CN101505387A - Audio mode identification circuit and audio mode identification method - Google Patents
Audio mode identification circuit and audio mode identification method Download PDFInfo
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Abstract
The invention discloses an audio format recognition circuit and an audio format recognition method. The circuit comprises the following components: a frequency point setting unit, which is used for polling a plurality of known audio formats, setting a first matching frequency point according to a first carrier frequency point of the known audio format polled currently, and setting a second matching frequency point according to a second carrier frequency point; a matching unit, which is used for detecting whether an accompanying sound intermediate frequency signal comprises carrier signals at the first matching frequency point and the second matching frequency point, and outputting the detection result; and a control unit, which is used for judging whether the accompanying sound intermediate frequency signal comprises the carrier signals at the first matching frequency point and the second matching frequency point: if so, determining the audio format of the accompanying sound intermediate frequency signal is the audio format polled currently; and otherwise, controlling the frequency point setting unit to poll the next known audio format in the plurality of the audio formats continuously. According to the audio format recognition circuit and the audio format recognition method, the audio format of the received accompanying sound intermediate frequency signal can be recognized simply and reliably.
Description
Technical field
The present invention relates generally to field of audio processing, relates in particular to a kind of audio system identifying circuit and audio mode recognition methods.
Background technology
Along with science and technology development, television broadcasting and radio broadcasting are increasing to the influence of people's lives, can receive various audio-frequency informations and video information by television broadcasting.The different countries and regions in the world, there is multiple different standard in the simulated television sound accompaniment, and is as shown in table 1 below:
| Numbering | | Carrier wave | 1 frequency (MHz) | Carrier wave 2 frequencies (MHz) |
| 1 | BTSC | 4.5 | 0 | |
| 2 | A2BG | 5.5 | 5.74 | |
| 3 | A2?DK?option?1 | 6.5 | 6.62 | |
| 4 | A2?DK?option?2 | 6.5 | 6.74 | |
| 5 | A2?DK?option?3 | 6.5 | 5.74 | |
| 6 | A2?M | 4.5 | 4.7 | |
| 7 | NICAM?I | 6.55 | 6.0 | |
| 8 | NICAM?BG | 5.85 | 5.5 | |
| 9 | NICAM?DK | 5.85 | 6.5 |
Table 1
Multiple different audio mode standard has been described in the above-mentioned table, and the carrier frequency point of each audio mode.The kind of simulated television sound accompaniment standard is many and complicated as can be seen, therefore, for the accompanying sound intermediate frequency signal that receives (SIF, Sound Intermediate Frequency), how can identify its sound accompaniment standard simply and effectively, be a urgent problem.
Summary of the invention
The present invention proposes a kind of audio system identifying circuit and audio mode recognition methods, can discern the accompanying sound intermediate frequency signal that receives simply and effectively.
For solving the problems of the technologies described above, it is as follows to the invention provides scheme:
A kind of audio system identifying circuit is applied to discern the audio mode of accompanying sound intermediate frequency signal, and described audio system identifying circuit comprises:
Frequency point setting unit, be used for a plurality of known audio mode that poll is selected in advance, and according to the first carrier frequency point setting first coupling frequency of the current known audio mode that is polled to, second carrier frequency point according to the current known audio mode that is polled to is provided with the second coupling frequency, wherein, each described known audio mode has included two carrier frequency points, and the carrier frequency point of any two described known audio modes is incomplete same;
Matching unit is used to detect described accompanying sound intermediate frequency signal and whether has carrier signal at described first coupling frequency and the described second coupling frequency place, and the output testing result;
Control unit, be used to receive described testing result, and represent described accompanying sound intermediate frequency signal when all there are carrier signal in the described first coupling frequency and the described second coupling frequency place in described testing result, the audio mode of judging described accompanying sound intermediate frequency signal is the current known audio mode that is polled to; Otherwise, control the next known audio mode in the described a plurality of known audio modes of described frequency point setting unit continuation poll.
In the above-mentioned audio system identifying circuit, described matching unit comprises:
Splitter is used to receive described accompanying sound intermediate frequency signal, and described accompanying sound intermediate frequency signal is divided into two-way sends;
First frequency mixer is used to receive the road accompanying sound intermediate frequency signal that described splitter sends, and according to the described first coupling frequency described accompanying sound intermediate frequency signal is carried out mixing, and the signal that obtains after the output mixing;
First energy detector is used for the signal of described first frequency mixer output is carried out low-pass filtering, and the signal that obtains after the filtering is carried out energy integral, and the result of output energy integral;
First determining device, whether be used for result according to the energy integral of described first energy detector output greater than the first default energy threshold, output is used to indicate described accompanying sound intermediate frequency signal whether to have first testing result of carrier signal at described first carrier frequency;
Second frequency mixer is used to receive another road accompanying sound intermediate frequency signal that described splitter sends, and according to the described second coupling frequency described accompanying sound intermediate frequency signal is carried out mixing, and the signal that obtains after the output mixing;
Second energy detector is used for the signal of described second frequency mixer output is carried out low-pass filtering, and the signal that obtains after the filtering is carried out energy integral, and the result of output energy integral;
Second determining device, whether be used for result according to the energy integral of described second energy detector output greater than the second default energy threshold, output is used to indicate described accompanying sound intermediate frequency signal whether to have second testing result of carrier signal at described second carrier frequency point.
In the above-mentioned audio system identifying circuit, described first energy detector comprises: first low pass filter, be used for the signal of described first frequency mixer output is carried out low-pass filtering, and the signal that obtains after the output filtering; First integrator is used for the signal of described first low pass filter output is carried out energy integral, and the result of output energy integral;
Described second energy detector comprises: second low pass filter, be used for the signal of described second frequency mixer output is carried out low-pass filtering, and the signal that obtains after the output filtering; The second integral device is used for the signal of described second low pass filter output is carried out energy integral, and the result of output energy integral.
In the above-mentioned audio system identifying circuit, described frequency point setting unit, the first carrier frequency point setting that is further used for the current known audio mode that is polled to is the described first coupling frequency, and second carrier frequency point of the current known audio mode that is polled to is set to the described second coupling frequency.
In the above-mentioned audio system identifying circuit, comprise one first audio mode and one second audio mode in described a plurality of known audio mode, the first carrier frequency of first audio mode is identical with the first carrier frequency of second audio mode, and the frequency-splitting between second carrier frequency point of first audio mode and second carrier frequency point of second audio mode is less than or equal to predetermined first threshold;
Described frequency point setting unit comprises:
Poll units is used for a plurality of known audio modes of poll, and determines two carrier frequency points of the current known audio mode that is polled to;
Translation unit, be used for when described poll units is polled to described first audio mode, with second carrier frequency point of first audio mode towards direction translation away from second carrier frequency point of second audio mode, make between second carrier frequency point of second carrier frequency point of first audio mode after the translation and second audio mode frequency-splitting greater than described first threshold, and the translational movement of second carrier frequency point of described first audio mode is less than the second predetermined threshold value;
The unit is set, be used for when described poll units is polled to described first audio mode, with the first carrier frequency point setting of first audio mode is the described first coupling frequency, and second carrier frequency point of first audio mode after the translation is set to the described second coupling frequency.
In the above-mentioned audio system identifying circuit, described first threshold equals the twice of the maximum frequency deviation of described accompanying sound intermediate frequency signal, and described second threshold value equals the bandwidth and the described maximum frequency deviation sum of described second low pass filter.
The present invention also provides a kind of audio mode recognition methods, is applied to discern the audio mode of accompanying sound intermediate frequency signal, comprising:
Steps A, the a plurality of known audio mode that poll is selected in advance, and according to the first carrier frequency point setting first coupling frequency of the current known audio mode that is polled to, second carrier frequency point according to the current known audio mode that is polled to is provided with the second coupling frequency, wherein, each described known audio mode has included two carrier frequency points, and the carrier frequency point of any two described known audio modes is incomplete same;
Step B detects described accompanying sound intermediate frequency signal and whether has carrier signal at the described first coupling frequency and the second coupling frequency place, and the output testing result;
Step C, according to described testing result, judge whether described accompanying sound intermediate frequency signal all exists carrier signal at described first coupling frequency and the described second coupling frequency place: if the audio mode of then judging described accompanying sound intermediate frequency signal is the current audio mode that is polled to; Otherwise, continue the next known audio mode in the described a plurality of known audio modes of poll, and return steps A.
In the above-mentioned audio mode recognition methods, described steps A comprises:
Described accompanying sound intermediate frequency signal is divided into two-way, is sent to first detection branch and second detection branch respectively;
On first detection branch, according to the described first coupling frequency described accompanying sound intermediate frequency signal is carried out mixing, and the signal that obtains after the mixing carried out low-pass filtering, and the signal that obtains after the filtering carried out energy integral, and according to the result of energy integral whether greater than the first default energy threshold, output is used to indicate described accompanying sound intermediate frequency signal whether to have first testing result of carrier signal at the first carrier frequency;
On second detection branch, according to the described second coupling frequency described accompanying sound intermediate frequency signal is carried out mixing, and the signal that obtains after the mixing carried out low-pass filtering, and the signal that obtains after the filtering carried out energy integral, and according to the result of energy integral whether greater than the second default energy threshold, output is used to indicate described accompanying sound intermediate frequency signal whether to have second testing result of carrier signal at second carrier frequency point.
In the above-mentioned audio mode recognition methods, in the described steps A,
On first detection branch, utilize one first low pass filter, the signal that obtains after the mixing is carried out low-pass filtering; And utilizing a first integrator, the signal that first low pass filter is exported carries out energy integral;
On first detection branch, utilize one second low pass filter, the signal that obtains after the mixing is carried out low-pass filtering; And utilizing a second integral device, the signal that first low pass filter is exported carries out energy integral.
In the above-mentioned audio mode recognition methods, in the described steps A, further the first carrier frequency point setting with the current known audio mode that is polled to is the described first coupling frequency, and second carrier frequency point of the current known audio mode that is polled to is set to the described second coupling frequency.
In the above-mentioned audio mode recognition methods, comprise one first audio mode and one second audio mode in described a plurality of known audio mode, the first carrier frequency of first audio mode is identical with the first carrier frequency of second audio mode, and the frequency-splitting between second carrier frequency point of first audio mode and second carrier frequency point of second audio mode is less than or equal to predetermined first threshold;
In the described steps A, when being polled to described first audio mode, further with second carrier frequency point of first audio mode towards direction translation away from second carrier frequency point of second audio mode, make between second carrier frequency point of second carrier frequency point of first audio mode after the translation and second audio mode frequency-splitting greater than described first threshold, and the translational movement of second carrier frequency point of first audio mode is less than the second predetermined threshold value; And be the described first coupling frequency with the first carrier frequency point setting of first audio mode, and second carrier frequency point of first audio mode after the translation is set to the described second coupling frequency.
In the above-mentioned audio mode recognition methods, described first threshold equals the twice of the maximum frequency deviation of described accompanying sound intermediate frequency signal, and described second threshold value equals the bandwidth and the described maximum frequency deviation sum of described second low pass filter.
The present invention also provides a kind of audio mode recognition methods in addition, is applied to discern frequency modulation accompanying sound intermediate frequency signal and amplitude-modulated sound intermediate-freuqncy signal, comprising:
The accompanying sound intermediate frequency signal that receives is carried out the absolute value detection, and the signal after the output detection;
Signal after the described detection is carried out low-pass filtering, and the signal that obtains after the filtering is carried out energy integral, the result of output energy integral;
Whether the result who judges described energy integral is greater than default energy threshold: if judge that then the accompanying sound intermediate frequency signal that receives is the amplitude-modulated sound intermediate-freuqncy signal; Otherwise, judge that the accompanying sound intermediate frequency signal that receives is the frequency modulation accompanying sound intermediate frequency signal.
The present invention also provides a kind of audio system identifying circuit in addition, is applied to discern frequency modulation accompanying sound intermediate frequency signal and amplitude-modulated sound intermediate-freuqncy signal, and described audio system identifying circuit comprises:
The absolute value detection unit is used for the accompanying sound intermediate frequency signal that receives is carried out the absolute value detection, and the signal after the output detection;
Energy detection unit is used for the signal after the described absolute value detection unit output detection is carried out low-pass filtering, and the signal that obtains after the filtering is carried out energy integral, the result of output energy integral;
Judging unit, whether the result who is used to judge described energy integral is greater than default energy threshold: if it is the judged result of amplitude-modulated sound intermediate-freuqncy signal that output one is used to indicate the accompanying sound intermediate frequency signal that receives; Otherwise it is the judged result of frequency modulation accompanying sound intermediate frequency signal that output one is used to indicate the accompanying sound intermediate frequency signal that receives.
In the above-mentioned audio system identifying circuit, described energy detection unit comprises:
Low pass filter is used for the signal after the described absolute value detection unit output detection is carried out low-pass filtering, and the signal that obtains after the output filtering;
Integrator is used for the signal of described low pass filter output is carried out energy integral, and the result of output energy integral.
From the above as can be seen, audio system identifying circuit provided by the invention and audio mode recognition methods, at a plurality of possible audio modes, whether the carrier frequency point place of judging the correspondence under each audio mode respectively has carrier signal, discerns the audio mode of the accompanying sound intermediate frequency signal that receives in view of the above.The present invention can be simply and effectively to identifying multiple known audio mode.And, the method that the present invention also enlarges by frequency difference, the coupling frequency of the different audio modes that the expansion frequency is close with the mistake identification of avoiding energy interference to cause, has improved the reliability of audio mode identification.At last, the present invention also provides a kind of circuit and method of discerning frequency modulation accompanying sound intermediate frequency signal and amplitude-modulated sound intermediate-freuqncy signal.
Description of drawings
Fig. 1 is the structural representation of the described audio system identifying circuit of first embodiment of the invention;
Fig. 2 is the structural representation of the described matching unit of first embodiment of the invention; .
Fig. 3 is the structural representation of described first energy detector of first embodiment of the invention;
Fig. 4 is the structural representation of described second energy detector of first embodiment of the invention;
Fig. 5 is the spectrum diagram of audio signal;
Fig. 6 is the erroneous judgement schematic diagram of the accompanying sound intermediate frequency signal of A2BG audio mode;
Fig. 7 is the erroneous judgement schematic diagram of the accompanying sound intermediate frequency signal of NICAM BG audio mode;
Fig. 8 is the structural representation of the described frequency point setting unit of second embodiment of the invention;
Fig. 9 is the schematic diagram of second embodiment of the invention identification A2BG audio mode;
Figure 10 is the schematic diagram of second embodiment of the invention identification NICAM BG audio mode;
Figure 11 is the flow chart of the described audio mode recognition methods of the embodiment of the invention.
Embodiment
Below in conjunction with the accompanying drawing in the embodiment of the invention, the technical scheme in the embodiment of the invention is clearly and completely described, obviously, described embodiment only is the present invention's part embodiment, rather than whole embodiment.Based on the embodiment among the present invention, those of ordinary skills belong to the scope of protection of the invention not making the every other embodiment that is obtained under the creative work prerequisite.
＜the first embodiment 〉
With reference to Fig. 1, show the structural representation of a kind of audio system identifying circuit first embodiment of the present invention.This audio system identifying circuit is applied to discern the audio mode of accompanying sound intermediate frequency signal.Here, the audio mode of described accompanying sound intermediate frequency signal may be a kind of in the table 1.As shown in Figure 1, this audio system identifying circuit comprises:
Frequency point setting unit 10, be used for a plurality of known audio mode that poll is selected in advance, and, the second coupling frequency is set according to second carrier frequency point of the current known audio mode that is polled to according to the first carrier frequency point setting first coupling frequency of the current known audio mode that is polled to.Here, shown in a plurality of known audio modes can be the audio mode shown in the table 1, wherein, each known audio mode has included two carrier frequency points, and the carrier frequency point of any two known audio modes is incomplete same.
Here, described control unit 12 also is used for controlling described frequency point setting unit and stopping the described a plurality of known audio modes of poll when the audio mode of judging described accompanying sound intermediate frequency signal is the current audio mode that is polled to.Described frequency point setting unit 10, a plurality of known audio mode selected in advance of poll one by one.Each known audio mode in described a plurality of known audio mode has included 2 carrier frequency points, and the carrier frequency point of any two known audio modes is incomplete same in a plurality of known audio modes, and promptly any two known audio modes have at least a carrier frequency point inequality.Frequency point setting unit 10 is according to the current known audio mode that is polled to, search the frequency of each known audio mode of preserving in advance, to determine two carrier frequency points of the current known audio mode that is polled to, then, directly a carrier frequency point in these two carrier frequency points is set to the first coupling frequency, and another carrier frequency point is provided with carrier frequency point and is set to the second coupling frequency.For example, during A2M standard in being polled to table 1, two carrier frequency points that frequency point setting unit 10 finds this standard correspondence are respectively 4.5 and 4.7MHz, and therefore, 4.5MHz is set to the first coupling frequency, and 4.7MHz is set to the second coupling frequency.
In the present embodiment, by each possible audio mode of control unit 12 polls, two carrier frequency points at each possible audio mode, judge whether the accompanying sound intermediate frequency signal that receives has carrier signal at two carrier frequency point places of the current audio mode that is polled to:, illustrate that then the current audio mode that is polled to is the audio mode of the accompanying sound intermediate frequency signal that receives if carrier signal is all arranged; Otherwise, continue poll and handle next possible audio mode.
Among Fig. 1, matching unit 11 can judge whether to have carrier signal at certain frequency place based on signal energy.The carrier frequency point of the audio mode shown in the table 1 is in the intermediate frequency zone mostly, whether has carrier signal if directly judge this carrier frequency point place, can utilize band pass filter that the signal at corresponding carrier frequency point place is carried out filtering; Certainly, also accompanying sound intermediate frequency signal can be mixed to base band, utilize a unified low pass filter to carry out low-pass filtering then, implement more simple like this.
Please refer to Fig. 2, concrete structure schematic diagram for matching unit described in the present embodiment 11, matching unit 11 among Fig. 2 by first mixing after the mode of low-pass filtering judge whether the carrier frequency point place exists carrier signal, as shown in Figure 2, this matching unit 11 specifically comprises:
First determining device 114, whether be used for result according to the energy integral of first energy detector 113 output greater than the first default energy threshold, output is used to indicate described accompanying sound intermediate frequency signal whether to have first testing result of carrier signal at the first carrier frequency;
Second determining device 117, whether be used for result according to the energy integral of second energy detector 116 output greater than the second default energy threshold, output is used to indicate described accompanying sound intermediate frequency signal whether to have second testing result of carrier signal at second carrier frequency point.
Here, first determining device 114 and second determining device 117 are used to carry out first, second energy threshold of judgement, can be according to the concrete debug results of this audio system identifying circuit being selected and being set.For example, by importing the accompanying sound intermediate frequency signal of each audio mode in the table 1 successively to this this audio system identifying circuit, and, set concrete energy threshold according to the result of the energy integral of first energy detector 113 and second energy detector 116.
The concrete structure of above-mentioned first energy detector 113 and second energy detector 116, respectively as shown in Figure 3 and Figure 4:
Below the operation principle of the described audio system identifying circuit of present embodiment is described.Owing to all be in identical, the following description unification to be described on the course of work and the operation principle, do not distinguish first, second.The accompanying sound intermediate frequency signal of unknown audio mode is displaced downwardly to accompanying sound intermediate frequency signal near the base band through the two-way frequency mixer simultaneously, and the complicated low-pass filtering of energy detector filters non-baseband signal, and integral and calculating baseband signal energy.Determining device compares by energy and the energy threshold with energy detector output, judges whether coupling frequency place has carrier wave.If there is carrier wave at coupling frequency place, energy detector just has bigger output so, and greater than threshold energy, determining device just exports 1 like this, show in the SIF signal and carrier signal is arranged at corresponding carrier frequency point, otherwise judge and just export 0 that expression SIF signal does not have carrier signal at corresponding carrier frequency point.Control unit 12 is to utilize a recurrent state machine, control described frequency point setting unit 10 and remove to attempt different audio modes, and the output of analysis matching unit 11, thereby judge which kind of audio mode SIF meets, when capturing correct audio mode, stop poll, export this correct audio mode, and can be locked under this standard.
From the above as can be seen, present embodiment detects the accompanying sound intermediate frequency signal that receives and whether has carrier signal at each possible carrier frequency point, and then judge whether testing result is consistent with the carrier frequency point situation of certain known audio mode, thereby identify the audio mode of accompanying sound intermediate frequency signal.Present embodiment can detect judgement automatically to the multiple possible audio mode of selecting in advance, can discern the accompanying sound intermediate frequency signal that receives simply and effectively.
＜the second embodiment 〉
Known audio mode shown in the his-and-hers watches 1 is analyzed, can see: the carrier frequency point of A2BG and these two kinds of audio modes of NICAM BG has one to be the same, all be 5.5MHz, and the another one carrier frequency point of these two kinds of audio modes is respectively 5.74MHz and 5.85MHz.Figure 5 shows that the carrier signal spectrum diagram of A2BG and NICAM BG audio mode.Among Fig. 5, the A2BG audio mode has a carrier spectrum at the carrier frequency point place of 5.74MHz, and NICAM BG audio mode also has a carrier spectrum at the carrier frequency point place of 5.85MHz.Frequency-splitting between two carrier frequency point 5.74MHz and the 5.85MHz only is 0.11MHz, and the maximum frequency deviation that in fact adopts the audio signal of these audio modes approximately is 50～60KHz, as the frequency spectrum of audio signal has been shown among Fig. 5, therefrom the maximum frequency deviation of this audio signal is 60KHz as can be seen, like this, will occur partially overlapping between two frequency spectrums.In this case, energy detector may detect accompanying sound intermediate frequency signal and all have carrier signal at 5.74MHz and 5.85MHz, thereby causes mistake identification easily.The erroneous judgement that Fig. 6 and Fig. 7 may occur when showing input accompanying sound intermediate frequency signal (SIF) for A2BG and NICAM BG audio mode respectively, wherein testing result " 1 " is to be illustrated in this carrier frequency point place not have carrier signal, and testing result " 0 " is to be illustrated in this carrier frequency point place carrier signal is arranged.For other audio mode in the table 1, also there is same problem.
At the problems referred to above, adopt the mode of frequency translation in the present embodiment by frequency point setting unit, enlarge the distance between the different audio mode carrier frequency points, to improve the reliability of audio mode identification.
The structure of the audio system identifying circuit of present embodiment is identical with Fig. 1, also comprises frequency point setting unit, matching unit and control unit.And matching unit 11 corresponding among the matching unit of present embodiment and the function of control unit and first embodiment is identical with control unit 12.Present embodiment improves the function of the frequency point setting unit among Fig. 1 10, below the explanation present embodiment frequency point setting unit concrete structure and how to be provided with first, second the coupling frequency.
In the present embodiment, include one first audio mode and one second audio mode in a plurality of known audio mode of frequency point setting unit poll, the first carrier frequency of first audio mode is identical with the first carrier frequency of second audio mode, and the frequency-splitting between second carrier frequency point of first audio mode and second carrier frequency point of second audio mode is less than or equal to predetermined first threshold.Here, described first audio mode and second audio mode are not to refer in particular to certain audio mode, just are used for representing any two audio modes that satisfy above-mentioned condition in described a plurality of known audio mode.As shown in Figure 8, the frequency point setting unit of present embodiment comprises:
Poll units is used for a plurality of known audio modes of poll, and determines two carrier frequency points of the current known audio mode that is polled to;
Translation unit, be used for when being polled to described first audio mode, with second carrier frequency point of first audio mode towards direction translation away from second carrier frequency point of second audio mode, make between second carrier frequency point of second carrier frequency point of first audio mode after the translation and second audio mode frequency-splitting greater than described first threshold, and the translational movement of second carrier frequency point of first audio mode is less than the second predetermined threshold value;
The unit being set, being used for when being polled to described first audio mode, be the described first coupling frequency with the first carrier frequency point setting of first audio mode, and second carrier frequency point of first audio mode after the translation is set to the described second coupling frequency.
Be example with A2 BG and NICAM BG audio mode still below, how the frequency point setting unit that specifies present embodiment works.
When poll units was polled to the A2BG audio mode, owing to have a carrier frequency point identical between A2BG and the NICAM BG, another carrier frequency point differed 110KHz.Supposing to preestablish first threshold is 120KHz, and so, translation unit will be carried out translation to the carrier frequency point of the 5.74MHz of A2 BG audio mode, makes it the carrier frequency point away from the 5.85MHz of NICAM BG audio mode.Here, concrete translational movement can be determined according to the frequency-splitting between the bandwidth of second low pass filter, two carrier frequency points and the factors such as maximum frequency deviation of audio signal.Fig. 9 and Figure 10 show the input accompanying sound intermediate frequency signal respectively when being A2 BG and NICAM BG audio mode, adopt the testing result schematic diagram after the translation of present embodiment frequency.In order under the close situation of two carrier frequency points, to distinguish this two kinds of audio modes more accurately, pass through to enlarge the frequency difference of carrier frequency point among Fig. 9 and Figure 10, be moved to 5.70MHz as a carrier frequency point from 5.74MHz A2 BG, the carrier frequency point of NICAM BG is moved to 5.95MHz from 5.85MHz, thereby make the carrier beat of A2 BG and NICAM BG expand 0.25MHz to from 0.11MHz, owing to enlarged frequency difference, thereby mistake identification can not take place in the identification of back, improve the accuracy of identification.
Here, described first threshold can be set accordingly according to corresponding required precision, as required precision when very high, first threshold can be set at a bigger value, as 0.20MHz, as required precision when not high, can set the threshold to a less value, as 0.10MHz.To the not strict qualification of described first threshold, can get different numerical value as required in the embodiment of the invention, the interval of first threshold can be [100KHz, 200KHz].Described translational movement also can be provided with different values according to the processing of reality, as 5.74MHz being moved to 5.70MHz, also it can be moved to 5.65MHz or other numerical value, 5.85MHz is moved to 5.95MHz, also it can be moved to 5.90MHz or other numerical value.In order to enlarge frequency difference each other and better to handle, usually with past littler numerical value direction displacement less in two carrier frequency points, past bigger numerical value direction displacement that will be bigger, thereby enlarge frequency difference each other, as between 5.74MHz and 5.85MHz, with the past little displacement of 5.74MHz, with the past big displacement of 5.85MHz, thus expansion frequency difference between the two.
Below, the translational movement of described first threshold and carrier frequency point is described in more detail by analyzing.Here, pre-determine accompanying sound intermediate frequency signal in the possible maximum frequency deviation in carrier frequency point place, as shown in Figure 5, this maximum frequency deviation is at 50～60KHz usually, and shown in Fig. 5 is 60KHz.The accompanying sound intermediate frequency signal of first audio mode is input to second frequency mixer, 115, the second frequency mixers 115 and according to the second coupling frequency this accompanying sound intermediate frequency signal is carried out mixing, is sent to second low pass filter 1161 then and carries out filtering.Obviously, if exist overlappingly between the signal spectrum of first audio mode and second audio mode, cause mistake identification easily.Therefore, above-mentioned first threshold should equal the twice of maximum frequency deviation at least, promptly just do not have overlapping between the signal spectrum of first audio mode and second audio mode, in this case, select the bandwidth of second low pass filter by strictness, make second low pass filter filters out exceed signal outside the maximum frequency deviation, can not carry out the frequency translation.Therefore, the minimum value of first threshold is the twice of maximum frequency deviation.Certainly, can also establish first threshold bigger, the filtering performance to filter requires lower like this.
Here, the bandwidth of further supposing second low pass filter is a, and promptly the signal of frequency range between [a, a] can pass through this second low pass filter.For the carrier signal that guarantees the second carrier frequency point place after being carried out mixing according to the second coupling frequency by second frequency mixer, still near base band, keep certain energy, need above-mentioned translational movement must not surpass the bandwidth and the above-mentioned maximum frequency deviation sum of second low pass filter usually, preferably, can be a numerical value less than the bandwidth of second low pass filter.
More than by two embodiment audio system identifying circuit of the present invention has been described.Based on the foregoing description, the embodiment of the invention also provides a kind of audio mode recognition methods, is applied to discern the audio mode of accompanying sound intermediate frequency signal, and as shown in figure 11, the method comprising the steps of:
Here, described step 91 specifically can comprise:
Described accompanying sound intermediate frequency signal is divided into two-way, is sent to first detection branch and second detection branch respectively;
On first detection branch, according to the described first coupling frequency described accompanying sound intermediate frequency signal is carried out mixing, and the signal that obtains after the mixing carried out low-pass filtering, and the signal that obtains after the filtering carried out energy integral, and according to the result of energy integral whether greater than the first default energy threshold, output is used to indicate described accompanying sound intermediate frequency signal whether to have first testing result of carrier signal at the first carrier frequency;
On second detection branch, according to the described second coupling frequency described accompanying sound intermediate frequency signal is carried out mixing, and the signal that obtains after the mixing carried out low-pass filtering, and the signal that obtains after the filtering carried out energy integral, and according to the result of energy integral whether greater than the second default energy threshold, output is used to indicate described accompanying sound intermediate frequency signal whether to have second testing result of carrier signal at second carrier frequency point.
Wherein, on first detection branch, utilize one first low pass filter, the signal that obtains after the mixing is carried out low-pass filtering; And utilizing a first integrator, the signal that first low pass filter is exported carries out energy integral; On first detection branch, utilize one second low pass filter, the signal that obtains after the mixing is carried out low-pass filtering; And utilizing a second integral device, the signal that first low pass filter is exported carries out energy integral.
In the above-mentioned steps 91, the coupling frequency is set dual mode is arranged, a kind of is that directly carrier frequency point is set to mate frequency, that is: the first carrier frequency point setting with the current known audio mode that is polled to is the described first coupling frequency, and second carrier frequency point of the current known audio mode that is polled to is set to the described second coupling frequency.Another kind of mode is to comprise one first audio mode and one second audio mode in described a plurality of known audio modes, and the first carrier frequency of first audio mode is identical with the first carrier frequency of second audio mode, when the frequency-splitting between second carrier frequency point of first audio mode and second carrier frequency point of second audio mode is less than or equal to predetermined first threshold, advanced line frequency point translation, again according to the coupling of the frequency point setting after translation frequency, specifically: when being polled to described first audio mode, further with second carrier frequency point of first audio mode towards direction translation away from second carrier frequency point of second audio mode, make between second carrier frequency point of second carrier frequency point of first audio mode after the translation and second audio mode frequency-splitting greater than described first threshold, and the translational movement of second carrier frequency point of first audio mode is less than the second predetermined threshold value; And be the described first coupling frequency with the first carrier frequency point setting of first audio mode, and second carrier frequency point of first audio mode after the translation is set to the described second coupling frequency.Here, described first threshold equals the twice of the audio signal of first audio mode in the maximum frequency deviation at the second carrier frequency point place of this first audio mode, and described second threshold value equals the bandwidth and the described maximum frequency deviation sum of described second low pass filter.
＜the three embodiment 〉
In the audio mode of existing accompanying sound intermediate frequency signal, also include the identical different audio modes of carrier frequency point.As shown in table 2 below, two carrier frequency points of NICAM L and these two kinds of audio modes of NICAM DK are identical, and also for example, these two kinds of audio modes of AM MONO and FM MONO have only a carrier frequency point, and carrier frequency point between the two is identical.Identification for these audio modes is a difficult point of the prior art always.
| Numbering | Standard | Carrier wave 1 (MHz) | Carrier wave 2 (MHz) | |
| 1 | NICAM?L | 5.85 | 6.5 | AM |
| 2 | NICAM?DK | 5.85 | 6.5 | FM |
Table 2
Present embodiment has proposed corresponding recognition method and circuit at the problems referred to above, below describes in detail.
In the NICAM L audio mode, the modulation system of analog signal part is amplitude modulation (AM, AmplitudeModulation) modulation; And in NICAM DK audio mode, the modulation system of analog signal part is frequency modulation (FM, Frequency Modulation) modulation.Again for example, AM MONO is the AM modulation, and FM MONO is the FM modulation.Wherein, NICAM L is the audio mode of dual track television field frame, and being has increased digital beautiful sound on the basis of AM MONO monophony television field frame.NICAM DK also is that the basis from FM MONO monophony television field frame grows up.Because the signal after the AM modulation certainly exists certain signal energy near base band, near the signal energy of signal base band after the FM modulation is very little, approach noise, therefore, present embodiment has proposed a kind of audio system identifying circuit, be applied to discern frequency modulation accompanying sound intermediate frequency signal and amplitude-modulated sound intermediate-freuqncy signal, this audio system identifying circuit comprises:
The absolute value detection unit is used for the accompanying sound intermediate frequency signal that receives is carried out the absolute value detection, and the signal after the output detection;
Energy detection unit is used for the signal after the described absolute value detection unit output detection is carried out low-pass filtering, and the signal that obtains after the filtering is carried out energy integral, the result of output energy integral;
Judging unit, whether the result who is used to judge described energy integral is greater than default energy threshold: if it is the judged result of amplitude-modulated sound intermediate-freuqncy signal that output one is used to indicate the accompanying sound intermediate frequency signal that receives; Otherwise it is the judged result of frequency modulation accompanying sound intermediate frequency signal that output one is used to indicate the accompanying sound intermediate frequency signal that receives.
Here, the absolute value detection is that the accompanying sound intermediate frequency signal that receives is carried out signed magnitude arithmetic(al), and the range value that makes accompanying sound intermediate frequency signal is for just.Above-mentioned energy detection unit specifically can comprise:
One low pass filter is used for the signal after the described absolute value detection unit output detection is carried out low-pass filtering, and the signal that obtains after the output filtering;
One integrator is used for the signal of described low pass filter output is carried out energy integral, and the result of output energy integral.
Present embodiment also provides a kind of audio mode recognition methods, is applied to discern frequency modulation accompanying sound intermediate frequency signal and amplitude-modulated sound intermediate-freuqncy signal, and this method may further comprise the steps:
The accompanying sound intermediate frequency signal that receives is carried out the absolute value detection, and the signal after the output detection;
Signal after the described detection is carried out low-pass filtering, and the signal that obtains after the filtering is carried out energy integral, the result of output energy integral;
Whether the result who judges described energy integral is greater than default energy threshold: if judge that then the accompanying sound intermediate frequency signal that receives is the amplitude-modulated sound intermediate-freuqncy signal; Otherwise, judge that the accompanying sound intermediate frequency signal that receives is the frequency modulation accompanying sound intermediate frequency signal.
By above circuit and method, the signal after the absolute value detection is carried out low-pass filtering, judge again whether the signal energy after the low-pass filtering reaches the predetermined power threshold value, promptly can judge the accompanying sound intermediate frequency signal that receives is FM or AM modulation.
In sum, audio system identifying circuit that the embodiment of the invention provided and method, can simple and reliable ground the audio mode of the unknown accompanying sound intermediate frequency signal of automatic equipment.
The above only is preferred embodiment of the present invention, and is in order to restriction the present invention, within the spirit and principles in the present invention not all, any modification of being done, is equal to replacement, improvement etc., all should be included within protection scope of the present invention.
Claims (15)
1. audio system identifying circuit is applied to discern the audio mode of accompanying sound intermediate frequency signal, it is characterized in that described audio system identifying circuit comprises:
Frequency point setting unit, be used for a plurality of known audio mode that poll is selected in advance, and according to the first carrier frequency point setting first coupling frequency of the current known audio mode that is polled to, second carrier frequency point according to the current known audio mode that is polled to is provided with the second coupling frequency, wherein, each described known audio mode has included two carrier frequency points, and the carrier frequency point of any two described known audio modes is incomplete same;
Matching unit is used to detect described accompanying sound intermediate frequency signal and whether has carrier signal at described first coupling frequency and the described second coupling frequency place, and the output testing result;
Control unit, be used to receive described testing result, and represent described accompanying sound intermediate frequency signal when all there are carrier signal in the described first coupling frequency and the described second coupling frequency place in described testing result, the audio mode of judging described accompanying sound intermediate frequency signal is the current known audio mode that is polled to; Otherwise, control the next known audio mode in the described a plurality of known audio modes of described frequency point setting unit continuation poll.
2. audio system identifying circuit as claimed in claim 1 is characterized in that, described matching unit comprises:
Splitter is used to receive described accompanying sound intermediate frequency signal, and described accompanying sound intermediate frequency signal is divided into two-way sends;
First frequency mixer is used to receive the road accompanying sound intermediate frequency signal that described splitter sends, and according to the described first coupling frequency described accompanying sound intermediate frequency signal is carried out mixing, and the signal that obtains after the output mixing;
First energy detector is used for the signal of described first frequency mixer output is carried out low-pass filtering, and the signal that obtains after the filtering is carried out energy integral, and the result of output energy integral;
First determining device, whether be used for result according to the energy integral of described first energy detector output greater than the first default energy threshold, output is used to indicate described accompanying sound intermediate frequency signal whether to have first testing result of carrier signal at described first carrier frequency;
Second frequency mixer is used to receive another road accompanying sound intermediate frequency signal that described splitter sends, and according to the described second coupling frequency described accompanying sound intermediate frequency signal is carried out mixing, and the signal that obtains after the output mixing;
Second energy detector is used for the signal of described second frequency mixer output is carried out low-pass filtering, and the signal that obtains after the filtering is carried out energy integral, and the result of output energy integral;
Second determining device, whether be used for result according to the energy integral of described second energy detector output greater than the second default energy threshold, output is used to indicate described accompanying sound intermediate frequency signal whether to have second testing result of carrier signal at described second carrier frequency point.
3. audio system identifying circuit as claimed in claim 2 is characterized in that,
Described first energy detector comprises: first low pass filter, be used for the signal of described first frequency mixer output is carried out low-pass filtering, and the signal that obtains after the output filtering; First integrator is used for the signal of described first low pass filter output is carried out energy integral, and the result of output energy integral;
Described second energy detector comprises: second low pass filter, be used for the signal of described second frequency mixer output is carried out low-pass filtering, and the signal that obtains after the output filtering; The second integral device is used for the signal of described second low pass filter output is carried out energy integral, and the result of output energy integral.
4. as each described audio system identifying circuit of claim 1 to 3, it is characterized in that,
Described frequency point setting unit, the first carrier frequency point setting that is further used for the current known audio mode that is polled to is the described first coupling frequency, second carrier frequency point of the current known audio mode that is polled to is set to the described second coupling frequency.
5. as claim 3 or 4 described audio system identifying circuits, it is characterized in that,
Comprise one first audio mode and one second audio mode in described a plurality of known audio mode, the first carrier frequency of first audio mode is identical with the first carrier frequency of second audio mode, and the frequency-splitting between second carrier frequency point of first audio mode and second carrier frequency point of second audio mode is less than or equal to predetermined first threshold;
Described frequency point setting unit comprises:
Poll units is used for a plurality of known audio modes of poll, and determines two carrier frequency points of the current known audio mode that is polled to;
Translation unit, be used for when described poll units is polled to described first audio mode, with second carrier frequency point of first audio mode towards direction translation away from second carrier frequency point of second audio mode, make between second carrier frequency point of second carrier frequency point of first audio mode after the translation and second audio mode frequency-splitting greater than described first threshold, and the translational movement of second carrier frequency point of described first audio mode is less than the second predetermined threshold value;
The unit is set, be used for when described poll units is polled to described first audio mode, with the first carrier frequency point setting of first audio mode is the described first coupling frequency, and second carrier frequency point of first audio mode after the translation is set to the described second coupling frequency.
6. audio system identifying circuit as claimed in claim 5 is characterized in that described first threshold equals the twice of the maximum frequency deviation of described accompanying sound intermediate frequency signal, and described second threshold value equals the bandwidth and the described maximum frequency deviation sum of described second low pass filter.
7. audio mode recognition methods is applied to discern the audio mode of accompanying sound intermediate frequency signal, it is characterized in that, comprising:
Steps A, the a plurality of known audio mode that poll is selected in advance, and according to the first carrier frequency point setting first coupling frequency of the current known audio mode that is polled to, second carrier frequency point according to the current known audio mode that is polled to is provided with the second coupling frequency, wherein, each described known audio mode has included two carrier frequency points, and the carrier frequency point of any two described known audio modes is incomplete same;
Step B detects described accompanying sound intermediate frequency signal and whether has carrier signal at the described first coupling frequency and the second coupling frequency place, and the output testing result;
Step C, according to described testing result, judge whether described accompanying sound intermediate frequency signal all exists carrier signal at described first coupling frequency and the described second coupling frequency place: if the audio mode of then judging described accompanying sound intermediate frequency signal is the current audio mode that is polled to; Otherwise, continue the next known audio mode in the described a plurality of known audio modes of poll, and return steps A.
8. audio mode recognition methods as claimed in claim 7 is characterized in that, described steps A comprises:
Described accompanying sound intermediate frequency signal is divided into two-way, is sent to first detection branch and second detection branch respectively;
On first detection branch, according to the described first coupling frequency described accompanying sound intermediate frequency signal is carried out mixing, and the signal that obtains after the mixing carried out low-pass filtering, and the signal that obtains after the filtering carried out energy integral, and according to the result of energy integral whether greater than the first default energy threshold, output is used to indicate described accompanying sound intermediate frequency signal whether to have first testing result of carrier signal at the first carrier frequency;
On second detection branch, according to the described second coupling frequency described accompanying sound intermediate frequency signal is carried out mixing, and the signal that obtains after the mixing carried out low-pass filtering, and the signal that obtains after the filtering carried out energy integral, and according to the result of energy integral whether greater than the second default energy threshold, output is used to indicate described accompanying sound intermediate frequency signal whether to have second testing result of carrier signal at second carrier frequency point.
9. audio mode recognition methods as claimed in claim 8 is characterized in that, in the described steps A, on first detection branch, utilizes one first low pass filter, and the signal that obtains after the mixing is carried out low-pass filtering; And utilizing a first integrator, the signal that first low pass filter is exported carries out energy integral;
On first detection branch, utilize one second low pass filter, the signal that obtains after the mixing is carried out low-pass filtering; And utilizing a second integral device, the signal that first low pass filter is exported carries out energy integral.
10. as each described audio mode recognition methods of claim 7 to 9, it is characterized in that,
In the described steps A, further the first carrier frequency point setting with the current known audio mode that is polled to is the described first coupling frequency, and second carrier frequency point of the current known audio mode that is polled to is set to the described second coupling frequency.
11. as claim 9 or 10 described audio mode recognition methodss, it is characterized in that,
Comprise one first audio mode and one second audio mode in described a plurality of known audio mode, the first carrier frequency of first audio mode is identical with the first carrier frequency of second audio mode, and the frequency-splitting between second carrier frequency point of first audio mode and second carrier frequency point of second audio mode is less than or equal to predetermined first threshold;
In the described steps A, when being polled to described first audio mode, further with second carrier frequency point of first audio mode towards direction translation away from second carrier frequency point of second audio mode, make between second carrier frequency point of second carrier frequency point of first audio mode after the translation and second audio mode frequency-splitting greater than described first threshold, and the translational movement of second carrier frequency point of first audio mode is less than the second predetermined threshold value; And be the described first coupling frequency with the first carrier frequency point setting of first audio mode, and second carrier frequency point of first audio mode after the translation is set to the described second coupling frequency.
12. audio mode recognition methods as claimed in claim 11 is characterized in that described first threshold equals the twice of the maximum frequency deviation of described accompanying sound intermediate frequency signal, described second threshold value equals the bandwidth and the described maximum frequency deviation sum of described second low pass filter.
13. an audio mode recognition methods is applied to discern frequency modulation accompanying sound intermediate frequency signal and amplitude-modulated sound intermediate-freuqncy signal, it is characterized in that, comprising:
The accompanying sound intermediate frequency signal that receives is carried out the absolute value detection, and the signal after the output detection;
Signal after the described detection is carried out low-pass filtering, and the signal that obtains after the filtering is carried out energy integral, the result of output energy integral;
Whether the result who judges described energy integral is greater than default energy threshold: if judge that then the accompanying sound intermediate frequency signal that receives is the amplitude-modulated sound intermediate-freuqncy signal; Otherwise, judge that the accompanying sound intermediate frequency signal that receives is the frequency modulation accompanying sound intermediate frequency signal.
14. an audio system identifying circuit is applied to discern frequency modulation accompanying sound intermediate frequency signal and amplitude-modulated sound intermediate-freuqncy signal, it is characterized in that described audio system identifying circuit comprises:
The absolute value detection unit is used for the accompanying sound intermediate frequency signal that receives is carried out the absolute value detection, and the signal after the output detection;
Energy detection unit is used for the signal after the described absolute value detection unit output detection is carried out low-pass filtering, and the signal that obtains after the filtering is carried out energy integral, the result of output energy integral;
Judging unit, whether the result who is used to judge described energy integral is greater than default energy threshold: if it is the judged result of amplitude-modulated sound intermediate-freuqncy signal that output one is used to indicate the accompanying sound intermediate frequency signal that receives; Otherwise it is the judged result of frequency modulation accompanying sound intermediate frequency signal that output one is used to indicate the accompanying sound intermediate frequency signal that receives.
15. audio system identifying circuit as claimed in claim 14 is characterized in that, described energy detection unit comprises:
Low pass filter is used for the signal after the described absolute value detection unit output detection is carried out low-pass filtering, and the signal that obtains after the output filtering;
Integrator is used for the signal of described low pass filter output is carried out energy integral, and the result of output energy integral.
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| CN107345828A (en) * | 2017-07-31 | 2017-11-14 | 迈克医疗电子有限公司 | Detecting liquid level methods, devices and systems |
| US11039101B2 (en) | 2017-03-17 | 2021-06-15 | Zhejiang Xinsheng Electronic Technology Co., Ltd. | Systems and methods for identifying formality standard |
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| KR960007407B1 (en) * | 1993-03-12 | 1996-05-31 | 삼성전자주식회사 | Stereo/dual voice checking system |
| JPH10500263A (en) * | 1994-03-31 | 1998-01-06 | セリディアン コーポレイション | Apparatus and method for including and decoding a code in an audio signal |
| JP4928737B2 (en) * | 2005-04-26 | 2012-05-09 | 株式会社東芝 | Electronic device and broadcasting method judgment method |
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| US11039101B2 (en) | 2017-03-17 | 2021-06-15 | Zhejiang Xinsheng Electronic Technology Co., Ltd. | Systems and methods for identifying formality standard |
| US11425327B2 (en) | 2017-03-17 | 2022-08-23 | Zhejiang Xinsheng Electronic Technology Co., Ltd. | Systems and methods for identifying formality standard |
| CN107345828A (en) * | 2017-07-31 | 2017-11-14 | 迈克医疗电子有限公司 | Detecting liquid level methods, devices and systems |
| CN107345828B (en) * | 2017-07-31 | 2019-12-06 | 迈克医疗电子有限公司 | Liquid level detection method, device and system |
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Effective date of registration: 20210218 Address after: No. 607, 6th floor, shining building, 35 Xueyuan Road, Haidian District, Beijing 100083 Patentee after: BEIJING VIMICRO ARTIFICIAL INTELLIGENCE CHIP TECHNOLOGY Co.,Ltd. Address before: 100083, Haidian District, Xueyuan Road, Beijing No. 35, Nanjing Ning building, 15 Floor Patentee before: Vimicro Corp. |