A signal generating circuit and system

Abstract

The present application provides a signal generating circuit and system, which relates to the field of signal processing technology. The signal generating circuit includes a modulation chip, a frequency-selective amplifier, a bandpass filter and a signal amplifier, which are electrically connected in sequence, wherein the modulation chip is used to generate a frequency-modulated carrier signal containing a target signal; the frequency-selective amplifier is used to separate and amplify the target signal from the frequency-modulated carrier signal; the bandpass filter is used to attenuate and filter out noise signals other than the target signal; the signal amplifier is used to amplify the target signal and compensate for the loss of the bandpass filter to output the target signal. The signal generating circuit and system provided by the present application have the advantages of lower cost, simpler circuit and less development difficulty.

Description

Technical Field

[0001] The present application relates to the field of signal processing technology, and in particular to a signal generating circuit and system. Background Art

[0002] In the existing RDS (Radio Data System) signal generator, the commonly used solution is that the CPU (central processing unit) and FPGA (Field-Programmable Gate Array) generate the required data and send it to the DAC (Digital to analog converter), and the DAC generates an RDS rectangular pulse signal with adjustable width, amplitude and repetition frequency. The RDS signal generated by this circuit has the characteristics of high reliability and good signal quality. It is widely used in various FM signal transmitters.

[0003] However, due to the application of complex and high-value devices such as CPU, FPGA, DAC, on the one hand, the cost of RDS signal generator is relatively high, which is not conducive to the promotion and application of RDS signal generator; on the other hand, due to the existence of devices such as CPU, FPGA, DAC, etc., the development of RDS signal generator is difficult and the requirements for circuits are relatively high.

[0004] In summary, the existing RDS signal generator has the problems of high device cost, great development difficulty and high price. Summary of the invention

[0005] The purpose of the present application is to provide a signal generating circuit and system to solve the problems of high device cost, great development difficulty and high price of RDS signal generator in the prior art.

[0006] In order to achieve the above purpose, the technical solution adopted in the embodiment of the present application is as follows:

[0007] On the one hand, an embodiment of the present application provides a signal generating circuit, which includes a modulation chip, a frequency selective amplifier, a bandpass filter and a signal amplifier, wherein the modulation chip, the frequency selective amplifier, the bandpass filter and the signal amplifier are electrically connected in sequence, wherein the modulation chip is used to generate a frequency modulated carrier signal containing a target signal; the frequency selective amplifier is used to separate and amplify the target signal from the frequency modulated carrier signal; the bandpass filter is used to attenuate and filter out noise signals other than the target signal; and the signal amplifier is used to amplify the target signal and compensate for the loss of the bandpass filter to output the target signal.

[0008] Optionally, the frequency selection amplifier includes a frequency selection module, a first switch tube and a first bias resistor module, the 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, the second end of the first switch tube is electrically connected to the frequency selection module and the bandpass filter respectively, the frequency selection module is also used to connect the power supply, the second end of the first switch tube is also electrically connected to the bandpass filter, the 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 first bias resistor module is used to adjust the first switch 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.

[0009] Optionally, the frequency selective amplifier also 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; wherein the first coupling module is used to filter out the DC signal in the frequency modulated carrier signal.

[0010] Optionally, the switching tube includes a transistor, the frequency selection module includes a first capacitor and a first inductor, one end of the first capacitor and the first inductor are electrically connected to the power supply, the other end of the first capacitor and the first inductor are electrically connected to the collector of the transistor, and the base and emitter of the transistor are electrically connected to the bias resistor module.

[0011] Optionally, the bandpass 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.

[0012] Optionally, the first low-pass filter includes a second coupling module and a first two-stage filtering circuit, and the frequency selective amplifier, the second coupling module, the first two-stage filtering circuit and the first signal amplifier are electrically connected in sequence; wherein, the second coupling module is used to filter out the DC signal in the target signal; the first two-stage filtering circuit is used to filter out the carrier signal higher than the first target frequency, wherein the first target frequency is the highest frequency of the target signal.

[0013] Optionally, the first signal amplifier includes a third coupling module, a second switch tube and a second bias resistor module, the first end of the second switch tube is electrically connected to the third coupling module and the second bias resistor module respectively, and the 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 also electrically connected to the first low-pass filter, the second end of the second switch tube is also electrically connected to the power supply through the second bias resistor module, and the second end of the second switch tube is also used to be electrically connected to the high-pass filter, and the third end of the second switch tube is grounded through the second bias resistor module; wherein the third coupling module is used to filter out the DC signal in the target signal; and the second bias resistor module is used to adjust the second switch tube to operate in an amplification state.

[0014] Optionally, the high-pass filter includes a second two-stage filtering circuit, which is electrically connected to the first signal amplifier and the second signal amplifier respectively; the second two-stage filtering circuit is used to filter out carrier signals lower than a second target frequency, and the second target frequency is the lowest frequency of the target signal.

[0015] Optionally, the second signal amplifier includes a fourth coupling module, a third switch tube, a load resistor and a third bias resistor module, the first end of the third switch tube is electrically connected to the fourth coupling module and the third bias resistor module respectively, and the first end of the third switch 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, the second end of the third switch tube is also electrically connected to the power supply through the third bias resistor module, and the second end of the third switch tube is electrically connected to the second low-pass filter, and the third end of the third switch tube is grounded through the third bias resistor module; wherein the fourth coupling module is used to filter out the DC signal in the target signal. The third bias resistor module is used to adjust the third switch tube to work in an amplification state.

[0016] On the other hand, an embodiment of the present application further provides a signal generating system, which includes a signal receiving device and the above-mentioned signal generating circuit, and the signal receiving device is communicatively connected to the signal generating circuit.

[0017] Compared with the prior art, the embodiments of the present application have the following beneficial effects:

[0018] The present application provides a signal generating circuit and system, the signal generating circuit includes a modulation chip, a frequency-selective amplifier, a bandpass filter and a signal amplifier, the modulation chip, the frequency-selective amplifier, the bandpass filter and the signal amplifier are electrically connected in sequence, wherein the modulation chip is used to generate a frequency-modulated carrier signal containing a target signal; the frequency-selective amplifier is used to separate and amplify the target signal from the frequency-modulated carrier signal; the bandpass filter is used to attenuate and filter out noise signals other than the target signal; the signal amplifier is used to amplify the target signal and compensate for the loss of the bandpass filter to output the target signal. Since the signal generating circuit provided by the present application abandons the existing complex and costly devices such as CPU, FPGA and DAC, and adopts relatively simple and cost-effective modules to form the signal generating circuit, the signal generating circuit provided by the present application is lower in cost as a whole, the circuit is simpler and the development difficulty is lower; at the same time, due to the processing of frequency-selective amplification, bandpass filter and signal amplification, the quality of the generated signal is also better.

[0019] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, preferred embodiments are specifically cited below and described in detail with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 It is a module schematic diagram of an RDS signal generator in the prior art.

[0022] Figure 2 A module schematic diagram of a signal generating circuit provided in an embodiment of the present application.

[0023] Figure 3 A circuit diagram of a signal generating circuit provided in an embodiment of the present application.

[0024] Figure 4 A circuit diagram of a frequency selective amplifier provided in an embodiment of the present application.

[0025] Figure 5 A circuit diagram of a first low-pass filter provided in an embodiment of the present application.

[0026] Figure 6 A circuit diagram of a first signal amplifier provided in an embodiment of the present application.

[0027] Figure 7A circuit diagram of a high-pass filter provided in an embodiment of the present application.

[0028] Figure 8 This is a circuit diagram of a second signal amplifier provided in an embodiment of the present application.

[0029] Fig. 9 A circuit diagram of a second low-pass filter provided in an embodiment of the present application.

[0030] In the figure: 100-signal generating circuit; 110-modulation chip; 120-frequency selection amplifier; 130-bandpass filter; 140-signal amplifier; 131-first low-pass filter; 132-high-pass filter; 133-second low-pass filter; 141-first signal amplifier; 142-second signal amplifier; 121-frequency selection module; 122-first bias resistor module; 123-second filtering module; 1311-second coupling module; 1312-first two-stage filtering circuit; 1411-third coupling module; 1412-second bias resistor module; 1413-third filtering module; 1421-fourth coupling module; 1422-third bias resistor module; 1423-fourth filtering module; 1331-fifth coupling module; 1332-third two-stage filtering circuit. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0032] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for which protection is sought, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0033] It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings. At the same time, in the description of this application, the terms "first", "second", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0034] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0035] In the description of the present application, it should be noted that the terms "upper", "lower", "inside", "outside", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships in which the product of the application is usually placed when in use. They are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0036] In the description of this application, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "disposed" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0037] In conjunction with the accompanying drawings, some embodiments of the present application are described in detail below. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0038] As described in the background technology, in the existing RDS (Radio Data System) signal generator, the following are often used: Figure 1 The method shown in the figure is to first generate the required data by the CPU and FPGA (Field-Programmable Gate Array) and send it to the 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 this circuit has the characteristics of high reliability and good signal quality. It is widely used in various FM signal transmitters.

[0039] However, due to the application of complex and high-value devices such as CPU, FPGA, DAC, etc., the development is difficult, the circuit requirements are high, and the implementation cost is high. Therefore, the existing RDS signal generator has the problems of high device cost, high development difficulty and high price.

[0040] In view of this, the present application provides a signal generating circuit, which realizes the generation of RDS signals by using simple modules such as modulation chips, frequency selective amplifiers, bandpass filters and signal amplifiers, thereby improving the problems of high device cost, great development difficulty and high price of RDS signal generators in the prior art.

[0041] The signal generating circuit provided in this application is exemplarily described below:

[0042] As an alternative implementation, see Figure 2 and Figure 3 The circuit includes a modulation chip 110, a frequency-selective amplifier 120, a bandpass filter 130, and a signal amplifier 140, which are electrically connected in sequence. The modulation chip 110 is used to generate a frequency-modulated carrier signal containing a target signal, the frequency-selective amplifier 120 is used to separate and amplify the target signal from the frequency-modulated carrier signal, the bandpass filter 130 is used to attenuate and filter out noise signals other than the target signal, and the signal amplifier 140 is used to amplify the target signal and compensate for the loss of the bandpass filter 130 to output the target signal.

[0043] Optionally, the modulation chip 110 provided in the present application is an FM stereo modulation chip 110 with RDS, which is used to generate an FM carrier signal with an RDS signal, wherein the frequency of the FM carrier signal is 88MHz to 108MHz. It can be understood that the RDS signal is the target signal.

[0044] In addition, the RDS baseband center frequency of 57±2.4kHz has two upper and lower sidebands, 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 to generate a target signal of the lower sideband. Of course, in some other embodiments, the target signal of the upper sideband can also be generated by the signal generating circuit 100, and it is only necessary to change the parameters in the circuit. The present application does not impose any limitation on this.

[0045] As an optional implementation, the model of the modulation chip 110 selected in the present application may be si4711, which can generate a frequency modulated carrier signal (frequency of 88MHz to 108MHz) including an RDS signal (baseband center frequency of 57±2.4kHz). It can be understood that the above model is only an example, and the present application does not limit the model of the modulation chip 110. As long as the chip can generate a frequency modulated carrier signal including an RDS signal, it is the modulation chip 110 described in the present application.

[0046] The frequency selective amplifier 120 can separate the lower sideband spectrum (ie, the frequency is 54.6KHz to 57KHz) of the FM baseband signal with RDS whose center frequency is 55.8KHz from the FM carrier signal and amplify the signal.

[0047] As an implementation, see Figure 4 The frequency selection amplifier 120 includes a frequency selection module 121, a first switch tube and a first bias resistor module 122. The first end of the first switch tube is electrically connected to the modulation chip 110 and the first bias resistor module 122 respectively, and the first end of the first switch tube is connected to a power supply through the first bias resistor module 122. The second end of the first switch tube is electrically connected to the frequency selection module 121 and the bandpass filter 130 respectively. The frequency selection module 121 is also used to connect the power supply. The second end of the first switch tube is also electrically connected to the bandpass filter 130. The 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. Among them, the first bias resistor module 122 is used to adjust the first switch tube to work in the amplification state. The resonant frequency of the frequency selection module 121 is the same as the frequency of the target signal, so that the first switch tube outputs the target signal when working.

[0048] As an implementation method, the first switch tube may be a transistor, which has a current amplification function and can amplify the signal. For ease of explanation, the present application takes an N-type transistor as an example for explanation.

[0049] The frequency selection module 121 includes a first capacitor and a first inductor, the first capacitor and the first inductor are connected in parallel, and one end of the first capacitor and the first inductor are both electrically connected to the power supply, the other ends of the first capacitor and the first inductor are both electrically connected to the collector of the transistor, and the base and emitter of the transistor are both electrically connected to the bias resistor module. In addition, the capacitance of the first capacitor is 22nF, and the inductive reactance of the first inductor is 380uH, so that the resonant frequency of the first capacitor and the first inductor is equal to the center frequency of the RDS signal, that is, 55.8KHz.

[0050] When the first transistor is in working state, due to the action of the frequency selection module 121, the first transistor only allows the signal with a center frequency of 55.8KHz to pass through, thereby achieving the effect of separating the RDS signal from the FM carrier signal.

[0051] As an implementation, the first bias resistor module 122 includes a first resistor, a second resistor and a third resistor, one end of the first resistor is electrically connected to the power supply, and the other end is electrically connected to the base of the first triode, one end of the second resistor is electrically connected to the base of the first triode, and the other end is grounded, and one end of the third resistor is electrically connected to the collector of the first triode, and the other end is grounded. Through the above setting, the first triode can be adjusted to be in an amplification state when working, so that the first triode has a certain amplification effect on the RDS signal.

[0052] Optionally, the frequency-selective amplifier 120 further includes a first coupling module, one end of which is electrically connected to the modulation chip 110, and the other end of which is electrically connected to the first end of the first switch tube; wherein the first coupling module is used to filter out the DC signal in the frequency-modulated carrier signal. Optionally, the first coupling module can be a second capacitor, which uses the function of blocking direct current and passing alternating current to achieve the effect of filtering out the DC signal in the frequency-modulated carrier signal, and the frequency-modulated carrier signal after filtering out the DC signal is transmitted to the first transistor and the frequency-selective module 121, and then undergoes signal separation processing by the first transistor and the frequency-selective module 121, thereby separating out the RDS signal.

[0053] Among them, the power supply connected to the first resistor and the frequency selection module 121 is used as the driving power supply of the first triode, and optionally, the power supply is 5V. In order to achieve the power supply filtering effect, the signal generating circuit 100 includes a first filtering module, and 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 selection amplifier 120 respectively. It can be understood that the second inductor and the third capacitor form an LC filtering circuit, thereby achieving the effect of power supply filtering.

[0054] Since the power supply and the frequency selection amplifier 120 are connected by wires and there is a certain physical distance between them, in order to make the noise of the input frequency selection amplifier 120 smaller, the frequency selection amplifier 120 also includes a second filtering module 123. The second filtering module 123 includes a fourth capacitor and a fifth capacitor. The fourth capacitor and the fifth capacitor are connected in parallel, and one end of the fourth capacitor and the fifth capacitor after being connected in parallel is connected to the second inductor, and the other end is grounded. Therefore, the filtering effect of the voltage input to the frequency selection amplifier 120 is achieved through the second filtering module 123.

[0055] As an implementation, the bandpass 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 the present application adopts a two-stage low-pass filter, 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 bandpass filter 130 and the signal amplifier 140 can also be set according to actual needs, for example, it can be set to one stage or three stages, and the present application does not make any limitation on this.

[0056] Optionally, see Figure 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; wherein the second coupling module 1311 is used to filter out the DC signal in the target signal; the first two-stage filter circuit 1312 is used to filter out the carrier signal higher than the first target frequency, wherein the first target frequency is the highest frequency of the target signal.

[0057] Since the frequency selective amplifier 120 may still generate a DC signal when it is working, or the DC signal input by the modulation chip 110 is not completely filtered out by the first coupling module, it is necessary to first filter out the DC signal of the target signal through the second coupling module 1311. Then the signal is transmitted to the first two-stage filtering circuit 1312 for processing.

[0058] Optionally, the second coupling module 1311 includes a sixth capacitor and a seventh capacitor, one end of the sixth capacitor and the seventh capacitor 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 .

[0059] Among them, the first two-stage filtering circuit 1312 includes a third inductor, a fourth inductor, an eighth capacitor, a ninth capacitor, a tenth capacitor and an eleventh capacitor, one end of the third inductor is electrically connected to the output end of the first coupling module and one end of the eighth capacitor, respectively, 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, respectively, the other end of the fourth inductor is electrically connected to the first signal amplifier 141 and one end of the eleventh capacitor, respectively, and the other ends of the eighth capacitor, the ninth capacitor, the tenth capacitor and the eleventh capacitor are all grounded.

[0060] It can be understood that the third inductor, the fourth inductor, the eighth capacitor, the ninth capacitor, the tenth capacitor and the eleventh capacitor form two groups of LC filters, so 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. Among them, the inductive reactance values ​​of the third inductor and the fourth inductor are both 380uF, and the capacitance values ​​of the eighth capacitor, the ninth capacitor, the tenth capacitor and the eleventh capacitor are all 22nF, so that the first two-stage filter circuit 1312 is used to attenuate the carrier signal higher than 57KHz, that is, the first target frequency described in the present application is 57KHz.

[0061] As an implementation, see Figure 6 The first signal amplifier 141 includes a third coupling module 1411, a second switch tube and a second bias resistor module 1412. The first end of the second switch tube is electrically connected to the third coupling module 1411 and the second bias resistor module 1412 respectively, and the first end of the second switch tube is electrically connected to a power supply through the second bias resistor module 1412. The third coupling module 1411 is also electrically connected to the first low-pass filter 131, and the second end of the second switch tube is also electrically connected to the power supply through the second bias resistor module 1412. The second end of the second switch tube is also used to be electrically connected to the high-pass filter 132, and the third end of the second switch tube is grounded through the second bias resistor module 1412; wherein the third coupling module 1411 is used to filter out the DC signal in the target signal, and the second bias resistor module 1412 is used to adjust the second switch tube to work in an amplification state.

[0062] The third coupling module 1411 includes a twelfth capacitor and a thirteenth capacitor, one end of the twelfth capacitor and the thirteenth capacitor connected in parallel is electrically connected to the first low-pass filter 131 , and the other end is electrically connected to the second bias resistor module 1412 .

[0063] It should be noted that the second triode can 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, the 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 respectively, the collector of the second triode is electrically connected to one end of the sixth resistor and the high-pass filter 132 respectively, the emitter of the second triode is electrically connected to one end of the eighth resistor, the other end of the fifth resistor and the sixth resistor is used to connect to the power supply, and the other end of the seventh resistor and the eighth resistor is grounded. Since the signal strength will be weakened after passing through the first low-pass filter 131, by setting the second bias resistor module 1412, it can be ensured that the second triode works in an amplified state, thereby achieving the target signal to reach the required signal amplitude and compensating for the loss of the first low-pass filter 131.

[0064] Similarly, since the second transistor also needs to be connected to the driving power supply, in order to effectively filter the driving power supply input signal, the first signal amplifier 141 also 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 and the fifteenth capacitor after being connected in parallel is electrically connected to the power supply, and the other end is grounded to achieve the effect of filtering the input voltage.

[0065] As an alternative implementation, see Figure 7 The high-pass filter 132 includes a second two-stage filter circuit, which is electrically connected to the first signal amplifier 141 and the second signal amplifier 142 respectively. The second two-stage filter circuit is used to filter out carrier signals lower than the second target frequency, and the second target frequency is the lowest frequency of the target signal.

[0066] 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, the eighteenth capacitor and the fifth inductor respectively, the other ends of the seventeenth capacitor and the eighteenth capacitor are both electrically connected to one end of the nineteenth capacitor and the sixth inductor, the other end of the nineteenth capacitor is used to be electrically connected to the second signal amplifier 142, and the other ends of the fifth inductor and the sixth inductor are grounded.

[0067] Through the above connection relationship, the two groups of LC circuits composed of the sixteenth capacitor, the seventeenth capacitor, the eighteenth capacitor, the nineteenth capacitor, the fifth inductor and the sixth inductor are filtered. At the same time, the capacitance of the sixteenth capacitor and the nineteenth capacitor is set to 68nF, the capacitance of the seventeenth capacitor and the eighteenth capacitor is set to 22nF, and the inductive reactance of the fifth inductor and the sixth inductor is set to 230uH, so that the high-pass filter 132 can be used to attenuate signals below 54.6KHz. In other words, the second target frequency provided in the present application is 54.6KHz.

[0068] As an alternative implementation, see Figure 8The second signal amplifier 142 includes a fourth coupling module 1421, a third switch tube, a load resistor and a third bias resistor module 1422. The first end of the third switch tube is electrically connected to the fourth coupling module 1421 and the third bias resistor module 1422 respectively, and the first end of the third switch 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, and the other end of the load resistor is grounded. The second end of the third switch tube is also electrically connected to the power supply through the third bias resistor module 1422, and the second end of the third switch tube is electrically connected to the second low-pass filter 133, and the third end of the third switch tube is grounded through the third bias resistor module 1422; wherein the fourth coupling module 1421 is used to filter out the DC signal in the target signal, and the third bias resistor module 1422 is used to adjust the third switch tube to work in the amplification state.

[0069] 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 and the twenty-first capacitor connected in parallel 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 .

[0070] It should be noted that the third triode can 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, the base of the third triode is electrically connected to one end of the ninth resistor, the eleventh resistor and the fourth coupling module 1421 respectively, the collector of the third triode is electrically connected to one end of the tenth resistor and the second low-pass filter 133 respectively, the emitter of the third triode is electrically connected to one end of the twelfth resistor, the other end of the ninth resistor and the tenth resistor is used to connect to the power supply, and the other end of the eleventh resistor and the twelfth resistor is grounded. Since the signal strength will be weakened after passing through the high-pass filter 132, by setting the third bias resistor module 1422, it can be ensured that the third triode works in an amplified state, thereby achieving the target signal to reach the required signal amplitude and compensating for the loss of the high-pass filter 132.

[0071] Similarly, since the third transistor also needs to be connected to the driving power supply, in order to effectively filter the driving power supply input signal, the second signal amplifier 142 also 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 and the twenty-third capacitor after being connected in parallel is electrically connected to the power supply, and the other end is grounded to achieve the effect of filtering the input voltage.

[0072] Furthermore, 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 is grounded.

[0073] As an implementation, see 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; wherein the fifth coupling module 1331 is used to filter out the DC signal in the target signal; the third two-stage filter circuit 1332 is used to filter out the carrier signal higher than the first target frequency, wherein the first target frequency is the highest frequency of the target signal.

[0074] Since there may still be a DC signal when the frequency selective amplifier 120 is working, the DC signal of the target signal needs to be filtered out by the fifth coupling module 1331. The target signal is then transmitted to the third two-stage filtering circuit 1332 for processing.

[0075] Optionally, the fifth coupling module 1331 includes a twenty-fourth capacitor and a twenty-fifth capacitor, one end of the twenty-fourth capacitor and the twenty-fifth capacitor connected in parallel 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 .

[0076] Among them, the third two-stage filtering 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, respectively, the other end of the seventh inductor is electrically connected to one end of the eighth inductor, the twenty-seventh capacitor and one end of the twenty-eighth capacitor, respectively, the other end of the eighth inductor is electrically connected to 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.

[0077] It can 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, so 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 filtering circuit 1332. Among them, the inductive reactance values ​​of the seventh inductor and the eighth inductor are both 380uF, and the capacitance values ​​of the twenty-sixth capacitor, the twenty-seventh capacitor, the twenty-eighth capacitor and the twenty-ninth capacitor are all 22nF, so that the third two-stage filtering circuit 1332 is used to attenuate the carrier signal higher than 57KHz. In other words, after the low-pass filtering is performed by the first low-pass filter 131, the present application can also be further filtered by the second low-pass filter 133, so that the filtering effect is better.

[0078] The invention uses the RDS frequency modulation stereo modulation chip 110 to replace the FPGA and DAC devices in the existing RDS signal generator, which are difficult to develop and have high device prices, thereby greatly reducing the development cost and device cost. Although the frequency selection amplifier circuit, the bandpass filter 130 and the signal amplifier 140 are added, these devices are all composed of ordinary resistors, capacitors, inductors, and triodes. Compared with the cost savings of reducing the FPGA and DAC devices, the cost is almost negligible. In addition, since FPGA devices are no longer used, the difficulty of product development is reduced and the research and development cycle is shortened. Since resistors, capacitors, triodes, and RDS frequency modulation stereo modulation chips 110 are widely used in ordinary consumer products, are easy to obtain, and are inexpensive, the actual cost is low and the technical requirements are low. It can be used in various occasions where RDS signals need to be generated but the implementation method needs to be simple and low-cost.

[0079] Based on the above embodiments, the embodiments of the present application further provide a signal generating system, which includes a signal receiving device and the above-mentioned signal generating circuit 100, and the signal receiving device is communicatively connected to the signal generating circuit 100 to achieve reception of the RDS signal.

[0080] In summary, the present application provides a signal generating circuit and system, the signal generating circuit includes a modulation chip, a frequency-selective amplifier, a bandpass filter and a signal amplifier, the modulation chip, the frequency-selective amplifier, the bandpass filter and the signal amplifier are electrically connected in sequence, wherein the modulation chip is used to generate a frequency-modulated carrier signal containing a target signal; the frequency-selective amplifier is used to separate and amplify the target signal from the frequency-modulated carrier signal; the bandpass filter is used to attenuate and filter out noise signals other than the target signal; the signal amplifier is used to amplify the target signal and compensate for the loss of the bandpass filter to output the target signal. Since the signal generating circuit provided by the present application abandons the existing complex and costly devices such as CPU, FPGA and DAC, and adopts relatively simple and cost-effective modules to form the signal generating circuit, the signal generating circuit provided by the present application is lower in cost as a whole, the circuit is simpler and the development difficulty is lower; at the same time, due to the processing of frequency-selective amplification, bandpass filter and signal amplification, the quality of the generated signal is also better.

[0081] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

[0082] It will be apparent to those skilled in the art that the present application is not limited to the details of the exemplary embodiments described above, and that the present application can be implemented in other specific forms without departing from the spirit or essential features of the present application. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the present application is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present application. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

Claims

1. A signal generating circuit, characterized in that: The circuit includes a modulation chip, a frequency-selective amplifier, a bandpass filter, and a signal amplifier, wherein the modulation chip, the frequency-selective amplifier, the bandpass filter, and the signal amplifier are electrically connected in sequence, wherein: The modulation chip is used to generate a frequency modulated carrier signal containing a target signal; The frequency selective amplifier is used to separate and amplify the target signal from the frequency modulated carrier signal; The bandpass filter is used to attenuate and filter out noise signals other than the target signal; The signal amplifier is used to amplify the target signal and compensate for the loss of the bandpass filter to output the target signal; The frequency selection amplifier includes a frequency selection module, a first switch tube and a first bias resistor module, wherein the 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, the second end of the first switch tube is electrically connected to the frequency selection module and the bandpass filter respectively, the frequency selection module is also used to connect the power supply, the second end of the first switch tube is also electrically connected to the bandpass filter, the 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 first bias resistor module is used to adjust the first switch 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; The frequency selective amplifier further comprises a first coupling module, one end of which is electrically connected to the modulation chip, and the other end of which is electrically connected to the first end of the first switch tube; wherein The first coupling module is used to filter out the DC signal in the frequency modulated carrier signal; 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 the first inductor are both electrically connected to the power supply, the other ends of the first capacitor and the first inductor are both electrically connected to the collector of the triode, and the base and emitter of the triode are both electrically connected to the bias resistor module; The bandpass 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; 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; Wherein, the second coupling module is used to filter out the DC signal in the target signal; The first two-stage filtering circuit is used to filter out carrier signals higher than a first target frequency, wherein the first target frequency is the highest frequency of the target signal; The first signal amplifier includes a third coupling module, a second switch tube and a second bias resistor module, the first end of the second switch tube is electrically connected to the third coupling module and the second bias resistor module respectively, and the 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 also electrically connected to the first low-pass filter, the second end of the second switch tube is also electrically connected to the power supply through the second bias resistor module, and the second end of the second switch tube is also used to be electrically connected to the high-pass filter, and the third end of the second switch tube is grounded through the second bias resistor module; wherein, The third coupling module is used to filter out the DC signal in the target signal; The second bias resistor module is used to adjust the second switch tube to work in an amplification state; The high-pass filter comprises 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 to filter out carrier signals lower than a second target frequency, and the second target frequency is the lowest frequency of the target signal; The second signal amplifier includes a fourth coupling module, a third switch tube, a load resistor and a third bias resistor module, the first end of the third switch tube is electrically connected to the fourth coupling module and the third bias resistor module respectively, and the first end of the third switch 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, the second end of the third switch tube is also electrically connected to the power supply through the third bias resistor module, and the second end of the third switch tube is electrically connected to the second low-pass filter, and the third end of the third switch tube is grounded through the third bias resistor module; wherein, The fourth coupling module is used to filter out the DC signal in the target signal; The third bias resistor module is used to adjust the third switch tube to operate in an amplification state.

2. A signal generating system, characterized in that: The signal generating system comprises a signal receiving device and the signal generating circuit as claimed in claim 1, wherein the signal receiving device is communicatively connected with the signal generating circuit.

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