阅读说明：本技术 一种信号产生电路与系统 (Signal generating circuit and system ) 是由 余波 龙涛 雷建平 李波 于 2020-08-04 设计创作，主要内容包括：本申请提供了一种信号产生电路与系统,涉及信号处理技术领域。该信号产生电路包括调制芯片、选频放大器、带通滤波器以及信号放大器,调制芯片、选频放大器、带通滤波器以及信号放大器依次电连接,其中,调制芯片用于产生包含目标信号的调频载波信号；选频放大器用于将目标信号从调频载波信号中进行分离并放大；带通滤波器用于将除目标信号以外的噪声信号进行衰减滤除；信号放大器用于将目标信号进行放大并补偿带通滤波器的损耗,以输出目标信号。本申请提供的信号产生电路与系统具有成本较低,电路更加简单且开发难度更小的优点。(The application provides a signal generating circuit and a signal generating system, and relates to the technical field of signal processing. The signal generating circuit comprises a modulation chip, a frequency selection amplifier, a band-pass filter and a signal amplifier, wherein the modulation chip, the frequency selection amplifier, the band-pass filter and the signal amplifier are electrically connected in sequence, and the modulation chip is used for generating a frequency modulation carrier signal containing a target signal; the frequency-selective amplifier is used for separating and amplifying a target signal from a frequency modulation carrier signal; the band-pass filter is used for attenuating and filtering noise signals except the target signal; the signal amplifier is used for amplifying the target signal and compensating the loss of the band-pass filter so as to output the target signal. The signal generation circuit and the signal generation system have the advantages of being low in cost, simple in circuit and low in development difficulty.)

1. A signal generating circuit, characterized in that the circuit comprises a modulation chip, a frequency-selective amplifier, a band-pass filter and a signal amplifier, the modulation chip, the frequency-selective amplifier, the band-pass filter and the signal amplifier are electrically connected in turn, wherein,

the modulation chip is used for generating a frequency modulation carrier signal containing a target signal;

the frequency-selective amplifier is used for separating and amplifying the target signal from the frequency modulation carrier signal;

the band-pass filter is used for attenuating and filtering noise signals except the target signal;

the signal amplifier is used for amplifying the target signal and compensating the loss of the band-pass filter so as to output the target signal.

2. The signal generating circuit according to claim 1, wherein the frequency selective amplifier includes a frequency selective module, a first switch tube and a first bias resistor module, a first end of the first switch tube is electrically connected to the modulation chip and the first bias resistor module, respectively, and the first end of the first switch tube is connected to a power supply through the first bias resistor module, a second end of the first switch tube is electrically connected to the frequency selective module and the band-pass filter, respectively, the frequency selective module is further configured to be connected to the power supply, the second end of the first switch tube is further electrically connected to the band-pass filter, a third end of the first switch tube is also electrically connected to the first bias resistor module, and the first bias resistor module is grounded; wherein the content of the first and second substances,

the first bias resistance module is used for adjusting the first switching tube to work in an amplifying state;

the resonant frequency of the frequency selection module is the same as the frequency of the target signal, so that the first switch tube outputs the target signal when working.

3. The signal generating circuit of claim 2, wherein the frequency selective amplifier further comprises a first coupling module, one end of the first coupling module is electrically connected to the modulation chip, and the other end of the first coupling module is electrically connected to the first end of the first switch tube; wherein the content of the first and second substances,

the first coupling module is used for filtering out direct current signals in the frequency modulation carrier signals.

4. The signal generating circuit as claimed in claim 2, wherein the switch tube comprises a transistor, the frequency selecting module comprises a first capacitor and a first inductor, one end of the first capacitor and one end of the first inductor are electrically connected to the power supply, the other end of the first capacitor and the other end of the first inductor are electrically connected to a collector of the transistor, and a base and an emitter of the transistor are electrically connected to the bias resistor module.

5. The signal generating circuit according to claim 1, wherein the band-pass filter includes a first low-pass filter, a high-pass filter, and a second low-pass filter, the signal amplifier includes a first signal amplifier and a second signal amplifier, and the frequency-selective amplifier, the first low-pass filter, the first signal amplifier, the high-pass filter, the second signal amplifier, and the second low-pass filter are electrically connected in this order.

6. The signal generating circuit according to claim 5, wherein the first low pass filter comprises a second coupling module and a first two-stage filter circuit, and the frequency selective amplifier, the second coupling module, the first two-stage filter circuit and the first signal amplifier are electrically connected in sequence;

the second coupling module is used for filtering out a direct current signal in the target signal;

the first two-stage filter circuit is used for filtering carrier signals higher than a first target frequency, wherein the first target frequency is the highest frequency of the target signals.

7. The signal generating circuit of claim 5, wherein the first signal amplifier comprises a third coupling module, a second switch tube and a second bias resistor module, a first end of the second switch tube is electrically connected to the third coupling module and the second bias resistor module, respectively, and a first end of the second switch tube is electrically connected to a power supply through the second bias resistor module, the third coupling module is further electrically connected to the first low pass filter, a second end of the second switch tube is also electrically connected to the power supply through the second bias resistor module, and a second end of the second switch tube is further electrically connected to the high pass filter, and a third end of the second switch tube is grounded through the second bias resistor module; wherein the content of the first and second substances,

the third coupling module is used for filtering out direct current signals in the target signals;

the second bias resistance module is used for adjusting the second switching tube to work in an amplification state.

8. The signal generating circuit of claim 5, wherein the high pass filter comprises a second two-stage filter circuit electrically coupled to the first signal amplifier and the second signal amplifier, respectively;

the second two-stage filter circuit is used for filtering carrier signals lower than a second target frequency, and the second target frequency is the lowest frequency of the target signals.

9. The signal generating circuit of claim 5, wherein the second signal amplifier comprises a fourth coupling module, a third switching tube, a load resistor, and a third bias resistor module, the first end of the third switching tube is electrically connected with the fourth coupling module and the third bias resistance module respectively, and the first end of the third switch tube is electrically connected with a power supply through the third bias resistance module, the fourth coupling module is electrically connected with the high-pass filter, one end of the load resistor is electrically connected with the fourth coupling module, the other end of the load resistor is grounded, the second end of the third switching tube is also electrically connected with the power supply through the third bias resistor module, the second end of the third switching tube is electrically connected with the second low-pass filter, and the third end of the third switching tube is grounded through the third bias resistance module; wherein the content of the first and second substances,

the fourth coupling module is used for filtering out direct current signals in the target signals;

the third bias resistance module is used for adjusting the third switching tube to work in an amplification state.

10. A signal generating system, comprising a signal receiving device and a signal generating circuit as claimed in any one of claims 1 to 9, the signal receiving device being communicatively coupled to the signal generating circuit.

Technical Field

The present application relates to the field of signal processing technologies, and in particular, to a signal generating circuit and system.

Background

In an existing RDS (Radio Data System, Radio Data broadcasting System) signal generator. A scheme often adopted is that a Central Processing Unit (CPU) and a Field Programmable Gate Array (FPGA) generate required data to a Digital to analog converter (DAC), and the DAC generates an RDS rectangular pulse signal with adjustable width, amplitude and repetition frequency. The RDS signal generated by the circuit has the characteristics of high reliability and good signal quality. The method is widely applied to various frequency modulation signal transmitters.

However, due to the application of complex and high-value devices such as a CPU, an FPGA, and a DAC, on one hand, the cost of the RDS signal generator is high, which is not favorable for the popularization and application of the RDS signal generator; on the other hand, due to the existence of devices such as a CPU, an FPGA, a DAC and the like, the development difficulty of the RDS signal generator is high, and the requirement on the circuit is relatively high.

In conclusion, the existing RDS signal generator has the problems of high device cost, great development difficulty and high price.

Disclosure of Invention

The application aims to provide a signal generation circuit and a signal generation system so as to solve the problems that in the prior art, an RDS signal generator is high in device cost, large in development difficulty and high in price.

In order to achieve the above purpose, the embodiments of the present application employ the following technical solutions:

on one hand, the embodiment of the application provides a signal generating circuit, which comprises a modulation chip, a frequency-selective amplifier, a band-pass filter and a signal amplifier, wherein the modulation chip, the frequency-selective amplifier, the band-pass filter and the signal amplifier are electrically connected in sequence, and the modulation chip is used for generating a frequency modulation carrier signal containing a target signal; the frequency-selective amplifier is used for separating and amplifying the target signal from the frequency modulation carrier signal; the band-pass filter is used for attenuating and filtering noise signals except the target signal; the signal amplifier is used for amplifying the target signal and compensating the loss of the band-pass filter so as to output the target signal.

Optionally, the frequency selective amplifier includes a frequency selective module, a first switch tube and a first bias resistor module, a first end of the first switch tube is electrically connected to the modulation chip and the first bias resistor module, and the first end of the first switch tube is connected to a power supply through the first bias resistor module, a second end of the first switch tube is electrically connected to the frequency selective module and the band-pass filter, respectively, the frequency selective module is further configured to be connected to the power supply, the second end of the first switch tube is further electrically connected to the band-pass filter, a third end of the first switch tube is also electrically connected to the first bias resistor module, and the first bias resistor module is grounded; the first bias resistance module is used for adjusting the first switching tube to work in an amplification state; the resonant frequency of the frequency selection module is the same as the frequency of the target signal, so that the first switch tube outputs the target signal when working.

Optionally, the frequency selective amplifier further includes a first coupling module, one end of the first coupling module is electrically connected to the modulation chip, and the other end of the first coupling module is electrically connected to the first end of the switching tube; the first coupling module is used for filtering out direct current signals in the frequency modulation carrier signals.

Optionally, the switch tube includes a triode, the frequency selection module includes a first capacitor and a first inductor, one end of the first capacitor and one end of the first inductor are both electrically connected to the power supply, the other end of the first capacitor and the other end of the first inductor are both electrically connected to a collector of the triode, and a base and an emitter of the triode are both electrically connected to the bias resistor module.

Optionally, the band-pass filter includes a first low-pass filter, a high-pass filter and a second low-pass filter, the signal amplifier includes a first signal amplifier and a second signal amplifier, and the frequency-selective amplifier, the first low-pass filter, the first signal amplifier, the high-pass filter, the second signal amplifier and the second low-pass filter are electrically connected in sequence.

Optionally, the first low-pass filter includes a second coupling module and a first two-stage filter circuit, and the frequency-selective amplifier, the second coupling module, the first two-stage filter circuit and the first signal amplifier are electrically connected in sequence; the second coupling module is used for filtering out a direct current signal in the target signal; the first two-stage filter circuit is used for filtering carrier signals higher than a first target frequency, wherein the first target frequency is the highest frequency of the target signals.

Optionally, the first signal amplifier includes a third coupling module, a second switching tube and a second bias resistor module, a first end of the second switching tube is electrically connected to the third coupling module and the second bias resistor module, respectively, and a first end of the second switching tube is electrically connected to a power supply through the second bias resistor module, the third coupling module is further electrically connected to the first low-pass filter, a second end of the second switching tube is also electrically connected to the power supply through the second bias resistor module, and a second end of the second switching tube is further electrically connected to the high-pass filter, and a third end of the second switching tube is grounded through the second bias resistor module; the third coupling module is used for filtering out a direct current signal in the target signal; the second bias resistance module is used for adjusting the second switching tube to work in an amplification state.

Optionally, the high-pass filter includes a second two-stage filter circuit, and the second two-stage filter circuit is electrically connected to the first signal amplifier and the second signal amplifier, respectively; the second two-stage filter circuit is used for filtering carrier signals lower than a second target frequency, and the second target frequency is the lowest frequency of the target signals.

Optionally, the second signal amplifier includes a fourth coupling module, a third switching tube, a load resistor, and a third bias resistor module, a first end of the third switching tube is electrically connected to the fourth coupling module and the third bias resistor module, respectively, and the first end of the third switching tube is electrically connected to a power supply through the third bias resistor module, the fourth coupling module is electrically connected to the high-pass filter, one end of the load resistor is electrically connected to the fourth coupling module, the other end of the load resistor is grounded, a second end of the third switching tube is also electrically connected to the power supply through the third bias resistor module, and the second end of the third switching tube is electrically connected to the second low-pass filter, and a third end of the third switching tube is grounded through the third bias resistor module; the fourth coupling module is used for filtering out a direct current signal in the target signal. The third bias resistance module is used for adjusting the third switching tube to work in an amplification state.

On the other hand, the embodiment of the present application further provides a signal generating system, where the signal generating system includes a signal receiving device and the above-mentioned signal generating circuit, and the signal receiving device is connected to the signal generating circuit in communication.

Compared with the prior art, the embodiment of the application has the following beneficial effects:

the application provides a signal generating circuit and a system, wherein the signal generating circuit comprises a modulation chip, a frequency selection amplifier, a band-pass filter and a signal amplifier, the modulation chip, the frequency selection amplifier, the band-pass filter and the signal amplifier are electrically connected in sequence, and the modulation chip is used for generating a frequency modulation carrier signal containing a target signal; the frequency-selective amplifier is used for separating and amplifying a target signal from a frequency modulation carrier signal; the band-pass filter is used for attenuating and filtering noise signals except the target signal; the signal amplifier is used for amplifying the target signal and compensating the loss of the band-pass filter so as to output the target signal. Because the signal generating circuit provided by the application abandons the existing complex and high-cost devices such as a CPU, an FPGA and a DAC, and adopts a relatively simple and low-cost module to form the signal generating circuit, the signal generating circuit provided by the application has low cost on the whole, and the circuit is simpler and has less development difficulty; meanwhile, the quality of the generated signals is better due to the processing of frequency selection amplification, band-pass filter, signal amplification and the like.

In order to make the aforementioned objects, features and advantages of the present application more comprehensible, preferred embodiments accompanied with figures are described in detail below.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are required to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope, and it will be apparent to those skilled in the art that other related drawings can be obtained from the drawings without inventive effort.

Fig. 1 is a block diagram of an RDS signal generator in the prior art.

Fig. 2 is a block diagram of a signal generating circuit according to an embodiment of the present disclosure.

Fig. 3 is a circuit diagram of a signal generating circuit according to an embodiment of the present disclosure.

Fig. 4 is a circuit diagram of a frequency selective amplifier according to an embodiment of the present application.

Fig. 5 is a circuit diagram of a first low-pass filter according to an embodiment of the present application.

Fig. 6 is a circuit diagram of a first signal amplifier according to an embodiment of the present application.

Fig. 7 is a circuit diagram of a high-pass filter according to an embodiment of the present application.

Fig. 8 is a circuit diagram of a second signal amplifier according to an embodiment of the present application.

Fig. 9 is a circuit diagram of a second low-pass filter provided in an embodiment of the present application.

In the figure: 100-a signal generating circuit; 110-a modulation chip; 120-a frequency selective amplifier; 130-band pass filter; 140-a signal amplifier; 131-a first low-pass filter; 132-a high pass filter; 133-a second low pass filter; 141-a first signal amplifier; 142-a second signal amplifier; 121-frequency selection module; 122-a first bias resistance module; 123-a second filtering module; 1311-a second coupling module; 1312-a first two-stage filter circuit; 1411-a third coupling module; 1412-a second bias resistance module; 1413-a third filtering module; 1421-fourth coupling module; 1422 — a third bias resistance module; 1423 — a fourth filtering module; 1331-a fifth coupling module; 1332-a third two-stage filter circuit.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some embodiments of the present application, but not all embodiments. The components of the embodiments of the present application, generally described and illustrated in the figures herein, can be arranged and designed in a wide variety of different configurations.

Thus, the following detailed description of the embodiments of the present application, presented in the accompanying drawings, is not intended to limit the scope of the claimed application, but is merely representative of selected embodiments of the application. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures. Meanwhile, in the description of the present application, the terms "first", "second", and the like are used only for distinguishing the description, and are not to be construed as indicating or implying relative importance.

It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

In the description of the present application, it should be noted that the terms "upper", "lower", "inner", "outer", and the like indicate orientations or positional relationships based on orientations or positional relationships shown in the drawings or orientations or positional relationships conventionally found in use of products of the application, and are used only for convenience in describing the present application and for simplification of description, but do not indicate or imply that the referred devices or elements must have a specific orientation, be constructed in a specific orientation, and be operated, and thus should not be construed as limiting the present application.

In the description of the present application, it is also to be noted that, unless otherwise explicitly specified or limited, the terms "disposed" and "connected" are to be interpreted broadly, e.g., as being either fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present application can be understood in a specific case by those of ordinary skill in the art.

Some embodiments of the present application will be described in detail below with reference to the accompanying drawings. The embodiments described below and the features of the embodiments can be combined with each other without conflict.

As described in the background, in an existing RDS (Radio Data System Radio Data broadcasting System) signal generator. The method is usually generated as shown in fig. 1, firstly, a CPU and an FPGA (Field-Programmable gate array) generate required data to a DAC (Digital to analog converter), and then the DAC generates an RDS rectangular pulse signal with adjustable width, amplitude and repetition frequency. The RDS signal generated by the circuit has the characteristics of high reliability and good signal quality. The method is widely applied to various frequency modulation signal transmitters.

However, due to the application of complex and high-value devices such as a CPU, an FPGA, and a DAC, the development difficulty is high, the circuit requirement is high, and the implementation cost is high, so that the existing RDS signal generator has the problems of high device cost, development difficulty, and price.

In view of this, the present application provides a signal generating circuit, which generates an RDS signal by using simple modules such as a modulation chip, a frequency selective amplifier, a band pass filter, and a signal amplifier, and solves the problems of high device cost, high development difficulty, and high price of an RDS signal generator in the prior art.

The following is an exemplary description of the signal generation circuit provided in the present application:

as an alternative implementation manner, referring to fig. 2 and fig. 3, the circuit includes a modulation chip 110, a frequency-selective amplifier 120, a band-pass filter 130, and a signal amplifier 140, and the modulation chip 110, the frequency-selective amplifier 120, the band-pass filter 130, and the signal amplifier 140 are electrically connected in sequence. The modulation chip 110 is configured to generate a frequency modulated carrier signal including a target signal, the frequency selective amplifier 120 is configured to separate and amplify the target signal from the frequency modulated carrier signal, the band pass filter 130 is configured to attenuate and filter noise signals other than the target signal, and the signal amplifier 140 is configured to amplify the target signal and compensate for loss of the band pass filter 130, so as to output the target signal.

Optionally, the modulation chip 110 provided in the present application is an fm stereo modulation chip 110 with RDS, which is configured to generate an fm carrier signal with RDS signals, wherein the frequency of the fm carrier signal is 88MHz to 108 MHz. It will be appreciated that the RDS signal is the target signal.

Moreover, the RDS baseband center frequency 57 ± 2.4kHz has an upper sideband and a lower sideband, namely, an upper sideband of 57kHz to 59.4kHz and a lower sideband of 54.6kHz to 57kHz, the signal generating circuit 100 provided in the present application is only used for generating a target signal of the lower sideband, and certainly, in some other embodiments, the signal generating circuit 100 may also be used for generating a target signal of the upper sideband, only parameters in the circuit need to be changed, and the present application does not limit the above.

As an alternative implementation, the model of the modulation chip 110 selected by the application may be si4711, which is capable of generating a frequency modulated carrier signal (with a frequency of 88MHz to 108MHz) containing an RDS signal (with a baseband center frequency of 57 +/-2.4 kHz). It is understood that the above models are only examples, and the present application does not limit the model of the modulation chip 110, as long as the chip capable of generating the fm carrier signal including the RDS signal is the modulation chip 110 described in the present application.

The selective frequency amplifier 120 can separate the lower sideband frequency spectrum (i.e., frequency of 54.6KHz to 57KHz) with the center frequency of the frequency modulation baseband signal with RDS being 55.8KHz from the frequency modulation carrier signal and amplify the signal.

As an implementation manner, please refer to fig. 4, the frequency selective amplifier 120 includes a frequency selective module 121, a first switch tube and a first bias resistor module 122, a first end of the first switch tube is electrically connected to the modulation chip 110 and the first bias resistor module 122, the first end of the first switch tube is connected to a power supply through the first bias resistor module 122, a second end of the first switch tube is electrically connected to the frequency selective module 121 and the band pass filter 130, the frequency selective module 121 is further configured to be connected to the power supply, the second end of the first switch tube is further electrically connected to the band pass filter 130, a third end of the first switch tube is also electrically connected to the first bias resistor module 122, and the first bias resistor module 122 is grounded. The first bias resistor module 122 is configured to adjust the first switch tube to operate in an amplification state, and a resonant frequency of the frequency selecting module 121 is the same as a frequency of the target signal, so that the first switch tube outputs the target signal when operating.

As one implementation, the first switching tube may be a transistor, the transistor has a current amplification function, and can amplify a signal, and for convenience of description, the present application takes an N-type transistor as an example.

The frequency selection module 121 includes a first capacitor and a first inductor, the first capacitor is connected in parallel with the first inductor, one end of the first capacitor and one end of the first inductor are both electrically connected to the power supply, the other end of the first capacitor and the other end of the first inductor are both electrically connected to the collector of the triode, and the base and the emitter of the triode are both electrically connected to the bias resistor module. And, the capacitance value of the first capacitor is 22nF, and the inductive reactance of the first inductor is 380uH, so that the resonance frequency of the first capacitor and the first inductor is equal to the center frequency of the RDS signal, namely 55.8 KHz.

When the first triode is in a working state, the frequency selection module 121 acts, so that the first triode only allows a signal with the center frequency of 55.8KHz to pass through, and the effect of separating the RDS signal from the frequency modulation carrier signal is further realized.

As an implementation manner, the first bias resistor module 122 includes a first resistor, a second resistor, and a third resistor, where one end of the first resistor is electrically connected to the power supply, the other end of the first resistor is electrically connected to the base of the first transistor, one end of the second resistor is electrically connected to the base of the first transistor, the other end of the second resistor is grounded, one end of the third resistor is electrically connected to the collector of the first transistor, and the other end of the third resistor is grounded. Through the setting mode, the first triode can be adjusted to be in an amplification state when in work, so that the first triode has a certain amplification effect on the RDS signal.

Optionally, the frequency selective amplifier 120 further includes a first coupling module, one end of the first coupling module is electrically connected to the modulation chip 110, and the other end of the first coupling module is electrically connected to the first end of the first switch tube; the first coupling module is used for filtering direct current signals in the frequency modulation carrier signals. Optionally, the first coupling module may be a second capacitor, the function of capacitance that the resistance is direct-current and alternating-current is used to achieve the effect of filtering the direct-current signal in the frequency modulation carrier signal, the frequency modulation carrier signal after the direct-current signal is filtered is transmitted to the first triode and the frequency selection module 121, and then the signal is separated and processed by the first triode and the frequency selection module 121, so as to separate the RDS signal.

The power supply connected to the first resistor and the frequency selection module 121 is used as a driving power supply of the first triode, and optionally, the power supply is 5V. In order to achieve the power filtering effect, the signal generating circuit 100 includes a first filtering module, the first filtering module includes a second inductor and a third capacitor, one end of the second inductor is electrically connected to the power supply, and the other end of the second inductor is electrically connected to the third capacitor and the frequency selective amplifier 120, respectively. Understandably, the second inductor and the third capacitor form an LC filter circuit, so as to achieve the effect of filtering the power supply.

Because the power supply is connected with the frequency selective amplifier 120 through a wire, a certain physical distance exists, in order to make the noise of the input frequency selective amplifier 120 smaller, the frequency selective amplifier 120 further comprises a second filtering module 123, the second filtering module 123 comprises a fourth capacitor and a fifth capacitor, the fourth capacitor is connected with the fifth capacitor in parallel, one end of the fourth capacitor connected with the fifth capacitor in parallel is connected with a second inductor, the other end of the fourth capacitor connected with the fifth capacitor in parallel is grounded, and then the second filtering module 123 realizes the filtering effect on the voltage of the input frequency selective amplifier 120.

In one implementation, the band-pass filter 130 includes a first low-pass filter 131, a high-pass filter 132, and a second low-pass filter 133, the signal amplifier 140 includes a first signal amplifier 141 and a second signal amplifier 142, and the frequency-selective amplifier 120, the first low-pass filter 131, the first signal amplifier 141, the high-pass filter 132, the second signal amplifier 142, and the second low-pass filter 133 are electrically connected in sequence. It should be noted that the low-pass filter in this application adopts two-stage low-pass filters, and the number of stages of the signal amplifier 140 also adopts two stages, but in some other embodiments, the number of stages of the band-pass filter 130 and the signal amplifier 140 may also be set according to actual requirements, for example, it may be set as one stage, or it may be set as three stages, which is not limited in this application.

Optionally, referring to fig. 5, the first low-pass filter 131 includes a second coupling module 1311 and a first two-stage filter circuit 1312, and the frequency selective amplifier 120, the first coupling module, the first two-stage filter circuit 1312 and the first signal amplifier 141 are electrically connected in sequence; the second coupling module 1311 is configured to filter a direct current signal in the target signal; the first two-stage filter 1312 is configured to filter out a carrier signal higher than a first target frequency, where the first target frequency is the highest frequency of the target signal.

Since the frequency selective amplifier 120 may still generate a dc signal when operating, or the dc signal input by the modulation chip 110 is not completely filtered by the first coupling module, the dc signal of the target signal needs to be filtered by the second coupling module 1311. The signal is then passed to a first two-stage filter 1312 for processing.

Optionally, the second coupling module 1311 includes a sixth capacitor and a seventh capacitor, one end of the sixth capacitor and the seventh capacitor after being connected in parallel is electrically connected to the output end of the frequency selective amplifier 120, and the other end is electrically connected to the first two-stage filter circuit 1312.

The first two-stage filter circuit 1312 includes a third inductor, a fourth inductor, an eighth capacitor, a ninth capacitor, a tenth capacitor and an eleventh capacitor, wherein one end of the third inductor is electrically connected to the output terminal of the first coupling module and one end of the eighth capacitor, the other end of the third inductor is electrically connected to one end of the fourth inductor, one end of the ninth capacitor and one end of the tenth capacitor, the other end of the fourth inductor is electrically connected to one end of the first signal amplifier 141 and one end of the eleventh capacitor, and the other ends of the eighth capacitor, the ninth capacitor, the tenth capacitor and the eleventh capacitor are all grounded.

It is understood that the third inductor, the fourth inductor, the eighth capacitor, the ninth capacitor, the tenth capacitor and the eleventh capacitor constitute two sets of LC filters, and therefore the third inductor, the fourth inductor, the eighth capacitor, the ninth capacitor, the tenth capacitor and the eleventh capacitor are used as the first two-stage filter circuit 1312. The inductive reactance values of the third inductor and the fourth inductor are 380uF, and the capacitance values of the eighth capacitor, the ninth capacitor, the tenth capacitor and the eleventh capacitor are 22nF, so that the attenuation of the carrier signal higher than 57KHz is realized by using the first two-stage filter circuit 1312, that is, the first target frequency is 57KHz in the present application.

As an implementation manner, please refer to fig. 6, the first signal amplifier 141 includes a third coupling module 1411, a second switching tube and a second bias resistor module 1412, a first end of the second switching tube is electrically connected to the third coupling module 1411 and the second bias resistor module 1412, respectively, and a first end of the second switching tube is electrically connected to a power supply through the second bias resistor module 1412, the third coupling module 1411 is further electrically connected to the first low pass filter 131, a second end of the second switching tube is also electrically connected to the power supply through the second bias resistor module 1412, and a second end of the second switching tube is further electrically connected to the high pass filter 132, and a third end of the second switching tube is grounded through the second bias resistor module 1412; the third coupling module 1411 is configured to filter a direct current signal in the target signal, and the second bias resistor module 1412 is configured to adjust the second switching tube to operate in an amplifying state.

The third coupling module 1411 includes a twelfth capacitor and a thirteenth capacitor, one end of the twelfth capacitor and one end of the thirteenth capacitor connected in parallel is electrically connected to the first low-pass filter 131, and the other end of the twelfth capacitor and the thirteenth capacitor are electrically connected to the second bias resistor module 1412.

It should be noted that the second triode may also be an N-type triode, the second bias resistor module 1412 includes a fifth resistor, a sixth resistor, a seventh resistor, and an eighth resistor, a base of the second triode is electrically connected to one end of the fifth resistor, one end of the seventh resistor, and the third coupling module 1411, a collector of the second triode is electrically connected to one end of the sixth resistor and the high-pass filter 132, an emitter of the second triode is electrically connected to one end of the eighth resistor, the other ends of the fifth resistor and the sixth resistor are used for connecting to a power supply, and the other ends of the seventh resistor and the eighth resistor are grounded. Since the signal strength of the signal is weakened after the signal passes through the first low pass filter 131, the second transistor can be ensured to operate in an amplification state by the second bias resistor module 1412, so that the target signal can reach a required signal amplitude and the loss of the first low pass filter 131 is compensated.

Similarly, since the second transistor also needs to be connected to the driving power supply, in order to effectively filter the input signal of the driving power supply, the first signal amplifier 141 further includes a third filtering module 1413, the third filtering module 1413 includes a fourteenth capacitor and a fifteenth capacitor, one end of the fourteenth capacitor connected in parallel with the fifteenth capacitor is electrically connected to the power supply, and the other end of the fourteenth capacitor is grounded, so as to achieve the effect of filtering the input voltage.

As an alternative implementation manner, please refer to fig. 7, the high-pass filter 132 includes a second two-stage filter circuit, the second two-stage filter circuit is electrically connected to the first signal amplifier 141 and the second signal amplifier 142, respectively, and the second two-stage filter circuit is configured to filter a carrier signal lower than a second target frequency, where the second target frequency is the lowest frequency of the target signal.

Optionally, the high-pass filter 132 includes a sixteenth capacitor, a seventeenth capacitor, an eighteenth capacitor, a nineteenth capacitor, a fifth inductor and a sixth inductor, one end of the sixteenth capacitor is electrically connected to the output end of the first signal amplifier 141, the other end of the sixteenth capacitor is electrically connected to one end of the seventeenth capacitor, one end of the eighteenth capacitor and one end of the fifth inductor, the other ends of the seventeenth capacitor and the eighteenth capacitor are electrically connected to one end of the nineteenth capacitor and one end of the sixth inductor, the other end of the nineteenth capacitor is electrically connected to the second signal amplifier 142, and the other end of the fifth inductor and the other end of the sixth inductor are grounded.

Through the connection relationship, two groups of LC circuits formed by the sixteenth capacitor, the seventeenth capacitor, the eighteenth capacitor, the nineteenth capacitor, the fifth inductor and the sixth inductor perform filtering, meanwhile, the capacitance value of the sixteenth capacitor and the nineteenth capacitor is set to 68nF, the capacitance value of the seventeenth capacitor and the eighteenth capacitor is set to 22nF, the inductance value of the fifth inductor and the sixth inductor is set to 230uH, and then the attenuation of signals lower than 54.6KHz can be realized through the high-pass filter 132, in other words, the second target frequency provided by the application is 54.6 KHz.

As an optional implementation manner, please refer to fig. 8, the second signal amplifier 142 includes a fourth coupling module 1421, a third switching tube, a load resistor, and a third bias resistor module 1422, a first end of the third switching tube is electrically connected to the fourth coupling module 1421 and the third bias resistor module 1422, respectively, and a first end of the third switching tube is electrically connected to a power supply through the third bias resistor module 1422, the fourth coupling module 1421 is electrically connected to the high-pass filter 132, one end of the load resistor is electrically connected to the fourth coupling module 1421, the other end of the load resistor is grounded, a second end of the third switching tube is also electrically connected to the power supply through the third bias resistor module 1422, a second end of the third switching tube is electrically connected to the second low-pass filter 133, and a third end of the third switching tube is grounded through the third bias resistor module 1422; the fourth coupling module 1421 is configured to filter a direct current signal in the target signal, and the third bias resistor 1422 is configured to adjust the third switching tube to operate in an amplification state.

Similar to the first signal amplifier 141, the fourth coupling module 1421 includes a twentieth capacitor and a twenty-first capacitor, one end of the twentieth capacitor connected in parallel with the twenty-first capacitor is electrically connected to the high-pass filter 132 and the load resistor, and the other end is electrically connected to the third bias resistor module 1422.

It should be noted that the third triode may also be an N-type triode, the third bias resistor module 1422 includes a ninth resistor, a tenth resistor, an eleventh resistor, and a twelfth resistor, a base of the third triode is electrically connected to one end of the ninth resistor, one end of the eleventh resistor, and the fourth coupling module 1421, a collector of the third triode is electrically connected to one end of the tenth resistor and the second low-pass filter 133, an emitter of the third triode is electrically connected to one end of the twelfth resistor, the other end of the ninth resistor and the other end of the tenth resistor are used for connecting to a power supply, and the other end of the eleventh resistor and the other end of the twelfth resistor are grounded. Since the signal strength of the signal is weakened after passing through the high pass filter 132, the third triode can be ensured to work in an amplification state by the third bias resistor module 1422, so that the target signal can reach a required signal amplitude and the loss of the high pass filter 132 is compensated.

Similarly, since the third transistor also needs to be connected to the driving power supply, in order to effectively filter the input signal of the driving power supply, the second signal amplifier 142 further includes a fourth filtering module 1423, the fourth filtering module 1423 includes a twenty-second capacitor and a twenty-third capacitor, one end of the twenty-second capacitor connected in parallel with the twenty-third capacitor is electrically connected to the power supply, and the other end of the twenty-second capacitor is grounded, so as to achieve the effect of filtering the input voltage.

In addition, in order to achieve the effect of adjusting the signal strength, the second signal amplifier 142 provided in the present application includes a load resistor, one end of the load resistor is electrically connected to the fourth coupling module 1421, and the other end of the load resistor is grounded.

As an implementation manner, please refer to fig. 9, the second low-pass filter 133 includes a fifth coupling module 1331 and a third two-stage filter circuit 1332, and the frequency selective amplifier 120, the first coupling module, the third two-stage filter circuit 1332 and the first signal amplifier 141 are electrically connected in sequence; the fifth coupling module 1331 is configured to filter a direct current signal in the target signal; the third two-stage filter circuit 1332 is used to filter out carrier signals higher than a first target frequency, where the first target frequency is the highest frequency of the target signal.

Since there may still be a dc signal in the frequency selective amplifier 120 during operation, the dc signal of the target signal needs to be filtered by the fifth coupling module 1331. The target signal is then passed to a third two-stage filter circuit 1332 for processing.

Optionally, the fifth coupling module 1331 includes a twenty-fourth capacitor and a twenty-fifth capacitor, one end of the twenty-fourth capacitor connected in parallel with the twenty-fifth capacitor is electrically connected to the output end of the second signal amplifier 142, and the other end is electrically connected to the third two-stage filter circuit 1332.

The third two-stage filter circuit 1332 includes a seventh inductor, an eighth inductor, a twenty-sixth capacitor, a twenty-seventh capacitor, a twenty-eighth capacitor and a twenty-ninth capacitor, one end of the seventh inductor is electrically connected to the output end of the fifth coupling module 1331 and one end of the twenty-sixth capacitor, the other end of the seventh inductor is electrically connected to one end of the eighth inductor, one end of the twenty-seventh capacitor and one end of the twenty-eighth capacitor, the other end of the eighth inductor is electrically connected to one end of the signal output port and one end of the twenty-ninth capacitor, and the other ends of the twenty-sixth capacitor, the twenty-seventh capacitor, the twenty-eighth capacitor and the twenty-ninth capacitor are all grounded.

It is to be understood that the seventh inductor, the eighth inductor, the twenty-sixth capacitor, the twenty-seventh capacitor, the twenty-eighth capacitor, and the twenty-ninth capacitor form two groups of LC filters, and therefore the seventh inductor, the eighth inductor, the twenty-sixth capacitor, the twenty-seventh capacitor, the twenty-eighth capacitor, and the twenty-ninth capacitor are used as the third two-stage filter circuit 1332. The inductance values of the seventh inductor and the eighth inductor are 380uF, and the capacitance values of the twenty-sixth capacitor, the twenty-seventh capacitor, the twenty-eighth capacitor and the twenty-ninth capacitor are 22nF, so that the third two-stage filter circuit 1332 is used for attenuating the carrier signal higher than 57KHz, in other words, after the low-pass filtering is performed through the first low-pass filter 131, the further filtering can be performed through the second low-pass filter 133, and the filtering effect is better.

The invention replaces the FPGA and DAC devices with high development difficulty and high device price in the existing RDS signal generator by using the RDS frequency modulation stereo modulation chip 110, thereby greatly reducing the development cost and the device cost, although the frequency selection amplifying circuit, the band-pass filter 130 and the signal amplifier 140 are added, the devices are all composed of common resistors, capacitors, inductors and triodes, and the cost sample ratio saved by reducing the FPGA and DAC devices can be almost ignored. In addition, as the FPGA device is not used any more, the product development difficulty is reduced, and the research and development period is shortened. The resistor, the capacitor, the triode and the RDS FM stereo modulation chip 110 are widely applied in common consumer products, are easy to obtain and have low price, so the actual cost is low and the technical requirement is low. The method can be used in various occasions needing to generate the RDS signal and needing simple implementation mode and low cost.

Based on the foregoing embodiment, the present application further provides a signal generating system, where the signal generating system includes a signal receiving device and the signal generating circuit 100, and the signal receiving device is in communication connection with the signal generating circuit 100, so as to receive the RDS signal.

In summary, the present application provides a signal generating circuit and a system, where the signal generating circuit includes a modulation chip, a frequency selective amplifier, a band pass filter, and a signal amplifier, and the modulation chip, the frequency selective amplifier, the band pass filter, and the signal amplifier are electrically connected in sequence, where the modulation chip is configured to generate a frequency modulated carrier signal including a target signal; the frequency-selective amplifier is used for separating and amplifying a target signal from a frequency modulation carrier signal; the band-pass filter is used for attenuating and filtering noise signals except the target signal; the signal amplifier is used for amplifying the target signal and compensating the loss of the band-pass filter so as to output the target signal. Because the signal generating circuit provided by the application abandons the existing complex and high-cost devices such as a CPU, an FPGA and a DAC, and adopts a relatively simple and low-cost module to form the signal generating circuit, the signal generating circuit provided by the application has low cost on the whole, and the circuit is simpler and has less development difficulty; meanwhile, the quality of the generated signals is better due to the processing of frequency selection amplification, band-pass filter, signal amplification and the like.

The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.

It will be evident to those skilled in the art that the present application is not limited to the details of the foregoing illustrative embodiments, and that the present application may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the application being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.