CN113194386A - Howling suppression device and method for civil aviation ground-air communication - Google Patents
Howling suppression device and method for civil aviation ground-air communication Download PDFInfo
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- CN113194386A CN113194386A CN202110411035.4A CN202110411035A CN113194386A CN 113194386 A CN113194386 A CN 113194386A CN 202110411035 A CN202110411035 A CN 202110411035A CN 113194386 A CN113194386 A CN 113194386A
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- H04—ELECTRIC COMMUNICATION TECHNIQUE
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Abstract
The invention discloses a howling suppression device and a howling suppression method for civil aviation ground-air communication.A programmable filter is controlled by a howling detection circuit, and the howling frequency detection circuit comprises an ADC (analog to digital converter), a band-pass filter, an FPGA (field programmable gate array) with a howling frequency detection function and a DAC (digital to analog converter) which are connected in series; the FPGA with the howling frequency detection function is used for carrying out howling frequency detection on audio data to obtain a howling frequency value, when howling occurs, the programmable filter is controlled to be set to be a band elimination filter with the center frequency being the howling frequency value, and when the howling does not occur, the programmable filter is controlled to be set to be a band-pass filter with a normal voice bandwidth. The programmable filter is controlled by a programmable device with a howling frequency detection function to set a filtering mode, howling detection and inhibition of voice signals are realized, a digital processing process is realized, and the signal-to-noise ratio and the voice quality of voice are improved.
Description
Technical Field
The invention relates to the field of civil aviation very high frequency ground-air communication, in particular to a howling suppression device and method for civil aviation ground-air communication.
Background
In the air traffic control field of civil aviation, the very high frequency ground air communication radio station remote control unit of civil aviation is terminal equipment, and the controller uses it to control the very high frequency ground air communication radio station of civil aviation, accomplishes and talks with the pilot, controls civil aviation traffic.
The traditional connection mode of the civil aviation very high frequency ground-air communication radio station and the remote control box is an E & M interface, the defects of short transmission distance, easy interference of voice signals, poor system expansibility and the like exist, and the defects can be well solved by applying a VoIP (Voice over IP) technology to develop the VoIP remote control box.
In daily use, when a remote control device of a civil aviation very high frequency ground-air communication radio station sends voice, a common phenomenon is as follows: the speaker emits a sharp and harsh sound, i.e., howling. The whistling sound is light, so that the workers feel uncomfortable, and the workers cannot normally work when the whistling sound is heavy, so that the traffic order and the flight safety are seriously influenced. One of the reasons for this phenomenon is: when sending voice, the voice signal enters the voice processing channel inside the remote control box through the microphone; then, the voice signal amplified by the channel is output through a loudspeaker; then, the voice signal output by the loudspeaker is transmitted in space and then reenters the microphone, the voice processing channel and the loudspeaker to be output. The process is repeated, namely, positive feedback of the voice signal is formed. Meanwhile, due to the audio frequency response characteristics of the loudspeaker and the microphone, voice signals of certain frequencies form peak values, and the peak value signals are output through the loudspeaker to form howling.
Although howling can be reduced by optimizing the gain distribution of the voice signal path, appropriately reducing the sensitivity of the microphone, and adjusting the relative position between the speaker and the microphone, howling often occurs because the position of the microphone (controller) is constantly changing and thus the positive feedback of the voice signal cannot be satisfactorily coped with.
Disclosure of Invention
The technical problem to be solved by the invention is that howling sound generated when a remote control device of a civil aviation very high frequency ground-air communication radio station sends voice cannot be weakened well; the aim is to provide a howling suppression device and a howling suppression method for civil aviation ground-air communication, which are used for carrying out voice howling suppression and voice quality improvement on the existing remote control device for the civil aviation very high frequency ground-air communication radio station.
The invention is realized by the following technical scheme:
a howling suppression device for civil aviation ground-air communication comprises an audio preprocessing circuit, an audio amplifying circuit and an audio output circuit which are connected in sequence, wherein a howling frequency detection circuit is arranged between the audio preprocessing circuit and the audio amplifying circuit, a programmable filter is arranged between the audio amplifying circuit and the audio output circuit, and the howling frequency detection circuit comprises an ADC (analog-to-digital converter), a band-pass filter, an FPGA (field programmable gate array) and a DAC (digital-to-analog converter) which are connected in series, and the FPGA and the DAC have the howling frequency detection function; the ADC converter is connected with the output end of the audio preprocessing circuit, and the DAC converter is connected with the input end of the audio amplifying circuit; the FPGA with the howling frequency detection function is used for carrying out howling frequency detection on the audio data converted by the ADC to obtain a howling frequency value, when howling occurs, the programmable filter is set to be a band elimination filter with the center frequency being the howling frequency value, and when the howling does not occur, the programmable filter is set to be a band-pass filter with a normal voice bandwidth.
The audio amplifying circuit comprises a first audio amplifier, a digital potentiometer, a second audio amplifier and an RC filter circuit which are connected in series, the first audio amplifier is connected with the DAC, the RC filter circuit is connected with the programmable filter, the quality of voice signals is improved after the voice signals are amplified by the two-stage audio amplifier, and the voice signals are input into the programmable filter for howling suppression after being filtered.
Furthermore, the audio output circuit comprises a shunt switch, an E & M interface and a PC with a sound card, wherein the E & M interface and the PC with the sound card are respectively connected with the shunt switch, the shunt switch is connected with the programmable filter, the shunt switch selects a corresponding output port to send a voice signal to the outside according to the interface to be transmitted, and the E & M interface is suitable for the condition of short transmission distance.
Furthermore, the PC with the sound card comprises a VoIP application program and a LAN port, the audio signal is processed by the VoIP application program and then outputs a VoIP audio data packet through the LAN port, and the voice signal needing long-distance transmission is sent through the LAN port, so that the anti-interference capability of the signal is improved.
In the prior art, howling in a communication radio station can be weakened by optimizing gain distribution of a voice signal path, properly reducing sensitivity of a microphone, adjusting relative positions of a loudspeaker and the microphone and the like, but the position of the microphone (controller) is changed continuously, positive feedback of the voice signal cannot be perfectly responded, and the weakening effect of the howling needs to be improved; the scheme is characterized in that: a howling frequency detection circuit is arranged in a remote control device of an existing civil aviation very high frequency ground-air communication radio station, and a programmable filter is controlled by the howling frequency detection circuit to set a filtering mode.
In addition, the invention provides a howling suppression method for civil aviation ground-air communication, which is applied to the howling suppression device for civil aviation very high frequency ground-air communication and comprises the following steps:
step S1, inputting the voice data converted by the ADC into a band-pass filter with normal voice bandwidth to obtain a voice signal sn;
step S2, performing howling frequency detection on the obtained voice signal S [ n ] to obtain a howling frequency detection value;
step S3, smoothing the howling frequency detection value, and judging whether the howling frequency detection value subjected to smoothing filtering changes within a set time;
step S4, if the judgment result in the step S3 is that no change occurs, and the howling is proved to have occurred, the center frequency of the programmable filter is set as a howling frequency detection value, and the howling frequency of the voice signal S [ n ] is filtered by the programmable filter;
and step S5, if the judgment result in the step S3 is changed and the howling is not generated, setting the programmable filter as a band-pass filter with normal voice bandwidth, and outputting the voice signal S [ n ] after filtering.
Further, the specific process of detecting the howling frequency in step S2 is as follows:
s21, carrying out sign operation on the voice signal S [ n ] to obtain voice data x [ n ];
step S22, performing operation on the voice data x [ n ] and fitting a spectrum sequence P (k), and searching a spectral line peak value in the spectrum sequence to obtain a spectral line peak value frequency f;
and step S23, calculating according to the peak value of the spectral line to obtain a howling frequency detection value f 0.
Further, the specific process of performing the operation on the speech data x [ n ] is as follows:
step S221, carrying out orthogonal transformation operation on the voice data x [ n ] to obtain orthogonal variables Xs (k) and Xc (k);
step S222, calculating absolute values of the orthogonal variables Xs (k) and Xc (k) to obtain absolute values | Xs (k) and | Xc (k) of the orthogonal variables, and calculating a maximum absolute value Max and a minimum absolute value Min of orthogonal transformation according to the absolute values of the orthogonal variables;
step S223, sum 1/2 of the positive alternating minimum absolute value Min and the maximum absolute value Max, and fit a spectrum sequence p (k). Further, the specific calculation process for obtaining the two orthogonal variables xs (k) and xc (k) is as follows: and (3) performing sign operation on x [ n ] in sine and cosine directions respectively, wherein the calculation formula is as follows:
wherein N is a serial number, k has a value range of 1-N, and N is the length of the data frame.
Further, the calculation process of the howling frequency detection value is as follows:
f0 ═ f fs/N; wherein fs is the sampling rate; n is the length of the data frame.
Compared with the prior art, the invention has the following advantages and beneficial effects:
1. the invention relates to a howling suppression device and a howling suppression method for civil aviation ground-air communication, wherein a programmable filter is controlled by a programmable device with a howling frequency detection function to set a filtering mode, two-stage amplification and multiple digital filtering processing are set, the signal-to-noise ratio and the quality of voice are improved, and the MOS score of the voice can reach more than 4.0; based on VoIP technology, the voice transmission distance is basically not limited, voice signals are basically not interfered, and the system expansibility is good (the device can monitor 32 radio stations at most at the same time); meanwhile, the system has two connection modes such as an E & M interface and a VoIP, and has good adaptability;
2. the invention relates to a howling suppression device and a howling suppression method for civil aviation ground-air communication.
The accompanying drawings, which are included to provide a further understanding of the embodiments of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principles of the invention. In the drawings:
FIG. 1 is a schematic diagram of the internal structure of the remote control device of the communication station of the present invention;
FIG. 2 is a schematic diagram of a voice processing module according to the present invention;
FIG. 3 is a flow chart of the method of the present invention;
FIG. 4 is a schematic diagram of a communication station remote control device and a communication station in an implementation method;
fig. 5 is a schematic diagram of a communication station remote control device connected with a plurality of communication stations in an implementation method.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to examples and accompanying drawings, and the exemplary embodiments and descriptions thereof are only used for explaining the present invention and are not meant to limit the present invention.
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be apparent to one of ordinary skill in the art that: it is not necessary to employ these specific details to practice the present invention. In other instances, well-known structures, circuits, materials, or methods have not been described in detail so as not to obscure the present invention.
Throughout the specification, reference to "one embodiment," "an embodiment," "one example," or "an example" means: the particular features, structures, or characteristics described in connection with the embodiment or example are included in at least one embodiment of the invention. Thus, the appearances of the phrases "one embodiment," "an embodiment," "one example" or "an example" in various places throughout this specification are not necessarily all referring to the same embodiment or example. Furthermore, the particular features, structures, or characteristics may be combined in any suitable combination and/or sub-combination in one or more embodiments or examples. Further, those of ordinary skill in the art will appreciate that the illustrations provided herein are for illustrative purposes and are not necessarily drawn to scale. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
In the description of the present invention, it is to be understood that the terms "front", "rear", "left", "right", "upper", "lower", "vertical", "horizontal", "high", "low", "inner", "outer", etc. indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplicity of description, and do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and therefore, are not to be construed as limiting the scope of the present invention.
Example 1
As shown in fig. 1, the embodiment uses the howling suppression device for civil aviation ground-air communication in the ground-air communication radio station remote control device, the ground-air communication radio station remote control device includes an input/output path and an audio board card, the audio board card is provided with a shunt switch, a receiving voice processing path and a transmitting voice processing path which are connected in sequence, and the audio board card is used for receiving/transmitting voice signals and processing a recording interface.
The prior art can reduce the howling sound by optimizing the gain distribution of a voice signal path, properly reducing the sensitivity of a microphone, adjusting the relative positions of a loudspeaker and the microphone and the like for the howling sound in a communication station, but because the position of the microphone (controller) is constantly changed, it can not perfectly deal with the positive feedback of voice signal, the attenuation effect of the howling sound is to be improved, therefore, in this embodiment, as shown in fig. 2, the speech processing path includes an audio preprocessing circuit, an audio amplifying circuit and an audio output circuit connected in sequence, a howling frequency detection circuit is arranged between the audio preprocessing circuit and the audio amplifying circuit, a programmable filter is arranged between the audio amplifying circuit and the audio output circuit, the howling frequency detection circuit comprises an ADC (analog to digital converter), a band-pass filter, an FPGA (field programmable gate array) with a howling frequency detection function and a DAC (digital to analog converter) which are connected in series; the ADC converter is connected with the output end of the audio preprocessing circuit, and the DAC converter is connected with the input end of the audio amplifying circuit; the FPGA with the howling frequency detection function is used for carrying out howling frequency detection on the audio data converted by the ADC to obtain a howling frequency value, when howling occurs, the programmable filter is set to be a band elimination filter with the center frequency being the howling frequency value, and when the howling does not occur, the programmable filter is set to be a band-pass filter with a normal voice bandwidth; the howling frequency detection process is realized in a Field Programmable Gate Array (FPGA), and a successfully compiled howling frequency detection program is downloaded in the FPGA; and the howling detection method and the calculation process are not limited.
The processing procedure of this embodiment is: when voice is transmitted, firstly, voice signals are sent into an audio preprocessing circuit in the remote control device through a microphone, and the voice signals are filtered, AGC (automatic gain control) gained and the like; then, ADC conversion is carried out on the processed voice signal, an analog audio signal is converted into a digital signal, the converted voice data is sent into a band-pass filter for digital filtering processing, the filtered voice data is sent into an FPGA with a howling frequency detection function for howling frequency detection to obtain a howling frequency value, whether the howling is generated or not is judged, if the howling is generated, a programmable filter is controlled to be set into a band-stop filter with the center frequency being the howling frequency value, the voice signal transmitted from an audio amplification circuit is sent into a shunt switch after the howling frequency is filtered, if the howling is not generated in the detection result, the programmable filter is controlled to be set into the band-pass filter with the normal voice bandwidth, the voice signal amplified and filtered by the audio amplification circuit is output to the shunt switch after the filtering processing, the shunt switch selects the corresponding output interface to output according to the actual use condition.
The audio amplifying circuit comprises a first audio amplifier, a digital potentiometer, a second audio amplifier and an RC filter circuit which are connected in series, the first audio amplifier is connected with the DAC converter, the RC filter circuit is connected with the programmable filter, voice signals are subjected to volume adjustment through the digital potentiometer and are amplified through the two-stage audio amplifier, the quality of the voice signals is improved, and the voice signals are input into the programmable filter for howling suppression after being filtered.
In one embodiment, the audio output circuit includes a shunt switch, an E & M interface, and a PC with a sound card, where the E & M interface and the PC with the sound card are respectively connected to the shunt switch, the shunt switch is connected to the programmable filter, the shunt switch selects a corresponding output port according to an interface to be transmitted to send a voice signal to the outside, and the E & M interface is suitable for a case where a transmission distance is short. The PC with the sound card comprises a VoIP application program and a LAN port, voice signals are converted into digital audio through the sound card, VoIP audio data packets are output through the LAN port after being processed through the VoIP application program, the voice signals needing long-distance transmission are sent through the LAN port, the anti-interference capacity of the signals is improved, and a user can set an output interface according to a specific use scene to realize high-quality transmission of the voice signals.
In one embodiment, as shown in fig. 4, the connection between the remote control device of the civil aviation vhf ground-air communication radio station and the communication radio station may be one-to-one connection, including the vhf ground-air communication radio station, the howling suppression remote control device, and the control seat, where the vhf ground-air communication radio station is used to receive/transmit a spatial radio frequency signal, perform radio frequency modulation on the audio signal, and output the audio signal to the outside through an antenna; after carrying out howling suppression processing on the voice signal, the howling suppression remote control device sends the voice signal to a very high frequency ground-to-air communication radio station; the controller seat is the specific environment in which the controller works.
In another embodiment, as shown in fig. 5, a howling suppression remote control device may be connected to a plurality of civil aviation vhf ground-to-air communication stations through switches for switching audio signal paths, and the voice signal processing procedure and howling suppression are identical to the above-described procedure.
Example 2
The embodiment provides a howling suppression method for civil aviation ground-air communication, which is applied to the above-mentioned howling suppression device for civil aviation very high frequency ground-air communication, and as shown in fig. 3, the method includes the following steps:
step S1, inputting the voice data converted by the ADC into a band-pass filter with normal voice bandwidth to obtain a voice signal sn;
step S2, performing howling frequency detection on the obtained voice signal S [ n ] to obtain a howling frequency detection value;
step S3, smoothing the howling frequency detection value, and judging whether the howling frequency detection value subjected to smoothing filtering changes within a set time;
step S4, if the judgment result in the step S3 is that no change occurs, and the howling is proved to have occurred, the center frequency of the programmable filter is set as a howling frequency detection value, and the howling frequency of the voice signal S [ n ] is filtered by the programmable filter;
and step S5, if the judgment result in the step S3 is changed and the howling is not generated, setting the programmable filter as a band-pass filter with normal voice bandwidth, and outputting the voice signal S [ n ] after filtering.
The specific process of detecting the howling frequency in step S2 is as follows:
s21, carrying out sign operation on the voice signal S [ n ] to obtain voice data x [ n ];
step S22, performing operation on the voice data x [ n ] and fitting a spectrum sequence P (k), and searching a spectral line peak value in the spectrum sequence to obtain a spectral line peak value frequency f;
step S23, calculating a howling frequency detection value f0 according to the peak value of the spectral line, wherein f0 is f fs/N; wherein fs is the sampling rate; n is the length of the data frame.
The specific process of the operation of the voice data x [ n ] is as follows:
step S221, carrying out orthogonal transformation operation on the voice data x [ n ] to obtain orthogonal variables Xs (k) and Xc (k);
and (3) performing sign operation on x [ n ] in sine and cosine directions respectively, wherein the calculation formula is as follows:
wherein N is a serial number, k has a value range of 1-N, and N is the length of the data frame.
Step S222, calculating absolute values of the orthogonal variables Xs (k) and Xc (k) to obtain absolute values | Xs (k) and | Xc (k) of the orthogonal variables, and calculating a maximum absolute value Max and a minimum absolute value Min of orthogonal transformation according to the absolute values of the orthogonal variables;
step S223, sum 1/2 of the positive alternating minimum absolute value Min and the maximum absolute value Max, and fit a spectrum sequence p (k).
In the embodiment, the howling frequency detection value is found by fitting the spectrum sequence, and whether howling is generated is judged by judging whether the howling frequency detection value changes within the set time, the detection method is simple, the related calculation process only needs simple four arithmetic operations, and the hardware processing speed is higher.
The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are merely exemplary embodiments of the present invention, and are not intended to limit the scope of the present invention, and any modifications, equivalent substitutions, improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (9)
1. A howling suppression device for civil aviation ground-air communication comprises an audio preprocessing circuit, an audio amplifying circuit and an audio output circuit which are sequentially connected, and is characterized in that a howling frequency detection circuit is arranged between the audio preprocessing circuit and the audio amplifying circuit, and a programmable filter is arranged between the audio amplifying circuit and the audio output circuit.
The howling frequency detection circuit comprises an ADC (analog to digital converter), a band-pass filter, an FPGA (field programmable gate array) with a howling frequency detection function and a DAC (digital to analog converter) which are connected in series; the ADC converter is connected with the output end of the audio preprocessing circuit, and the DAC converter is connected with the input end of the audio amplifying circuit; the FPGA with the howling frequency detection function is used for carrying out howling frequency detection on the audio data converted by the ADC to obtain a howling frequency value, when howling occurs, the programmable filter is set to be a band elimination filter with the center frequency being the howling frequency value, and when the howling does not occur, the programmable filter is set to be a band-pass filter with a normal voice bandwidth.
2. The howling suppression device for civil aviation ground-air communication according to claim 1, wherein said audio amplification circuit comprises a first audio amplifier, a digital potentiometer, a second audio amplifier and an RC filter circuit connected in series, said first audio amplifier is connected with said DAC converter, and said RC filter circuit is connected with said programmable filter.
3. The howling suppression device for civil aviation ground-air communication according to claim 1, wherein the audio output circuit comprises a shunt switch, an E & M interface and a PC with a sound card, the E & M interface and the PC with the sound card are respectively connected with the shunt switch, and the shunt switch is connected with the programmable filter.
4. The howling suppression device for civil aviation ground-air communication according to claim 3, wherein said PC with sound card comprises a VoIP application program and a LAN port, and the audio signal is processed by the VoIP application program and then outputs VoIP audio data packet through the LAN port.
5. A howling suppression method for civil aviation ground-to-air communication, applied to the device for suppressing howling for civil aviation very high frequency ground-to-air communication according to claim 1, comprising the steps of:
step S1, inputting the voice data converted by the ADC into a band-pass filter with normal voice bandwidth to obtain a voice signal sn;
step S2, performing howling frequency detection on the obtained voice signal S [ n ] to obtain a howling frequency detection value;
step S3, smoothing the howling frequency detection value, and judging whether the howling frequency detection value subjected to smoothing filtering changes within a set time;
step S4, if the judgment result in the step S3 is that no change occurs, the center frequency of the programmable filter is set as a howling frequency detection value, and the howling frequency of the voice signal S [ n ] is filtered by the programmable filter;
and step S5, if the judgment result in the step S3 is changed, setting the programmable filter as a band-pass filter with normal voice bandwidth, and outputting the voice signal S [ n ] after filtering.
6. The method for suppressing howling in civil aviation very high frequency ground-to-air communication according to claim 5, wherein the specific process of detecting the howling frequency in step S2 is as follows:
s21, carrying out sign operation on the voice signal S [ n ] to obtain voice data x [ n ];
step S22, performing operation on the voice data x [ n ] and fitting a spectrum sequence P (k), and searching a spectral line peak value in the spectrum sequence to obtain a spectral line peak value frequency f;
and step S23, calculating according to the peak value of the spectral line to obtain a howling frequency detection value f 0.
7. The method for suppressing the civil aviation very high frequency ground-to-air communication howling as claimed in claim 6, wherein the specific process of operating the voice data x [ n ] is as follows:
step S221, carrying out orthogonal transformation operation on the voice data x [ n ] to obtain orthogonal variables Xs (k) and Xc (k);
step S222, calculating absolute values of the orthogonal variables Xs (k) and Xc (k) to obtain absolute values | Xs (k) and | Xc (k) of the orthogonal variables, and calculating a maximum absolute value Max and a minimum absolute value Min of orthogonal transformation according to the absolute values of the orthogonal variables;
step S223, sum 1/2 of the positive alternating minimum absolute value Min and the maximum absolute value Max, and fit a spectrum sequence p (k).
8. The method for suppressing the civil aviation very high frequency ground-to-air communication howling according to claim 7, wherein the specific calculation process for obtaining the two orthogonal variables xs (k) and xc (k) is as follows: and (3) performing sign operation on x [ n ] in sine and cosine directions respectively, wherein the calculation formula is as follows:
wherein N is a serial number, k has a value range of 1-N, and N is the length of the data frame.
9. The method for suppressing howling in civil aviation VHF ground-to-air communication according to claim 6, wherein the howling frequency detection value is calculated by:
f0 ═ f fs/N; wherein fs is the sampling rate; n is the length of the data frame.
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| CN113473304A (en) * | 2021-08-17 | 2021-10-01 | 北京小米移动软件有限公司 | Howling suppression method, howling suppression device, earphone and storage medium |
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| CN113473304A (en) * | 2021-08-17 | 2021-10-01 | 北京小米移动软件有限公司 | Howling suppression method, howling suppression device, earphone and storage medium |
| CN113473304B (en) * | 2021-08-17 | 2024-01-23 | 北京小米移动软件有限公司 | Howling suppression method, device, earphone and storage medium |
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