiment determines the frequency deviation based on the product of the relevant frequency range with the quotient of the detected to the maximum permissible high frequency radiation. For this purpose, the control device 26 has a corresponding data processing device.
Diese vorgenannten Ausführungsformen eigenen sich Störungen innerhalb von anderen Schaltkreisen zu vermeiden, wie sie z.B. in einem Fahrzeug verwenden werden. Sollen jedoch Störungen im Rundfunkempfang und insbesondere im UKW-Empfang von frequenzmodulierten Trägersignalen (FM- Empfänger) auf Grund von Hochfrequenzabstrahlungen unterdrückt werden, dann sind noch weitere Aspekte zu berücksichtigen, wie nachfolgend ausgeführt wird. Ein FM-Empfänger erfasst die Modulation der Oszillationsfrequenz fτ (in der Funktechnik entsprechend als Trägerfrequenz bezeichnet) als Informationssignal mit einer Frequenz, welcher der Modulationsfrequenz fM entspricht und eine Amplitude, welche dem Frequenzhub entspricht. Ein Radiohörer nimmt somit bei einem sinusförmigen Steuersignal 30 mit der Modulationsfrequenz fM (in der Funk- technik entsprechend Informationsfrequenz bezeichnet) ein Pfeifen in einer Tonhöhe wahr, welche der Modulationsfrequenz fM entspricht. Daher ist es notwendig die Modulationsfrequenz fM außerhalb der Bereiche zu wählen, welche durch einen FM-Empfänger demoduliert werden.These aforementioned embodiments are susceptible to avoid interference within other circuits, such as those used in a vehicle. However, if disturbances in the radio reception and in particular in the FM reception of frequency-modulated carrier signals (FM receivers) due to high-frequency emissions are to be suppressed, then further aspects have to be taken into account, as explained below. An FM receiver detects the modulation of the oscillation frequency f τ (correspondingly referred to in the radio technology as the carrier frequency) as an information signal having a frequency which corresponds to the modulation frequency f M and an amplitude which corresponds to the frequency deviation. A radio handset adopts thus to a sinusoidal control signal 30 with the modulation frequency f M (in the radio technology information corresponding frequency) a pipe in a pitch true, which corresponds to the modulation frequency f M. Therefore, it is necessary to select the modulation frequency f M outside the ranges which are demodulated by an FM receiver.
In Fig. 2 ist dazu der verwendete Frequenzbereich um eine Trägerfrequenz fτ für eine typische Stereo- Signalübertragung eines UKW-Senders dargestellt. In drei Bändern werden ein Monosignal und zwei Stereosignale übertragen, zudem werden in einem Band zwischen 54,6 kHz und 59,4 kHz Datensignale zur Identifizierung des Radiosenders und/oder der Musiktitel übermittelt. Daraus ergibt sich, dass die Modulationsfrequenz fM mindestens 59,4 kHz sein muss, um durch einen FM-Empfänger nicht in ein hörbares Radiosignal umgewandelt zu werden.In FIG. 2, the frequency range used is represented by a carrier frequency f T for a typical stereo signal transmission of a VHF transmitter. In three bands, a mono signal and two stereo signals are transmitted, also be transmitted in a band between 54.6 kHz and 59.4 kHz data signals for identification of the radio station and / or the music tracks. As a result, the modulation frequency f M must be at least 59.4 kHz so as not to be converted into an audible radio signal by an FM receiver.
In Fig. 3 ist schematisch der verwendete Frequenzbereich eines einzelnen Senders bzw. Empfängers eines UKW-Systems dargestellt. Die Bandbreite B ist symmetrisch um eine Trägerfrequenz fτ angeordnet, wobei f, die Informationsfrequenz und Δf den Frequenzhub bezeichnen. Sowohl die Informationsfrequenz f, als auch der Frequenzhub Δf liegen innerhalb der Bandbreite.In Fig. 3, the frequency range used by a single transmitter or receiver of a VHF system is shown schematically. The bandwidth B is arranged symmetrically about a carrier frequency f τ , where f, the information frequency and Δf denote the frequency deviation. Both the information frequency f and the frequency deviation Δf are within the bandwidth.
Überraschenderweise zeigen sich jedoch auch bei Modulationsfrequenzen fM von > 60 kHz Störsignale beim Empfang von UKW-Signalen. Eine Ursache dafür liegt in dem Aufbau von herkömmlichen FM-Empfängern, deren erste Empfangsstufen schematisch in Fig. 4 dargestellt sind. Ein Signal wird von einer Antenne 1 empfangen, in der folgenden Reihenfolge über einen Verstärker 2 an einen steu- erbaren Bandpassfilter 3, einem einstellbaren Hochfrequenzverstärker 17, einem zweiten einstellbaren Bandpassfilter 4 und einem Mischer 5 zugeführt. Dem Mischer 5 wird zusätzlich die Trägerfrequenz zugeführt, welche von einem Hochfrequenzgenerator 12 generiert wird. Der Hochfrequenzgenerator 12 weist typischerweise einstellbare Frequenzelemente, wie Kapazitätsdioden auf, welche sich durch das Steuersignal 15 einstellen lassen. Das von dem Mischer 5 gemischte Signal wird an einen Zwi- schenkreisfilter 6 weitergeleitet, welcher nur Signale passieren lässt, welche der Bandbreite des Rundfunkempfängers entsprechen. Das gefilterte Signal wird einem weiteren Verstärker 7 zugeführt, welche mit einer Steuerungseinrichtung 8 kommuniziert und mittels eines Steuersignals die Aussteuerung des Hochfrequenzverstärkers 17 anpasst. Das Zwischenfrequenz-Signal wird an einen zweiten Zwi- schenkreisfϊlter 9 übermittelt. Basierend auf dem demodulierten Signal regelt eine Steuerungseinrich- tung/Demodulator 10 die Frequenz des Hochfrequenzoszillators 12 mittels eines Steuersignals 15 nach, wenn das demodulierte Trägersignal nicht bei 0 Hz liegt, also das Trägersignal, mit der Frequenz von dem Hochfrequenzoszillator moduliert, die Zwischenfrequenz ergibt. Wird ein frequenzmoduliertes Signal mit großen Frequenzhub empfangen, so wandeln die steuerbaren Bandpassfϊlter 3, 4 die Frequenzmodulation in eine Amplitudenmodulation um. Die Ursache liegt darin, dass einzelne Frequenzen innerhalb des Frequenzhubes durch die Filter 3, 4 stärker gedämpft werden als andere Frequenzen. Da Informationssignale des FM-Empfangs nur einen geringen Fre- quenzhub aufweisen und damit zu einer vernachlässigbaren Amplitudenmodulation fuhren, werden in herkömmlichen FM-Empfängern keine Vorkehrungen getroffen nichtlineare Effekte in dem Mischer 5 durch die erwähnten Amplitudenmodulationen zu vermeiden. Die nichtlinearen Effekte resultieren unter anderem in einer parasitären Frequenzmodulation des gemischten Trägersignals nach dem Mischer 5. Da das amplitudenmodulierte Störsignal über den Pfad 4 den Mischer beeinflusst. Je nach Ausführung des Empfängers kann sich auf dem Pfad 4 das amplitudenmodulierte, oder das demodulierte Störsignal befinden. Dies führt zu Störungen im Empfang, welcher sich in unangenehmen Pfeifgeräuschen bemerkbar machen kann. In Figur 5 ist angedeutet, dass eine Hochfrequenzabstrahlung mit einer Frequenz von fs durch die nichtlinearen Effekte zu einer Störung mit einer geringeren Frequenz fS' führen kann, welche geringer als 60 kHz ist.Surprisingly, however, even at modulation frequencies f M of> 60 kHz interference signals in the reception of VHF signals. One reason for this lies in the structure of conventional FM receivers whose first receiving stages are shown schematically in FIG. A signal is received by an antenna 1, supplied in the following order via an amplifier 2 to a controllable band-pass filter 3, an adjustable high-frequency amplifier 17, a second adjustable band-pass filter 4 and a mixer 5. The mixer 5 is additionally supplied with the carrier frequency, which is generated by a high-frequency generator 12. The high-frequency generator 12 typically has adjustable frequency elements, such as capacitance diodes, which can be adjusted by the control signal 15. The signal mixed by the mixer 5 is forwarded to an intermediate circuit filter 6, which passes only signals which correspond to the bandwidth of the radio receiver. The filtered signal is fed to a further amplifier 7, which communicates with a control device 8 and adapts the modulation of the high-frequency amplifier 17 by means of a control signal. The intermediate frequency signal is transmitted to a second intermediate circuit filter 9. Based on the demodulated signal, a control device / demodulator 10 regulates the frequency of the high-frequency oscillator 12 by means of a control signal 15 if the demodulated carrier signal is not at 0 Hz, ie the carrier signal modulated at the frequency by the high-frequency oscillator yields the intermediate frequency. If a frequency-modulated signal with a large frequency deviation is received, then the controllable bandpass filters 3, 4 convert the frequency modulation into an amplitude modulation. The reason is that individual frequencies within the frequency sweep are more strongly attenuated by the filters 3, 4 than other frequencies. Since information signals of the FM reception have only a small frequency deviation and thus lead to negligible amplitude modulation, no provision is made in conventional FM receivers for avoiding non-linear effects in the mixer 5 due to the aforementioned amplitude modulations. The nonlinear effects result, inter alia, in a parasitic frequency modulation of the mixed carrier signal after the mixer 5. Since the amplitude-modulated interference signal via the path 4 influences the mixer. Depending on the design of the receiver can be on the path 4, the amplitude modulated, or the demodulated interference signal. This leads to disturbances in the reception, which can be felt in unpleasant whistling noises. It is indicated in FIG. 5 that high-frequency radiation with a frequency of f s as a result of the nonlinear effects can lead to interference with a lower frequency f S ' , which is less than 60 kHz.
Außerdem kann sich die amplitudenmodulierte Störung im Filter mit Hilfe von Kapazitätsdioden mit dem frequenzmodulierten Signal mischen. Dieses neue frequenzmodulierte Signal führt dann zu einem Pfeifen im Radio.In addition, the amplitude modulated noise in the filter can mix with the frequency modulated signal using capacitance diodes. This new frequency-modulated signal then leads to a whistle in the radio.
Eine Ausführungsform der vorliegenden Erfindung nützt, dass die Zwischenkreisfilter 6, 9 Signale ausfiltern, welche außerhalb der Bandbreite des Zwischenfrequenzfilters sind. Signale, welche eine größere Modulationsfrequenz fM aufweisen, werden als Signale eines Senders mit einer benachbarten Übertragungsfrequenz erachtet und dementsprechend durch die Zwischenkreisfilter 6, 9 unterdrückt. Daher wird ein Oszillationssignal mit einer Modulationsfrequenz fM moduliert, welche größer als die Bandbreite B des Rundfunkempfängers ist. Dann passieren die parasitären Frequenzmodulationen nicht die Zwischenkreisfilter 6, 7 und beeinflussen somit nicht die Steuerungseinrichtung 10 und den Hochfrequenzgenerator 12. Typischerweise liegen entsprechende Entstörfrequenzen über 400 kHz. Schematisch ist in Figur 6 angedeutet, dass die Modulationsfrequenz fM größer als die Bandbreite zu wählen ist. An embodiment of the present invention makes use of the fact that the intermediate circuit filters 6, 9 filter out signals which are outside the bandwidth of the intermediate frequency filter. Signals which have a greater modulation frequency f M are considered to be signals of a transmitter with an adjacent transmission frequency and accordingly suppressed by the intermediate circuit filters 6, 9. Therefore, an oscillation signal having a modulation frequency f M which is larger than the bandwidth B of the broadcasting receiver is modulated. Then the parasitic frequency modulations do not pass through the intermediate circuit filters 6, 7 and thus do not affect the control device 10 and the high-frequency generator 12. Typically, corresponding interference suppression frequencies are above 400 kHz. Schematically, it is indicated in FIG. 6 that the modulation frequency f M must be greater than the bandwidth to be selected.

Claims

PATENTANSPRÜCHE
1. Verfahren zur Dämpfung einer Hochfrequenzabstrahlung eines getakteten Systems mit einem anregenden Oszillator, mit den Schritten:1. A method for attenuating a high-frequency radiation of a clocked system with a stimulating oscillator, comprising the steps:
Bestimmen eines zeitlich gemittelten Maximalwertes, welchen die Leistung der Hochfrequenzabstrahlung des getakteten Systems (21) in einem vorgegebenen Frequenzband nicht überschreiten soll;Determining a time-averaged maximum value which the power of the radio-frequency emission of the clocked system (21) in a given frequency band should not exceed;
Modulieren einer Oszillationsfrequenz (fτ) des anregenden Oszillators (22) mit einem Frequenzhub, derart dass die mittlere Leistung in dem vorgegebenen Frequenzband unterhalb dem Maximalwert liegt;Modulating an oscillation frequency (f τ ) of the exciting oscillator (22) with a frequency sweep such that the average power in the predetermined frequency band is below the maximum value;
Bestimmen einer Bandbreite (B) eines Funkempfängers des vorgegebenen Frequenzbandes; undDetermining a bandwidth (B) of a radio receiver of the predetermined frequency band; and
Modulieren der Oszillationsfrequenz (fτ) mit einer Modulationsfrequenz (fM), welche größer als die Bandbreite des Funkempfängers ist.Modulating the oscillation frequency (f τ ) with a modulation frequency (f M ), which is greater than the bandwidth of the radio receiver.
2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, dass die Modulationsfrequenz (fM) auf mehr als 400 kHz eingestellt wird, um einen UKW-Empfang nicht zu stören.2. The method according to claim 1, characterized in that the modulation frequency (f M ) is set to more than 400 kHz in order not to disturb an FM reception.
3. Verfahren nach einem der vorhergehenden Ansprüche, mit den weiteren Schritten: Erfassen eines der Leistung der Hochfrequenzabstrahlung entsprechenden Signals; Steuern des Frequenzhubes ansprechend auf das Signal, derart dass das Signal unterhalb einem dem Maximalwert entsprechenden maximalen Signal bleibt.3. The method according to any one of the preceding claims, further comprising the steps of: detecting a signal corresponding to the power of the high frequency radiation; Controlling the frequency sweep in response to the signal such that the signal remains below a maximum signal corresponding to the maximum value.
4. Verfahren nach einem der vorhergehenden Ansprüche 1 bis 3, mit den weiteren Schritten: Erfassen eines der Leistung der Hochfrequenzabstrahlung entsprechenden Signals; Bestimmen des Frequenzhubs basierend auf einem Verhältnis des Maximalwertes zu dem Signal; 4. The method according to any one of the preceding claims 1 to 3, comprising the further steps of: detecting a signal corresponding to the power of the high-frequency radiation; Determining the frequency sweep based on a ratio of the maximum value to the signal;
5. Vorrichtung zur Dämpfung einer Hochfrequenzabstrahlung eines getakteten Systems mit einem anregenden Oszillator, wobei der anregende Oszillator (22) derart eingerichtet ist, dass dessen Oszillationsfrequenz (fτ) durch ein Steuersignal (10) einstellbar ist; und5. A device for attenuating a high-frequency radiation of a clocked system with a stimulating oscillator, wherein the exciting oscillator (22) is arranged such that the oscillation frequency (f τ ) by a control signal (10) is adjustable; and
einen Modulationsoszillator (24) aufweist, welcher mit dem anregenden Oszillator (22) verbunden ist und eingerichtet ist ein periodisches Steuersignal (10) zum Modulieren einer Oszillationsfrequenz (fτ) des anregenden Oszillators (22) auszugeben, derart dass die mittlere Leistung einer Hochfrequenzabstrahlung in einem vorgegebenen Frequenzband unterhalb ei- nem Maximalwert liegt.a modulation oscillator (24) connected to the exciting oscillator (22) and adapted to output a periodic control signal (10) for modulating an oscillation frequency ( fτ ) of the exciting oscillator (22) such that the average power of a high frequency radiation in a predetermined frequency band is below a maximum value.
6. Vorrichtung nach Anspruch 6, dadurch gekennzeichnet, dass eine Verstärkungseinrichtung (23) zum Verstärken des Steuersignals (10) zwischen dem anregenden Oszillator (22) und dem Modulationsoszillator (24) vorgesehen ist, wobei die Verstärkungseinrichtung (22) eine ein- stellbare Verstärkung aufweist, um den Frequenzhub einzustellen. 6. Apparatus according to claim 6, characterized in that an amplifying means (23) for amplifying the control signal (10) between the exciting oscillator (22) and the modulation oscillator (24) is provided, wherein the amplifying means (22) has an adjustable gain has to adjust the frequency deviation.
EP06721180A 2005-03-24 2006-01-31 Method for damping a high-frequency radiation of a clocked system Withdrawn EP1864413A1 (en)

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