CN111294304B - Frequency modulation signal processing method and device, storage medium and frequency modulation receiver - Google Patents
Frequency modulation signal processing method and device, storage medium and frequency modulation receiver Download PDFInfo
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- CN111294304B CN111294304B CN201910295251.XA CN201910295251A CN111294304B CN 111294304 B CN111294304 B CN 111294304B CN 201910295251 A CN201910295251 A CN 201910295251A CN 111294304 B CN111294304 B CN 111294304B
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Abstract
A frequency modulation signal processing method and device, a storage medium and a frequency modulation receiver are provided, wherein the frequency modulation signal processing method comprises the following steps: receiving a frequency modulated signal per unit time; detecting the signal quality of the frequency-modulated signal in unit time; and determining the currently played audio signal according to the signal quality of the frequency modulation signal in the unit time. The technical scheme of the invention can eliminate the tail tone of the frequency modulation signal and improve the communication quality.
Description
Technical Field
The present invention relates to the field of signal processing technologies, and in particular, to a frequency modulation signal processing method and apparatus, a storage medium, and a frequency modulation receiver.
Background
The Frequency Modulation system includes a conventional analog Frequency Modulation (FM) system and a digital Frequency Shift Keying (FSK) system, and is generally used for short data or voice communication, and the Frequency Modulation system generally adopts a digital Frequency discrimination demodulation method.
For the communication method of the analog FM system, a special Tone signal or an analog Dual Tone Multi Frequency (DTMF) signaling similar to the sub-Tone of the FM interphone is not provided as the end flag in many cases. Even if the setting is similar, the receiving end and the transmitting end must be configured at the same time to be effective, thereby increasing much inconvenience and complicating operation. Therefore, when the call at the transmitting end is over, the receiving end can only confirm the hang-up through the change of the receiving level at many times.
However, the method of confirming hang-up through the change of the receiving level is easy to detect wrongly in the public network frequency band with severe signal noise fluctuation, so that the receiving party is hung up or not hung up wrongly, and harsh 'snap' tail sound is often generated due to white noise demodulation when the call is ended; for the FSK signal, if the end signaling cannot be successfully received, the FSK signal cannot be turned off in time, and the power consumption of the battery is wasted due to long-time reception.
Disclosure of Invention
The invention solves the technical problem of how to eliminate the tail tone of the frequency modulation signal and improve the conversation quality.
In order to solve the foregoing technical problem, an embodiment of the present invention provides a frequency modulation signal processing method, where the frequency modulation signal processing method includes: receiving a frequency modulated signal per unit time; detecting the signal quality of the frequency-modulated signal in unit time; and determining the currently played audio signal according to the signal quality of the frequency modulation signal in the unit time.
Optionally, the determining the currently played signal according to the signal quality of the frequency-modulated signal in the unit time includes: and when the signal quality of the frequency modulation signal in the unit time is less than a preset threshold, determining that the currently played audio signal is a comfortable noise or null signal with the amplitude less than the preset threshold.
Optionally, the frequency modulation signal processing method further includes: and if the signal quality of the frequency modulation signals in the unit time of the continuous preset number is less than the preset threshold, switching from the current connection state to the standby state.
Optionally, the modulation scheme of the frequency modulated signal is digital frequency shift keying, and determining the currently played signal according to the signal quality of the frequency modulated signal in the unit time includes: and if the ending signaling is not received in the unit time, determining the currently played signal according to the signal quality of the frequency modulation signal in the unit time.
Optionally, the detecting the signal quality of the frequency-modulated signal in unit time includes: determining the maximum limit frequency offset of the frequency modulation signal, and determining a frequency offset peak value at least according to the maximum limit frequency offset; determining a digital frequency discrimination output result of the frequency-modulated signal received in the unit time, wherein the digital frequency discrimination output result comprises an instantaneous frequency offset; comparing the digital frequency discrimination output result with the frequency deviation peak value to obtain a first quantity, and/or calculating the average frequency deviation in unit time according to the digital frequency discrimination output result, wherein the first quantity is the quantity of instant frequency deviations when the frequency deviation reaches the frequency deviation peak value; and determining the signal quality of the frequency modulation signal according to the first quantity and a preset mapping relation, and/or the average frequency offset and the preset mapping relation, wherein the preset mapping relation comprises the signal quality of each grade and the corresponding first quantity thereof, and/or the signal quality of each grade and the corresponding average frequency offset thereof.
Optionally, the preset mapping relationship includes signal qualities of various levels and first quantities corresponding to the signal qualities, and the determining the signal quality of the frequency modulation signal according to the first quantities includes: matching the first quantity with each first quantity in the preset mapping relation; and if the first number of matches exists, taking the signal quality corresponding to the first number of matches as the signal quality of the frequency modulation signal.
Optionally, the preset mapping relationship includes signal quality of each level and average frequency offset corresponding to the signal quality, and the determining the signal quality of the frequency modulation signal according to the average frequency offset and the preset mapping relationship includes: matching the average frequency deviation with each average frequency deviation in the preset mapping relation; and if the matched average frequency offset exists, taking the signal quality corresponding to the matched average frequency offset as the signal quality of the frequency modulation signal.
Optionally, the determining the signal quality of the frequency modulation signal according to the first number, the preset mapping relationship, the average frequency offset and the preset mapping relationship includes: judging whether the average frequency deviation falls into a preset range or not; if the average frequency offset falls into the preset range, matching the first quantity with each first quantity in the preset mapping relation, and determining the signal quality corresponding to the matched first quantity as the signal quality of the frequency modulation signal; if the average frequency deviation is lower than the lower limit value of the preset range, determining that the frequency modulation signal is an interference signal of other systems; and if the average frequency offset is higher than the upper limit value of the preset range, determining that the frequency modulation signal is noise or an interference signal of other systems.
Optionally, the modulation system of the frequency modulation signal is digital frequency shift keying, the preset range includes a numerical range between a minimum value of the average frequency offset and a maximum value of the first average frequency offset, and the determining whether the average frequency offset falls into the preset range includes: and judging whether the average frequency deviation is larger than the average frequency deviation minimum value and smaller than the first average frequency deviation maximum value.
Optionally, the modulation format of the frequency modulation signal is analog frequency modulation, the preset range includes a numerical range smaller than a second average frequency offset maximum value, and the determining whether the average frequency offset falls into the preset range includes: and judging whether the average frequency offset is smaller than the second average frequency offset maximum value or not.
In order to solve the above technical problem, an embodiment of the present invention further discloses a frequency modulation signal processing apparatus, where the frequency modulation signal processing apparatus includes: the receiving module is suitable for receiving the frequency modulation signal according to unit time; the signal quality detection module is suitable for detecting the signal quality of the frequency modulation signal in unit time; and the currently played audio signal determining module is suitable for determining the currently played audio signal according to the signal quality of the frequency modulation signal in the unit time.
The embodiment of the invention also discloses a storage medium, wherein computer instructions are stored on the storage medium, and the steps of the frequency modulation signal processing method are executed when the computer instructions are operated.
The embodiment of the invention also discloses a frequency modulation receiver which comprises a memory and a processor, wherein the memory is stored with a computer instruction capable of running on the processor, and the processor executes the steps of the frequency modulation signal processing method when running the computer instruction.
Compared with the prior art, the technical scheme of the embodiment of the invention has the following beneficial effects:
according to the technical scheme, the signal quality of the frequency modulation signal in unit time is detected, whether the demodulated frequency modulation signal generates a tail tone or not can be determined through the signal quality, so that whether the frequency modulation signal is suitable for playing or not can be determined, the currently played audio signal can be determined, the tail tone generated by mistakenly playing noise is avoided, the signal playing fluency of a frequency modulation receiver is ensured, and the conversation quality is improved.
Further, if the signal quality of the frequency modulation signals in the unit time of the continuous preset number is less than the preset threshold, the current connection state is switched to the standby state. In the technical scheme of the invention, if the quality of the received frequency modulation signals is poor in a long time, the fact that the call is hung up by the frequency modulation signal sending end can be determined, so that the call can be determined to be finished, the current connection state can be converted into the standby state, the tail tone generated by the demodulation signal of the white noise is prevented from being played by mistake, and the call quality is further ensured.
Further, in the technical solution of the present invention, a preset mapping relationship may be preset, where the preset mapping relationship indicates a correspondence between signal quality of each level and the number of instantaneous frequency offsets where the frequency offset reaches a peak frequency offset, or may also indicate a correspondence between signal quality of each level and average frequency offset in unit time. Therefore, the signal quality of the frequency modulation signal can be determined by determining the number of instantaneous frequency offsets when the frequency offset of the received frequency modulation signal reaches the peak frequency offset after digital frequency discrimination, or determining the average frequency offset in unit time, the situation that the signal and the background noise cannot be distinguished under the condition that an interference signal exists by adopting a signal receiving level judging mode is avoided, and the accuracy of the detection of the frequency modulation signal quality is improved.
Drawings
Fig. 1 is a flow chart of a method for processing a frequency modulated signal according to an embodiment of the present invention;
FIG. 2 is a flowchart of one embodiment of step S102 shown in FIG. 1;
FIG. 3 is a flowchart of one embodiment of step S204 shown in FIG. 2;
FIG. 4 is a flowchart of another embodiment of step S204 shown in FIG. 2;
FIG. 5 is a flowchart of yet another embodiment of step S204 shown in FIG. 2;
fig. 6 is a schematic structural diagram of a frequency modulation signal processing apparatus according to an embodiment of the present invention.
Detailed Description
As described in the background art, the method of confirming hang-up through the change of the reception level is easy to perform false detection in the public network frequency band with severe signal noise fluctuation, which results in the receiver being mistakenly hung up or not hung up, and a harsh "snap" tail is often generated due to the white noise demodulation when the call is ended; for the FSK signal, if the end signaling cannot be successfully received, the FSK signal cannot be turned off in time, and the power consumption of the battery is wasted due to long-time reception. According to the technical scheme, the signal quality of the frequency modulation signal in unit time is detected, whether the demodulated frequency modulation signal generates a tail tone or not can be determined through the signal quality, so that whether the frequency modulation signal is suitable for playing or not can be determined, the currently played audio signal can be determined, the tail tone generated by mistakenly playing noise is avoided, the signal playing fluency of a frequency modulation receiver is ensured, and the conversation quality is improved.
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below.
Fig. 1 is a flowchart of a frequency modulation signal processing method according to an embodiment of the present invention.
The frequency modulation signal quality detection method can be used on the side of a frequency modulation receiver. That is, the various steps shown in fig. 1 may be performed by a fm receiver.
The frequency modulated signal processing method of fig. 1 may comprise the steps of:
step S101: receiving a frequency modulated signal per unit time;
step S102: detecting the signal quality of the frequency-modulated signal in unit time;
step S103: and determining the currently played audio signal according to the signal quality of the frequency modulation signal in the unit time.
It should be noted that the sequence numbers of the steps in this embodiment do not represent a limitation on the execution sequence of the steps.
In an implementation of step S101, the fm receiver may receive the fm signal per unit time. The Frequency Modulation signal may be an analog Frequency Modulation (FM) signal or a digital Frequency-shift keying (FSK) signal.
It is to be understood that the frequency modulation signal may also be a frequency modulation signal of any other implementable standard, and the embodiment of the present invention is not limited thereto.
Specifically, the fm receiver receives a frequency modulated signal having a time length of a unit time, demodulates the frequency modulated signal in the unit time, and detects signal quality.
It should be noted that the length of the unit time may be set differently according to the actual application requirement, for example, may be 30 milliseconds (ms) or 20ms, and the embodiment of the present invention is not limited to this.
In the implementation of step S102, the signal quality of the received frequency-modulated signal per unit time may be detected.
In this embodiment, the Signal quality may be represented by a Signal to Interference plus Noise Ratio (SINR). In other words, the signal quality of the frequency modulated signal can be detected by detecting the SINR of the frequency modulated signal. For example, when the frequency modulation signal is a 4FSK signal and SINR > is 9dB, the received FSK signal is considered to be good; when the SINR is between 3dB and 6dB, the quality of the received FSK signal is considered to be general and is near the sensitivity; when the SINR is between 0dB and 3dB, the received FSK signal is considered to be poor, and the demodulated voice signal has a large amount of noise or deformation and may not be understood; when the SINR is between-3 dB and 0dB, the received FSK signal is considered to be very poor and cannot be synchronously received; SINR < -3dB, the received FM signal is considered to be possibly completely noise or interference signal.
It should be noted that the signal quality in the embodiment of the present invention may be expressed by a specific value, or may be expressed by a range of values, for example, the signal quality is 0dB, or the signal quality is 0-3 dB.
In a specific implementation of step S103, the currently played audio signal may be determined according to the signal quality of the fm signal in the unit time.
Specifically, when the signal quality of the frequency modulated signal is good, it may be determined that the demodulation of the frequency modulated signal does not generate a tail tone, and then it may be determined that the currently played audio signal is the frequency modulated signal. When the signal quality of the frequency modulation signal is poor, the fact that more noise exists in the frequency modulation signal can be determined, tail sound is generated by demodulating the frequency modulation signal, and the demodulated signal can not be played.
It can be understood by those skilled in the art that the criterion for determining the signal quality of the frequency modulated signal may refer to the prior art, for example, the higher the SINR, the higher the signal quality, and the embodiment of the present invention is not limited thereto.
In the embodiment of the invention, the signal quality of the frequency modulation signal in unit time is detected, and whether the demodulation of the frequency modulation signal generates the tail tone can be determined according to the signal quality, so that whether the frequency modulation signal is suitable for playing can be determined, the currently played audio signal can be determined, the tail tone generated by mistakenly playing noise is avoided, the signal playing fluency of a frequency modulation receiver is ensured, and the conversation quality is improved.
In one non-limiting embodiment of the present invention, step S103 shown in fig. 1 may include the following steps: and when the signal quality of the frequency modulation signal in the unit time is less than a preset threshold, determining that the currently played audio signal is a comfortable noise or null signal with the amplitude less than the preset threshold.
The comfort noise in this embodiment is a special noise that plays a role of relaxing or arousing alertness by a specific sound. Comfort noise is different from general noise and generally does not cause irritation or harm to the body of the user. The comfort noise includes, but is not limited to, the click sound of an alarm clock, the currency count sound of an ATM cash dispenser, the mouse button sound, etc., and the specific type can refer to the prior art, which is not described herein.
That is, when the signal quality of the frequency modulated signal in the unit time is less than the preset threshold, it indicates that the signal quality of the frequency modulated signal is poor, and if the frequency modulated signal is demodulated, the comfort noise is demodulated, and a tail tone is generated. Thus, in this case, comfort noise having an amplitude less than a preset threshold value, or a null signal may be played. Playing a null signal means not playing any signal, any signal including the frequency modulated signal.
It should be noted that the preset threshold and the preset threshold may be set by self-defining according to an actual application environment, which is not limited in this embodiment of the present invention.
In a specific embodiment, if the signal quality of the frequency modulation signal in the unit time is greater than the preset threshold, it indicates that the signal quality of the frequency modulation signal is good, and no tail tone is generated after demodulation. In this case, the fm signal may be directly used as the currently played audio signal to demodulate and play the fm signal.
Further, the method shown in fig. 1 may further include the following steps: and if the signal quality of the frequency modulation signals in the unit time of the continuous preset number is less than the preset threshold, switching from the current connection state to the standby state. Otherwise, the demodulated frequency modulated signal continues to be received in the next unit time.
In this embodiment, the signal quality of the frequency modulation signals in a unit time of a preset number of continuous units is smaller than the preset threshold, which indicates that the signal quality of the frequency modulation signals is poor in a long period of time. Under the condition, the fact that the frequency modulation signal sending end hangs up the call can be determined, therefore, the call can be determined to be finished, the current connection state can be converted into the standby state, tail sounds generated by the fact that the demodulation signal of the white noise is played by mistake are further avoided, and the call quality is further guaranteed.
In a specific embodiment, when the fm receiver switches from the current connection state to the standby state, the speaker may be turned off to notify the user that the call is over.
In a specific application scene, detecting the signal quality of the frequency modulation signal in unit time T, if the signal quality is less than a preset threshold, considering that the signal quality is poor, and not playing audio frequency or playing comfortable noise with small playing amplitude on the frequency modulation signal received in the unit time T; and the count of the timer counter is incremented by one, i.e., k ═ k + 1. And comparing the count K of the counter with the preset number K, and if the count K is greater than the preset number K, determining that the sender hangs up the call and the receiver removes the receiving link.
And if the count K is less than the preset number K, continuously receiving the frequency modulation signal in the next unit time T.
If the signal quality in the current unit time T is larger than the preset threshold, the frequency modulation signal can be demodulated, the demodulated sound data can be played, and the counting k of the counter is reset to be 0. And continues to receive the frequency modulated signal for the next unit time T.
In a non-limiting embodiment, the modulation scheme of the frequency modulated signal is digital frequency shift keying, and the step S103 shown in fig. 1 may include the following steps: and if the ending signaling is not received in the unit time, determining the currently played signal according to the signal quality of the frequency modulation signal in the unit time.
In one embodiment, for FSK fm signals, an end signal is typically sent to the fm receiver to indicate that the fm signal transmission is complete and the call can be ended. However, under the condition that the FM receiver fails to receive the ending signaling, the currently played audio signal can be determined according to the signal quality so as to avoid tail sound generated by playing the demodulated noise signal, thereby ensuring the conversation quality of the FSK FM signal.
In a non-limiting embodiment, referring to fig. 2, step S102 shown in fig. 1 may include the following steps:
step S201: determining the maximum limit frequency offset of the frequency modulation signal, and determining a frequency offset peak value at least according to the maximum limit frequency offset;
step S202: determining a digital frequency discrimination output result of the frequency-modulated signal received in the unit time, wherein the digital frequency discrimination output result comprises an instantaneous frequency offset;
step S203: comparing the digital frequency discrimination output result with the frequency deviation peak value to obtain a first quantity, and/or calculating the average frequency deviation in unit time according to the digital frequency discrimination output result, wherein the first quantity is the quantity of instant frequency deviations when the frequency deviation reaches the frequency deviation peak value;
step S204: and determining the signal quality of the frequency modulation signal according to the first quantity and a preset mapping relation, and/or the average frequency offset and the preset mapping relation, wherein the preset mapping relation comprises the signal quality of each grade and the corresponding first quantity thereof, and/or the signal quality of each grade and the corresponding average frequency offset thereof.
In an implementation of step S201, after receiving the frequency modulated signal, a maximum limit frequency offset of the frequency modulated signal may be determined. The frequency modulation method can be determined by parameters such as the frequency modulation system of the frequency modulation signal, the bandwidth of the transmission frequency modulation signal and the like.
In a specific example, taking an interphone as an example, according to the national standard GB12192, the Channel bandwidth of the interphone can be divided into two types, 12.5kHz and 25kHz, the 12.5kHz Channel must satisfy the narrow-band (8K5F3E) limit, the 25kHz Channel must satisfy the wide-band (16K0F3E) limit, and the Adjacent Channel Power (Adjacent Channel Power) requirement of 60dBc is satisfied, so that the frequency offset of the interphone frequency modulation signal of the Channel with 12.5kHz bandwidth needs to be limited to maximum 4kHz, and the frequency offset of the interphone frequency modulation signal of the Channel with 25kHz bandwidth needs to be limited to maximum 8 kHz. That is, the maximum limit frequency offset of the frequency-modulated signal with the channel bandwidth of 12.5kHz is 4kHz, and the maximum limit frequency offset of the frequency-modulated signal with the channel bandwidth of 25kHz is 8 kHz.
When determining the peak frequency offset, the peak frequency offset may be determined only according to the maximum limit frequency offset, and specifically, the frequency offset higher than the preset value of the maximum limit frequency offset may be determined as the peak frequency offset. If the maximum limited frequency offset is 8KHz, the peak frequency offset may be 9 KHz.
Or, the peak frequency offset may be determined according to the maximum limit frequency offset and an SINR corresponding to a receiving sensitivity of the fm receiver, specifically, the setting of the peak frequency offset should be greater than the maximum limit frequency offset, and after the set peak frequency offset, the SINR and the first quantity corresponding relation can cover the SINR corresponding to the receiving sensitivity. For example, in table 1 below, if the maximum limited frequency offset is 8KHz and the receive sensitivity is SINR 0dB, then the first amount corresponding to the sensitivity SINR is 15 and the peak frequency offset may be 16 KHz.
In one implementation of step S202, the frequency modulated signal received in a unit time may be digitally frequency discriminated to obtain a digital frequency discriminated output result. The digital frequency discrimination output result comprises instantaneous frequency deviation of the frequency modulation signal in unit time, and the number of the instantaneous frequency deviation in unit time is more than 0.
Further, in the implementation of step S203, the digital frequency discrimination output result may be compared with the peak frequency offset to obtain a first quantity. Specifically, by comparing the instantaneous frequency offset in the digital frequency discrimination output result with the peak frequency offset, the magnitude relationship between the instantaneous frequency offset and the peak frequency offset can be determined, so that the number of the instantaneous frequency offsets, that is, the first number, of which the frequency offsets reach the peak frequency offset can be calculated.
In the implementation of step S203, the average frequency offset per unit time may also be calculated according to the digital frequency discrimination output result. Specifically, an average value of all instantaneous frequency offsets in the digital frequency discrimination output result per unit time may be calculated as the average frequency offset.
In this embodiment, in an actual wireless receiving environment, due to interference and noise, a large number of glitches (or referred to as noise signals) far larger than a maximum frequency offset (that is, a peak frequency offset) designed by a system may appear in a frequency modulation signal after digital frequency discrimination, or an average frequency offset value is far larger than a designed frequency average value, where the number of the glitches and an SINR of the signal are in an inverse relationship, and since the FM signal and an FSK signal before synchronization is realized, the SINR cannot be measured, and even if the SINR is measured by pilot frequency, a measured value of the SINR is also a statistical average value, which cannot directly represent a signal quality of a current unit time, and the signal receiving quality of the current unit time can be intuitively estimated by counting the number of the glitches and the average frequency offset value in the unit time.
Further, in the specific implementation of step S204, the signal quality of the frequency modulation signal is determined according to the first number and a preset mapping relationship, and/or the average frequency offset and a preset mapping relationship.
The preset mapping relationship may be preset, and the preset mapping relationship includes signal quality of each level and a first quantity corresponding to the signal quality, and/or signal quality of each level and an average frequency offset corresponding to the signal quality.
Table 1 may be referred to for specific preset mapping relationships. The signal quality is represented by SINR, the peak frequency offset is 10KHz, and the first quantity represents the quantity of instantaneous frequency offsets of which the frequency offsets are larger than 10KHz in unit time.
TABLE 1
| SINR(dB) | A first amount | Average frequency deviation (Hz) |
| 30 | 0 | 4517 |
| 9 | 0 | 4755 |
| 6 | 0 | 4906 |
| 3 | 4 | 5219 |
| 0 | 15 | 5800 |
| -3 | 27 | 6429 |
| White noise | 45 | 7610 |
As shown in table 1, when the SINR is 30dB, the corresponding first quantity is 0, and the corresponding average frequency offset is 4517 Hz; the SINR is 3dB, which corresponds to an average frequency offset of 5219 Hz.
When the peak frequency offset is 4KHz, the preset mapping relationship is shown in table 2. Wherein the first number represents a number of instantaneous frequency offsets per unit time having a frequency offset greater than 4 KHz.
TABLE 2
| SINR(dB) | A first amount | Average frequency deviation (Hz) |
| 30 | 0 | 4517 |
| 9 | 4 | 4755 |
| 6 | 25 | 4906 |
| 3 | 56 | 5219 |
| 0 | 92 | 5800 |
| -3 | 123 | 6429 |
| White noise | 187 | 7610 |
In specific implementation, the preset mapping relationship may be obtained through algorithm simulation or actual measurement using an instrument. Specifically, for a digital FSK signal, since the frequency offset of each modulation symbol is fixed, the algorithm simulates or actually measures to obtain a first number and average frequency offset under different SINRs in unit time.
It should be noted that the SINR range and the peak frequency offset to be measured may be determined as required. Taking digital modulation as an example, if the SINR range to be measured is greater than 9dB, 9dB to-3 dB and less than-3 dB, the peak frequency offset can be selected to be 4 kHz; if the SINR range to be measured is greater than 3dB, 3dB to-3 dB and less than-3 dB, the peak frequency offset may be 10 kHz. Taking an analog interphone with a channel bandwidth of 25kHz as an example, the maximum limit frequency offset of transmission is 8kHz, the peak frequency offset can be 16kHz, and the SINR range to be measured can be more than 5dB, 5dB to-5 dB, and less than-5 dB.
In a non-limiting embodiment of the present invention, referring to fig. 3, step S204 shown in fig. 2 may include the following steps:
step S301: matching the first quantity with each first quantity in the preset mapping relation;
step S302: and if the first number of matches exists, taking the signal quality corresponding to the first number of matches as the signal quality of the frequency modulation signal.
In a specific implementation, the first number of matches refers to a first number in a preset mapping relation equal to the first number corresponding to the frequency modulation signal, or a range defined by two first numbers in a preset mapping relation including the first number corresponding to the frequency modulation signal. For example, referring to Table 1, if the first number of FM signals is 10, the first number in Table 1 matching the first number 10 defines a range of 4-15, and the signal quality of the FM signals is 0-3 dB.
In this embodiment, the signal quality of the frequency modulation signal may be determined only according to the first quantity and the preset mapping relationship.
For example, referring to table 2, if the first number is less than or equal to 4, it may be determined that the SINR is greater than or equal to 9dB, and thus it may be determined that the received frequency modulated signal is better.
Furthermore, in the embodiment of step S103 shown in fig. 1, the currently played audio signal may be determined according to the first number.
Specifically, if the first number is greater than a first threshold, it may be determined that the currently played audio signal is a comfort noise or null signal whose amplitude is less than a preset threshold.
In a non-limiting embodiment of the present invention, referring to fig. 4, step S204 shown in fig. 2 may include the following steps:
step S401: matching the average frequency deviation with each average frequency deviation in the preset mapping relation;
step S402: and if the matched average frequency offset exists, taking the signal quality corresponding to the matched average frequency offset as the signal quality of the frequency modulation signal.
In a specific implementation, the matched average frequency offset is an average frequency offset in a preset mapping relation equal to the average frequency offset corresponding to the frequency modulation signal, or a range defined by two average frequency offsets in a preset mapping relation including the average frequency offset corresponding to the frequency modulation signal. For example, referring to table 1, when the average frequency offset of the frequency modulated signal is 5500Hz, the range of the average frequency offset in table 1 matching with the average frequency offset 5500 is 5219-5800Hz, and the signal quality of the frequency modulated signal is 0-3 dB.
Different from the foregoing embodiment, the embodiment of the present invention may determine the signal quality of the frequency modulation signal only according to the average frequency offset and the preset mapping relationship.
For example, referring to table 2, if the average frequency offset is greater than 6500Hz, it may be determined that the frequency modulated signal is a noise signal, i.e., the frequency modulated signal has poor signal quality.
Furthermore, in the specific implementation of step S103 shown in fig. 1, the currently played audio signal may be determined according to the average frequency offset.
Specifically, if the average frequency offset is greater than the second threshold, it may be determined that the currently played audio signal is a comfort noise or null signal whose amplitude is less than a preset threshold.
In a non-limiting embodiment of the present invention, referring to fig. 5, step S204 shown in fig. 2 may include the following steps:
step S501: judging whether the average frequency deviation falls into a preset range or not;
step S502: if the average frequency offset falls into the preset range, matching the first quantity with each first quantity in the preset mapping relation, and determining the signal quality corresponding to the matched first quantity as the signal quality of the frequency modulation signal;
step S503: if the average frequency deviation is lower than the lower limit value of the preset range, determining that the frequency modulation signal is an interference signal of other systems;
step S504: and if the average frequency offset is higher than the upper limit value of the preset range, determining that the frequency modulation signal is noise or an interference signal of other systems.
Different from the foregoing embodiment, in the embodiment of the present invention, the signal quality of the frequency modulation signal may be determined according to the average frequency offset and the preset mapping relationship between the first quantity and the preset value.
When the average frequency offset is lower than the lower limit value of the preset range, the interference signals of other systems can be frequency modulation signals or single-tone signals; when the average Frequency offset is higher than the upper limit value of the preset range, the interference signals of other systems may be Orthogonal Frequency Division Multiplexing (OFDM) symbols or the like.
In a specific implementation, different preset ranges may be set for different frequency modulation signals, which is not limited in the embodiment of the present invention.
The embodiment of the invention combines the first quantity and the average frequency deviation to determine the signal quality of the frequency modulation signal, thereby ensuring the reliability of signal quality determination.
Further, when the modulation system of the frequency modulation signal is digital frequency shift keying, the preset range includes a numerical range between the minimum average frequency offset and the maximum first average frequency offset. Step S401 shown in fig. 4 may include the steps of: and judging whether the average frequency deviation is larger than the average frequency deviation minimum value and smaller than the first average frequency deviation maximum value.
In this embodiment, the minimum value of the average frequency offset and the maximum value of the first average frequency offset may be set for the FSK signal.
In a specific application scenario, the peak frequency offset is 4K Hz. The minimum value of the average frequency offset may be 2000Hz and the first maximum value of the average frequency offset may be 6500 Hz. It is determined whether the average frequency offset freq _ AveOffset is greater than 2000Hz and less than 6500Hz, and if so, the frequency modulated signal may be determined to be a 4FSK signal, and the signal quality may be determined in combination with the first quantity. If not, and the average frequency offset freq _ AveOffset is less than 2000Hz and the first number is less than or equal to 92, then it may be determined that the modulated frequency signal may be other non-4 FSK modulated frequency signals, and reception of the modulated frequency signal may be interrupted directly, otherwise it may be determined that the modulated frequency signal is a noise or interference signal.
Furthermore, in the specific implementation of step S103 shown in fig. 1, the currently played audio signal may be determined according to the first number and the average frequency offset.
Specifically, if the average frequency offset falls within the preset range and the first number is greater than a first threshold, it may be determined that the currently played audio signal is a comfort noise or null signal whose amplitude is less than a preset threshold. If the average frequency offset does not fall within the preset range, it may be determined that the currently played audio signal is a comfort noise or null signal whose amplitude is smaller than a preset threshold.
Further, the modulation system of the frequency modulation signal is analog frequency modulation, the preset range includes a numerical range smaller than the second average frequency offset maximum value, and step S501 shown in fig. 5 may include the following steps: and judging whether the average frequency offset is smaller than the second average frequency offset maximum value or not.
In this embodiment, a second average frequency offset maximum value may be set for the FM signal.
In a specific application scenario, if the average frequency offset of the frequency modulation signal is smaller than the second average frequency offset maximum value, the frequency modulation signal may be determined to be an FM signal; otherwise, the fm signal may be determined to be a noise or interference signal, i.e., the signal quality is poor.
In a specific application scenario of the present invention, for an analog FM signal with a channel bandwidth of 25kHz and a maximum limit frequency offset of 7kHz, the peak frequency offset freq _ OffsetLmt of the analog FM signal is determined to be 17 kHz. The preset number K is determined to be 20 and the count K of the counter is reset to 0.
Carrying out digital frequency discrimination on the FM receiving signal of the unit time T, comparing the instantaneous frequency deviation in the digital frequency discrimination output result with the peak frequency deviation freq _ LmtOffset, and counting a first quantity freq _ OutRangeNum of the instantaneous frequency deviation larger than freq _ LmtOffset.
If the first number freq _ outrangennum is smaller than the preset threshold freq _ OutRangeLmtNum, the signal quality is considered to be poor, the frequency modulation signal received in the unit time T is not played in audio frequency, or the playing amplitude is small, and the counting k of the counter is k + 1. And comparing the count K of the counter with the preset number K, and if the count K is greater than the preset number K, determining that the sender hangs up the call and removing the receiving link by the receiver.
And if the count K is less than the preset number K, continuously receiving the frequency modulation signal in the next unit time T.
If the signal quality is greater than the preset threshold, the frequency modulation signal can be demodulated and the demodulated sound data can be played, and the count k of the counter is reset to be 0. And continues to receive the frequency modulated signal for the next unit time T.
Referring to fig. 6, the embodiment of the present invention further discloses a fm signal processing apparatus 60, and the fm signal processing apparatus 60 may include a receiving module 601, a signal quality detecting module 602, and a currently playing signal determining module 603.
Wherein, the receiving module 601 is adapted to receive the frequency modulation signal according to a unit time; the signal quality detection module 602 is adapted to detect the signal quality of the frequency modulated signal per unit time; the currently played audio signal determining module 603 is adapted to determine the currently played audio signal according to the signal quality of the frequency modulated signal in the unit time.
For more details of the operating principle and the operating mode of the fm signal processing apparatus 60, reference may be made to the related descriptions in fig. 1 to 5, which are not described herein again.
The embodiment of the invention also discloses a storage medium, wherein computer instructions are stored on the storage medium, and when the computer instructions are operated, the steps of the method shown in the figures 1 to 5 can be executed. The storage medium may include ROM, RAM, magnetic or optical disks, etc. The storage medium may further include a non-volatile memory (non-volatile) or a non-transitory memory (non-transient), and the like.
The embodiment of the invention also discloses a frequency modulation receiver which can comprise a memory and a processor, wherein the memory stores computer instructions capable of running on the processor. The processor, when executing the computer instructions, may perform the steps of the methods shown in fig. 1-5. The FM receiver comprises but is not limited to a mobile phone, a computer, a tablet computer and other terminal equipment.
Although the present invention is disclosed above, the present invention is not limited thereto. Various changes and modifications may be effected therein by one skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.
Claims (12)
1. A method of frequency modulated signal processing, comprising:
receiving a frequency modulated signal per unit time;
detecting the signal quality of the frequency-modulated signal in unit time;
determining the currently played audio signal according to the signal quality of the frequency modulation signal in the unit time;
the detecting the signal quality of the frequency-modulated signal in the unit time comprises:
determining the maximum limit frequency offset of the frequency modulation signal, and determining a frequency offset peak value at least according to the maximum limit frequency offset;
determining a digital frequency discrimination output result of the frequency-modulated signal received in the unit time, wherein the digital frequency discrimination output result comprises an instantaneous frequency offset;
comparing the digital frequency discrimination output result with the frequency deviation peak value to obtain a first quantity, wherein the first quantity is the quantity of instantaneous frequency deviation when the frequency deviation reaches the frequency deviation peak value;
and determining the signal quality of the frequency modulation signal according to the first quantity and a preset mapping relation, wherein the preset mapping relation comprises the signal quality of each grade and the corresponding first quantity.
2. A method of processing a frequency modulated signal as claimed in claim 1, wherein said determining a currently played signal based on the signal quality of the frequency modulated signal per unit time comprises:
and when the signal quality of the frequency modulation signal in the unit time is less than a preset threshold, determining that the currently played audio signal is a comfortable noise or null signal with the amplitude less than the preset threshold.
3. A method of processing a frequency modulated signal according to claim 2, further comprising:
and if the signal quality of the frequency modulation signals in the unit time of the continuous preset number is less than the preset threshold, switching from the current connection state to the standby state.
4. A method for processing frequency-modulated signals according to claim 1, wherein the modulation scheme of the frequency-modulated signals is digital frequency shift keying, and the determining the currently played signals according to the signal quality of the frequency-modulated signals in the unit time comprises:
and if the ending signaling is not received in the unit time, determining the currently played signal according to the signal quality of the frequency modulation signal in the unit time.
5. A method as claimed in claim 1, wherein the predetermined mapping comprises signal qualities of respective levels and corresponding first quantities, and the determining the signal quality of the fm signal according to the first quantities comprises:
matching the first quantity with each first quantity in the preset mapping relation;
and if the first number of matches exists, taking the signal quality corresponding to the first number of matches as the signal quality of the frequency modulation signal.
6. The method of claim 1, wherein the predetermined mapping relationship comprises signal quality of each level and average frequency offset corresponding thereto, and the determining the signal quality of the fm signal according to the average frequency offset and the predetermined mapping relationship comprises:
matching the average frequency deviation with each average frequency deviation in the preset mapping relation;
and if the matched average frequency offset exists, taking the signal quality corresponding to the matched average frequency offset as the signal quality of the frequency modulation signal.
7. The method of claim 1, wherein the predetermined mapping relationship comprises signal quality of each level and average frequency offset corresponding thereto, and the determining the signal quality of the frequency modulated signal according to the first quantity and the predetermined mapping relationship and the average frequency offset and the predetermined mapping relationship comprises:
judging whether the average frequency deviation falls into a preset range or not;
if the average frequency offset falls into the preset range, matching the first quantity with each first quantity in the preset mapping relation, and determining the signal quality corresponding to the matched first quantity as the signal quality of the frequency modulation signal;
if the average frequency deviation is lower than the lower limit value of the preset range, determining that the frequency modulation signal is an interference signal of other systems;
and if the average frequency offset is higher than the upper limit value of the preset range, determining that the frequency modulation signal is noise or an interference signal of other systems.
8. The method of claim 7, wherein the modulation scheme of the frequency modulated signal is digital frequency shift keying, the predetermined range includes a range of values between a minimum value of the average frequency offset and a maximum value of the first average frequency offset, and the determining whether the average frequency offset falls within the predetermined range includes:
and judging whether the average frequency deviation is larger than the average frequency deviation minimum value and smaller than the first average frequency deviation maximum value.
9. The method of claim 7, wherein the modulation scheme of the frequency modulated signal is analog frequency modulation, the predetermined range includes a range of values smaller than a second average frequency offset maximum, and the determining whether the average frequency offset falls within the predetermined range includes:
and judging whether the average frequency offset is smaller than the second average frequency offset maximum value or not.
10. A frequency modulated signal processing apparatus, comprising:
the receiving module is suitable for receiving the frequency modulation signal according to unit time;
the signal quality detection module is suitable for detecting the signal quality of the frequency modulation signal in unit time;
the current playing signal determining module is suitable for determining the currently played audio signal according to the signal quality of the frequency modulation signal in the unit time;
the signal quality detection module detects the signal quality by:
determining the maximum limit frequency offset of the frequency modulation signal, and determining a frequency offset peak value at least according to the maximum limit frequency offset;
determining a digital frequency discrimination output result of the frequency-modulated signal received in the unit time, wherein the digital frequency discrimination output result comprises an instantaneous frequency offset;
comparing the digital frequency discrimination output result with the frequency deviation peak value to obtain a first quantity, wherein the first quantity is the quantity of instantaneous frequency deviation when the frequency deviation reaches the frequency deviation peak value;
and determining the signal quality of the frequency modulation signal according to the first quantity and a preset mapping relation, wherein the preset mapping relation comprises the signal quality of each grade and the corresponding first quantity.
11. A storage medium having stored thereon computer instructions, wherein said computer instructions are operable to perform the steps of the frequency modulated signal processing method of any one of claims 1 to 9.
12. A fm receiver comprising a memory and a processor, said memory having stored thereon computer instructions executable on said processor, wherein said processor when executing said computer instructions performs the steps of the fm signal processing method of any of claims 1 to 9.
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| US6816555B2 (en) * | 2000-02-18 | 2004-11-09 | Sony Corporation | Signal component demultiplexing apparatus, filter apparatus, receiving apparatus, communication apparatus, and communication method |
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| CN102045117A (en) * | 2009-10-19 | 2011-05-04 | 创杰科技股份有限公司 | Apparatus and method for signal quality measurement on gfsk signals |
| CN103227650A (en) * | 2012-01-31 | 2013-07-31 | 美国博通公司 | Systems and methods for enhancing audio quality of FM receivers |
| CN108155913A (en) * | 2018-01-12 | 2018-06-12 | 福建飞通通讯科技股份有限公司 | FM signal squelch method, apparatus and system |
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