METHOD AND APPARATUS FOR DETERMINING THE AGREEMENT BETWEEN AN ANALYSIS SIGNAL AND AT LEAST ONE REFERENCE SIGNAL

Abstract: A method and apparatus for determining concordance between an analysis signal with at least one reference signal. The smoothed signals or envelopes are formed of a signal which is to be examined and at least one reference signal. A pulse train is generated for each of the smoothed signals or envelopes, and comprises pulses present during the time for a predetermined polarity of the smoothed signal or envelopes relative a threshold signal. The pulse trains are compared at regular intervals with each other, simultaneous coincidence of pulses in both trains at a predetermined number of consecutive comparisons constituting the criterion that the signals which are to be examined are in concordance with the reference signal. For carrying out this signal examination there are means (2, 4) adapted for forming said smoothed signals or envelopes of the signals. The outputs from said means are connected to one input of a comparator (6) for each signal. A threshold signal (URef1, URef2) is applied to the second input of the comparators for generating an output pulse train comprising pulses generated at a predetermined polarity of said smoothed signals or envelopes relative the threshold signals. Means (12, 14, 16, 18) are further adapted for comparing the pulse trains and registering simultaneous coincidence of pulses in the two trains for a predetermined number of consecutive comparisons as the criterion that the examined signal and a given reference signal are in concordance. The invention is primarily intended for utilizing in automatic debiting of utilized video service in a hotel or the like. The invention may also be used for monitoring processes or machines which have specific sound spectra for faults.

Description: Method and apparatus for determining the agreement between an analysis signal and at least one reference signal. The present invention relates to a method and apparatus for determining the agreement between an analysis signal and at least one reference signal. The object of the present invention is to propose a method and provide an apparatus for monitoring, where a charac¬ teristic signal from the apparatus, process or the like which is to be monitored is utilized for analysis. This object is achieved by a method in accordance with claim 1 and an apparatus in accordance with claim . The invention is particularly suitable for use in monitoring apparatus and processes having specific sound spectra, so that audio signals can be utilized for analysis. It- is thus possible to determine with the aid of the invention whether a given signal agrees with one or more given signals, and in the latter case which one of the signals it agrees with. The analysis takes place such that the signals are smoothed and pulse trains corresponding to said smoothed signals or envelopes are generated, a predetermined number of consecutive agreements in the pulse train being required for the signals to be considered in agreement. This is a safety measure so that the signals will not be registered as being in agreement with randomly coinciding pulses in the corresponding pulse trains. The method in accordance with the invention can be utilized for comparing a signal with an optional number of given signals, the apparatus in accordance with the invention being built up with a corresponding number of parallel OMPI _ ^R τ\( branches for analysis of the signals and comparison of the analysis signal with each of the given signals. A preferred embodiment of the apparatus in accordance with the invention, selected here as an example, will be described in the following in conjunction with the appended drawings on which Figure 1 is a block diagram of the principal construction of the apparatus in accordance with the invention in an em¬ bodiment for two reference signals, and Figure 2 is an example of the use of the apparatus in accor¬ dance with the invention for automatic debiting of utilized video service. To build the smoothed signal or the envelope of the signal which is to be examined it is fed to a rectifier 2 and the rectified output signal is filtered in a bandpass filter 4, the passband of which is between 0,5 and 10 Hz, see Figure 1. It has been found advantageous for the subsequent signal analysis to work within this low-frequency range, inter alia from the noise elimination aspect. The signal DC voltage level is also cut away in the filter 4. The rectifier 2 comprises two operation amplifiers, diodes and resistances, and the filter 4 is an active filter with operation amplifier. The signal envelope or smoothed signal obtained from the filter output is applied to one input of a comparator 6. A threshold signal U R f - is applied to the other input of the comparator 6 to prevent undesired changes of the state of the comparator due to noise. An output pulse is obtained from the comparator when the input signal exceeds the applied thres- hold signal and the pulse length is determined by the dura¬ tion of this state. The comparator 6 is an operation amplifier. For each of the reference signals A and B in Figure 1 there is a like circuit 8 and 10, respectively, comprising recti¬ fier, bandpass filter and comparator. The threshold signal U f? to the comparators in the referen signal circuits 8, 10 is somewhat higher than the threshold signal U f1 . The output pulses from the comparators in the reference signal circuits 8 and 10 will thus be somewhat narrower than the output pulses from the comparator 6, and the reference signal pulses will be contained within the pul from the comparator 6. The output pulse train from the comparator 6 is applied to the data input of two D flip-flops 12, 14. The output pulse train from the reference signal circuits 8 and 10 are applie as clock signals to the flip-flops 12 and 14, respectively. The flip-flops 12, 14 go to a one state (send an output puls for concordant signals. The flip-flops thus have an AND gate function. The flip-flops gate on the flanks from the pulses from the comparators, and by ~_ being greater than U_ fl the output pulses from the reference signal circuits are, in time, contained within the pulses from the comparator 6, i.e the signal from the comparator 6 is at the flip-flops 12, 14, when there is applied to these the output pulses from the reference signal circuits 8, 10, the latter pulses also havi the character of gate pulses. The output signals from flip-flops 12 and 14, which thus give information as to the agreement between the pulse trains repr senting the signal to be examined and the reference signals, are applied to the data input of shift registers 16 and 18, respectively. The registers 16, 18 are scanned at regular intervals by applying a scanning pulse, and at a predetermine number of consecutive, positive answers regarding the concor¬ dance of the compared pulse trains said registers 16, 18 trigger a following counter (not shown in Figure 1). OMPI The apparatus of Figure 1 is shown in Figure 2 in use for automatic debiting of utilized video service in a hotel or the like, where the ordinary television programs or one or more available video programs can be connected to the television receivers in the rooms. In such a case the video program utilization shall be debited, but not that of the ordinary TV programs. This is enabled with the present invention in a simple manner without any extra equipment on the television receiver. The principle forming the basis of the invention here is that speech and music consist of more or less distinct soun packages, e.g. accentuated syllables, individual words, accentuated portions of a beat in music etc., the smoothed signals or envelopes of these sound packages being compared with the smoothed signal or envelope of the reference sound package. The same units in Figures 1 and 2 have been given the same reference denotations. A television receiver 20 is connected to an antenna 22 for receiving ordinary television programs, and to two videotap players 24, 26 for receiving programs from them. An audio signal is taken from the television receiver 20 an fed to a regulating amplifier 28. The audio signal is suitably taken out before the televisio receiver volume control via a buffer amplifier to separate the receiver high voltage from the signal taken out. The signal level is adjusted by means of the regulating amplifier 28 so that a suitable level is applied to the input of the comparator 6. A.feedback loop is arranged for this purpose from the comparator input to the amplifier 28. 0Λ1PI After the amplifier 28 there is the circuit described in connection with Figure 1, comprising the rectifier 2, band¬ pass filter 4 and comparator 6. The appearance of the signals after the regulating amplifie 28, after rectifying and after filtering, as well as the output pulse train from the comparator 6 are illustrated in the Figure. An audio signal is similarly taken out from the video tape players 24, 26. This is obtained by the intermediate-freque signal being transposed down to the audio range. The audio signals from the video tape players 24, 26 are treated in the same way as the audio signal from the televi¬ sion receiver 20 in like circuits 30, 32, 34, 36. As mentioned in conjunction with Figure 1. the threshold signal U_ - 2 applied to the comparator 36 is higher than the threshold signal U R f1 which is applied to the comparator 6. As was also mentioned in conjunction with Figure 1 , the out¬ put signal from the comparator 6 is applied to the flip-flop 12 and 14, and the output signals from the comparators 36 ar applied as clock signals to each of the flip-flops 12 and 14 The video tape players 24, 26 can naturally be connected to several different television sets, and for that reason there is schematically indicated outputs at 38 and 40 for taking t output signals from the comparators 36 to other flip-flops, which are also supplied with the processed audio signal from other television receivers. After the flip-flops 12 and 14 there are the register and counter as mentioned in conjunction with Figure 1. In order to ensure that randomly coinciding sound packages do not achieve incorrect registration of concordance, there is required in the apparatus in accordance with the inventio a plurality of consecutive, positive answers for agreement between analysis and reference signals to be considered pres As mentioned above, the registers are scanned at regular intervals. For an automatic system for debiting of the kind mentioned above, the scanning interval for the shift registe can be of the order of magnitude of one minute, and the numb of consecutive positive answers for triggering the following counter can be 6 or 7. The shift registers will thus.act as a unit for generating a time lag of 6 or 7 minutes before th counter is triggered. The shift registers 16, 18 are further arranged so that the whole register is zeroed after two consecutive, negative answers regarding the concordance of the compared pulse trai The counter can be one of the type used in ordinary tele¬ phone conversation counting, and it is triggered at regular intervals, e.g. in the range of.0.1 - 100 seconds. In the example described above there is illustrated an embodiment in which two different video tape players (two reference signals) with different programs can be connected to a television receiver, which can also receive the ordinary broadcast television programs. The apparatus can of course in principle be extended for any number of video tape players (reference signals) and for an optional number of television receivers. The invention may also be utilized in other fields than the ones given above. The invention is utilizable in applications where it is desired to determine concordance between differen signals e.g. for measuring the duration of a signal or for th JUREΛT OMPI purpose of monitoring. As is indicated in the introduction the invention may also be utilized for monitoring processe and machines. For example, a machine bearing may be moni¬ tored by having the characteristic sound signal stored for comparison with the current sound signal which is measured during operation of the machine. In this application con¬ cordance between the signals is the normal condition, whil difference in the signals denotes an abnormal function. Th apparatus described in conjunction with Figures 1 and 2 mus therefore be modified, e.g. so that an alarm is triggered for different signals. This is a trivial measure for one skilled in the art.

Claims: Claims 1. A method of determining concordance of an analysis signal with at least one reference signal, c h a r a c t e¬ r i z e d in that the smoothed signals or envelopes of the analysis signal and the reference signal are formed, a pulse train then being generated for each of the smoothed signals or envelopes, comprising pulses which are present during the time for a predetermined polarity of the smoothe signals.,or envelopes relative a threshold signal, subsequen to which the pulse trains are compared with each other at regular intervals, the simultaneous occurance of pulses in the two trains in a predetermined number of consecutive com parisons constituting the criterion for the analysis signal and the reference signal being in concordance. 2. Method as claimed in claim 1, c h a r a c t e r i z e d in that the smoothed signals or envelopes are formed by rectifying and bandpass filtering. 3. Method as claimed in claim 1 or 2, c h a r a c t e - r i z e d in that the signals are audio signals. 4. Apparatus for determining the concordance of an ana- lysis signal with at least one reference signal, c h a r a t e r i z e d in that means are disposed for forming the smoothed signals or envelopes of the signals and that the outputs from said means are connected to one input of a comparator for each signal, a threshold signal being applie to the second input of the comparators for generating an output pulse train consisting of pulses generated at a pre¬ determined polarity of the smoothed signals or envelopes relative to the threshold signals, there also being means disposed for comparing the pulse trains and registering simultaneous occurance of pulses in both pulse trains in a predetermined number of consecutive comparisons as the criterion for concordance between analysis and reference signals. OMPI 5. .Jpparatus as claimed in claim 4, c h a r a c t e r i z in that the means for forming the smoothed signals or envelopes include, for each signal, a rectifier followed b a bandpass filter. 6. Apparatus as claimed in claim 4 or 5, c h a r a c t e ¬ r i z e d in that the threshold signal for the reference signal comparator is higher than the threshold signal for the analysis signal comparator, the comparators thus sendin output pulses when said smoothed signals or envelopes excee the threshold signals. 7. Apparatus as claimed in any of claims 4-6, c h a r a c - t e r i z e d in that said comparison and registrating mean include a flip-flop on the inputs of which pulse trains corresponding to the analysis signal and the reference sign are applied, said flip-flop being adapted for sending an output signal to a register at simultaneous occurance of pulses in the applied pulse trains, said register being adapted for triggering a counter for registering the analy¬ sis and reference signals as being in concordance after the register has received said output signal from the flip-flop for a predetermined number of consecutive instants. 8. Apparatus as claimed in any of claims 5-7, c h a r a c ¬ t e r i z e d in that the signals are audio signals and that the passband of the bandpass filter is between 0.5 and 10 Herz. 9. Apparatus as claimed in any of claims 4-8, the analysis signal being intended for comparison with a plurality of reference signals, c h a r a c t e r i z e d in that a parallel branch, including means for smoothed signal or envelope formation, comparator and comparison and registra¬ tion means are disposed for each reference signal. 10. Apparatus as claimed in claim 9, c h a r a c t e ¬ r i z e d in that the analysis signal is an audio signal from a television receiver and the reference signals are audio signals from a video tape player connectable to the television receiver for registering the time during which the player is in curcuit with the receiver, " B UREA OMP1

Inventors: KOEHLER HANS OLOF, STROEMVALL STEN KENNETH, KOEHLER, HANS, OLOF, STROEMVALL, STEN, KENNETH
Applicants: KOEHLER HANS OLOF, STROEMVALL STEN KENNETH, KOEHLER, HANS, OLOF, STROEMVALL, STEN, KENNETH
Application year: 1982
Main classification: G10L1
IPC codes: G01R23, G10L15, H03K5