CN109004930B - Circuit system for directly demodulating frequency modulation signal based on phase-locked loop and control method - Google Patents
Circuit system for directly demodulating frequency modulation signal based on phase-locked loop and control method Download PDFInfo
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03L—AUTOMATIC CONTROL, STARTING, SYNCHRONISATION OR STABILISATION OF GENERATORS OF ELECTRONIC OSCILLATIONS OR PULSES
- H03L7/00—Automatic control of frequency or phase; Synchronisation
- H03L7/06—Automatic control of frequency or phase; Synchronisation using a reference signal applied to a frequency- or phase-locked loop
- H03L7/08—Details of the phase-locked loop
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- H—ELECTRICITY
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Abstract
The invention provides a circuit system and a control method for directly demodulating a frequency modulation signal based on a phase-locked loop, wherein the system comprises: an amplifying module for amplifying the input radio frequency signal; the phase/frequency discrimination module is used for acquiring the frequency difference and the phase difference of the local oscillator and the amplified radio frequency signal; the frequency band limiting module is connected with the phase discrimination/frequency discrimination module to limit the bandwidth according to the frequency difference and the phase difference and amplify the bandwidth; the controllable gain amplifying module is used for adjusting the amplitude of the output signal of the frequency band limiting module in a controllable mode; the frequency synthesizer module with controllable frequency is connected with the controllable gain amplifying module and the frequency/phase discrimination module, and generates corresponding frequency change according to the frequency difference and the phase difference signal after gain adjustment so as to carry out frequency adjustment and tracking. The system has the advantages of capability of carrying out carrier frequency tracking and carrier error elimination on the basis of realizing conventional frequency shift keying demodulation, simple structure, low power consumption and strong performance.
Description
Technical Field
The invention relates to the technical field of frequency demodulation, in particular to a circuit system and a control method for directly demodulating a frequency modulation signal based on a phase-locked loop.
Background
With the development of wireless communication systems, conventional Frequency modulation signals such as BFSK (Binary Frequency-shift keying), MSK (Minimum-SHIFT KEYING, minimum Frequency-shift keying), GFSK (gaussian Frequency-shift keying) and the like are difficult to bring about significant performance improvement to the communication system. The most original BFSK communication mode provides the simplest system structure, the more complex MSK and GFSK provide better frequency spectrum occupancy rate, but as a new modulation mode enters the bottleneck, the system structure is gradually solidified, and the system performance is difficult to be improved.
The existing system mainly comprises a primary down-conversion receiver (zero intermediate frequency receiver) and a secondary down-conversion receiver, and has larger limitation on a circuit structure, namely, a main core module cannot be reduced, power consumption cannot be reduced continuously, and the structure cannot be simplified continuously. With the gradual development of wireless communication systems, conventional frequency modulation signals such as BFSK use two frequencies to represent whether to transmit 1 or 0; MSK changes the frequency when the signal crosses zero, keep the phase place continuous; GFSK uses gaussian envelopes and the like on the basis of MSK, and it is difficult to bring about significant performance improvement to a communication system. The most original BFSK communication mode provides the simplest system structure, the more complex MSK and GFSK provide better frequency spectrum occupancy rate, but as a new modulation mode enters the bottleneck, the system structure is gradually solidified, and the system performance is difficult to be improved.
The main stream receiver mainly comprises three parts of pre-amplifying, down-converting and signal demodulating. The power consumption of the pre-amplifying and down-converting part cannot be reduced due to the fact that the radio frequency amplifying module and the local oscillator are used. Whereas the signal demodulation part usually requires a high-performance analog-to-digital converter or frequency demodulator to convert the signal into a binary level signal, the power consumption is still high.
Disclosure of Invention
The present invention aims to solve at least one of the technical problems in the related art to some extent.
Therefore, the invention aims to provide a circuit system for directly demodulating a frequency modulation signal based on a phase-locked loop, which can carry out carrier frequency tracking and carrier error elimination, eliminates an analog-to-digital converter or a frequency demodulator, and simultaneously still provides frequency demodulation output.
To achieve the above object, the present invention provides a circuit system for directly demodulating a frequency modulation signal based on a phase-locked loop, comprising: a radio frequency amplifying module for amplifying the input radio frequency signal; the phase/frequency discrimination module is connected with the radio frequency amplifying module and the frequency synthesizer module with controllable frequency to obtain the frequency difference and the phase difference of signals generated by the radio frequency amplifying module and the frequency synthesizer module with controllable frequency; the frequency band limiting module is connected with the frequency/phase discrimination module to limit the bandwidths of the frequency difference and phase difference signals; the controllable gain amplifying module is connected with the frequency band limiting module to linearly amplify the bandwidth limiting signal representing the frequency difference and the phase difference; the frequency synthesizer module is connected with the controllable gain amplifying module and the frequency/phase discrimination module, receives the signals representing the frequency difference and the phase difference, and controls the output frequency according to the signals so as to realize the adjustment and tracking of the frequency and carry out frequency negative feedback.
The circuit system based on the phase-locked loop for directly demodulating the frequency modulation signal acquires the frequency difference and the phase difference of the frequency-controllable frequency synthesizer module and the radio frequency signal amplified by the radio frequency amplifying module through the frequency discrimination/phase discrimination module, limits the frequency bandwidth and amplifies the frequency difference through the frequency band limiting module and the controllable gain amplifying module, generates corresponding frequency change according to the frequency difference and the phase difference of the two signals so as to carry out frequency adjustment and tracking, and achieves the aims of carrying out carrier frequency tracking and carrier error elimination on the basis of realizing conventional frequency shift keying demodulation.
Further, in an embodiment of the present invention, the frequency synthesizer module is a frequency controllable oscillator, a frequency controllable signal generator or other form of signal source whose frequency can be controlled by a signal.
Further, in an embodiment of the present invention, the phase/frequency discrimination module is a circuit module or unit that generates a specific form of output according to a frequency difference and a phase difference of two signals connected to the frequency controllable frequency synthesizer module and the radio frequency amplifying module. The frequency difference and the phase difference of the output signal and the two signals have a specific linear or non-linear relationship, and this relationship needs to be monotonic, i.e. when the phase difference or the frequency difference absolute value is large, the absolute value of the amplitude of the generated output signal needs to be not lower than when the phase difference or the frequency difference absolute value is small.
Further, in an embodiment of the present invention, the band limiting module is a low pass filter with a bandwidth higher than a loop bandwidth of the circuitry for directly demodulating the frequency modulated signal based on the phase locked loop.
Further, in one embodiment of the present invention, the controllable gain amplifying module is an amplifier capable of adjusting the amplification of the input signal and the output signal, wherein the amplitude of the output signal is a specific multiple of the amplitude of the input signal, and the multiple is adjustable.
Further, in an embodiment of the present invention, the rf amplifying module is an amplifier operating in an rf band, and amplifies a signal linearly.
Further, in one embodiment of the present invention, the method further includes: and the acquisition module is used for acquiring a signal at the output end of the controllable gain amplification module as the output of system demodulation, wherein the signal can be voltage or current.
Further, in an embodiment of the present invention, the signal generated by the phase/frequency discrimination module may be a voltage or a current.
Further, in one embodiment of the present invention, the monotonicity of the output of the phase/frequency discrimination module can be achieved in two ways:
Digital implementation mode: in the two signals, the signal output by the radio frequency amplification module gives a high level when the phase is advanced, and gives a low level when the phase is lagged; or vice versa.
Simulation implementation mode: when the phase of the output signal of the radio frequency amplification module is advanced, positive voltage or current is given out, the larger the phase difference is, the larger the amplitude of the voltage or current is, and when the phase of the output signal of the radio frequency amplification module is lagged, negative voltage or current is given out, and the larger the phase difference is, the larger the amplitude of the voltage or current is; or vice versa.
Another object of the present invention is to provide a control method of a circuit system for directly demodulating a frequency modulation signal based on a phase-locked loop, comprising the following steps: amplifying an input radio frequency signal; acquiring the frequency difference and the phase difference of the local oscillator and the amplified radio frequency signal; limiting a bandwidth according to the frequency difference and the phase difference; amplifying the controllable and adjustable gain according to the frequency difference and the phase difference signals subjected to bandwidth limitation; and generating corresponding frequency change according to the frequency difference and the phase difference after the gain amplification which are subjected to the frequency band limitation and the controllable and adjustable so as to carry out frequency adjustment and tracking.
Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Drawings
The foregoing and/or additional aspects and advantages of the invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings, in which:
FIG. 1 is a schematic diagram of a conventional once down-conversion receiver system;
fig. 2 is a schematic diagram of a receiver capable of distinguishing and demodulating BFSK and GFSK signals;
Fig. 3 is a schematic diagram of a control system of a circuit system for directly demodulating a frequency modulation signal based on a phase-locked loop according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of a modulation scheme for debugging BFSK signals according to one embodiment of the present invention;
FIG. 5 is a schematic diagram of signal waveforms observed at the output of a low pass filter for debugging a BFSK signal in accordance with one embodiment of the present invention; and
Fig. 6 is a flow chart of a control method of a circuit system for directly demodulating a frequency modulated signal based on a phase locked loop according to an embodiment of the present invention.
Detailed Description
Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to like or similar elements or elements having like or similar functions throughout. The embodiments described below by referring to the drawings are illustrative and intended to explain the present invention and should not be construed as limiting the invention.
First, before describing the circuit system for directly demodulating a frequency modulation signal based on a phase-locked loop according to the embodiment of the present invention, a digital demodulation receiver and an analog demodulation receiver for demodulating a frequency modulation signal, which are commonly known in the related art, will be described. Fig. 1 is a schematic diagram of a conventional once down-conversion digital demodulation receiver system, in which, as shown in fig. 1, a signal is input from a left amplifier, converted to a low frequency by a mixer, amplified by a low frequency amplifier again, converted into a digital signal by an analog-to-digital converter, and processed by a digital filter to obtain a modulated baseband signal.
However, when the frequency conversion receiver works, when carrier deviation exists between the receiver and the transmitter, the down-conversion result of the mixer is inaccurate, so that after the analog-to-digital converter is adopted, the center frequency point of the digital filter is different from the center frequency point of each down-converted signal, and effective demodulation cannot be realized.
Furthermore, the frequency conversion receiver has a simple structure, but still needs local oscillation signal generation, needs manual adjustment of the local oscillation signal to synchronize with the transmitter, and is troublesome because the local oscillation signal is only appointed in advance in actual use. And when there is a deviation in the system, it cannot be automatically adjusted.
Fig. 2 is a schematic diagram of an analog demodulation receiver capable of distinguishing and demodulating BFSK and GFSK signals, as shown in fig. 2: after the signal is amplified, mixed and amplified again, the frequency information of the signal is extracted through the frequency discriminator, and the signal amplitude after passing through the module can be understood to represent the frequency of the signal, and then the frequency information is translated into a digital signal through the analog-to-digital converter. The digital signal passes through a matched filter of square waves and Gaussian waves to obtain two paths of output. For comparison, the use of a digital filter in fig. 1 yields a signal representing frequency information; the analog circuit module in fig. 2 directly generates the signal, and the signal is converted into a digital signal by an analog-to-digital converter and then directly output. The filter connected after the analog-to-digital converter in fig. 2 is only used for distinguishing between different modulation modes, and can be omitted when the modulation modes do not need to be distinguished. In fig. 2, output 1 corresponds to the square wave matched filter, and when output 1 is effective, the frequency change of the received signal is similar to a square wave, and is more similar to the BFSK signal; when output 2 is active, this indicates that the frequency of the received signal varies more closely to GFSK, like a gaussian wave. And simultaneously observing the output 1 and the output 2, the current received signal is BFSK or GFSK signal can be obtained by comparison, and meanwhile, the 0/1 code stream (i.e. the demodulated signal) of the signal can be obtained. However, the receiver cannot provide automatic carrier tracking, and performance degradation may still occur when the local frequencies of the transmitter and the receiver are different, and the configuration is complex. However, since the architecture of fig. 2 uses circuit blocks to directly perform frequency demodulation, the performance of the analog-to-digital converter in the circuitry can be relaxed appropriately, thereby reducing the stress of the system design compared to 1.
The present invention is based on the above-mentioned problems, and provides a circuit system for directly demodulating a frequency modulation signal based on a phase-locked loop.
The following describes a circuit system and a method for directly demodulating a frequency modulation signal based on a phase-locked loop according to an embodiment of the present invention with reference to the accompanying drawings.
Fig. 3 is a schematic diagram of circuitry for directly demodulating a frequency modulated signal based on a phase locked loop according to an embodiment of the present invention.
As shown in fig. 3, the circuitry 10 for directly demodulating a frequency modulated signal based on a phase locked loop includes: a radio frequency amplification module 100, a phase/frequency discrimination module 200, a band limiting module 300, a controllable gain amplification module 400 and a frequency synthesizer module 500 with controllable frequency.
A radio frequency amplifying module 100 amplifying an inputted radio frequency signal.
In one embodiment of the present invention, the rf amplifying module 100 is an amplifier operating in the rf band, and amplifies signals linearly.
The phase/frequency discrimination module 200 is connected with the radio frequency amplifying module and the frequency controllable synthesizer module to obtain the frequency difference and the phase difference of the local oscillator and the amplified radio frequency signal.
In one embodiment of the present invention, the phase/frequency discrimination module 200 is a circuit module or unit that generates a specific form of output according to the frequency difference and the phase difference of two signals accessed by the connected frequency controllable frequency synthesizer module and the radio frequency amplifying module. The frequency difference and the phase difference of the output signal and the two signals have a specific linear or non-linear relationship, and this relationship needs to be monotonic, i.e. when the phase difference or the frequency difference absolute value is large, the absolute value of the amplitude of the generated output signal needs to be not lower than when the phase difference or the frequency difference absolute value is small.
In one embodiment of the present invention, the signal generated by the phase/frequency discrimination module 200 may be either a voltage or a current.
In one embodiment of the present invention, the monotonicity of the output of the phase/frequency discrimination module 200 can be achieved in two ways: digital implementation mode: in the two signals, the signal output by the radio frequency amplification module gives a high level when the phase is advanced, and gives a low level when the phase is lagged; or vice versa. Simulation implementation mode: when the phase of the output signal of the radio frequency amplification module is advanced, positive voltage or current is given out, the larger the phase difference is, the larger the amplitude of the voltage or current is, and when the phase of the output signal of the radio frequency amplification module is lagged, negative voltage or current is given out, and the larger the phase difference is, the larger the amplitude of the voltage or current is; or vice versa.
In one embodiment of the present invention, the output of the phase/frequency discrimination module 200 is in the form of a voltage with an adjustable or predefined common mode voltage to assist in the circuit design of the subsequent modules.
Specifically, in another embodiment of the present invention, the phase/frequency discrimination module 200 may be a frequency discriminator and/or a phase discriminator. When a frequency discriminator is used in the above circuit, positive feedback may be caused, resulting in failure to establish stable frequency negative feedback. However, this problem can be avoided by using a phase detector, so in the above-described circuit configuration, only the phase detector may be used; and the frequency discriminator can be started when the frequency difference is large (for example, when the frequency difference is just started), and the phase discriminator is started after the feedback loop is gradually established. In summary, the loop can automatically establish negative feedback to reach equilibrium under the set structure.
The band limiting module 300, the band limiting module 300 is connected with the phase/frequency discrimination module 200 to limit the bandwidth according to the frequency difference and the phase difference.
In one embodiment of the invention, band limiting module 300 is a low pass filter with a bandwidth higher than the loop bandwidth of circuitry based on phase locked loops to directly demodulate frequency modulated signals.
The controllable gain amplifying module 400, the controllable gain amplifying module 100 is connected 300 with the band limiting module to amplify the controllable and adjustable gain according to the frequency difference and the phase difference signal after the bandwidth limitation.
In one embodiment of the present invention, the controllable gain amplification module 400 is an amplifier that can adjust the amplification of an input signal and an output signal, wherein the amplitude of the output signal is a specific multiple of the amplitude of the input signal, and this multiple can be adjusted.
The frequency synthesizer module 500 with controllable frequency, the frequency synthesizer module 500 with controllable gain amplifying module 400 and phase/frequency discrimination module 200 are connected to generate corresponding frequency variation according to the frequency difference and the phase difference after the frequency band limitation and the controllable and adjustable gain amplification, so as to perform frequency adjustment and tracking.
In one embodiment of the invention, the frequency synthesizer module 500 is a frequency controllable oscillator, a frequency controllable signal generator or other form of signal source whose frequency can be controlled by a signal.
Specifically, in one embodiment of the present invention, as shown in fig. 4 and 5, when modulating the BFSK signal (assuming that the signal to be transmitted is 1011), the procedure is as follows: when there is a frequency offset between the transmitter and the receiver, and the frequency offset is within a certain range, a signal behavior proportional to (or having some relation to) the frequency offset is observed at the low-pass filter output. Meanwhile, after the frequency deviation is tracked, this phenomenon disappears. That is, when a frequency offset is suddenly generated, the output of the low-pass filter changes accordingly, and there is a short "output disable" time.
It will be appreciated that the linearity of the local oscillator determines the linearity of the frequency discrimination, which greatly simplifies the design of the frequency discriminator and greatly improves the linearity (for digitally controllable oscillators, the chirp profile is easier to obtain).
The circuit system based on the phase-locked loop for directly demodulating the frequency modulation signal acquires the frequency difference and the phase difference of the frequency-controllable frequency synthesizer module and the radio frequency signal amplified by the radio frequency amplifying module through the frequency discrimination/phase discrimination module, limits the frequency bandwidth and amplifies the frequency difference through the frequency band limiting module and the controllable gain amplifying module, generates corresponding frequency change according to the frequency difference and the phase difference of the two signals so as to carry out frequency adjustment and tracking, and achieves the aims of carrying out carrier frequency tracking and carrier error elimination on the basis of realizing conventional frequency shift keying demodulation.
Next, a control method of a circuit system for directly demodulating a frequency modulation signal based on a phase-locked loop according to an embodiment of the present invention will be described with reference to the accompanying drawings.
Fig. 6 is a flowchart of a control method of a circuit system method for directly demodulating a frequency modulation signal based on a phase locked loop according to an embodiment of the present invention.
As shown in fig. 6, the control method of the circuit system for directly demodulating the frequency modulation signal based on the phase-locked loop includes the following steps: s101, amplifying an input radio frequency signal; s102, obtaining the frequency difference and the phase difference of a local oscillator and the amplified radio frequency signals; s103, limiting the bandwidth according to the frequency difference and the phase difference; s104, a controllable gain amplifying module, which is connected with the band limiting module to amplify the controllable and adjustable gain according to the frequency difference and the phase difference signal which are subjected to the bandwidth limitation; s105, a frequency synthesizer module with controllable frequency is connected with the controllable gain amplifying module and the phase/frequency discrimination module to generate corresponding frequency change according to the frequency difference and the phase difference after the frequency band limitation and the controllable and adjustable gain amplification so as to carry out frequency adjustment and tracking.
It should be noted that the foregoing explanation of the embodiment of the circuit system for directly demodulating the frequency modulation signal based on the phase-locked loop is also applicable to the control method of this embodiment, and will not be repeated here.
According to the control method of the circuit system based on the phase-locked loop direct demodulation frequency modulation signal, the frequency difference and the phase difference of the local oscillator and the amplified radio frequency signal are obtained and amplified, and corresponding frequency changes are generated according to the frequency difference and the phase difference, so that frequency adjustment and tracking are performed, the purposes of carrier frequency tracking and carrier error elimination are achieved on the basis of conventional frequency shift keying demodulation, and the control method is simple in structure, low in power consumption and high in performance.
In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings are merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the device or element being referred to must have a specific orientation, be configured and operated in a specific orientation, and therefore should not be construed as limiting the present invention.
Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In the description of the present invention, the meaning of "plurality" means at least two, for example, two, three, etc., unless specifically defined otherwise.
In the present invention, unless explicitly specified and limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; either directly or indirectly, through intermediaries, or both, may be in communication with each other or in interaction with each other, unless expressly defined otherwise. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.
In the present invention, unless expressly stated or limited otherwise, a first feature "up" or "down" a second feature may be the first and second features in direct contact, or the first and second features in indirect contact via an intervening medium. Moreover, a first feature being "above," "over" and "on" a second feature may be a first feature being directly above or obliquely above the second feature, or simply indicating that the first feature is level higher than the second feature. The first feature being "under", "below" and "beneath" the second feature may be the first feature being directly under or obliquely below the second feature, or simply indicating that the first feature is less level than the second feature.
In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, the different embodiments or examples described in this specification and the features of the different embodiments or examples may be combined and combined by those skilled in the art without contradiction.
While embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and not to be construed as limiting the invention, and that variations, modifications, alternatives and variations may be made to the above embodiments by one of ordinary skill in the art within the scope of the invention.
Claims (8)
1. A circuitry for directly demodulating a frequency modulated signal based on a phase locked loop, comprising:
the radio frequency amplifying module is used for amplifying the input radio frequency signals;
The phase/frequency discrimination module is connected with the radio frequency amplification module to acquire the frequency difference and the phase difference of the local oscillator and the amplified radio frequency signal;
The frequency band limiting module is connected with the phase/frequency discrimination module to limit the bandwidth according to the frequency difference and the phase difference;
The controllable gain amplification module is connected with the frequency band limiting module to perform controllable and adjustable gain amplification according to the signals of the frequency difference and the phase difference subjected to bandwidth limitation; and
The frequency synthesizer module is connected with the controllable gain amplifying module and the phase/frequency discrimination module respectively, so as to generate corresponding frequency change according to the frequency difference and the phase difference after the frequency band limitation and the controllable and adjustable gain amplification, and carry out frequency adjustment and tracking;
The phase/frequency discrimination module is a circuit module or a unit for generating specific output according to the frequency difference and the phase difference of two signals connected with the frequency-controllable frequency synthesizer module and the radio frequency amplification module, the frequency difference and the phase difference of the output signals and the two signals have specific linear or nonlinear relation, the relation needs to be monotonous, and when the absolute value of the phase difference or the frequency difference is larger, the absolute value of the amplitude of the generated output signals needs to be not lower than the absolute value when the absolute value of the phase difference or the frequency difference is smaller;
wherein, the monotonicity of the output of the phase/frequency discrimination module is realized by two modes:
digital implementation mode: in the two signals, the signal output by the radio frequency amplification module gives a high level when the phase is advanced, and gives a low level when the phase is lagged; or vice versa;
Simulation implementation mode: when the phase of the output signal of the radio frequency amplification module is advanced, positive voltage or current is given out, the larger the phase difference is, the larger the amplitude of the voltage or current is, and when the phase of the output signal of the radio frequency amplification module is lagged, negative voltage or current is given out, and the larger the phase difference is, the larger the amplitude of the voltage or current is; or vice versa.
2. The phase locked loop direct demodulation frequency modulated signal based circuit system of claim 1 wherein the frequency controllable frequency synthesizer module is a frequency controllable oscillator, a frequency controllable signal generator or a signal source controlled by a signal.
3. The pll-based direct-demodulation frequency modulated signal circuitry of claim 1 wherein the band limiting module is a low pass filter having a bandwidth higher than a loop bandwidth of the pll-based direct-demodulation frequency modulated signal circuitry.
4. The circuitry for direct demodulation of a frequency modulated signal based on a phase locked loop of claim 1 wherein the controllable gain amplification module is an amplifier that adjusts the amplification of the input signal and the output signal, wherein the amplitude of the output signal is a preset multiple of the amplitude of the input signal.
5. The circuitry for directly demodulating a frequency modulated signal based on a phase locked loop as claimed in claim 1, wherein said rf amplifying module is an amplifier operating in an rf band for linear amplification of the signal.
6. The phase locked loop direct demodulation frequency modulated signal based circuitry of claim 1 further comprising:
The acquisition module is used for acquiring signals at the output end of the controllable gain amplification module, the signals are used as output of system demodulation, and the signals are voltages or currents.
7. The circuitry for directly demodulating a frequency modulated signal based on a phase locked loop according to claim 1, wherein the signal generated by the phase/frequency discrimination module is a voltage or a current.
8. A control method of a circuit system for directly demodulating a frequency modulated signal based on a phase locked loop, characterized in that the circuit system for directly demodulating a frequency modulated signal based on a phase locked loop according to any one of claims 1 to 7 is used, wherein the method comprises the steps of:
Amplifying an input radio frequency signal;
acquiring the frequency difference and the phase difference of the local oscillator and the amplified radio frequency signal;
limiting a bandwidth according to the frequency difference and the phase difference;
Amplifying the controllable and adjustable gain according to the frequency difference and the phase difference signals subjected to bandwidth limitation; and
And generating corresponding frequency change according to the frequency difference and the phase difference after the gain amplification which are subjected to frequency band limitation and controllable and adjustable so as to carry out frequency adjustment and tracking.
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| CN109004930A (en) | 2018-12-14 |
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