EP0473731B1 - Method and device for comparing two variable analog signals - Google Patents
Method and device for comparing two variable analog signals Download PDFInfo
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- EP0473731B1 EP0473731B1 EP91900037A EP91900037A EP0473731B1 EP 0473731 B1 EP0473731 B1 EP 0473731B1 EP 91900037 A EP91900037 A EP 91900037A EP 91900037 A EP91900037 A EP 91900037A EP 0473731 B1 EP0473731 B1 EP 0473731B1
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- 238000000034 method Methods 0.000 title claims description 16
- 230000001131 transforming effect Effects 0.000 claims description 8
- 238000009499 grossing Methods 0.000 claims description 3
- 230000005236 sound signal Effects 0.000 claims description 3
- 230000001747 exhibiting effect Effects 0.000 claims 1
- 230000000737 periodic effect Effects 0.000 claims 1
- 230000006870 function Effects 0.000 description 10
- 230000010363 phase shift Effects 0.000 description 8
- 238000004364 calculation method Methods 0.000 description 5
- 238000001514 detection method Methods 0.000 description 3
- 230000009466 transformation Effects 0.000 description 3
- 238000005314 correlation function Methods 0.000 description 2
- 230000010365 information processing Effects 0.000 description 2
- 230000001419 dependent effect Effects 0.000 description 1
- 235000021183 entrée Nutrition 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 230000009897 systematic effect Effects 0.000 description 1
- 238000005307 time correlation function Methods 0.000 description 1
Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R23/00—Arrangements for measuring frequencies; Arrangements for analysing frequency spectra
- G01R23/005—Circuits for comparing several input signals and for indicating the result of this comparison, e.g. equal, different, greater, smaller (comparing phase or frequency of 2 mutually independent oscillations in demodulators)
Definitions
- the invention relates to a method and a device. comparison of two variable analog signals, for example over time, such as audio signals or video, which are either different from each other, or identical but shifted in time.
- correlation function which lead to use steep slope band filters, analog-to-digital converters, a system of information processing allowing calculation in time correlation function, and an algorithm for complex treatment capable of taking into account and compensate for any offset between the signals.
- the cost systems allowing this calculation is generally quite Student.
- phase comparator which includes two channels analog signal processing, these two channels each comprising in series transformation circuits from analog signals to binary logic signals, a logic circuit of the exclusive OR type and an establishment circuit of a signal by summation.
- phase comparator which uses an integrated correlation circuit.
- This comparator comprises two parallel signal processing channels, one of which includes means for shifting one of the signals over time with respect to the other, the offset being equal to ⁇ 2 . Furthermore, said comparator uses a circuit for adding the absolute values of the two correlation signals.
- the object of the invention is in particular to simplify the aforementioned methods and systems of numerical computation and therefore greatly lower their cost while retaining the desired speed and accuracy of establishing the correlation.
- Transformation of analog signals into binary logic signals allows working on a single bit and then use a logical operator to perform the correlation between the signals. This results in a simplification important of the correlation process compared to classical numerical calculation methods.
- the third correlation signal obtained is substantially independent of the time lag between signals to compare, without the need to measure this shift.
- this process also consists in transforming each analog signal into binary logic signal by detection of zero crossings of this analog signal, and assigning a first logical value to the signal when positive, and a second logical value when it is negative.
- Detection of zero crossing signals analog provides simple excellent dynamic (of the order of 60 to 80dB) which would correspond at least 12 bit resolution within known methods of numerical calculation.
- the method also consists in connecting the logic circuit output to a low pass filter to achieve the aforementioned sum function.
- the invention also provides a device for comparison of two variable analog signals, including means for establishing a correlation signal between these two analog signals and means of comparison of this signal with a predetermined value to check whether there is identity or not between the signals analog, characterized in that, these analog signals being either identical and time-shifted, either different, and covering a predetermined frequency band, this device includes two parallel tracks analog signal processing, one of which includes means for shifting one of the signals over time relative to each other, the offset being equal to 1/4 of period at the center frequency of the frequency band above, these two channels each comprising in series of circuits for transforming analog signals into binary logic signals, a logic circuit of the type multiplier or exclusive OR, an establishment circuit by summing a correlation signal S1, S2, and a circuit for adding the absolute values of the two signals correlation S1, S2, producing an output signal correlation S substantially independent of an offset in the time between the above analog signals.
- a low-pass filter at the output of each circuit logic provides the value of the correlation signal S1, S2 corresponding to a given offset between analog signals.
- the output of the addition circuit is connected to the input of a low-pass filter, realizing smoothing the correlation signal.
- the device according to the invention also includes leveling circuits as input analog signals, such as for example automatic gain control circuits, and filters band pass.
- leveling circuits as input analog signals, such as for example automatic gain control circuits, and filters band pass.
- the circuits for transforming analog signals into binary logic signals are advantageously circuits for comparing analog signals to a determined value, in particular the value zero, allowing the detection of passages of analog signals by zero and the attribution to these signals of two binary values depending on whether they are positive or negative .
- the cost of a device according to the invention is far inferior to that of the devices classics of numerical computation of a function of correlation, and its performance is excellent.
- Figure 1 represents an example of application of the method and the device according to the invention.
- Reference 10 designates a radio receiver or television, connected to an antenna 12 and associated with a apparatus 14 for detecting the frequency on which is tuned the receiver 10.
- This device 14 includes a reference receiver 16, also connected to the antenna 12, a device correlation 18 according to the invention, a microprocessor 20 information processing, memory 22 data logging, an interface circuit 24 electronics to control receiver 16 under microprocessor control 20, and a dating clock 25.
- receivers 10 and 16 are connected at the inputs of the correlation device 18, the output is connected to an input of the microprocessor 20.
- This by means of the interface 24, performs a scanning systematic of the frequencies received by the receiver 16 of reference, whose output signals are compared to those of the receiver 10 by the device 18.
- the correlation between these signals establishes that receivers 10 and 16 are set to the same frequency. Correlation dates and the corresponding frequencies are saved in memory 22 from which they can then be extracted and used.
- Figure 2 shows schematically the constitution of a correlation device 18 according to the invention.
- audio or video signals produced by receptors 10 and 16 are applied to input circuits including circuits 26 of upgrade, such as automatic control circuits gain, generating analog signals with determined maximum voltage levels, and filters bandpass 28, reducing the frequency range signals at a predetermined band.
- circuits 26 of upgrade such as automatic control circuits gain, generating analog signals with determined maximum voltage levels, and filters bandpass 28, reducing the frequency range signals at a predetermined band.
- the bandwidth of the filters 28 is by example of an octave or more (e.g. 500-1000 Hz) for audio signals.
- each filter 28 is applied to the input of an analog signal transformation circuit 30 in binary logic signal compared to a predetermined value, which is preferably the value zero.
- the circuits 30 can therefore be simple comparators, whose positive inputs receive signals filters 28 and whose negative inputs are connected to ground.
- the outputs of the two comparators 30 are connected to the two inputs of a logic circuit 32 of the OR type exclusive, whose output signal is a logic signal binary, high level (e.g. 1) when both input signals are identical, and low level (0 or -1), when the two input signals are different.
- the function of circuit 32 is therefore equivalent to a multiplication logic.
- the output of circuit 32 is connected to a filter low pass 34 which performs a summation of the output of logic circuit 32, and which produces a signal correlation between the signals to be compared.
- x (i) and y (i) are the signals to compare, ⁇ is the offset between the signals.
- Circuit 34 provides this function of creation for a zero value of the offset between the signals. One thus obtains at the output of circuit 34 a signal S1 which is equal to the correlation signal S0 between the signals to compare when their offset is zero and which is less than this signal when there is an offset between the signals to be compared.
- this ratio is equal to 1 when the phase shift is zero or multiple of 2 ⁇ , that it is equal to 0 for phase shifts of 90 degrees, 270 degrees etc ... and that it is equal to -1 for phase shifts of ⁇ , 3 ⁇ , etc. (the variation of this ratio between the values 1 and -1 assumes that the binary values of the output signal from the logic circuit 32 are 1 and -1).
- the graph in Figure 3 shows that we have makes a total loss of correlation at the output of the circuit 34 when the phase difference between the signals to be compared is close to ⁇ / 2, 3 ⁇ / 2, etc.
- the invention provides ( Figure 2) that the outputs circuits 28 are connected to the inputs of a circuit 36 adding a quarter shift T / 4 to the frequency central filter bandwidth 28 to one of the analog signals, relative to the other signal analog.
- the outputs of circuit 36 are connected to the positive inputs of comparators 30 whose outputs are connected to the inputs of a logic circuit 32 identical to circuit 32 previously described.
- the exit of this logic circuit is connected to the input of a filter low pass 34 with comparable S2 output signal to the aforementioned output signal S1, but is offset by compared to this one.
- the graph in Figure 4 represents the variation of the S2 / S0 ratio as a function of a phase shift between the signals to be compared.
- the outputs of the filters 34 are therefore connected to the inputs of circuits 38 absolute value (e.g. rectification circuits double alternation) whose outputs are connected to the inputs of an adder circuit 40.
- the output signal S of circuit 40 is a correlation signal which is substantially independent of the offset between the signals to be compared, and whose variation in the ratio to the correlation signal S0 is shown in Figure 5.
- This signal S can be applied to the input of a smoothing circuit 42 such as a low-pass filter, the output is connected to the positive input of a comparator 44.
- the negative input of this comparator receives a voltage of predetermined value to which the output signal from circuit 42.
- the output signal from comparator 44 is applicable to an input of the microprocessor 20 of the apparatus 14 of FIG. 1.
- the audio or video signals produced by the receivers 10 and 16 are applied to the leveling circuits 26, then processed by the bandpass filters 28 and transformed into binary logic signals by the comparators 30. They are then compared with each other by the logic circuit 32, a first time directly, a second time after one of these signals has undergone a shift of a quarter of a period at the center frequency of the pass band of the filters 28, correlation signals are established by the low-pass filters 34, and the absolute values of these signals are added to obtain a correlation signal little dependent on the offset between the initial analog signals. This correlation signal is smoothed and compared to a predetermined value. If it is greater than this value, the analog signals will be considered to be identical, while they will be considered to be different from each other if the correlation signal is less than the predetermined value.
- the correlation device whose components essentials have been represented in figure 2, is therefore relatively simple and has the important advantage of work on a single bit, unlike systems comparable numerical computations used in the art anterior, which generally work on 8 or 16 bits of digital resolution.
- each exclusive 32 OR driver circuit an up-down circuit 46, which counts by increase when the output signal of circuit 32 is level +1, and by decrease when this output signal is at level -1.
- a timer circuit 48 associated with a clock 50 periodically resets the circuits 46. After a time T, the sum of the absolute values contents of the two circuits 46 is calculated by a adder circuit 52 and compared by a circuit 54 to a double threshold (symmetrical thresholds with respect to zero).
- the output of comparator 54 provides a decision signal of correlation or non-correlation between the signals initial analogs.
- the adder circuit 52 performs either the sum of signals S1 and S2 of circuits 46 when they are of the same sign, that is to say their subtraction when they are of opposite sign. It is controlled for this by bits of sign s1 and s2 of signals S1 and S2.
- the invention is of course applicable to other analog signals than audio and video signals, and it also applies to analog signals which vary according to another parameter than the weather.
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Description
L'invention concerne un procédé et un dispositif de comparaison de deux signaux analogiques variables, par exemple dans le temps, tels que des signaux audio ou vidéo, qui sont soit différents l'un de l'autre, soit identiques mais décalés dans le temps. The invention relates to a method and a device. comparison of two variable analog signals, for example over time, such as audio signals or video, which are either different from each other, or identical but shifted in time.
Il est connu, pour comparer entre eux deux signaux analogiques variables, de déterminer une fonction de corrélation entre ces signaux et de vérifier à partir des valeurs de cette fonction s'il y a identité ou non entre les signaux. It is known to compare two signals with each other variable analog, determine a function of correlation between these signals and check from values of this function if there is identity or not between signals.
On utilise pour cela des méthodes de calcul numérique de la fonction de corrélation, qui amènent à utiliser des filtres de bande à pentes abruptes, des convertisseurs analogiques-numériques, un système de traitement de l'information permettant le calcul en temps réel de la fonction de corrélation, et un algorithme de traitement complexe capable de prendre en compte et de compenser un éventuel décalage entre les signaux. Le coût des systèmes permettant ce calcul est en général assez élevé. We use for this calculation methods correlation function, which lead to use steep slope band filters, analog-to-digital converters, a system of information processing allowing calculation in time correlation function, and an algorithm for complex treatment capable of taking into account and compensate for any offset between the signals. The cost systems allowing this calculation is generally quite Student.
On connaít également divers dispositifs de mesure du déphasage entre deux signaux analogiques sinusoïdaux de même fréquence. Toutefois, ces dispositifs ne sont pas applicables à des signaux qui ne sont pas purement sinusoïdaux, tels que des signaux audio ou vidéo reçus ou produits par des récepteurs radio ou de télévision. We also know various measuring devices phase shift between two analog signals sine waves of the same frequency. However, these devices are not applicable to signals which are not purely sinusoidal, such as audio or video signals received or produced by radio receivers or television.
Le document Electronic Design, vol. 37, no. 10, 11 mai 1989, p.115, divulgue un comparateur de phase qui comprend deux voies parallèles de traitement des signaux analogiques, ces deux voies comprenant chacune en série des circuits de transformation des signaux analogiques en signaux logiques binaires, un circuit logique du type OU exclusif et un circuit d'établissement d'un signal par sommation. The document Electronic Design, vol. 37, no. 10, 11 May 1989, p.115, discloses a phase comparator which includes two channels analog signal processing, these two channels each comprising in series transformation circuits from analog signals to binary logic signals, a logic circuit of the exclusive OR type and an establishment circuit of a signal by summation.
On connait également, voir le document Wescon Technical
Papers (1984), Oct. 30 - Nov. 2., pages 1-7, un comparateur de phase
qui utilise un circuit intégré de corrélation. Ce comparateur
comprend deux voies parallèles de traitement des signaux dont
l'une comprend des moyens de décalage dans le temps de
l'un des signaux par rapport à l'autre, le décalage étant
égal à
L'invention a notamment pour but de simplifier les procédés et systèmes précités de calcul numérique et donc d'abaisser largement leur coût tout en conservant la rapidité et la précision souhaitées d'établissement de la corrélation. The object of the invention is in particular to simplify the aforementioned methods and systems of numerical computation and therefore greatly lower their cost while retaining the desired speed and accuracy of establishing the correlation.
Elle a également pour but une mesure de corrélation entre deux signaux analogiques du type précité, qui ne fasse pas appel à une mesure de temps ou de phase. It also aims to measure correlation between two analog signals of the aforementioned type, which does not use a time or phase measurement.
L'invention propose, à cet effet, un procédé de comparaison de deux signaux analogiques variables consistant à établir un signal de corrélation entre les signaux analogiques et à vérifier à partir des valeurs de ce signal s'il y a identité ou non entre les signaux analogiques, caractérisé en ce que, les signaux à comparer étant soit identiques mais décalés dans le temps, soit différents, et couvrant une bande de fréquences prédéterminée, il consiste :
- à transformer lesdits signaux analogiques en signaux logiques binaires, à appliquer ces derniers aux entrées d'un circuit logique 32 du type OU exclusif ou multiplieur, puis à appliquer une fonction somme au signal de sortie de ce circuit logique pour obtenir un premier signal de corrélation S1,
- à effectuer également ces opérations sur lesdits signaux analogiques après avoir décalé l'un d'eux d'un intervalle égal à 1/4 de période à la fréquence centrale de la bande de fréquences précitée, pour obtenir un deuxième signal de corrélation S2,
- et à faire la somme des valeurs absolues des premier et deuxième signaux de corrélation pour obtenir un troisième signal de corrélation S sensiblement indépendant d'un décalage dans le temps entre les signaux analogiques précités.
- transforming said analog signals into binary logic signals, applying the latter to the inputs of a logic circuit 32 of the exclusive OR type or multiplier, then applying a sum function to the output signal of this logic circuit to obtain a first correlation signal S1,
- also to carry out these operations on said analog signals after having shifted one of them by an interval equal to 1/4 of period at the center frequency of the aforementioned frequency band, in order to obtain a second correlation signal S2,
- and summing the absolute values of the first and second correlation signals to obtain a third correlation signal S substantially independent of a time shift between the aforementioned analog signals.
La transformation des signaux analogiques en signaux logiques binaires (qui ne peuvent avoir que deux valeurs distinctes) permet de travailler sur un seul bit et d'utiliser ensuite un opérateur logique pour effectuer la corrélation entre les signaux. Il en résulte une simplification importante du procédé de corrélation par rapport aux procédés classiques de calcul numérique. Par ailleurs, le troisième signal de corrélation obtenu est sensiblement indépendant du décalage dans le temps entre les signaux à comparer, sans qu'il soit nécessaire de mesurer ce décalage. Transformation of analog signals into binary logic signals (which can only have two distinct values) allows working on a single bit and then use a logical operator to perform the correlation between the signals. This results in a simplification important of the correlation process compared to classical numerical calculation methods. By elsewhere, the third correlation signal obtained is substantially independent of the time lag between signals to compare, without the need to measure this shift.
Dans un mode de réalisation de l'invention, ce procédé consiste également à transformer chaque signal analogique en signal logique binaire par détection des passages par zéro de ce signal analogique, et attribution d'une première valeur logique au signal lorsqu'il est positif, et d'une seconde valeur logique lorsqu'il est négatif. In one embodiment of the invention, this process also consists in transforming each analog signal into binary logic signal by detection of zero crossings of this analog signal, and assigning a first logical value to the signal when positive, and a second logical value when it is negative.
La détection du passage par zéro des signaux analogiques permet d'obtenir de façon simple une excellente dynamique (de l'ordre de 60 à 80dB) qui correspondrait à au moins 12 bits de résolution dans les procédés connus de calcul numérique. Detection of zero crossing signals analog provides simple excellent dynamic (of the order of 60 to 80dB) which would correspond at least 12 bit resolution within known methods of numerical calculation.
Dans un mode de réalisation de l'invention, le procédé consiste également à relier la sortie du circuit logique à un filtre passe-bas pour réaliser la fonction somme précitée. In one embodiment of the invention, the method also consists in connecting the logic circuit output to a low pass filter to achieve the aforementioned sum function.
L'invention propose également un dispositif de comparaison de deux signaux analogiques variables, comprenant des moyens d'établissement d'un signal de correlation entre ces deux signaux analogiques et des moyens de comparaison de ce signal à une valeur prédéterminée pour vérifier s'il y a identité ou non entre les signaux analogiques, caractérisé en ce que, ces signaux analogiques étant soit identiques et décalés dans le temps, soit différents, et couvrant une bande de fréquences prédéterminée, ce dispositif comprend deux voies parallèles de traitement des signaux analogiques dont l'une comprend des moyens de décalage dans le temps de l'un des signaux par rapport à l'autre, le décalage étant égal à 1/4 de période à la fréquence centrale de la bande de fréquences précitée, ces deux voies comprenant chacune en série des circuits de transformation des signaux analogiques en signaux logiques binaires, un circuit logique du type multiplieur ou OU exclusif, un circuit d'établissement par sommation d'un signal S1, S2 de corrélation, et un circuit d'addition des valeurs absolues des deux signaux de corrélation S1, S2, produisant en sortie un signal de corrélation S sensiblement indépendant d'un décalage dans le temps entre les signaux analogiques précités. The invention also provides a device for comparison of two variable analog signals, including means for establishing a correlation signal between these two analog signals and means of comparison of this signal with a predetermined value to check whether there is identity or not between the signals analog, characterized in that, these analog signals being either identical and time-shifted, either different, and covering a predetermined frequency band, this device includes two parallel tracks analog signal processing, one of which includes means for shifting one of the signals over time relative to each other, the offset being equal to 1/4 of period at the center frequency of the frequency band above, these two channels each comprising in series of circuits for transforming analog signals into binary logic signals, a logic circuit of the type multiplier or exclusive OR, an establishment circuit by summing a correlation signal S1, S2, and a circuit for adding the absolute values of the two signals correlation S1, S2, producing an output signal correlation S substantially independent of an offset in the time between the above analog signals.
Un filtre passe-bas en sortie de chaque circuit logique permet d'obtenir la valeur du signal de corrélation S1, S2 correspondant à un décalage donné entre les signaux analogiques. A low-pass filter at the output of each circuit logic provides the value of the correlation signal S1, S2 corresponding to a given offset between analog signals.
La mise en valeur absolue de ces signaux de corrélation S1, S2 et l'addition de leurs valeurs absolues permettent de s'affranchir de ce décalage entre les signaux à comparer. The absolute enhancement of these correlation S1, S2 and the addition of their absolute values allow this shift between the signals to compare.
Avantageusement, la sortie du circuit d'addition est reliée à l'entrée d'un filtre passe-bas, réalisant un lissage du signal de corrélation. Advantageously, the output of the addition circuit is connected to the input of a low-pass filter, realizing smoothing the correlation signal.
On évite ainsi les inconvénients liés à la comparaison de ces signaux aux instants où ils ont des valeurs très faibles. This avoids the disadvantages associated with the comparison of these signals at times when they have very low values.
De préférence, le dispositif selon l'invention comprend également en entrée des circuits de mise à niveau des signaux analogiques, tels par exemple que des circuits à contrôle automatique de gain, et des filtres passe-bande. Preferably, the device according to the invention also includes leveling circuits as input analog signals, such as for example automatic gain control circuits, and filters band pass.
Les circuits de transformation des signaux analogiques en signaux logiques binaires sont avantageusement des circuits de comparaison des signaux analogiques à une valeur déterminée, en particulier la valeur zéro, permettant la détection des passages des signaux analogiques par zéro et l'attribution à ces signaux de deux valeurs binaires selon qu'ils sont positifs ou négatifs. The circuits for transforming analog signals into binary logic signals are advantageously circuits for comparing analog signals to a determined value, in particular the value zero, allowing the detection of passages of analog signals by zero and the attribution to these signals of two binary values depending on whether they are positive or negative .
De façon générale, le coût d'un dispositif selon l'invention est très inférieur à celui des dispositifs classiques de calcul numérique d'une fonction de corrélation, et ses performances sont excellentes. In general, the cost of a device according to the invention is far inferior to that of the devices classics of numerical computation of a function of correlation, and its performance is excellent.
L'invention sera mieux comprise et d'autres caractéristiques, détails et avantages de celle-ci apparaitront plus clairement à la lecture de la description qui suit, faite à titre d'exemple en référence aux dessins annexés dans lesquels :
- la figure 1 représente schématiquement un exemple d'application du dispositif de corrélation selon l'invention;
- la figure 2 représente schématiquement les circuits essentiels du dispositif selon l'invention;
- les figures 3, 4 et 5 sont des graphes représentant des variations de signaux de corrélation en fonction du déphasage entre deux signaux analogiques comparés;
- la figure 6 représente schématiquement une variante de réalisation du dispositif selon l'invention.
- FIG. 1 schematically represents an example of application of the correlation device according to the invention;
- FIG. 2 schematically represents the essential circuits of the device according to the invention;
- Figures 3, 4 and 5 are graphs showing variations in correlation signals as a function of the phase shift between two compared analog signals;
- FIG. 6 schematically represents an alternative embodiment of the device according to the invention.
Pour mieux faire comprendre l'intérêt de l'invention, on se réfère tout d'abord à la figure 1 qui représente un exemple d'application du procédé et du dispositif selon l'invention. To better understand the interest of the invention, we first refer to Figure 1 which represents an example of application of the method and the device according to the invention.
La référence 10 désigne un récepteur de radio ou de télévision, relié à une antenne 12 et associé à un appareil 14 de détection de la fréquence sur laquelle est accordé le récepteur 10. Reference 10 designates a radio receiver or television, connected to an antenna 12 and associated with a apparatus 14 for detecting the frequency on which is tuned the receiver 10.
Cet appareil 14 comprend un récepteur de référence 16, également relié à l'antenne 12, un dispositif de corrélation 18 selon l'invention, un micro-processeur 20 de traitement de l'information, une mémoire 22 d'enregistrement de données, un circuit 24 d'interface électronique permettant de piloter le récepteur 16 sous commande du micro-processeur 20, et une horloge de datation 25. This device 14 includes a reference receiver 16, also connected to the antenna 12, a device correlation 18 according to the invention, a microprocessor 20 information processing, memory 22 data logging, an interface circuit 24 electronics to control receiver 16 under microprocessor control 20, and a dating clock 25.
Les sorties des récepteurs 10 et 16 sont reliées aux entrées du dispositif de corrélation 18 dont la sortie est reliée à une entrée du micro-processeur 20. Celui-ci, au moyen de l'interface 24, réalise un balayage systématique des fréquences reçues par le récepteur 16 de référence, dont les signaux de sortie sont comparés à ceux du récepteur 10 par le dispositif 18. La corrélation entre ces signaux établit que les récepteurs 10 et 16 sont réglés sur la même fréquence. Les dates de corrélation et les fréquences correspondantes sont enregistrées dans la mémoire 22 d'où elles peuvent être ensuite extraites et utilisées. The outputs of receivers 10 and 16 are connected at the inputs of the correlation device 18, the output is connected to an input of the microprocessor 20. This, by means of the interface 24, performs a scanning systematic of the frequencies received by the receiver 16 of reference, whose output signals are compared to those of the receiver 10 by the device 18. The correlation between these signals establishes that receivers 10 and 16 are set to the same frequency. Correlation dates and the corresponding frequencies are saved in memory 22 from which they can then be extracted and used.
La figure 2 représente schématiquement la constitution d'un dispositif 18 de corrélation selon l'invention. Figure 2 shows schematically the constitution of a correlation device 18 according to the invention.
Dans ce dispositif, les signaux audio ou vidéo produits par les récepteurs 10 et 16 sont appliqués à des circuits d'entrée comprenant notamment des circuits 26 de mise à niveau, tels que des circuits à contrôle automatique de gain, générant des signaux analogiques ayant des niveaux de tension maximale déterminés, et des filtres passe-bande 28, permettant de réduire la gamme de fréquences des signaux à une bande prédéterminée. In this device, audio or video signals produced by receptors 10 and 16 are applied to input circuits including circuits 26 of upgrade, such as automatic control circuits gain, generating analog signals with determined maximum voltage levels, and filters bandpass 28, reducing the frequency range signals at a predetermined band.
La bande passante des filtres 28 est par exemple d'un octave ou plus (par exemple 500-1000 Hz) pour des signaux audio. Pour des signaux vidéo, elle est par exemple de 500 kHz à 1 MHz. The bandwidth of the filters 28 is by example of an octave or more (e.g. 500-1000 Hz) for audio signals. For video signals, it is for example from 500 kHz to 1 MHz.
La sortie de chaque filtre 28 est appliquée à l'entrée d'un circuit 30 de transformation du signal analogique en signal logique binaire par comparaison à une valeur prédéterminée, qui est de préférence la valeur zéro. Les circuits 30 peuvent donc être de simples comparateurs, dont les entrées positives reçoivent les signaux de sortie des filtres 28 et dont les entrées négatives sont reliées à la masse. The output of each filter 28 is applied to the input of an analog signal transformation circuit 30 in binary logic signal compared to a predetermined value, which is preferably the value zero. The circuits 30 can therefore be simple comparators, whose positive inputs receive signals filters 28 and whose negative inputs are connected to ground.
Les sorties des deux comparateurs 30 sont reliées aux deux entrées d'un circuit logique 32 du type OU exclusif, dont le signal de sortie est un signal logique binaire, de niveau haut (par exemple 1) quand les deux signaux d'entrée sont identiques, et de niveau bas (0 ou -1), quand les deux signaux d'entrée sont différents. La fonction du circuit 32 est donc équivalente à une multiplication logique. The outputs of the two comparators 30 are connected to the two inputs of a logic circuit 32 of the OR type exclusive, whose output signal is a logic signal binary, high level (e.g. 1) when both input signals are identical, and low level (0 or -1), when the two input signals are different. The function of circuit 32 is therefore equivalent to a multiplication logic.
La sortie du circuit 32 est reliée à un filtre passe-bas 34 qui réalise une sommation des signaux de sortie du circuit logique 32, et qui produit un signal de corrélation entre les signaux à comparer. The output of circuit 32 is connected to a filter low pass 34 which performs a summation of the output of logic circuit 32, and which produces a signal correlation between the signals to be compared.
On sait qu'une fonction de corrélation est du type donné par la relation suivante : We know that a correlation function is of the type given by the following relation:
où : x (i) et y (i) sont les signaux à comparer,
τ est le décalage entre les signaux. where: x (i) and y (i) are the signals to compare,
τ is the offset between the signals.
Le circuit 34 permet d'obtenir cette fonction de ccrréiation pour une valeur nulle du décalage entre les signaux. On obtient ainsi en sortie du circuit 34 un signal S1 qui est égal au signal de corrélation S0 entre les signaux à comparer quand leur décalage est nul et qui est inférieur à ce signal lorsqu'il existe un décalage entre les signaux à comparer. Circuit 34 provides this function of creation for a zero value of the offset between the signals. One thus obtains at the output of circuit 34 a signal S1 which is equal to the correlation signal S0 between the signals to compare when their offset is zero and which is less than this signal when there is an offset between the signals to be compared.
La variation du rapport S1/S0 a été représentée en figure 3 en fonction d'un déphasage entre les signaux à comparer. The variation of the S1 / S0 ratio has been represented in Figure 3 as a function of a phase shift between the signals to be compared.
On voit que ce rapport est égal à 1 lorsque le déphasage est nul ou multiple de 2 π , qu'il est égal à 0 pour des déphasages de 90 degrés, 270 degrés etc... et qu'il est égal à -1 pour des déphasages de π, 3 π, etc. (la variation de ce rapport entre les valeurs 1 et -1 suppose que les valeurs binaires du signal de sortie du circuit logique 32 sont 1 et -1). We see that this ratio is equal to 1 when the phase shift is zero or multiple of 2 π, that it is equal to 0 for phase shifts of 90 degrees, 270 degrees etc ... and that it is equal to -1 for phase shifts of π, 3 π, etc. (the variation of this ratio between the values 1 and -1 assumes that the binary values of the output signal from the logic circuit 32 are 1 and -1).
Le graphe de la figure 3 montre que l'on a en fait une perte totale de corrélation en sortie du circuit 34 lorsque le déphasage entre les signaux à comparer est voisin de π/2, 3π/2, etc... On peut éliminer cet inconvénient, en comparant une seconde fois les signaux analogiques initiaux, après avoir déphasé l'un d'entre eux de 90 degrés. L'invention prévoit (figure 2) que les sorties des circuits 28 sont reliées aux entrées d'un circuit 36 ajoutant un décalage d'un quart de période T/4 à la fréquence centrale de la bande passante des filtres 28 à l'un des signaux analogiques, par rapport à l'autre signal analogique. Les sorties du circuit 36 sont reliées aux entrées positives de comparateurs 30 dont les sorties sont reliées aux entrées d'un circuit logique 32 identique au circuit 32 précédemment décrit. La sortie de ce circuit logique est reliée à l'entrée d'un filtre passe-bas 34 dont le signal de sortie S2 est comparable au signal de sortie S1 précité, mais est décalé par rapport à celui-ci. Le graphe de la figure 4 représente la variation du rapport S2/S0 en fonction d'un déphasage entre les signaux à comparer. The graph in Figure 3 shows that we have makes a total loss of correlation at the output of the circuit 34 when the phase difference between the signals to be compared is close to π / 2, 3π / 2, etc. We can eliminate this drawback, by comparing the analog signals a second time initials, after having shifted one of them from 90 degrees. The invention provides (Figure 2) that the outputs circuits 28 are connected to the inputs of a circuit 36 adding a quarter shift T / 4 to the frequency central filter bandwidth 28 to one of the analog signals, relative to the other signal analog. The outputs of circuit 36 are connected to the positive inputs of comparators 30 whose outputs are connected to the inputs of a logic circuit 32 identical to circuit 32 previously described. The exit of this logic circuit is connected to the input of a filter low pass 34 with comparable S2 output signal to the aforementioned output signal S1, but is offset by compared to this one. The graph in Figure 4 represents the variation of the S2 / S0 ratio as a function of a phase shift between the signals to be compared.
On voit qu'il suffit d'ajouter l'une à l'autre les valeurs absolues des rapports S1/S0 et S2/S0 pour obtenir un rapport qui est constant et égal à 1, quel que soit le déphasage entre les signaux. We see that it is enough to add one to the other the absolute values of the S1 / S0 and S2 / S0 ratios to obtain a ratio which is constant and equal to 1, whatever or the phase shift between the signals.
Selon l'invention, les sorties des filtres 34 sont donc reliées aux entrées de circuits 38 de mise en valeur absolue (par exemple des circuits de redressement double alternance) dont les sorties sont reliées aux entrées d'un circuit additionneur 40. Le signal de sortie S du circuit 40 est un signal de corrélation qui est sensiblement indépendant du décalage entre les signaux à comparer, et dont la variation du rapport au signal de corrélation S0 est représentée figure 5. According to the invention, the outputs of the filters 34 are therefore connected to the inputs of circuits 38 absolute value (e.g. rectification circuits double alternation) whose outputs are connected to the inputs of an adder circuit 40. The output signal S of circuit 40 is a correlation signal which is substantially independent of the offset between the signals to be compared, and whose variation in the ratio to the correlation signal S0 is shown in Figure 5.
Ce signal S peut être appliqué à l'entrée d'un circuit 42 de lissage tel qu'un filtre passe-bas, dont la sortie est reliée à l'entrée positive d'un comparateur 44. L'entrée négative de ce comparateur reçoit une tension de valeur prédéterminée à laquelle est comparé le signal de sortie du circuit 42. Le signal de sortie du comparateur 44 est applicable à une entrée du microprocesseur 20 de l'appareil 14 de la figure 1. This signal S can be applied to the input of a smoothing circuit 42 such as a low-pass filter, the output is connected to the positive input of a comparator 44. The negative input of this comparator receives a voltage of predetermined value to which the output signal from circuit 42. The output signal from comparator 44 is applicable to an input of the microprocessor 20 of the apparatus 14 of FIG. 1.
Le fonctionnement de ce dispositif découle de
ce qui précède :
- les signaux audio ou vidéo produits par les
récepteurs 10 et 16 sont appliqués aux circuits de mise à
niveau 26, puis traités par les filtres passe-bande 28 et
transformés en signaux logiques binaires par les comparateurs
30. Ils sont ensuite comparés entre eux par le circuit
logique 32, une première fois directement, une seconde
fois après que l'un de ces signaux ait subi un décalage
d'un quart de période à la fréquence centrale de
la bande passante des filtres 28, des signaux de corrélation
sont établis par les filtres passe-bas 34, et
les valeurs absolues de ces signaux sont ajoutées pour
obtenir un signal de corrélation peu dépendant du décalage
entre les signaux analogiques initiaux. Ce signal de
corrélation est lissé et comparé à une valeur prédéterminée.
S'il est supérieur à cette valeur, les signaux analogiques
seront considérés comme identiques, tandis
qu'ils seront considérés comme différents l'un de l'autre
si le signal de corrélation est inférieur à la valeur
prédéterminée. The operation of this device follows from the above:
the audio or video signals produced by the receivers 10 and 16 are applied to the leveling circuits 26, then processed by the bandpass filters 28 and transformed into binary logic signals by the comparators 30. They are then compared with each other by the logic circuit 32, a first time directly, a second time after one of these signals has undergone a shift of a quarter of a period at the center frequency of the pass band of the filters 28, correlation signals are established by the low-pass filters 34, and the absolute values of these signals are added to obtain a correlation signal little dependent on the offset between the initial analog signals. This correlation signal is smoothed and compared to a predetermined value. If it is greater than this value, the analog signals will be considered to be identical, while they will be considered to be different from each other if the correlation signal is less than the predetermined value.
Le dispositif de corrélation, dont les composants essentiels ont été représentés en figure 2, est donc relativement simple et a l'avantage important de travailler sur un seul bit, au contraire des systèmes comparables de calcul numérique utilisés dans la technique antérieure, qui fonctionnent en général sur 8 ou 16 bits de résolution numérique. The correlation device, whose components essentials have been represented in figure 2, is therefore relatively simple and has the important advantage of work on a single bit, unlike systems comparable numerical computations used in the art anterior, which generally work on 8 or 16 bits of digital resolution.
Une variante de réalisation du dispositif est représenté schématiquement en figure 6. Dans cette variante, la sortie de chaque circuit OU exclusif 32 pilote un circuit compteur-décompteur 46, qui compte par augmentation quand le signal de sortie du circuit 32 est au niveau +1, et par diminution quand ce signal de sortie est au niveau -1. Un circuit de temporisation 48 associé à une horloge 50 remet périodiquement à zéro les circuits 46. Au bout d'un temps T, la somme des valeurs absolues des contenus des deux circuits 46 est calculée par un circuit additionneur 52 et comparée par un circuit 54 à un double seuil (seuils symétriques par rapport à zéro). La sortie du comparateur 54 fournit un signal de décision de corrélation ou de non-corrélation entre les signaux analogiques initiaux. An alternative embodiment of the device is shown schematically in Figure 6. In this variant, the output of each exclusive 32 OR driver circuit an up-down circuit 46, which counts by increase when the output signal of circuit 32 is level +1, and by decrease when this output signal is at level -1. A timer circuit 48 associated with a clock 50 periodically resets the circuits 46. After a time T, the sum of the absolute values contents of the two circuits 46 is calculated by a adder circuit 52 and compared by a circuit 54 to a double threshold (symmetrical thresholds with respect to zero). The output of comparator 54 provides a decision signal of correlation or non-correlation between the signals initial analogs.
Le circuit additionneur 52 effectue soit la somme des signaux S1 et S2 des circuits 46 quand ils sont de même signe, soit leur soustraction quand ils sont de signe contraire. Il est commandé pour cela par les bits de signe s1 et s2 des signaux S1 et S2. The adder circuit 52 performs either the sum of signals S1 and S2 of circuits 46 when they are of the same sign, that is to say their subtraction when they are of opposite sign. It is controlled for this by bits of sign s1 and s2 of signals S1 and S2.
L'invention est bien entendu applicable à d'autres signaux analogiques que les signaux audio et vidéo, et elle s'applique également à des signaux analogiques qui varient en fonction d'un autre paramètre que le temps. The invention is of course applicable to other analog signals than audio and video signals, and it also applies to analog signals which vary according to another parameter than the weather.
Claims (14)
- Method for comparing two variable analogue signals, consisting in establishing a correlation signal between analogue signals and verifying from the values of this signal whether or not the analogue signals are identical, characterized in that the signals to be compared being either identical but exhibiting a time shift, or different, and covering a preset frequency band, it consists in:transforming the said analogue signals into binary logic signals, in order to apply the latter to the inputs of a logic circuit (32) of the exclusive-OR or multiplier type, then applying a summing function to the output signal of this logic circuit so as to obtain a first correlation signal S1,also performing these operations on the said analogue signals after shifting one of them by a 1/4 period at the centre frequency of the above-mentioned frequency band so as to obtain a second correlation signal S2.and in summing the absolute values of the first and second correlation signals so as to obtain a third correlation signal S that is virtually independent of any time shift between the above-mentioned analogue signals.
- Method according to claim 1, characterized in that it consists in smoothing the third correlation signal S before comparing it to a preset value to verify identity or non-identity between the above-mentioned analogue signals.
- Method according to claim 1 or 2, characterized in that it consists in selecting the above-mentioned frequency band within a frequency range covered by the analogue signals, and to consider only variations of these signals within the said frequency band.
- Method according to any preceding claim, characterized in that it consists in transforming each analogue signal into a binary logic signal by detecting zero passings of this analogue signal, and by assigning a first logical value to the signal when it is positive and a second logical value when it is negative.
- Method according to any preceding claim, characterized in that it consists in connecting the output of the logic circuit (32) to a low-pass filter (34) to achieve the above-mentioned summing function.
- Method according to any one of claims 1 to 4, characterized in that it consists in connecting the output of the logic circuit (32) to an up-down counter (46) to achieve the above-mentioned summing function.
- Method according to any preceding claims, characterized in that the analogue signals to be compared are audio signals produced for example by radio receivers, or video signals produced for example by television receivers.
- Device for comparing two variable analogue signals, comprising means for establishing a correlation signal between these two analogue signals and means (44) for comparing this signal with a preset value in order to verify whether or not identity exists between the analogue signals, characterized in that these analogue signals are either identical and shifted in time, or different, and covering a preset frequency band, the device comprising two parallel channels for processing analogue signals of which one comprises means (36) for introducing a time shift of one signal relative to the other, this shift being equal to a 1/4 period at the centre frequency of the above-mentioned frequency band, each of these two channels including a series of circuits for transforming analogue signals into binary logic signals, a logic circuit (32) of the multiplier or exclusive-OR type, a circuit (34) for establishing a correlation signal S1, S2 by summing, and a circuit (38, 40, 52) for adding the absolute values of the two correlation signals S1, S2, producing at the output a correlation signal S that is virtually independent of any time shift between the above-mentioned analogue signals.
- Device according to claim 8, characterized in that the output of adder circuit (40) is connected to the input of a low-pass filter (42) that smooths correlation signal S.
- Device according to claim 9, characterized in that it comprises at the output a circuit for comparing correlation signal S with a preset threshold.
- Device according to claims 8 to 10, characterized in that the circuit for establishing each correlation signal S1, S2 by summing is a low-pass filter (34) whose output is connected to a circuit that provides absolute values (34) such as a full-wave rectifier.
- Device according to claim 8, characterized in that the circuit for establishing each correlation signal S1, S2 is an up-down counter (46) associated with a periodic reset circuit (48).
- Device according to one of the claims 8 to 12, characterized in that it comprises input circuits each of which is made up of a level-matching circuit (26) such as an automatic gain control circuit, and a bandpass filter (28) whose passband corresponds to the above-mentioned preset frequency band.
- Device according to one of the claims 8 to 13, characterized in that the binary logic signal transforming circuits comprise circuits (30) for comparing analogue signals with a given value, particularly zero.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AT91900037T ATE103077T1 (en) | 1989-12-01 | 1991-06-28 | METHOD AND ARRANGEMENT FOR COMPARISON OF TWO VARIABLE ANALOG SIGNALS. |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FR8915906 | 1989-12-01 | ||
FR8915906A FR2655439B1 (en) | 1989-12-01 | 1989-12-01 | METHOD AND DEVICE FOR COMPARING TWO VARIABLE ANALOG SIGNALS. |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0473731A1 EP0473731A1 (en) | 1992-03-11 |
EP0473731B1 true EP0473731B1 (en) | 1994-03-16 |
Family
ID=9388062
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP91900037A Expired - Lifetime EP0473731B1 (en) | 1989-12-01 | 1991-06-28 | Method and device for comparing two variable analog signals |
Country Status (7)
Country | Link |
---|---|
US (1) | US5305243A (en) |
EP (1) | EP0473731B1 (en) |
JP (1) | JPH04505366A (en) |
CA (1) | CA2046652A1 (en) |
DE (1) | DE69007477D1 (en) |
FR (1) | FR2655439B1 (en) |
WO (1) | WO1991008493A2 (en) |
Families Citing this family (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP3102734B2 (en) * | 1993-09-29 | 2000-10-23 | 株式会社ケンウッド | Correlation detector |
DE19749803A1 (en) * | 1997-11-11 | 1999-05-27 | Sensopart Industriesensorik Gm | Arrangement for determining illumination position of position sensitive photoelectric detector |
PL342033A1 (en) * | 1998-11-17 | 2001-05-21 | Koninkl Philips Electronics Nv | Inswertion and separation of additional data into and out of an information signal |
JP3675256B2 (en) * | 1999-10-15 | 2005-07-27 | 日本碍子株式会社 | Vector signal processing circuit |
DE102006007184A1 (en) * | 2006-02-15 | 2007-08-16 | Dr. Johannes Heidenhain Gmbh | Position measuring device |
JP5141052B2 (en) * | 2007-03-08 | 2013-02-13 | 日本電気株式会社 | Power supply noise measurement circuit and measurement method |
Family Cites Families (4)
Publication number | Priority date | Publication date | Assignee | Title |
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US3961172A (en) * | 1973-12-03 | 1976-06-01 | Robert Stewart Hutcheon | Real-time cross-correlation signal processor |
FR2314538A1 (en) * | 1975-06-10 | 1977-01-07 | Thomson Csf | CORRELATOR AND SYSTEM FOR MEASURING THE DELAY BETWEEN TWO SIGNALS INCLUDING SUCH A DEVICE |
US4224679A (en) * | 1978-10-16 | 1980-09-23 | Rca Corporation | Signal correlation means |
JPS61207973A (en) * | 1985-03-13 | 1986-09-16 | Mitsubishi Electric Corp | Correlation type time difference meter |
-
1989
- 1989-12-01 FR FR8915906A patent/FR2655439B1/en not_active Expired - Lifetime
-
1990
- 1990-11-28 WO PCT/FR1990/000863 patent/WO1991008493A2/en active IP Right Grant
- 1990-11-28 DE DE91900037T patent/DE69007477D1/en not_active Expired - Lifetime
- 1990-11-28 JP JP3500673A patent/JPH04505366A/en active Pending
- 1990-11-28 US US07/741,391 patent/US5305243A/en not_active Expired - Fee Related
- 1990-11-28 CA CA002046652A patent/CA2046652A1/en not_active Abandoned
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1991
- 1991-06-28 EP EP91900037A patent/EP0473731B1/en not_active Expired - Lifetime
Also Published As
Publication number | Publication date |
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JPH04505366A (en) | 1992-09-17 |
WO1991008493A2 (en) | 1991-06-13 |
DE69007477D1 (en) | 1994-04-21 |
FR2655439B1 (en) | 1992-05-15 |
CA2046652A1 (en) | 1991-06-02 |
EP0473731A1 (en) | 1992-03-11 |
FR2655439A1 (en) | 1991-06-07 |
US5305243A (en) | 1994-04-19 |
WO1991008493A3 (en) | 1996-09-19 |
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