EP0767553B1 - Circuit for generating short muting impulses in a car radio receiver - Google Patents
Circuit for generating short muting impulses in a car radio receiver Download PDFInfo
- Publication number
- EP0767553B1 EP0767553B1 EP19950115583 EP95115583A EP0767553B1 EP 0767553 B1 EP0767553 B1 EP 0767553B1 EP 19950115583 EP19950115583 EP 19950115583 EP 95115583 A EP95115583 A EP 95115583A EP 0767553 B1 EP0767553 B1 EP 0767553B1
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- signal
- input
- comparison stage
- circuit arrangement
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04H—BROADCAST COMMUNICATION
- H04H20/00—Arrangements for broadcast or for distribution combined with broadcast
- H04H20/20—Arrangements for broadcast or distribution of identical information via plural systems
- H04H20/22—Arrangements for broadcast of identical information via plural broadcast systems
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04H—BROADCAST COMMUNICATION
- H04H40/00—Arrangements specially adapted for receiving broadcast information
- H04H40/18—Arrangements characterised by circuits or components specially adapted for receiving
- H04H40/27—Arrangements characterised by circuits or components specially adapted for receiving specially adapted for broadcast systems covered by groups H04H20/53 - H04H20/95
- H04H40/36—Arrangements characterised by circuits or components specially adapted for receiving specially adapted for broadcast systems covered by groups H04H20/53 - H04H20/95 specially adapted for stereophonic broadcast receiving
- H04H40/45—Arrangements characterised by circuits or components specially adapted for receiving specially adapted for broadcast systems covered by groups H04H20/53 - H04H20/95 specially adapted for stereophonic broadcast receiving for FM stereophonic broadcast systems receiving
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04H—BROADCAST COMMUNICATION
- H04H2201/00—Aspects of broadcast communication
- H04H2201/10—Aspects of broadcast communication characterised by the type of broadcast system
- H04H2201/13—Aspects of broadcast communication characterised by the type of broadcast system radio data system/radio broadcast data system [RDS/RBDS]
Definitions
- the invention relates to a circuit arrangement for a car radio the preamble of claim 1.
- Such a circuit arrangement is for example in a mobile RDS receiver (radio data receiver) appropriate, with the alternative Transmitters are briefly checked for their reception quality. In order to during the duration of the check resulting interference signals not to Speaker, it is necessary to use the AF signal by means of a blanking pulse mute temporarily.
- Such circuit arrangements are known from the publications DE 4233738, DE 4316683, EP 507096 and EP 597492. As an abrupt However, mute during an existing LF level as annoying perceived pops arise, action is required to this reduce it so much that they are as far as possible no longer perceptible.
- the invention is based on the object, a circuit arrangement for a Car radio, with the control impulses for short-term alternative transmitter checks be generated with simultaneous muting, the mute is not from the human ear as a noise should be perceived.
- the advantages achieved by the invention are in particular that the short-term mutes within that of the circuitry recognized, caused by the decay of the hearing hearing shadow respectively. Because a frequent testing of alternative transmitters at high reception field strengths and modulation can be done is an intended control for station selection with decreasing reception field strength already up to date informed about the transmitter landscape, so that alternative frequency tests do not need to be done hastily.
- the output of a provided with an amplifier stage NF bandpass 1 is connected to the input of a double-path logarithm 2 whose Output via a full-wave rectifier 3 with the input of a Amplifier stage having low pass 2nd order 4 is connected, the has a cutoff frequency of about 23 Hz.
- the exit of the low pass 4 is connected to the input of an adder 5, with the input of a first Time constant element 6 and with the input of a second Time constant member 7 connected.
- the output of the adder 5 is connected to the first input A of a logic circuit formed Level comparison stage 8 connected.
- the output of the first Time constant element 6 is connected to the second input B of Level comparison stage 8 and the output of the second time constant element 7 connected to the third input C of the level comparing stage 8, whose Output D is connected to the input of a pulse shaper 9.
- Adder 5 adds a DC level to the input level applied to it of, for example, 0.6 volts.
- the first and the second Time constant element 6, 7 are designed such that their output levels change largely linearly as a function of time.
- For the first Time Constant 6 is a rate of change of, for example 18 volts per second and for the second time constant element 7 of, for example 1 volt per second provided.
- the pulse shaper 9 is such designed to be fed by a comparator at one of them Input signal a control pulse (S6) with a duration of, for example 5 ms and then for a duration equal to or greater than 100 ms is blocked for further activations.
- a multiplex signal (MPX signal) is available and that for a mute and for one during this mute time For example, 8 ms to be performed transmitter check a control pulse should be generated with a duration of about 5 ms.
- the filtered out of the MPX signal by means of the bandpass 1 LF signal S1 is transmitted through the double-path logarithm 2 and over the Double-way rectifier 3 the low pass 2nd order 4 supplied.
- Fig. 2 is a graph of such an LF signal S1 in a linear scale played.
- a signal S2 can be removed, its course of an envelope of the rectified and screened LF signal corresponds, wherein the logarithmic signal S2 to a value of 1 volt per 10 dB level change is amplified.
- the first entrance of the Logic circuit 8 becomes a DC voltage level of 0.6 volts raised envelope signal S2 supplied as a reference value level S3.
- the second input B of the logic circuit 8 is the on the first Time constant element 6 whose time constant largely the time constant corresponds to human being's incoming and outgoing vibrations guided signal S2 supplied as a hearing-related signal level S4.
- the third input C of the logic circuit 8 becomes the second Time constant member 7 supplied as the average level S5 taken signal.
- the levels S2 and S3 give the envelope curve of the LF signal S1 again. Is, as shown, in point a of Level S3 at the first input A of the logic circuit 8 is less than the level S4 at the second input B and also at point b, the level S3 is smaller than that Level S5, the output D of the logic circuit 8 produces a signal which starts the pulse shaper 9. This one now gives one Control pulse with a duration of about 5 ms and is followed by blocked for further actuations for a duration equal to or greater than 100 ms.
- the short-term AF blanking also takes place in the audio shadow, it is necessary to increase the level by means of the adder 5 so measured that the envelope level S2 on the one hand about 6 dB below the Ear Curve S4 and on the other hand about 6 dB below the average level S5 lies.
- the level increase selected in the present embodiment of 0.6 volts can in a practical circuit through a base-emitter threshold a transistor can be generated.
- the logarithmation of the LF signal ensures that the different volume (modulation range) of the transmitter has no effect on a changeable behavior of the system.
- Exclusively the Dynamics of modulation is the criterion for controlling the short Mute and verify times.
- mute signal is about 8 ms long - the invention is based Circuitry also insist that after a recognized Hearing shadow - not within about 8 ms - again a level increase he follows. Practical experiments have shown that about 95% of the 8 ms mutes are in the so-called Hörschatten. This means that only about every twentieth to thirtieth mute can be heard could. In the reality of a RDS concept with mute-occlusion For example, the logic provides the processor with an approximately 3 to 5 ms window for the processor Beginning of the AF test available. If this window is missed, it must open the next to be serviced. Does it come in critical reception situations to temporal problems, so it is in the hands of the software, AF jumps without approval.
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- Engineering & Computer Science (AREA)
- Signal Processing (AREA)
- Noise Elimination (AREA)
- Amplifiers (AREA)
Description
Die Erfindung betrifft eine Schaltungsanordnung für ein Autoradio nach dem Oberbegriff des Anspruchs 1.The invention relates to a circuit arrangement for a car radio the preamble of claim 1.
Eine derartige Schaltungsanordnung ist beispielsweise bei einem mobilen RDS-Empfänger (Radio-Data-Empfänger) zweckmäßig, mit dem alternative Sender kurzzeitig auf ihre Empfangsqualität überprüft werden. Damit während der Dauer der Überprüfung entstehende Störsignale nicht zum Lautsprecher gelangen können, ist es erforderlich, das NF-Signal mittels eines Austastimpulses kurzzeitig stumm zu schalten. Solche Schaltungsanordnungen sind aus den Veröffentlichungen DE 4233738, DE 4316683, EP 507096 und EP 597492 bakannt. Da bei einem abrupten Stummschalten während eines vorhandenen NF-Pegels jedoch als störend empfundene Knackgeräusche entstehen, sind Maßnahmen erforderlich, um diese soweit zu verringern, daß sie möglichst nicht mehr wahrnehmbar sind.Such a circuit arrangement is for example in a mobile RDS receiver (radio data receiver) appropriate, with the alternative Transmitters are briefly checked for their reception quality. In order to during the duration of the check resulting interference signals not to Speaker, it is necessary to use the AF signal by means of a blanking pulse mute temporarily. Such circuit arrangements are known from the publications DE 4233738, DE 4316683, EP 507096 and EP 597492. As an abrupt However, mute during an existing LF level as annoying perceived pops arise, action is required to this reduce it so much that they are as far as possible no longer perceptible.
Zur Verringerung derartiger Störungen ist es unter anderem bekannt, die Steuerimpulse für die Austastung und die Senderüberprüfung dann zu erzeugen, wenn das NF-Signal Modulationspausen aufweist. Da nicht verdeckte Alternativfrequenz-Tests (AF-Tests) bei kleineren Feldstärken auch in Modulationspausen hörbar sind, hat es sich als zweckmäßig erwiesen, einem Austastsignal von etwa 8 ms eine Verbotszeit von etwa 1 bis 2 s folgen zu lassen. Aus dem Handbuch "Tonstudiotechnik", 2. Auflage, Seiten 101 und 102, Johannes Webers, Franzis-Verlag München, ist es bekannt, daß beim plötzlichen Einwirken eines Dauertones konstanter Intensität die volle Lautstärke erst nach einer gewissen Zeit vom Gehör wahrgenommen wird. Der einen exponentiellen Charakter zeigende Einschwingvorgang hat eine Zeitkonstante von etwa 23 ms. Ähnlich verhält es sich auch mit dem Abklingvorgang des Gehörs, der ebenfalls exponentiell verläuft und eine Zeitkonstante von etwa 25 ms aufweist. To reduce such disturbances, it is known inter alia, the Then generate control pulses for blanking and transmitter verification if the LF signal has modulation pauses. Because not hidden Alternative frequency tests (AF tests) at lower field strengths also in Modulation pauses are audible, it has proved to be appropriate to a Blanking signal of about 8 ms followed by a prohibition period of about 1 to 2 s to let. From the manual "Tonstudiotechnik", 2nd edition, pages 101 and 102, Johannes Webers, Franzis-Verlag Munich, it is known that the sudden action of a constant tone of constant intensity the full Volume is perceived by the ear only after a certain time. Of the A transient process showing an exponential character has a time constant of about 23 ms. The situation is similar with the decay process of hearing, which also runs exponentially and has a time constant of about 25 ms.
Der Erfindung liegt die Aufgabe zugrunde, eine Schaltungsanordnung für ein Autoradio anzugeben, mit der Steuerimpulse für kurzzeitige Alternativsender-Überprüfungen bei gleichzeitigen Stummschaltungen erzeugt werden, wobei das Stummschalten nicht vom menschlichen Ohr als Störgeräusch wahrgenommen werden soll.The invention is based on the object, a circuit arrangement for a Car radio, with the control impulses for short-term alternative transmitter checks be generated with simultaneous muting, the mute is not from the human ear as a noise should be perceived.
Diese Aufgabe wird erfindungsgemäß durch die im kennzeichnenden Teil des Anspruchs 1 angegebenen Maßnahmen gelöst.This object is achieved by the characterizing part of Claim 1 specified measures solved.
Die mit der Erfindung erzielten Vorteile bestehen insbesondere darin, daß die kurzzeitigen Stummschaltungen innerhalb der von der Schaltungsanordnung erkannten, durch den Abklingvorgang des Gehörs bedingten Hörschatten erfolgen. Da ein häufiges Testen alternativer Sender bei großen Empfangsfeldstärken und bei Modulation erfolgen kann, ist eine vorgesehene Steuerung zur Senderauswahl bei abfallender Empfangsfeldstärke bereits aktuell über die Senderlandschaft informiert, so daß Alternativfrequenz-Tests nicht hastig durchgeführt werden brauchen.The advantages achieved by the invention are in particular that the short-term mutes within that of the circuitry recognized, caused by the decay of the hearing hearing shadow respectively. Because a frequent testing of alternative transmitters at high reception field strengths and modulation can be done is an intended control for station selection with decreasing reception field strength already up to date informed about the transmitter landscape, so that alternative frequency tests do not need to be done hastily.
Vorteilhafte Ausgestaltungen der Erfindung sind in den Unteransprüchen
angegeben. Durch die Einbeziehung des Mittelwert-Signalpegels nach
Anspruch 2 wird ein Wirksamwerden eines durch relativ steile Signalaustastflanken
entstehenden Störspektrums verhindert. Eine Impulsformerstufe nach
Anspruch 3 verbietet in sinnvoller Weise im Anschluß an den Steuerimpuls
für eine vorgegebene Zeitdauer eine weitere Impulsabgabe. Mit Anordnungen
und Bemessungen nach den Ansprüchen 4, 5 und 6 lassen sich in vorteilhafter
Weise dem Amplitudenverlauf der NF-Information entsprechende logarithmierte
Pegel erzeugen. Mit einer Anordnung nach Anspruch 7 läßt sich der
Ansprechpunkt bestimmen, der eine ausreichende Abdeckung des Störgeräusches
innerhalb eines Hörschattens garantiert. Durch die Ausbildung der
Zeitkonstantenglieder nach Anspruch 8 ist sichergestellt, daß unterschiedliche
Lautstärke (Modulationshub) des Senders keine Auswirkung auf ein
verändertes Verhalten des Systems hat. Das Kriterium für die Steuerung der
kurzzeitigen Alternativfrequenz-Austastung ist ausschließlich die Dynamik
der Modulation.Advantageous embodiments of the invention are in the subclaims
specified. By including the mean signal level after
Ein Ausführungsbeispiel der Erfindung ist in der Zeichnung dargestellt und wird im folgenden näher erläutert.An embodiment of the invention is shown in the drawing and will be explained in more detail below.
Es zeigen:
- Fig. 1
- ein prinzipielles Blockschaltbild einer Schaltungsanordnung für die Erzeugung kurzzeitiger, zur Stummschaltung und Senderüberprüfung dienende Steuerimpulse und
- Fig. 2
- einen NF-Signalverlauf und weitere daraus abgeleitete Signalverläufe.
- Fig. 1
- a schematic block diagram of a circuit arrangement for the generation of short-term, for mute and transmitter verification serving control pulses and
- Fig. 2
- a LF waveform and other derived waveforms.
Der Ausgang eines mit einer Verstärkerstufe versehenen NF-Bandpasses 1 ist
mit dem Eingang eines Doppelweg-Logarithmierers 2 verbunden, dessen
Ausgang über einen Doppelweg-Gleichrichter 3 mit dem Eingang eines eine
Verstärkerstufe aufweisenden Tiefpasses 2. Ordnung 4 verbunden ist, der
eine Grenzfrequenz von etwa 23 Hz aufweist. Der Ausgang des Tiefpasses 4
ist mit dem Eingang eines Addierers 5, mit dem Eingang eines ersten
Zeitkonstantengliedes 6 sowie mit dem Eingang eines zweiten
Zeitkonstantengliedes 7 verbunden. Der Ausgang des Addierers 5 ist mit dem
ersten Eingang A einer als Logikschaltung ausgebildeten
Pegelvergleichsstufe 8 verbunden. Der Ausgang des ersten
Zeitkonstantengliedes 6 ist mit dem zweiten Eingang B der
Pegelvergleichsstufe 8 und der Ausgang des zweiten Zeitkonstantengliedes 7
mit dem dritten Eingang C der Pegelvergleichsstufe 8 verbunden, deren
Ausgang D mit dem Eingang einer Impulsformerstufe 9 verbunden ist. Der
Addierer 5 addiert zu dem ihm zugeführten Eingangspegel einen Gleichspannungspegel
von beispielsweise 0,6 Volt. Das erste und das zweite
Zeitkonstantenglied 6, 7 sind derart ausgebildet, daß sich ihre Ausgangspegel
in Abhängigkeit von der Zeit weitgehend linear ändern. Für das erste
Zeitkonstantenglied 6 ist eine Änderungsgeschwindigkeit von beispielsweise
18 Volt pro Sekunde und für das zweite Zeitkonstantenglied 7 von beispielsweise
1 Volt pro Sekunde vorgesehen. Die Impulsformerstufe 9 ist derart
ausgelegt, daß sie bei einem ihr von der Vergleichsstufe zugeführten
Eingangssignal einen Steuerimpuls (S6) mit einer Dauer von beispielsweise
5 ms abgibt und daran'anschließend für eine Dauer von gleich/größer 100 ms
für weitere Ansteuerungen gesperrt ist.The output of a provided with an amplifier stage NF bandpass 1 is
connected to the input of a double-
Es wird davon ausgegangen, daß bei einem nicht dargestellten, an sich bekannten Autoradio ein Multiplexsignal (MPX-Signal) zur Verfügung steht und daß für eine Stummschaltung und für eine während dieser Stummschaltzeit von beispielsweise 8 ms durchzuführenden Senderüberprüfung ein Steuerimpuls mit einer Dauer von etwa 5 ms erzeugt werden soll.It is assumed that in a not shown, in itself known car radio a multiplex signal (MPX signal) is available and that for a mute and for one during this mute time For example, 8 ms to be performed transmitter check a control pulse should be generated with a duration of about 5 ms.
Das aus dem MPX-Signal mittels des Bandpasses 1 herausgefilterte
NF-Signal S1 wird über den Doppelweg-Logarithmierer 2 und über den
Doppelweg-Gleichrichter 3 dem Tiefpaß 2. Ordnung 4 zugeführt. In der
Fig. 2 ist der Verlauf eines derartigen NF-Signals S1 im linearen Maßstab
wiedergegeben. Am Ausgang des Tiefpasses 4 ist ein Signal S2 entnehmbar,
dessen Verlauf einer Hüllkurve des gleichgerichteten und gesiebten NF-Signals
entspricht, wobei das logarithmierte Signal S2 auf einen Wert von
1 Volt pro 10 dB Pegeländerung verstärkt wird. Dem ersten Eingang der
Logikschaltung 8 wird das um einen Gleichspannungspegel von 0,6 Volt
angehobene Hüllkurvensignal S2 als Referenzwertpegel S3 zugeführt. Dem
zweiten Eingang B der Logikschaltung 8 wird das über das erste
Zeitkonstantenglied 6, dessen Zeitkonstante weitgehend der Zeitkonstante
für Ein- und Ausschwingvorgänge des menschlichen Gehörs entspricht,
geführte Signal S2 als gehörbezogener Signalpegel S4 zugeführt. Dem
dritten Eingang C der Logikschaltung 8 wird das dem zweiten
Zeitkonstantenglied 7 als Mittelwertpegel S5 entnommene Signal zugeführt.The filtered out of the MPX signal by means of the bandpass 1
LF signal S1 is transmitted through the double-
Wie aus der Fig. 2 ersichtlich ist, geben die Pegel S2 und S3 den Hüllkurvenverlauf
des NF-Signals S1 wieder. Wird, wie dargestellt, im Punkt a der
Pegel S3 am ersten Eingang A der Logikschaltung 8 kleiner als der Pegel S4
am zweiten Eingang B und wird zudem im Punkt b der Pegel S3 kleiner als der
Pegel S5, so entsteht am Ausgang D der Logikschaltung 8 ein Signal,
welches die Impulsformerstufe 9 startet. Diese gibt nun ihrerseits einen
Steuerimpuls mit einer Dauer von etwa 5 ms ab und ist daran anschließend
für eine Dauer von gleich/größer 100 ms für weitere Ansteuerungen gesperrt.
Damit die kurzzeitige NF-Austastung auch im Hörschatten erfolgt,
ist es erforderlich, die Pegelanhebung mittels der Addierstufe 5 derart zu
bemessen, daß der Hüllkurvenpegel S2 zum einen etwa 6 dB unter dem
Ohrkurvengegel S4 und zum anderen etwa 6 dB unter dem Mittelwertpegel S5
liegt. Die beim vorliegenden Ausführungsbeispiel gewählte Pegelanhebung
von 0,6 Volt kann in einer praktischen Schaltung durch eine Basis-Emitter-Schwelle
eines Transistors erzeugt werden.As can be seen from FIG. 2, the levels S2 and S3 give the envelope curve
of the LF signal S1 again. Is, as shown, in point a of
Level S3 at the first input A of the
Durch die Logarithmierung des NF-Signals ist sichergestellt, daß die unterschiedliche Lautstärke (Modulationshub) der Sender keine Auswirkung auf ein veränderliches Verhalten des Systems hat. Ausschließlich die Dynamik der Modulation ist das Kriterium für die Steuerung der kurzen Stummschalt- und Überprüfzeiten.The logarithmation of the LF signal ensures that the different volume (modulation range) of the transmitter has no effect on a changeable behavior of the system. Exclusively the Dynamics of modulation is the criterion for controlling the short Mute and verify times.
Da es nicht möglich ist, in die Zukunft zu messen - das eigentliche Stummschaltsignal aber etwa 8 ms lang ist -, basiert die erfindungsgemäße Schaltungsanordnung außerdem darauf, daß nach einer erkannten Hörabschattung - nicht innerhalb von etwa 8 ms - wieder ein Pegelanstieg erfolgt. Praktische Versuche haben ergeben, daß zu etwa größer 95 % die 8 ms-Stummschaltungen im sogenannten Hörschatten liegen. Dieses bedeutet, daß nur etwa jede zwanzigste bis dreißigste Stummschaltung hörbar sein könnte. In der Realität eines RDS-Konzeptes mit Stummschalt-Verdeckung stellt die Logik dem Prozessor ein etwa 3 bis 5 ms langes Fenster für den Beginn des AF-Tests zur Verfügung. Wird dieses Fenster verpaßt, muß auf das nächste gewartet werden. Kommt es bei kritischen Empfangssituationen zu zeitlichen Problemen, so liegt es in der Hand der Software, AF-Sprünge ohne Freigabe zuzulassen.Since it is not possible to measure in the future - the real one But mute signal is about 8 ms long - the invention is based Circuitry also insist that after a recognized Hearing shadow - not within about 8 ms - again a level increase he follows. Practical experiments have shown that about 95% of the 8 ms mutes are in the so-called Hörschatten. This means that only about every twentieth to thirtieth mute can be heard could. In the reality of a RDS concept with mute-occlusion For example, the logic provides the processor with an approximately 3 to 5 ms window for the processor Beginning of the AF test available. If this window is missed, it must open the next to be serviced. Does it come in critical reception situations to temporal problems, so it is in the hands of the software, AF jumps without approval.
Claims (8)
- Circuit arrangement for a car radio, in which control pulses optained on the basis of an AF signal are used for briefly muting reproduction of the received station programme and for checking alternative stations for their reception suitability within the mute period,
characterized in that means (1, 2, 3, 4) are provided which obtain from an AF information item removed from the car radio's multiplex signal path a signal (S2) whose level corresponds to the shape of an envelope for the AF signal (S1) and which corresponds to the amplitude curve for the AF information item, and in that a level comparison stage (8) and a first time-constant element (6) are provided, so that the signal (S2) corresponding to the amplitude curve for the AF information item is firstly increased by a prescribed level value and is supplied undelayed as a reference-value level (S2) to a first input (A) of the level comparison stage (8) and is secondly supplied as a hearing-related signal level (S4) to a second input (B) of the level comparison stage (8) via the first time-constant element (6), whose time constant largely corresponds to the time constant for build-up and die-down processes in the perception of volume in human hearing, and in that the level comparison stage (8) is proportioned such that its output (D) outputs the control pulse (S6) initiating muting and station checking if the reference-value level (S3) applied to the first input (A) of the comparison stage (8) falls below the hearing-related signal level (S4) applied to the second input (B). - Circuit arrangement according to Claim 1,
characterized in that a second time-constant element (7) is provided, so that the signal (S2) corresponding to the amplitude curve for the AF information item is supplied to a third input (C) of the level comparison stage (8) via the second time-constant element (7), whose time constant is chosen such that it forms a mean value (S5), and
in that the level comparison stage (8) is proportioned such that its output (D) outputs the control pulse (S6) initiating muting and station checking if the reference level (S3) applied to the first input (A) of the comparison stage (8) falls below the signal level (S4) applied to the second input (B) and below the mean-value signal level (S5) applied to the third input (C). - Circuit arrangement according to one of Claims 1 or 2,
characterized in that a pulse shaper stage (9) is provided, so that the pulse shaper stage (9) is designed such that, upon an input signal supplied to it by the comparison stage (8), it outputs a control pulse (36) of prescribed duration and is then disabled for further control operations for a prescribed duration. - Circuit arrangement according to one of Claims 1 to 3,
characterized in that the means for obtaining the signal (S2) corresponding to the amplitude curve for the AF information item have an AF bandpass filter (1), a logarithmizer 2), a rectifier (3) and an AF low-pass filter (4). - Circuit arrangement according to Claim 4,
characterized in that the AF bandpass filter (1) has a bi-directional logarithmizer (2), a bi-directional rectifier (3) and a 2nd-order low-pass filter (4) connected downstream of it, with the order in which the logarithmizer (2) and the rectifier (3) appear being able to be arbitrary. - Circuit arrangement according to Claim 5,
characterized in that the low-pass filter (4) has a cut-off frequency of approximately 23 Hz. - Circuit arrangement according to one of Claims 1 to 6,
characterized in that an adder (5) is provided, so that the signal (S2) corresponding to the amplitude curve for the AF information item is supplied to the first input (A) of the comparison stage (8), in the form of a logic circuit, via the adder (5), which forms the reference-value level (S3) by adding the AF envelope level (S2) and a DC voltage level, and in that the DC voltage level is proportioned such that blank periods arising in the acoustic shadow are not perceptible. - Circuit arrangement according to one of Claims 2 or 3 to 7, in so far as they are dependent on Claim 2,
characterized in that the first and second time-constant elements (6, 7) are designed such that their output levels (S4, S5) change largely linearly as a function of time.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| EP19950115583 EP0767553B1 (en) | 1995-10-02 | 1995-10-02 | Circuit for generating short muting impulses in a car radio receiver |
| DE59510754T DE59510754D1 (en) | 1995-10-02 | 1995-10-02 | Circuit arrangement for a car radio for generating short-term mute pulses |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| EP19950115583 EP0767553B1 (en) | 1995-10-02 | 1995-10-02 | Circuit for generating short muting impulses in a car radio receiver |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| EP0767553A1 EP0767553A1 (en) | 1997-04-09 |
| EP0767553B1 true EP0767553B1 (en) | 2003-07-23 |
Family
ID=8219681
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP19950115583 Expired - Lifetime EP0767553B1 (en) | 1995-10-02 | 1995-10-02 | Circuit for generating short muting impulses in a car radio receiver |
Country Status (2)
| Country | Link |
|---|---|
| EP (1) | EP0767553B1 (en) |
| DE (1) | DE59510754D1 (en) |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2978263B2 (en) * | 1991-03-29 | 1999-11-15 | パイオニア株式会社 | RDS receiver |
| DE4233758C1 (en) * | 1992-10-07 | 1994-01-27 | Blaupunkt Werke Gmbh | Radio receiver |
| JP2841309B2 (en) * | 1992-11-13 | 1998-12-24 | クラリオン株式会社 | Multiplex broadcast receiver |
| DE4316683A1 (en) * | 1993-05-16 | 1994-11-17 | H U C Elektronik Gmbh | Method and circuit arrangement for broadcast reception |
-
1995
- 1995-10-02 EP EP19950115583 patent/EP0767553B1/en not_active Expired - Lifetime
- 1995-10-02 DE DE59510754T patent/DE59510754D1/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| EP0767553A1 (en) | 1997-04-09 |
| DE59510754D1 (en) | 2003-08-28 |
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