EP0963684A1 - Procede pour influer sur l'espacement des voies stereo d'un signal audio et dispositif correspondant - Google Patents

Procede pour influer sur l'espacement des voies stereo d'un signal audio et dispositif correspondant

Info

Publication number
EP0963684A1
EP0963684A1 EP98906842A EP98906842A EP0963684A1 EP 0963684 A1 EP0963684 A1 EP 0963684A1 EP 98906842 A EP98906842 A EP 98906842A EP 98906842 A EP98906842 A EP 98906842A EP 0963684 A1 EP0963684 A1 EP 0963684A1
Authority
EP
European Patent Office
Prior art keywords
signal
auxiliary signal
interference
auxiliary
field strength
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.)
Granted
Application number
EP98906842A
Other languages
German (de)
English (en)
Other versions
EP0963684B1 (fr
Inventor
Marcus Risse
Bjoern Jelonnek
Rüdiger Trinks
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 EP0963684A1 publication Critical patent/EP0963684A1/fr
Application granted granted Critical
Publication of EP0963684B1 publication Critical patent/EP0963684B1/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04S—STEREOPHONIC SYSTEMS 
    • H04S1/00—Two-channel systems
    • H04S1/007—Two-channel systems in which the audio signals are in digital form

Definitions

  • the invention is based on a method for influencing the stereo channel separation of an audio signal to be reproduced and a radio receiver for carrying out the method according to the type of the independent claims.
  • Modern radio transmitters emit radio signals, the signal format of which enables the transmission of stereophonic audio signals and the surround sound of stereophonic reproduction can be clearly heard on the receiver side.
  • Radio receivers in particular car radios, have long been equipped with a switching or sliding transition from stereophonic to monophonic reproduction, which is dependent on the reception field strength of a received radio signal. In such Radio receivers automatically reduce the channel separation if the reception field strength drops.
  • a circuit arrangement for such a radio receiver in which a signal indicating the reception field strength is derived from the received field strength of a received radio signal, in which an interference signal indicating interference received is also derived from the received radio signal, and in which the signal indicating the reception field strength and the interference signal are multiplicatively linked to form a factor supplied to a stereo decoder for influencing the stereo channel separation of an audio signal to be reproduced.
  • a signal indicating the reception field strength is derived from the received field strength of a received radio signal
  • an interference signal indicating interference received is also derived from the received radio signal
  • the signal indicating the reception field strength and the interference signal are multiplicatively linked to form a factor supplied to a stereo decoder for influencing the stereo channel separation of an audio signal to be reproduced.
  • radio receivers with the possibility of evaluating information transmitted by means of the radio data system (RDS) which, for the purpose of optimizing the reception quality of a received radio program, temporarily from a currently set transmission frequency to an alternative transmission frequency via which the same program is transmitted will be tuned, the reception quality being determined during the dwell time on the alternative transmission frequency and the receiver then being set to the transmission frequency with the best reception conditions.
  • the information about the alternative transmission frequency is taken, for example, from the AF (alternative frequencies) data transmitted via the radio data system.
  • the inventive method and the radio receiver according to the invention with the features of the independent claims have the advantage that with strongly fluctuating reception conditions or frequently occurring reception interference, such as. B. multipath reception, fast and frequent changes between stereophonic and monophonic
  • Reproduction and the associated negative auditory impression can be suppressed in favor of a partially or completely monophonic reproduction.
  • a counter to implement a signal that indicates the frequency of reception disturbances, which is decremented when a disturbance occurs and when there is no disturbance, since the clock required for this counter is simple for example from the System clock z. B. can be derived from the bit clock of the digital signals involved.
  • radio receivers for receiving radio data signals which carry out automatic alternative frequency tests to optimize reception quality, to keep the channel separation auxiliary signal P at its last value for the duration of an alternative frequency test and, if appropriate, only after the alternative frequency test change, as this can avoid strong fluctuations in the stereo channel separation in the course of alternative frequency tests.
  • FIG. 1 shows a block diagram of the part of a radio receiver according to the invention that is essential to the invention
  • FIG. 2 shows an example of a realization of the second evaluation circuit 6
  • FIG. 3 shows an implementation possibility for the stereo decoder 11
  • FIG. 4 shows an example of a first characteristic curve realized in the first evaluation circuit 4
  • FIG 5 shows a second characteristic curve implemented in the third evaluation circuit
  • FIG. 6 shows an example of the monotonically falling characteristic curve 62 implemented in the second evaluation circuit 6.
  • FIG. 1 An exemplary embodiment of the part of a radio receiver according to the invention essential to the invention for carrying out the method according to the invention is shown in FIG.
  • audio signals for a left and a right channel (1, r) can be removed.
  • the formation of the audio signals for the left and right stereo channels 1 and r from the stereo multiplex signal MPX is described with reference to the exemplary embodiment for the stereo decoder 11 shown in FIG.
  • the stereo multiplex signal MPX is processed in two signal paths, the sum signal (L + R) being isolated therefrom by low-pass filtering 113 of the stereo multiplex signal.
  • a phase difference multiplication 111 with a 38 kHz subcarrier obtained, for example, from a 19 kHz pilot tone contained in the stereo multiplex signal and subsequent elimination of undesired mixed products by means of a low-pass filter 112 results in a difference signal (L-R) which represents the difference of the signals for contains left and right audio channels.
  • any stereo channel separation between purely monophonic and purely stereophonic reproduction can be set.
  • the common interference signal is a threshold value decision
  • Threshold value decider 2 changes from a first to a second state when the predetermined threshold value is exceeded by the common interference signal.
  • the values 1 and 0 are selected for the first and the second state.
  • the output of the threshold value decider 2 is fed to an edge controller 3 for controlling the edge steepness of the supplied signal. This is designed such that its output signal, hereinafter referred to as the first interference auxiliary signal s, suddenly assumes a fourth value when the output of the threshold value decider two changes from the first to the second state and as soon as the output of the threshold value decider 2 returns to the first value, after a predetermined time function z. B. within a few 10 ms. goes back to the third value.
  • the predefined time function is implemented in the present case in the form of a linear profile, but it can also be provided that the first auxiliary auxiliary signal s returns to the third value after a non-linear, for example exponential profile and thus in the direction of stereophonic reproduction.
  • a field strength signal (FST) indicating the reception field strength is fed to a first evaluation circuit 4 to form a first field strength auxiliary signal x, which characterizes the reception field strength of the received broadcast signal.
  • the field strength signal FST is in the present case by rectification and low-pass filtering
  • the field strength signal FST is evaluated with a monotonically increasing, in the present case linear characteristic curve, so that higher values for the first field strength auxiliary signal x result for higher reception fields.
  • the characteristic curve has a saturation range, so that there are no changes in the first field strength auxiliary signal x for very high reception field strengths.
  • the range of values of the first auxiliary field strength signal lies in the present case between the values 0 for a very low reception field strength FST and 1 for high and highest reception field strengths.
  • a third signal path 5 to 8 comprises a second evaluation circuit 6 for forming a signal which characterizes the frequency of reception interference, ie the number of interference per unit of time, hereinafter referred to as the second auxiliary interference signal P s tör, to which the first auxiliary auxiliary signal s is supplied .
  • FIG. 2 An embodiment of the second evaluation circuit 6 is shown in Figure 2.
  • This comprises a counter 61, clocked in the present case of digital signal processing, to which the first auxiliary auxiliary signal s is fed.
  • the counter 61 is incremented by a fifth predetermined value, whereas it is decremented by a sixth predetermined value if there is no receiving error.
  • the clock T supplied to the counter is derived from the sampling clock for the demodulated received signal, so that the counter 61 operates synchronously with the samples of the stereo multiplex signal MPX.
  • the counter reading 61 is evaluated by means of a monotonically falling characteristic curve 62, so that for high counter readings Z of the counter 61 at the output of the second evaluation circuit 6 there are low values for the second auxiliary auxiliary signal P s tör at low counter readings Z.
  • An example of the characteristic curve 62 is shown in FIG. 6, from which the relationship between the counter reading Z of the counter 61 and the second auxiliary fault signal P s tör can be seen.
  • the simplified second exemplary embodiment corresponds to the second auxiliary auxiliary signal P s tör obtained in this way, which indicates the frequency of reception interference, and the second auxiliary signal P so n, from which a channel separation auxiliary signal P is obtained by means of a tracking circuit 8.
  • the tracking circuit 8 works in such a way that for values of the second auxiliary signal P S oll 'which are smaller than a current value of the channel auxiliary signal P, the value of
  • Channel separation auxiliary signal P quickly decreases to the value of the second auxiliary signal P so n, while for values of the second auxiliary signal P so n that are greater than a current value of the channel separation auxiliary signal P, the channel separation auxiliary signal P slowly decreases after a predetermined time function , in the present case after an exponential function, first very quickly, then increasing more slowly, approximating the value of the second auxiliary signal p soll.
  • a suitable further development provides for the channel separation auxiliary signal P to be kept at the value immediately preceding the frequency jump or alternative frequency test during an alternative frequency test or a jump to an alternative frequency. Only after completion of the jump to an alternative frequency (in the case of a frequency change to a transmission frequency that is easier to receive) or after the alternative frequency test is the tracking circuit 8 reactivated for tracking the channel separation auxiliary signal P.
  • the deactivation of the tracking 8 for the duration of a frequency hopping or alternative frequency test and the second auxiliary signal P may thus ll o f its such an event immediately preceding value are frozen.
  • the third signal path further comprises a third evaluation circuit 5, in which the field strength signal FST to form a second field strength auxiliary signal psT with a second monotonically increasing characteristic curve, an example of which is shown in FIG. 5, Is evaluated.
  • the second field strength auxiliary signal PpsT and the second interference auxiliary signal P s tör are fed to form a second auxiliary signal P so n in a link 7, in which, in the present case, the minimum of the two second auxiliary signals gtör » P FST is formed, and the second Auxiliary signal P is so equated to the smaller of the two auxiliary signals p interference P FST.
  • the first auxiliary auxiliary signal, the first auxiliary field strength signal x and the auxiliary channel separation signal P are combined with one another in a second link 9, 10 to form the factor influencing the stereo channel separation.
  • the first auxiliary auxiliary signal s and the first auxiliary field strength signal x are multiplied with one another in a first multiplier 9 to form a first auxiliary signal.
  • the first auxiliary signal y thus formed is then weighted with the channel separation auxiliary signal P in a second multiplier 10 to form the factor D.
  • the factor D is directly proportional to the first field strength auxiliary signal, so that the reception field strength of the received radio signal has a direct effect on the stereo channel identification.
  • the first interference auxiliary signal s is above a threshold value
  • Reception interference faded from stereophonic to monophonic playback.
  • the interference frequency in the form of the second interference auxiliary signal P s tör (with a high frequency of interference) or the reception field strength in affects the channel separation auxiliary signal P.
  • the signals ST indicating the disturbances mentioned at the beginning are generated in a manner known per se as follows.
  • a signal ⁇ FST which indicates fluctuations in the field strength is obtained, for example, by constant comparison of a signal which indicates the current received field strength.
  • B. generated by rectification of the intermediate frequency signal can be derived with the slowly changing field strength signal FST.
  • the signal ⁇ FST indicating field strength fluctuations can be formed by subtracting the current field strength from the field strength signal FST.
  • a noise indicating signal can e.g. B. by evaluating the high-frequency signal components, for. B. beyond 60 kHz, which are contained in the stereo multiplex signal MPX.
  • a multipath signal indicating interference is known in a known manner, for. B. derivable by evaluating the symmetry of the sidebands of the 38 kHz subcarrier HT, an asymmetry suggesting multipath reception.
  • the characteristic curves realized in the evaluation circuits 4 to 6 are designed in the form of staircase functions, which are shown in broken lines in FIGS. 4 and 5, so that the number of possible output values and thus also the word length of the signals x, s, P s ör ' P FST finite and less Number of steps is low.
  • the characteristic curves By executing the characteristic curves as staircase functions with a small number of steps, it is possible to represent them using fewer comparators.

Landscapes

  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Noise Elimination (AREA)
  • Stereo-Broadcasting Methods (AREA)

Abstract

L'invention concerne un procédé pour influer sur l'espacement des voies stéréo d'un signal audio à reproduire, obtenu à partir d'un signal radio reçu. L'invention concerne également un radiorécepteur conçu pour mettre en oeuvre ledit procédé. Selon l'invention, un signal auxiliaire d'intensité de champ, dérivé de l'intensité de champ de réception du signal radio reçu, et un signal auxiliaire d'interférence dérivé de signaux indiquant des interférences de réception sont combinés l'un à l'autre et à un signal auxiliaire d'espacement des voies, dérivé d'un signal indiquant la fréquence des interférences, pour former un facteur D influant sur l'espacement des voies stéréo.
EP98906842A 1997-02-26 1998-01-24 Procede pour influer sur la separation des voies stereo d'un signal audio et dispositif correspondant Expired - Lifetime EP0963684B1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE19707673A DE19707673A1 (de) 1997-02-26 1997-02-26 Verfahren zur Beeinflussung der Stereo-Kanaltrennung eines Audiosignals und Anordnung dazu
DE19707673 1997-02-26
PCT/DE1998/000215 WO1998038835A1 (fr) 1997-02-26 1998-01-24 Procede pour influer sur l'espacement des voies stereo d'un signal audio et dispositif correspondant

Publications (2)

Publication Number Publication Date
EP0963684A1 true EP0963684A1 (fr) 1999-12-15
EP0963684B1 EP0963684B1 (fr) 2001-10-17

Family

ID=7821531

Family Applications (1)

Application Number Title Priority Date Filing Date
EP98906842A Expired - Lifetime EP0963684B1 (fr) 1997-02-26 1998-01-24 Procede pour influer sur la separation des voies stereo d'un signal audio et dispositif correspondant

Country Status (5)

Country Link
US (1) US6522750B1 (fr)
EP (1) EP0963684B1 (fr)
JP (1) JP2001513280A (fr)
DE (2) DE19707673A1 (fr)
WO (1) WO1998038835A1 (fr)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10139823B4 (de) * 2001-08-14 2004-02-26 Harman Becker Automotive Systems (Becker Division) Gmbh Verfahren zum Umschalten eines Stereoempfängers von Stereo- auf Mono- und von Mono- auf Stereowiedergabe und Stereoempfänger
DE10224699A1 (de) 2002-06-04 2003-12-24 Bosch Gmbh Robert Verfahren und Schaltungsanordnung zum Beeinflussen der Höhenwiedergabe eines Audiosignals

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Publication number Priority date Publication date Assignee Title
US4390749A (en) * 1981-04-13 1983-06-28 Superscope, Inc. Noise control system for FM radio
US4415768A (en) * 1981-05-28 1983-11-15 Carver R W Tuning apparatus and method
JPH01251201A (ja) * 1988-03-31 1989-10-06 Yokogawa Electric Corp プロセス制御装置
US5077797A (en) * 1989-05-25 1991-12-31 Sanyo Electric Co., Ltd. Fm stereo receiver
JP2770475B2 (ja) * 1989-09-21 1998-07-02 ヤマハ株式会社 受信装置
US5201062A (en) * 1990-03-28 1993-04-06 Pioneer Electronic Corporation Noise reducing circuit
JP2601764Y2 (ja) * 1992-07-10 1999-12-06 パイオニア株式会社 Ｆｍチューナ
ES2165387T3 (es) * 1993-03-24 2002-03-16 Blaupunkt Werke Gmbh Receptor de radio con procesamiento digital de las señales.
US5661809A (en) * 1993-03-24 1997-08-26 Blaupunkt-Werke Gmbh Radio receiver having digital signal processing
DE4309518A1 (de) * 1993-03-24 1994-10-06 Blaupunkt Werke Gmbh Schaltungsanordnung zur Ableitung mindestens eines von der Qualität eines empfangenen Signals abhängigen Qualitätssignals
FR2724027A1 (fr) * 1994-11-25 1996-03-01 France Telecom Operateur neuronal
US5671286A (en) * 1995-06-09 1997-09-23 Ford Motor Company Strategy for controlling FM stereo separation and frequency response in noisy reception environments
JP2955497B2 (ja) * 1995-08-31 1999-10-04 富士通テン株式会社 ステレオ受信機
US5703954A (en) * 1996-02-20 1997-12-30 Usa Digital Radio Partners, L.P. Method and apparatus for improving the quality of AM compatible digital broadcast system signals in the presence of distortion

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See references of WO9838835A1 *

Also Published As

Publication number Publication date
EP0963684B1 (fr) 2001-10-17
US6522750B1 (en) 2003-02-18
DE59801767D1 (de) 2001-11-22
JP2001513280A (ja) 2001-08-28
WO1998038835A1 (fr) 1998-09-03
DE19707673A1 (de) 1998-08-27

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