CN108243132A - A signal modulation method and device - Google Patents

Abstract

The invention discloses a kind of signal modulating method and devices, belong to field of communication technology.The method includes：It is poor by target frequency when presetting carriers carry baseband digital signal to be determined according to the first data transfer rate, and target frequency difference is the difference preset in the frequency spectrum for the modulated signal for it is expected to obtain between the frequency of carrier wave and the frequency of an order harmonics；Target modulation index, the bandwidth for the modulated signal that target modulation index it is expected to obtain for control are determined from the modulation index range for meeting the first modulation condition；According to target frequency difference and target modulation index, target sub-carriers are determined；According to default carrier wave and target sub-carriers, baseband digital signal is modulated.The present invention determines the target sub-carriers for controlling default carrier frequency by the first data transfer rate and the first modulation condition, within the scope of the signal bandwidth of modulated signal is controlled to be in the narrow bandwidth of demand, can effectively improve spectrum efficiency.

Description

A signal modulation method and device

technical field

Embodiments of the present invention relate to the field of communication technologies, and in particular, to a signal modulation method and device.

Background technique

In a communication system, in order to enable the baseband signal generated by the source to be transmitted in a high-frequency channel with limited bandwidth, it is necessary to carry out carrier modulation on the baseband signal. The principle of modulation is to use the baseband signal to control certain parameters (amplitude, frequency or phase) of the carrier, so that these parameters change with the change of the baseband signal, and finally form a modulated signal centered on the carrier frequency. Among them, the baseband signal used to control the carrier parameter is called the modulation signal. When the modulation signal is an analog signal, the modulation process is called analog modulation, and when the modulation signal is a digital signal, the modulation process is called digital modulation.

In the related art, On-Off Keying (OOK) modulation is a kind of digital modulation, and the amplitude of the carrier is mainly controlled by a digital signal. As shown in Figure 1A, when the digital signal is sent 1, the amplitude of the modulated signal after OOK modulation remains unchanged, that is, the carrier itself; when the digital signal is sent 0, the amplitude of the modulated signal after OOK modulation is 0. Frequency modulation (Frequency Modulation, FM) is mainly to control the frequency of the carrier through the modulation signal, as shown in Figure 1B, the modulation signal is a sine wave, and the frequency of the carrier is controlled by the modulation signal in the form of FM, and the FM shown in Figure 1B is obtained. Wave.

Because OOK modulation radiates energy only when the digital signal is sending 1, OOK modulation is the most energy-saving modulation method. In OOK modulation, since most signals are sent with extremely low energy, a high signal-to-noise ratio is required for demodulation at the receiving end, and the signal quality of the modulated signal is easily affected by the channel during transmission. Due to the influence of non-ideal factors, the modulated signal of OOK modulation has poor anti-noise and anti-fading performance. In addition, according to the power density spectrum of the modulated signal, it can be seen that the signal bandwidth of the modulated signal obtained by OOK modulation is twice that of the modulated signal, so a higher bandwidth needs to be occupied during the transmission process. In the frequency spectrum of the modulated signal of FM modulation, besides the carrier component, there are many side frequency components, so a relatively high bandwidth needs to be occupied during the transmission process.

Contents of the invention

In order to solve the problem that the modulated signal obtained by OOK modulation and FM modulation occupies too much bandwidth during transmission, the embodiments of the present invention provide a signal modulation method and device. Described technical scheme is as follows:

In a first aspect, a signal modulation method is provided, the method comprising:

Determine the target frequency difference when the baseband digital signal is carried by the preset carrier according to the first data rate, the first data rate is a data rate that can be achieved by the modulated signal that is expected to be obtained, and the target frequency difference is the desired obtained one. the difference between the frequency of said predetermined carrier and the frequency of the first order harmonic in the frequency spectrum of the modulated signal;

determining a target modulation index from a modulation index range satisfying a first modulation condition, where the target modulation index is used to control the bandwidth of the modulated signal expected to be obtained;

determining a target subcarrier according to the target frequency difference and the target modulation index, where the target subcarrier is used to control the frequency of the preset carrier;

The baseband digital signal is modulated according to the preset carrier and the target subcarrier.

It should be noted that the first data rate is determined according to user requirements, that is, after the baseband digital signal is modulated, an expected data rate that can meet user requirements. In addition, the embodiment of the present invention also determines the first modulation condition. The first modulation condition is the condition that the modulated signal to be obtained needs to meet. Assuming that the modulated signal satisfies the first modulation condition, the signal bandwidth of the modulated signal will be limited within a narrow range, so by using the first data rate and the target subcarrier determined by the first modulation condition and the baseband digital signal to modulate the preset carrier, the obtained modulated signal is the expected modulated signal.

In the embodiment of the present invention, since the target subcarrier used to control the frequency of the preset carrier in the modulation process can be determined according to the first data rate and the first modulation condition, the target subcarrier can be used to control the frequency of the preset carrier Modulation is performed to obtain the desired modulated signal with a smaller bandwidth.

Optionally, the determining the target modulation index from the modulation index range satisfying the first modulation condition includes:

Acquiring the corresponding modulation index range from the stored correspondence between the modulation condition and the modulation index range according to the first modulation condition;

A modulation index is randomly selected from the acquired modulation index range as the target modulation index.

Wherein, the first modulation condition can be a specified value range, therefore, according to the first modulation condition, the corresponding modulation index range can be determined, and one can be selected from the modulation index range according to the modulation requirement. The modulation index of is used as the target modulation index.

In the embodiment of the present invention, since the target modulation index is used to control the signal bandwidth of the desired modulated signal, therefore, according to the first modulation condition, the modulation index range is determined, and the target modulation index is selected from the modulation index range, which can realize Controlling the signal bandwidth of the finally obtained modulated signal, that is, selecting a different modulation index from the modulation index range as a target modulation index, will result in modulated signals with different signal bandwidths.

Optionally, the determining the target subcarrier according to the target frequency difference and the target modulation index includes:

determining the frequency of the target subcarrier according to the target frequency difference;

determining an amplitude value of the target subcarrier according to the target frequency difference and the target modulation index;

The target subcarrier is determined according to the frequency and amplitude values of the target subcarrier.

It should be noted that since the target frequency difference is the difference between the frequency of the preset carrier and the frequency of the first-order harmonic in the frequency spectrum of the modulated signal that is expected to be obtained, the frequency of the target subcarrier is determined according to the target frequency difference , which is equivalent to determining the frequency of the harmonic component in the frequency spectrum of the modulated signal that is expected to be obtained. Afterwards, the amplitude value of the target subcarrier is determined according to the target frequency difference and the target modulation index, that is, the amplitude value of the target subcarrier that can satisfy the first modulation condition and the first data rate is determined. When both the frequency and amplitude values of the target subcarrier are determined, the target subcarrier is determined.

In the embodiment of the present invention, since the target subcarrier is determined by the target frequency difference and the target modulation index, when the target subcarrier is used to modulate the frequency of the preset carrier, the obtained modulated signal will be the desired modulated signal.

Optionally, the determining the amplitude value of the target subcarrier according to the target frequency difference and the target modulation index includes:

Acquiring a corresponding amplitude value from the stored correspondence between the frequency difference, modulation index, and amplitude value according to the target frequency difference and the target modulation index;

and determining the obtained amplitude value as the amplitude value of the target subcarrier.

It should be noted that, in the signal modulation process, in order to determine the amplitude value of the target subcarrier more conveniently and quickly, the corresponding relationships among multiple frequency differences, modulation indices, and amplitude values can be determined in advance and stored. When the amplitude value of the target subcarrier is determined, the corresponding amplitude value can be obtained directly from the stored correspondence between the frequency difference, the modulation index and the amplitude value according to the target frequency difference and the target modulation index.

Optionally, before obtaining the corresponding amplitude value from the stored correspondence between the frequency difference, modulation index, and amplitude value according to the target frequency difference and the target modulation index, the method further includes:

determining a modulation index range that satisfies the first modulation condition through the relationship between the Bessel function and the modulation index;

determining the frequency of the target subcarrier according to the target frequency difference;

Determine multiple modulation indices according to the frequency of the target subcarrier, where the multiple modulation indices are modulation indices obtained when the amplitude of the target subcarrier takes multiple different amplitude values;

selecting a modulation index within the range of modulation indices from the plurality of modulation indices;

The target frequency difference, the selected modulation index, and the amplitude value corresponding to the selected modulation index are stored in the correspondence between the frequency difference, the modulation index, and the amplitude value.

It should be noted that, since the determination of the amplitude value of the target subcarrier needs to be obtained from the stored correspondence between the frequency difference, modulation index and amplitude value, the corresponding relation needs to be obtained before obtaining.

In the embodiment of the present invention, according to the first modulation condition, the modulation index range is determined by the Bessel function; then, since the frequency of the target subcarrier has been determined, different amplitude values are taken for the target subcarrier, and multiple different amplitude values are determined. subcarriers, and thus determine multiple modulation indices. According to the modulation index range determined above, select the modulation index within the modulation index range from multiple modulation indices, so as to obtain the corresponding relationship between the frequency difference, modulation index and amplitude value. The frequency difference and the target modulation index can directly determine the target subcarrier, which brings convenience to signal modulation.

Optionally, the first modulation condition includes at least one of the following conditions:

The difference between the signal amplitude value of the preset carrier in the first signal spectrum and the signal amplitude value in the second signal spectrum is greater than the first value, and the first signal spectrum is the expected value when the baseband digital signal sends 1 The spectrum of the modulated signal obtained, the spectrum of the second signal is the spectrum of the modulated signal expected to be obtained when the baseband digital signal sends 0;

the difference between the signal amplitude value of the first order harmonic in the first signal spectrum and the signal amplitude value in the second signal spectrum is less than a second value;

Signal amplitude values of second order harmonics and higher order harmonics in the first signal spectrum are suppressed by a third value compared to signal amplitude values in the second signal spectrum.

It should be noted that when the modulated signal satisfies the first modulation condition, the second-order harmonic and its higher-order harmonics can be ignored, that is, the signal bandwidth of the modulated signal will be limited to two within the frequency range of the first harmonic.

In the embodiment of the present invention, since the first modulation condition is determined according to requirements, different first modulation conditions will correspond to different modulation indexes, that is, different first modulation conditions will obtain different modulated signals Therefore, the signal bandwidth of the finally obtained modulated signal can be controlled according to setting different first modulation conditions.

In a second aspect, a signal modulation device is provided, and the signal modulation device has the function of implementing the signal modulation method in the first aspect above. The signal modulation device includes at least one module, and the at least one module is configured to implement the signal modulation method provided in the first aspect above.

In a third aspect, an embodiment of the present invention provides a computer storage medium for storing computer software instructions used by the above-mentioned signal modulation device, or storing programs involved in executing the signal modulation device of the above-mentioned second aspect.

The above-mentioned technical effects obtained by the second aspect and the third aspect of the embodiments of the present invention are similar to those obtained by the corresponding technical means in the first aspect, and will not be repeated here.

The beneficial effect brought by the technical solution provided by the embodiment of the present invention is: in the embodiment of the present invention, the first data rate is determined according to the user's demand, that is, after the baseband digital signal is modulated, the expected and satisfying The data rate required by the user. In addition, the first modulation condition is a condition that the desired modulated signal needs to satisfy. Assuming that the modulated signal satisfies the first modulation condition, the signal bandwidth of the modulated signal will be limited within a narrow range. Therefore, Determine the target subcarrier used to control the preset carrier frequency in the modulation process according to the first data rate and the first modulation condition, so as to modulate the frequency of the preset carrier to obtain the desired modulated signal with a smaller bandwidth , that is, the signal modulation method according to the embodiment of the present invention modulates the signal, and the signal bandwidth of the modulated signal can be controlled within a narrow range as required, thereby effectively improving the spectrum efficiency.

Description of drawings

FIG. 1A is a schematic diagram of an OOK modulation principle provided by an embodiment of the present invention;

FIG. 1B is a schematic diagram of the principle of FM modulation provided by an embodiment of the present invention;

FIG. 2 is an application scenario diagram of a signal modulation method provided by an embodiment of the present invention;

FIG. 3 is a schematic structural diagram of a transmitter provided by an embodiment of the present invention;

Fig. 4A is a flowchart of a signal modulation method according to an exemplary embodiment;

Fig. 4B is a Bessel function curve diagram provided by an embodiment of the present invention;

Fig. 4C is a schematic diagram showing digitization of a triangle wave according to an exemplary embodiment;

Fig. 5 is a block diagram showing a signal modulation device according to an exemplary embodiment.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the implementation manner of the present invention will be further described in detail below in conjunction with the accompanying drawings.

Fig. 2 is a diagram showing an application scenario of a signal modulation method according to an exemplary embodiment. As shown in FIG. 2 , the application scenario includes an electrocardiogram sensor 201 , a pulse sensor 202 , a motion sensor 203 , a personal mobile device 204 , a base station 205 , a terminal 206 , a smart refrigerator 207 , and a fixed phone 208 .

With the development of science and technology, human health monitoring system has gradually entered people's life. Through the monitoring equipment such as the electrocardiogram sensor 201 , the pulse sensor 202 , and the motion sensor 203 worn by the human body, the physical parameters of the human body can be measured. Afterwards, the monitoring device can be connected with the personal mobile device 204 through the ZigBee protocol for information exchange. At the same time, the personal mobile device 204 can also be connected to the terminal 206 through a Bluetooth (Bluetooth) protocol or a wireless local area network (WirelessLocal Area Networks, WLAN) protocol, or communicate with the base station 205 using General Packet Radio Service (GPRS), In this way, the control of smart home devices such as smart refrigerator 207 and fixed phone 208 in the home is realized. Wherein, when the monitoring device and the personal mobile device 204 communicate through the ZigBee protocol, or when the personal mobile device 204 communicates with the terminal 206 through Bluetooth or WLAN, or when the personal mobile device communicates with the base station 205 through GPRS, the present invention can be used The signal modulation method provided in the embodiment modulates the baseband digital signal to be transmitted, and the signal modulation device provided in the embodiment of the present invention may be included in the equipment for transmitting the signal. Of course, in practical applications, the signal modulation method provided by the embodiment of the present invention can also be applied to other application scenarios, for example, in an office, multiple computers, printers, and cordless phones connected through ultra-broadband.

Figure 3 is a transmitter that transmits signals using the signal modulation method of the embodiment of the present invention according to an exemplary embodiment. As shown in Figure 3, the transmitter includes a reference signal terminal 01 and a baseband digital signal terminal 02 , control word terminal 03, hybrid phase-locked loop 04, gain control module 05, power amplifier 06 and differential integral modulator 07. Among them, the hybrid phase-locked loop 04 includes a charge pump/frequency phase detector 11, a low-pass filter 12, a numerically controlled/voltage-controlled oscillator 13, a binary phase detector 14, a digital filter 15, a differential integral modulator 16, Temperature code control module 17, current mode logic circuit 18 and frequency divider 19, wherein, charge pump/frequency discrimination phase detector 11, low-pass filter 12, numerical control/voltage-controlled oscillator 13 form hybrid phase-locked loop 04 The analog branch, the binary phase detector 14, the digital filter 15, the differential integral modulator 16, the temperature code control module 17 and the numerical control/voltage-controlled oscillator 13 form the digital branch of the hybrid phase-locked loop 04.

It should be noted that the reference signal terminal 01 is connected to the input terminal 11a of the charge pump frequency and phase detector 11 and the input terminal 14a of the binary phase detector 14, and the output terminal 11b of the charge pump frequency and phase detector 11 is connected to the low-pass filter The input terminal 12a of the device 12, the output terminal 12b of the low-pass filter 12 is connected with the input terminal 13a of the numerically controlled/voltage controlled oscillator 13. The output terminal 14b of binary phase detector 14 is connected with the input terminal 15a of digital filter 15, and the output terminal 15b of digital filter 15 is connected with the input terminal 16a of differential integral modulator 16, and the output terminal 16b of differential integral modulator 16 is connected with The input terminal 17a of the temperature code control module 17 is connected, and the output terminal 17b of the temperature code control module 17 is connected with the input terminal 13a of the numerically controlled/voltage controlled oscillator 13 . The baseband digital signal terminal 02 is connected to the input terminal 05a of the gain control module 05, the output terminal 05b of the gain control module 05 is connected to the input terminal 13a of the numerically controlled/voltage controlled oscillator 13, and the control word terminal 03 is connected to the numerically controlled/voltage controlled oscillator 13 The input terminal 13a is connected. The output terminal 13b of the numerically controlled/voltage controlled oscillator 13 is connected with the input terminal 06a of the power amplifier 06, meanwhile, the output terminal 13b of the numerically controlled/voltage controlled oscillator 13 is also connected with the input terminal 18a of the current mode logic circuit 18, and the current mode logic circuit The output terminal 18b of the circuit 18 is connected with the input terminal 19a of the frequency divider 19, and the output terminal 19b of the frequency divider 19 is connected with the input terminal 11a of the charge pump frequency detector 11 and the input terminal 14a of the binary phase detector 14. In addition, the control word terminal 03 can also be connected to the input terminal 07 a of the differential integral modulator 07 , and the output terminal 07 b of the differential integral modulator 07 is connected to the input terminal 19 a of the frequency divider 19 .

In practical applications, the reference signal output by the reference signal terminal 01 and the feedback signal output by the frequency divider 19 are respectively input into the analog branch and the digital branch. In the analog branch, the charge pump frequency and phase detector 11 converts the reference signal and The phase or frequency of the feedback signal is compared to obtain the phase difference or frequency difference, and the phase difference or frequency difference is converted into a current signal and then output. The low-pass filter 12 converts the current signal into a control voltage output, and the control voltage is used It is used to control the oscillation frequency of the numerically controlled/voltage controlled oscillator 13. In the digital branch, the binary phase detector 14 compares the feedback signal with the reference signal to obtain a phase difference or frequency difference, and converts the phase difference or frequency difference into a voltage signal to drive a digital filter 15 for digital filtering The signal obtained after filtering by the device 15 passes through the differential integral modulator 16, and then the oscillation frequency of the numerically controlled/voltage controlled oscillator 13 is controlled by the temperature code control module 17.

The baseband digital signal terminal outputs the baseband digital signal, and the baseband digital signal passes through the gain control module 05 and then is input to the numerically controlled/voltage controlled oscillator 13 to generate different frequency deviations by the control signal. The modulated signal output by the numerically controlled/voltage controlled oscillator 13 outputs a constant envelope signal through the power amplifier 06, and at the same time, the modulated signal output by the numerically controlled/voltage controlled oscillator 13 passes through the current mode logic circuit 18 and the frequency divider 19 The frequency division is input to the input terminal of the hybrid phase-locked loop 04 as a feedback signal.

In the transmitter provided by the embodiment of the present invention, a hybrid phase-locked loop is used to stabilize the signal frequency, which reduces the complexity of the design compared to an all-digital phase-locked loop, and reduces the complexity of the design compared to an analog phase-locked loop. Leakage and chip area are reduced. In addition, in the transmitter provided by the embodiment of the present invention, the baseband digital signal is directly added to the numerically controlled/voltage controlled oscillator only through the gain control module, and in the two-point modulation, the baseband digital signal is in the While inputting the voltage-controlled oscillator for high-point modulation, it is also necessary to perform low-point modulation through the crystal oscillator to ensure a good low-frequency response, and because both the voltage-controlled oscillator and the crystal oscillator must be Gain matching. Compared with the two-point modulation, the transmitter provided in the embodiment of the present invention saves the low-frequency response process of using a crystal oscillator for modulation, that is, only the high point in the two-point modulation is used in the embodiment of the present invention Modulation, therefore, there is no need for gain matching of two-point modulation, which reduces the complexity of the design. In addition, the transmitter provided by the embodiment of the present invention adopts a low power supply voltage design to ensure low power consumption due to reduced system complexity.

Fig. 4A is a flow chart of a signal modulation method according to an exemplary embodiment. Referring to Fig. 4A, the method includes:

Step 401: Determine the target frequency difference when the baseband digital signal is carried by the preset carrier according to the first data rate, the first data rate is the data rate that the expected modulated signal can achieve, the target frequency difference is the expected obtained The difference between the frequency of the preset carrier and the frequency of the first-order harmonic in the frequency spectrum of the modulated signal.

Typically, the frequency bandwidth of a signal that a communication channel allows to pass is called the channel bandwidth. When the passing signal is a digital signal, the channel bandwidth is characterized by a data rate. In the wireless communication system, due to the shortage of frequency band resources, the analog modulated signal obtained by modulating the preset carrier through the baseband digital signal cannot have an excessively high signal bandwidth, because the current wireless communication system contains a large number of digital devices , Therefore, in general, the channel bandwidth is characterized by the data rate, so that the obtained analog modulated signal needs to be converted into a digital modulated signal through sampling. When the signal bandwidth of the analog modulated signal is small, correspondingly, the digital modulated signal obtained by sampling the analog modulated signal will not have an excessively high data rate during transmission.

Based on the above relationship, when carrier modulation is performed on the baseband digital signal, the first data rate can be determined according to the bandwidth requirement. rate, the signal bandwidth of the expected analog modulated signal can be determined. One-half of the signal bandwidth is determined as the target frequency difference, since the target frequency difference is the difference between the frequency of the preset carrier and the frequency of the first-order harmonic in the frequency spectrum of the modulated signal expected to be obtained, therefore, It is equivalent to limiting the signal bandwidth of the expected modulated signal within the frequency range of the two first-order harmonics.

For example, when the signal bandwidth determined according to the first data rate is 2f _m , and the frequency of the preset carrier is f _c , then the target frequency difference is determined as f _m , that is, the frequency spectrum of the modulated signal expected to be obtained The difference between the frequency of the preset carrier f _c and the first-order harmonic is f _m , since the signal bandwidth of the modulated signal expected to be obtained is 2f _m , therefore, it is equivalent to limiting the signal bandwidth to f _c - between f _m and f _c +f _m .

After the target frequency difference is determined, the target modulation index can be determined through step 402, and thus the target subcarrier can be determined through step 403, so that the modulated signal obtained after the baseband digital signal is modulated is the desired modulated signal .

Step 402: Determine a target modulation index from the range of modulation indices satisfying the first modulation condition, where the target modulation index is used to control the bandwidth of the modulated signal expected to be obtained.

Based on the description in step 401, after the target frequency difference is determined, the target modulation index needs to be determined through the first modulation condition, so as to facilitate the subsequent further determination of the target subcarrier, so as to obtain the desired modulated signal.

It should be noted that the first modulation condition may include at least one of the following conditions:

(1) The difference between the signal amplitude value of the preset carrier in the first signal spectrum and the signal amplitude value in the second signal spectrum is greater than the first value;

(2) The difference between the signal amplitude value of the first-order harmonic in the first signal spectrum and the signal amplitude value in the second signal spectrum is smaller than the second value;

(3) The signal amplitude values of the second-order harmonic and its higher-order harmonics in the first signal spectrum are suppressed by the third value compared with the signal amplitude values in the second signal spectrum.

Wherein, the first signal spectrum is the spectrum of the modulated signal expected to be obtained when the baseband digital signal is sent 1, and the second signal spectrum is the spectrum of the modulated signal expected to be obtained when the baseband digital signal is sent 0. The first value, the second value and the third value can be determined according to different standards and requirements. For example, in the embodiment of the present invention, the first value may be determined as 10dB (decibel), the second value may be determined as 7dBm (decibel millivolt), and the third value may be determined as 19dB.

Certainly, in order to determine the modulation index range more accurately, so as to better control the signal bandwidth of the modulated signal through the target modulation index, the first modulation condition may also include any two of the above three conditions or all of the above three conditions. condition, when the first modulation condition includes more conditions, after using the target subcarrier determined by the first modulation condition to modulate the preset carrier, the signal bandwidth of the modulated signal obtained will be more in line with the expected modulated signal signal bandwidth.

It should be noted that the first modulation condition is a modulation condition that is expected to be satisfied by the modulated signal provided by the embodiment of the present invention. That is, when the baseband digital signal transmits 1, the first signal spectrum of the modulated signal is obtained; when the baseband digital signal transmits 0, the second signal spectrum of the modulated signal is obtained, and each frequency in the first signal spectrum corresponds to Only when the signal amplitude value and the signal amplitude value in the second signal frequency spectrum meet the first modulation condition can the purpose of controlling the bandwidth through the first data rate in step 401 be achieved.

Further, assuming that the modulated signal obtained by modulating the baseband digital signal satisfies the first modulation condition, since the second-order and higher-order harmonics are largely suppressed, when transmitting the modulated signal, The second-order and higher-order harmonics can be ignored, that is, when transmitting, the signal bandwidth of the modulated signal is the frequency difference between the frequencies corresponding to the two first-order harmonics. That is, if the signal amplitude values corresponding to each frequency component in the frequency spectrum of the modulated signal can satisfy the first modulation condition, it is equivalent to ensuring that the signal bandwidth of the modulated signal can satisfy the first data rate.

For example, the first modulation condition may include (2) and (3) in the above conditions, that is, the determined modulation index range must satisfy (2) and (3) at the same time, only in this way, from within the modulation index range The determined target modulation index can control the signal bandwidth of the finally obtained modulated signal to meet the first data rate.

Since the first modulation condition is about the numerical range of the signal amplitude value, the modulation index range can be determined according to the first modulation condition. When the first modulation conditions are different, it corresponds to different modulation index ranges. Therefore, the implementation manner of determining the target modulation index from the modulation index range satisfying the first modulation condition may be: according to the first modulation condition, obtain the corresponding modulation index from the stored correspondence between the modulation condition and the modulation index range range; after that, randomly select a modulation index from the acquired modulation index range as the target modulation index.

It should be noted that since the modulation index range is obtained from the corresponding relationship between the stored modulation conditions and the modulation index range, before obtaining the modulation index range, it is necessary to determine the number of different modulation index ranges based on different first modulation conditions. The correspondence between modulation conditions and modulation index ranges. Wherein, according to the first modulation condition, the corresponding relationship between the modulation condition and the range of the modulation index can be determined through the relationship between the modulation index in the Bessel function curve and the signal amplitude value of each frequency component.

Wherein, since the first modulation condition may include a plurality of conditions for limiting the signal amplitude values of the preset carrier and harmonics, the relationship between the modulation index and the signal amplitude values of each frequency component in the Bessel function curve may be , determine the corresponding modulation index range when each condition is satisfied, so as to obtain multiple modulation index ranges; then, determine the intersection of the determined multiple modulation index ranges as the modulation index range corresponding to the first modulation condition, and use the The first modulation condition and the determined modulation index range are stored in a correspondence between the modulation condition and the modulation index range.

Optionally, in order to save system resources of the signal modulation device, the modulation index range can also be determined directly through the Bessel function curve according to the first modulation condition, without storing the corresponding relationship between the modulation condition and the modulation index range .

Fig. 4B is the Bessel function curve provided by the embodiment of the present invention. Assuming that the current first modulation condition is that the second-order and higher-order harmonics are suppressed by more than 7dB, it can be seen from Fig. 4B that when the modulation index is 1 When the value is between 1.5 and 1.5, the difference between the signal amplitude value corresponding to the preset carrier and the signal amplitude value corresponding to the second-order harmonic is above 7dB. At this time, the modulation index range corresponding to the first modulation condition is 1 to 1.5.

Optionally, since the modulation index range is determined according to the first modulation condition, all modulation indices within the modulation index range can meet modulation requirements. The magnitude of the modulation index determines the magnitude of the frequency offset. The larger the modulation index, the larger the frequency offset. The true signal bandwidth of the modulated signal will be wider before harmonics and higher order harmonics are ignored. Therefore, in order to obtain the ideal real bandwidth of the modulated signal, the corresponding modulation index may also be selected from the acquired modulation indices as the target modulation index according to requirements.

Step 403: Determine a target subcarrier according to the target frequency difference and the target modulation index, and the target subcarrier is used to control the frequency of the preset carrier.

In the signal modulation process, since the frequency of the preset carrier is controlled by the target subcarrier, and in the frequency spectrum of the obtained modulated signal, each frequency component corresponds to the frequency of the preset carrier and the target subcarrier , therefore, after the target frequency difference and the target modulation index are determined, the target subcarrier can be determined according to the target frequency difference and the target modulation index; the target subcarrier can be determined according to the frequency and amplitude of the target subcarrier.

Wherein, according to the target frequency difference and the target modulation index, the implementation manner of determining the target subcarrier may be: according to the target frequency difference, the frequency of the target subcarrier is determined; according to the target frequency difference and the target modulation index, from the stored frequency difference, modulation index and In the corresponding relationship between the amplitude values, the corresponding amplitude value is acquired, and the acquired amplitude value is determined as the amplitude value of the target subcarrier.

In addition, by comparing the frequency spectrum and time-domain waveform of a single sine wave, a single sawtooth wave, and a sine wave superimposed by multiple integer multiple frequency sine waves, it is found that the sinusoidal signal composed of multiple integer multiple frequency sine waves superimposed The spectral bandwidth of is the narrowest. Therefore, the sinusoidal signal composed of multiple integer multiple frequency sinusoidal waves is selected as the target subcarrier, assuming that the time domain expression of the target subcarrier is A ₁ sin(ω _m t)+A ₂ sin(2ω _m t)+A ₃ sin(3ω _m t), where A ₁ , A ₂ and A ₃ are the amplitudes of the target subcarrier. According to the target frequency difference, the frequency of the target subcarrier is determined, that is, ω _m =2πf _m . Then, according to the determined frequency of the target subcarrier and the target modulation index, A ₁ , A ₂ and A ₃ are determined from the stored correspondence between the frequency difference, the modulation index and the amplitude value.

Since it is inconvenient to determine the amplitude value of the target subcarrier through multiple verifications in the real signal modulation process, before determining the amplitude value of the target subcarrier, multiple frequency differences, modulation index and For the corresponding relationship between the amplitude values, when performing signal modulation, the corresponding amplitude value can be directly selected according to the above implementation manner.

Wherein, the operation method of determining and storing the corresponding relationship among multiple frequency differences, modulation indices and amplitude values may be: through the relationship between the Bessel function and the modulation index, determine the range of the modulation index that satisfies the first modulation condition; According to the frequency of the target subcarrier, determine multiple modulation indices, the multiple modulation indices are the modulation indices obtained when the amplitude of the target subcarrier takes multiple different amplitude values; select the modulation within the range of the modulation index from the multiple modulation indices index; storing the target frequency difference, the selected modulation index, and the amplitude value corresponding to the selected modulation index in the correspondence between the frequency difference, the modulation index, and the amplitude value.

According to the relationship between the modulation index and the signal amplitude value of each frequency component in the Bessel function curve, the modulation index range can be determined by the first modulation condition; since the frequency of the target subcarrier has been determined, it is only necessary to determine the frequency of the target subcarrier amplitude value, the target subcarrier can be determined. After the modulation index is determined, multiple different amplitude values are taken for the amplitude of the target subcarrier to determine multiple target subcarriers; using the multiple target subcarriers, the same baseband digital signal is modulated by an analog method, and measured Obtain a plurality of modulation indices corresponding to the modulation by using the plurality of target subcarriers, select a modulation index within the modulation index range from the plurality of modulation indices, and then correspond the target frequency difference, the selected modulation index to the selected modulation index The amplitude value of is stored in the correspondence between frequency difference, modulation index, and amplitude value.

Furthermore, in the actual signal modulation process, subcarriers are often digitally coded. For the above-mentioned sinusoidal signal formed by superimposing sinusoidal waves with multiple integer multiples of frequency, a high oversampling clock is required when digitizing it. Not easy to achieve. Compared with sinusoidal signals and other shapes, triangular waves have better spectral characteristics. Considering the operability of digitizing subcarriers, triangular waves can also be selected when selecting the shape of target subcarriers.

FIG. 4C is a diagram of a triangle wave digitization process provided by this embodiment. As shown in FIG. 4C , when the shape of the target subcarrier is a triangle wave, firstly, the target subcarrier is controlled by a baseband digital signal. When the baseband digital signal sends 1, the target subcarrier itself is output; when the baseband digital signal sends 0, a straight line with an amplitude value of 0 is output. Afterwards, the target subcarrier obtained after the control is sampled and digitized through a digital phase-locked loop, and the digitized result shown in the last row is obtained through fast Fourier transform. Finally, by controlling the frequency of the preset carrier through the digitized triangle wave, the modulated signal corresponding to the baseband digital signal can be obtained.

In practical applications, when the transmitter shown in Figure 3 is used to transmit the signal, the baseband digital signal terminal 02 generates a baseband digital signal and inputs it to the gain control module 05, and the baseband digital signal controls the gate circuit in the gain control module 05 , and finally the digitized target subcarrier is output from the output terminal 05b of the gain control module 05 .

Step 404: Modulate the baseband digital signal according to the preset carrier and the target subcarrier.

After the target sub-carrier is determined, the frequency of the preset carrier is controlled through the target sub-carrier, wherein, referring to Figure 4C, when the baseband digital signal is sent 1, the frequency of the preset carrier is controlled through the determined target sub-carrier , which is equivalent to outputting an FM wave. When the baseband digital signal sends 0, the frequency of the preset carrier remains unchanged, that is, the preset carrier itself is output.

Based on the description of steps 401-403, since the target subcarrier is determined by the expected data rate of the modulated signal and the first modulation condition, the frequency of the preset carrier is controlled by the target subcarrier, and the output The modulated signal of is the desired modulated signal.

In the actual signal modulation process, when the signal modulation method provided by the embodiment of the present invention is used to transmit the signal through the transmitter shown in Figure 3, the baseband digital signal is directly added to the gain control module 05, when the baseband digital signal is sent 1 , the target subcarrier remains unchanged, and when the baseband digital signal sends 0, the amplitude and frequency are both 0. Afterwards, the above-mentioned modulated digitized target subcarrier is output by the gain control module 05 . The digitized target subcarrier enters the numerically controlled/voltage controlled oscillator 13, and modulates the frequency of the preset carrier wave generated by the numerically controlled/voltage controlled oscillator 13, and the modulated signal obtained after modulation is output through the constant envelope power amplifier 06, Thus, a modulated signal with a constant envelope is obtained.

To sum up, in the embodiment of the present invention, the first data rate is determined according to user requirements, that is, after the baseband digital signal is modulated, it is expected to achieve a data rate that can meet user requirements. In addition, the first modulation condition is a condition that the desired modulated signal needs to satisfy. Assuming that the modulated signal satisfies the first modulation condition, the signal bandwidth of the modulated signal will be limited within a narrow range. Therefore, Determine the target subcarrier used to control the preset carrier frequency in the modulation process according to the first data rate and the first modulation condition, so as to modulate the frequency of the preset carrier to obtain the desired modulated signal with a smaller bandwidth , that is, the signal modulation method according to the embodiment of the present invention modulates the signal, and the signal bandwidth of the modulated signal can be controlled within a narrow range as required, thereby effectively improving the spectrum efficiency. In addition, since the signal modulation method provided by the embodiment of the present invention controls the frequency of the preset carrier when the baseband digital signal is transmitted as 1, and outputs the preset carrier itself when the baseband digital signal is transmitted as 0, the obtained The modulated signal is equivalent to the combination of FM wave and OOK wave, which not only has the advantages of simple OOK implementation and low power consumption, but also has the advantage of good FM anti-noise performance.

FIG. 5 is a block diagram of a signal modulation device according to an exemplary embodiment. Referring to FIG. 5 , the signal modulation device includes: a processing module 501 .

Wherein, the processing module 501 is configured to execute step 401-step 404 in the above-mentioned embodiment.

Optionally, the processing module 501 is also used for:

Acquiring the corresponding modulation index range from the stored correspondence between the modulation condition and the modulation index range according to the first modulation condition;

Randomly select a modulation index from the acquired modulation index range as the target modulation index.

Optionally, the processing module 501 is also used for:

determining the frequency of the target subcarrier according to the target frequency difference;

determining the amplitude value of the target subcarrier according to the target frequency difference and the target modulation index;

The target subcarrier is determined according to the frequency and amplitude values of the target subcarrier.

Optionally, the processing module 501 is also used for:

According to the target frequency difference and the target modulation index, the corresponding amplitude value is obtained from the stored correspondence between the frequency difference, the modulation index, and the amplitude value;

The obtained amplitude value is determined as the amplitude value of the target subcarrier.

Optionally, the processing module 501 is also used for:

Determining the range of the modulation index satisfying the first modulation condition through the relationship between the Bessel function and the modulation index;

According to the frequency of the target subcarrier, determine a plurality of modulation indices, the plurality of modulation indices are the modulation indices obtained when the amplitude of the target subcarrier takes a plurality of different amplitude values;

selecting a modulation index within a range of modulation indices from a plurality of modulation indices;

The target frequency difference, the selected modulation index, and the amplitude value corresponding to the selected modulation index are stored in the correspondence between the frequency difference, the modulation index, and the amplitude value.

It should be noted that the first modulation condition includes at least one of the following conditions:

The amplitude difference between the signal amplitude value of the preset carrier in the first signal spectrum and the signal amplitude value in the second signal spectrum is greater than the first value, and the first signal spectrum is the modulated signal expected to be obtained when the baseband digital signal is sent 1 Spectrum, the spectrum of the second signal is the spectrum of the modulated signal expected to be obtained when the baseband digital signal sends 0;

the difference between the signal amplitude value of the first order harmonic in the first signal spectrum and the signal amplitude value in the second signal spectrum is less than a second value;

The signal amplitude values of the second order harmonic and its higher order harmonics in the spectrum of the first signal are suppressed by a third value compared to the signal amplitude values in the spectrum of the second signal.

In the embodiment of the present invention, the first data rate is determined according to the user's requirement, that is, after the baseband digital signal is modulated, the expected data rate can meet the user's requirement. In addition, the first modulation condition is formulated, which is the condition that the modulated signal that is expected to be obtained needs to be satisfied. Assuming that the modulated signal satisfies the first modulation condition, the signal bandwidth of the modulated signal will be limited to a relatively small Within a narrow range, therefore, according to the first data rate and the first modulation condition, the target subcarrier used to control the preset carrier frequency in the modulation process is determined, so as to modulate the frequency of the preset carrier, and the expected obtained , the modulated signal with a smaller bandwidth, that is, the signal modulation method according to the embodiment of the present invention modulates the signal, and the signal bandwidth of the modulated signal can be controlled within a narrow range according to the requirement, thereby effectively improving Spectral efficiency. In addition, since the signal modulation method provided by the embodiment of the present invention controls the frequency of the preset carrier when the baseband digital signal is transmitted as 1, and outputs the preset carrier itself when the baseband digital signal is transmitted as 0, the obtained The modulated signal is equivalent to the combination of FM wave and OOK wave, which not only has the advantages of simple OOK implementation and low power consumption, but also has the advantage of good FM anti-noise performance.

It should be noted that: when the signal modulation device provided in the above-mentioned embodiment modulates the baseband digital signal, the division of the above-mentioned functional modules is used as an example for illustration. In practical applications, the above-mentioned functions can be assigned to different functions according to needs Module completion means that the internal structure of the device is divided into different functional modules to complete all or part of the functions described above. In addition, the signal modulation device and the signal modulation method embodiment provided by the above embodiment belong to the same concept, and the specific implementation process thereof is detailed in the method embodiment, and will not be repeated here.

Those of ordinary skill in the art may understand that all or part of the steps for implementing the above embodiments may be implemented by hardware. The processing module 501 described in FIG. 5 may be implemented by a processor. The signal modulating means may also include a memory, which may be used to store program codes and data. Various components in the signal modulation device are coupled together to implement the signal modulation method involved in the embodiment as described in FIGS. 4A-4C . All or part of the steps in the above embodiments can also be completed by instructing related hardware through a program, and the program can be stored in a computer-readable storage medium, and the above-mentioned storage medium can be a read-only memory, a magnetic disk or an optical disk Wait.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection of the present invention. within range.

Claims (12)

1. A signal modulation method, characterized in that the method comprises: Determine the target frequency difference when the baseband digital signal is carried by the preset carrier according to the first data rate, the first data rate is a data rate that can be achieved by the modulated signal that is expected to be obtained, and the target frequency difference is the desired obtained one. the difference between the frequency of said predetermined carrier and the frequency of the first order harmonic in the frequency spectrum of the modulated signal; determining a target modulation index from a modulation index range satisfying a first modulation condition, where the target modulation index is used to control the bandwidth of the modulated signal expected to be obtained; determining a target subcarrier according to the target frequency difference and the target modulation index, where the target subcarrier is used to control the frequency of the preset carrier; The baseband digital signal is modulated according to the preset carrier and the target subcarrier. 2. The method according to claim 1, wherein the determining the target modulation index from the modulation index range satisfying the first modulation condition comprises: Acquiring the modulation index range from the stored correspondence between the modulation condition and the modulation index range according to the first modulation condition; Randomly select a modulation index from the acquired modulation index range as the target modulation index. 3. The method according to claim 1 or 2, wherein said determining a target subcarrier according to said target frequency difference and said target modulation index comprises: determining the frequency of the target subcarrier according to the target frequency difference; determining an amplitude value of the target subcarrier according to the target frequency difference and the target modulation index; The target subcarrier is determined according to the frequency and amplitude values of the target subcarrier. 4. The method according to claim 3, wherein the determining the amplitude value of the target subcarrier according to the target frequency difference and the target modulation index comprises: Acquiring a corresponding amplitude value from the stored correspondence between the frequency difference, modulation index, and amplitude value according to the target frequency difference and the target modulation index; and determining the obtained amplitude value as the amplitude value of the target subcarrier. 5. The method according to claim 4, wherein, according to the target frequency difference and the target modulation index, from the stored correspondence between the frequency difference, modulation index and amplitude value, the corresponding Before the amplitude value, also include: determining a modulation index range that satisfies the first modulation condition through the relationship between the Bessel function and the modulation index; Determine multiple modulation indices according to the frequency of the target subcarrier, where the multiple modulation indices are modulation indices obtained when the amplitude of the target subcarrier takes multiple different amplitude values; selecting a modulation index within the range of modulation indices from the plurality of modulation indices; The target frequency difference, the selected modulation index, and the amplitude value corresponding to the selected modulation index are stored in the correspondence between the frequency difference, the modulation index, and the amplitude value. 6. The method according to any one of claims 1-5, wherein the first modulation condition comprises at least one of the following conditions: The difference between the signal amplitude value of the preset carrier in the first signal spectrum and the signal amplitude value in the second signal spectrum is greater than the first value, and the first signal spectrum is the expected value when the baseband digital signal sends 1 The spectrum of the modulated signal obtained, the spectrum of the second signal is the spectrum of the modulated signal expected to be obtained when the baseband digital signal sends 0; the difference between the signal amplitude value of the first order harmonic in the first signal spectrum and the signal amplitude value in the second signal spectrum is less than a second value; Signal amplitude values of second order harmonics and higher order harmonics in the first signal spectrum are suppressed by a third value compared to signal amplitude values in the second signal spectrum. 7. A signal modulation device, characterized in that the device comprises: A processing module, configured to determine a target frequency difference when a baseband digital signal is carried by a preset carrier according to a first data rate, the first data rate is a data rate expected to be achieved by the modulated signal, and the target frequency difference is The difference between the frequency of the preset carrier and the frequency of the first-order harmonic in the spectrum of the expected modulated signal; The processing module is further configured to determine a target modulation index from a range of modulation indices satisfying the first modulation condition, where the target modulation index is used to control the bandwidth of the expected modulated signal; The processing module is further configured to determine a target subcarrier according to the target frequency difference and the target modulation index, and the target subcarrier is used to control the frequency of the preset carrier; The processing module is further configured to modulate the baseband digital signal according to the preset carrier and the target subcarrier. 8. The device according to claim 7, wherein the processing module is also used for: Acquiring the corresponding modulation index range from the stored correspondence between the modulation condition and the modulation index range according to the first modulation condition; A modulation index is randomly selected from the acquired modulation index range as the target modulation index. 9. The device according to claim 7 or 8, wherein the processing module is further used for: determining the frequency of the target subcarrier according to the target frequency difference; determining an amplitude value of the target subcarrier according to the target frequency difference and the target modulation index; The target subcarrier is determined according to the frequency and amplitude values of the target subcarrier. 10. The device according to claim 9, wherein the processing module is further used for: Acquiring a corresponding amplitude value from the stored correspondence between the frequency difference, modulation index, and amplitude value according to the target frequency difference and the target modulation index; and determining the obtained amplitude value as the amplitude value of the target subcarrier. 11. The device according to claim 10, wherein the processing module is also used for: determining a modulation index range that satisfies the first modulation condition through the relationship between the Bessel function and the modulation index; Determine multiple modulation indices according to the frequency of the target subcarrier, where the multiple modulation indices are modulation indices obtained when the amplitude of the target subcarrier takes multiple different amplitude values; selecting a modulation index within the range of modulation indices from the plurality of modulation indices; The target frequency difference, the selected modulation index, and the amplitude value corresponding to the selected modulation index are stored in the correspondence between the frequency difference, the modulation index, and the amplitude value. 12. The device according to any one of claims 7-11, wherein the first modulation condition includes at least one of the following conditions: The difference between the signal amplitude value of the preset carrier in the first signal spectrum and the signal amplitude value in the second signal spectrum is greater than the first value, and the first signal spectrum is the expected value when the baseband digital signal sends 1 The spectrum of the modulated signal obtained, the spectrum of the second signal is the spectrum of the modulated signal expected to be obtained when the baseband digital signal sends 0; the difference between the signal amplitude value of the first order harmonic in the first signal spectrum and the signal amplitude value in the second signal spectrum is less than a second value; Signal amplitude values of second order harmonics and higher order harmonics in the first signal spectrum are suppressed by a third value compared to signal amplitude values in the second signal spectrum.