Frequency modulation communication system based on surface acoustic wave filter array and frequency switching method

Abstract

The invention relates to the technical field of radio frequency communication, in particular to a frequency modulation communication system based on a surface acoustic wave filter array and a frequency switching method, the system comprises a surface acoustic wave filter array module, the surface acoustic wave filter array module comprises a plurality of surface acoustic wave filter branches which are connected in parallel and have different center frequencies, and each branch comprises at least one surface acoustic wave (SAW) filter; the input end of one radio frequency switch is used for receiving a broadband radio frequency signal, the output end of the radio frequency switch is connected with the input ends of the plurality of surface acoustic wave filter branches, the input end of the other radio frequency switch is connected with the output ends of the plurality of surface acoustic wave filter branches in a one-to-one correspondence manner, and the output end of the other radio frequency switch is used for outputting the filtered broadband radio frequency signal; and the control module sends parallel digital logic level control signals to the radio frequency switch module according to a preset frequency hopping sequence or an external instruction so as to gate a signal path corresponding to a target frequency. According to the scheme of the invention, the size and the integration cost of the frequency hopping system are effectively reduced while the excellent radio frequency performance is maintained.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of radio frequency communication technology. More particularly, the present application relates to a frequency modulation communication system based on a surface acoustic wave filter array and a frequency switching method. BACKGROUND

[0002] In modern wireless communication, electronic countermeasures and radar systems, frequency agility (or frequency hopping) capability is a key technology to improve the system's anti-interference, security and spectrum utilization. Frequency hopping communication technology is widely used in military, industrial control and other fields due to its good anti-interference and anti-interception capabilities. Traditional frequency hopping communication systems usually use frequency hopping filter banks composed of inductors, capacitors and other discrete components to achieve frequency switching, and send control instructions through a serial port (such as UART) to dynamically adjust the working frequency. In order to achieve this function, the system must include a filter unit that can quickly switch the working frequency according to the instructions.

[0003] Currently, one of the mainstream technical solutions to implement frequency hopping filter function is to use a single electrically tunable filter, such as a filter based on voltage-controlled varactor diode or YIG (yttrium iron garnet) technology. Its working principle is to change the resonant frequency of the filter through an external control signal, thereby selecting the signal of the target frequency band.

[0004] As shown in Figure 1 The existing frequency hopping system usually uses frequency hopping filter technology to achieve frequency switching, and its core is to send control instructions through a serial port to dynamically adjust the working frequency. In addition, the high voltage characteristics of the 28V power supply are easy to couple high-frequency noise, which leads to the degradation of the out-of-band rejection performance of the frequency hopping filter, and even causes frequency deviation. A typical existing frequency hopping system includes: an original signal input of 1.36-1.86GHz frequency band; a power divider for power dividing the input signal; a frequency hopping filter working under 28V high voltage to filter the signal to select a specific frequency band; and finally outputting the filtered signal. The specific composition is as follows:

[0005] Signal input: input the original signal of 1.3G-1.8G frequency band as the processing object;

[0006] Power divider: the signal enters the power divider, which divides the input radio frequency signal into power, and one way signal can be divided into multiple ways (the diagram is a simplified diagram of one way in and one way out, and the actual scene may be divided into multiple ways as needed), which is used for subsequent different processing or distribution to different loads, to ensure reasonable distribution of signal power;

[0007] Frequency hopping filter: working under 28V power supply, filtering the signal passing through the radio frequency switch, selecting specific signals within the 1.3G-1.8G frequency band, similar to a sieve, leaving the target frequency band "useful signal";

[0008] Signal output: After frequency hopping filter processing, output the filtered 1.3G-1.8G frequency band signal.

[0009] However, this technical solution exposes several inherent defects when dealing with increasingly stringent communication indicators. The existing small-size customized frequency hopping system has the following main shortcomings in hardware design, which limits its performance, cost and space optimization ability:

[0010] 1) Low space utilization: The existing frequency hopping filter is large in size, which is difficult to adapt to highly integrated compact design. The use of discrete components (such as large-size inductors and capacitors) leads to complex PCB layout, occupies too much space, and affects miniaturization requirements;

[0011] 2) Insufficient out-of-band rejection performance. The existing filter technology has limited out-of-band attenuation capability when wideband frequency hopping, which is easily affected by adjacent frequency bands. Power supply noise (such as 28V introduced ripple) may worsen the out-of-band rejection characteristics of the filter, affecting the system's anti-interference ability.

[0012] 3) Complex system design, high cost. Relying on high-precision frequency synthesizer and complex control circuit increases hardware complexity and BOM cost. Serial control mode requires additional FPGA support, further increasing system power consumption and cost.

[0013] 4) Switching speed is limited. The traditional filter has a long tuning time, which is difficult to meet the ultra-fast frequency hopping requirement. The instruction transmission delay of serial communication protocol (such as UART) may become the bottleneck of frequency hopping rate.

[0014] 5) Sensitive to power supply noise. The 28V power supply system is easy to introduce switching noise and conducted interference, affecting the frequency stability and signal purity of the filter, which requires additional filtering circuit, occupying more space.

[0015] Therefore, a new technical solution is needed to solve the technical problems of slow speed, limited performance and low integration of existing frequency hopping filters. SUMMARY

[0016] To solve the above technical problems of slow speed, limited performance and low integration of existing frequency hopping filters, the present application provides solutions in the following aspects.

[0017] In a first aspect, the present application provides a surface acoustic wave filter array based frequency hopping communication system, comprising: a surface acoustic wave filter array module, the surface acoustic wave filter array module comprising a plurality of surface acoustic wave filter branches connected in parallel, each branch comprising at least one surface acoustic wave filter and having a different center frequency; a radio frequency switch module, one radio frequency switch having an input end for receiving a wideband radio frequency signal and an output end connected to the input ends of the plurality of surface acoustic wave filter branches, another radio frequency switch having an input end connected to the output ends of the plurality of surface acoustic wave filter branches one by one and an output end for outputting a filtered wideband radio frequency signal; and a control module for sending parallel digital logic level control signals to the radio frequency switch module according to a preset frequency hopping sequence or external instructions to select the signal path corresponding to the target frequency, so that the wideband radio frequency signal is filtered through the selected surface acoustic wave filter branch.

[0018] In one embodiment, the surface acoustic wave filter array module comprises a plurality of surface acoustic wave filters, the passband ranges of which are connected to each other or partially overlap, and together cover the entire operating frequency band of the system.

[0019] In one embodiment, the entire operating frequency band of the frequency hopping communication system is 1.3 GHz to 1.8 GHz.

[0020] In one embodiment, the surface acoustic wave filter array module comprises 6 surface acoustic wave filters, and the coverage frequencies of the 6 surface acoustic wave filters are: 1300 MHz to 1400 MHz, 1380 MHz to 1480 MHz, 1460 MHz to 1560 MHz, 1540 MHz to 1640 MHz, 1620 MHz to 1720 MHz, and 1700 MHz to 1800 MHz.

[0021] In one embodiment, the out-of-band rejection capability of the plurality of surface acoustic wave filter branches at the edges of their respective passbands is not less than 29 dBc.

[0022] In one embodiment, the far-end rejection capability of the plurality of surface acoustic wave filter branches at the second harmonic frequency is not less than 40 dB.

[0023] In one embodiment, the insertion loss of the plurality of surface acoustic wave filter branches is less than 3 dB.

[0024] In one embodiment, the center frequency temperature drift coefficient of the plurality of surface acoustic wave filter branches is less than 50 ppm / ℃.

[0025] In one embodiment, the surface acoustic wave filter array module is integrated and packaged in a miniaturized package.

[0026] In a second aspect, the present application also provides a frequency switching method applied to the frequency modulation communication system based on the surface acoustic wave filter array in the one or more embodiments of the first aspect, comprising: obtaining a wideband radio frequency input signal; controlling the module to send a channel selection control signal to the radio frequency switch module according to a preset frequency hopping sequence or external instruction to select a specific signal path; the wideband radio frequency input signal enters the corresponding surface acoustic wave filter branch of the surface acoustic wave filter array for filtering processing through the selected path of the radio frequency switch; and the signal filtered by the surface acoustic wave filter branch is output through the radio frequency switch.

[0027] The present application has the advantages that: the frequency modulation communication system and the frequency switching method based on the surface acoustic wave filter array in the present application solve the problems of low space utilization and weak out-of-band suppression ability of the original method, in terms of space utilization, the present application adopts the miniaturized packaging surface acoustic wave filter array technology, cooperates with the high integration radio frequency switch technology, and has flexible frequency switching and efficient signal processing functions, so that the volume of the overall solution is greatly optimized compared with the original frequency hopping filter solution, and the layout flexibility is higher, which provides reliable technical support for miniaturized design. In terms of radio frequency performance, the present application fully utilizes the out-of-band suppression ability of the surface acoustic wave filter, and realizes the gapless continuous frequency coverage through the precise filter array frequency point matching technology. The present application successfully solves the technical bottlenecks of large volume and high cost existing in the traditional frequency hopping system while maintaining excellent radio frequency performance, provides an ideal solution for the new generation of compact frequency hopping communication equipment, and has important engineering application value and broad market prospect.

[0028] Further, the out-of-band suppression of the surface acoustic wave filter in the present application is 29dBc at 1.28G and 1.82G frequency points, which is higher than that of the frequency hopping filter under the same volume. BRIEF DESCRIPTION OF DRAWINGS

[0029] The above and other objects, features and advantages of the exemplary embodiments of the present application will be more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which several embodiments of the present application are shown by way of example, and wherein like reference numerals refer to like elements throughout. In the drawings:

[0030] Figure 1 is a schematic diagram of a frequency hopping system in the prior art;

[0031] Figure 2 is a schematic diagram showing a frequency modulation communication system based on a surface acoustic wave filter array according to an embodiment of the present application;

[0032] Figure 3 is a flowchart showing a frequency switching method applied to a frequency modulation communication system according to an embodiment of the present application. DETAILED DESCRIPTION

[0033] 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. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of the present application.

[0034] The embodiments of the present application aim to solve the technical problems of low space utilization, insufficient out-of-band suppression performance, complex system design, slow switching speed, and sensitivity to power supply noise caused by using a single frequency hopping filter for frequency switching in the prior art. The present application proposes a frequency modulation communication system and a frequency switching method based on a surface acoustic wave filter array, which realizes the miniaturization, high performance, and fast frequency switching of the system by using a miniaturized surface acoustic wave filter (SAW) array and a high-integration radio frequency switch.

[0035] The exemplary embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0036] Figure 2 is a schematic diagram showing a frequency modulation communication system based on a surface acoustic wave filter array according to an embodiment of the present application.

[0037] As shown in Figure 2 , the present application uses a high-integration switch filter and a miniaturized surface acoustic wave filter for modular design, and realizes frequency switching by controlling the switch filter group. The system is used for fast frequency selection and filtering of input broadband radio frequency signals. In one implementation scenario, the system can include a radio frequency switch module, a surface acoustic wave filter array module, and a control module not shown in the figure. The radio frequency switch connects the filter corresponding to the center frequency to the signal path according to the on-off of the control level, realizes frequency switching, and at the same time the surface acoustic wave filter further filters the passing signal, filters out the out-of-band signal interference by using its high selectivity and good out-of-band suppression characteristics, and improves the signal quality.

[0038] Specifically, the present application proposes a frequency modulation communication system based on a surface acoustic wave filter array, which includes:

[0039] The surface acoustic wave filter array module includes a plurality of parallelly connected surface acoustic wave filter branches with different center frequencies, and each branch includes at least one SAW filter. In some embodiments, the surface acoustic wave filter array module includes a plurality of SAW filters, and the passband ranges of the SAW filters are connected to each other or partially overlap, and together cover the entire working frequency band of the system.

[0040] The acoustic surface filter array is composed of multiple SAW filters with different center frequencies in parallel. In one application scenario, the array can specifically include six SAW filters, the frequency ranges of which are connected to each other or partially overlap, and together cover the entire working frequency band of 1.3-1.8 GHz. When a critical connection mode of end-to-end connection is adopted, the upper limit cutoff frequency of the last filter is required to be equal to the lower limit cutoff frequency of the next filter.

[0041] The existence of partial overlap in the frequency range, i.e., the existence of an overlapping region between the passband of the last filter and the passband of the next filter, can ensure that at any point in the entire target frequency range (such as 1.3-1.8 GHz), at least one filter can provide good passband performance, completely eliminating the blind area. In the overlapping region, both channels of the system can process signals. This provides a certain degree of redundancy for frequency switching, and if the performance of a certain channel deviates slightly, the other channel can make up for it. At the same time, during frequency hopping, if the target frequency point falls within the overlapping region, the filter with better performance can be selected, thereby achieving smoother performance transition. Based on this, in the present embodiment, the multiple SAW filters are preferably arranged in a manner in which the frequency range partially overlaps.

[0042] It should be noted that the number of filters in the array is only exemplary and not limiting, and those skilled in the art can select a suitable number according to actual needs. For example, 4 or 8 SAW filters are selected to divide the working frequency band.

[0043] The radio frequency switch module includes one radio frequency switch, the input end of which is used to receive a wideband radio frequency signal, and the output end of which is connected to the input ends of the multiple SAW filter branches; and another radio frequency switch, the input end of which is connected to the output ends of the multiple acoustic surface filter branches one by one, and the output end of which is used to output a filtered wideband radio frequency signal. The radio frequency switch module is the core executive component for realizing the frequency switching function, and the selection of the radio frequency switch module directly determines the key performance indicators of the system, such as switching speed, insertion loss, isolation, and power capacity. In some embodiments, the radio frequency switch module can adopt an integrated single-pole multi-throw (SPnT) absorption switch chip based on GaAs pHEMT or SOI technology, etc., which can meet most frequency hopping applications with a switching speed of microseconds, and has excellent isolation and insertion loss indicators. The single-chip integrates all switch units and control circuits, has few peripheral components, greatly saves the PCB area, and meets the requirements of "miniaturization" and "high integration". It usually supports CMOS / TTL level direct control, and the interface with the MCU is very simple, without the need for complex driving circuits. The best balance between performance and cost is achieved, which is conducive to reducing system cost and mass production applications.

[0044] A control module is configured to send a parallel digital logic level control signal to the radio frequency switch module according to a preset frequency hopping sequence or an external instruction, so as to select a signal path corresponding to a target frequency, and thus the wideband radio frequency signal is filtered by the selected SAW filter branch.

[0045] The whole working frequency band of the frequency modulation communication system can be 1.3 GHz to 1.8 GHz. As an example, the surface acoustic wave filter array module includes six SAW filters, and the six SAW filters cover the frequency bands of 1300 MHz to 1400 MHz, 1380 MHz to 1480 MHz, 1460 MHz to 1560 MHz, 1540 MHz to 1640 MHz, 1620 MHz to 1720 MHz, and 1700 MHz to 1800 MHz. The out-of-band rejection capability of the plurality of SAW filter branches at the edges of their respective passbands is not less than 29 dBc. The far-end rejection capability at the second harmonic frequency is not less than 40 dB. The insertion loss is less than 3 dB. In addition, the center frequency temperature drift coefficient of the plurality of SAW filter branches is less than 50 ppm / ℃.

[0046] Further, the surface acoustic wave filter array module can be integrated and packaged in a miniaturized package.

[0047] As shown in Figure 3 A frequency switching method based on a surface acoustic wave filter array provided by an embodiment of the present application can include the following steps:

[0048] In step S301, a wideband radio frequency input signal is obtained. As an example, the frequency range of the input signal can be 1.3 GHz to 1.8 GHz. The signal as the original signal for subsequent processing contains a plurality of potential target communication frequency bands. It should be noted that the frequency range of the input signal is only exemplary and not limiting, and those skilled in the art can configure the parameters of the components in the system according to actual needs to process signals of other frequency ranges.

[0049] In step S302, a control module sends a channel selection control signal to a radio frequency switch module according to a preset frequency hopping sequence or an external instruction, so as to select a specific signal path. Through the selection of the radio frequency switch module, the radio frequency switch determines the signal to enter a certain surface acoustic wave filter branch and outputs a certain signal.

[0050] Unlike the prior art which sends complex instructions using serial communication protocols such as UART, the present embodiment can use simple parallel digital logic signals (such as GPIO levels) to control the RF switches. For example, when the acoustic surface filter array contains 6 filters, the control module only needs to output a 3-bit binary code to uniquely determine a signal path. This direct logic level control greatly simplifies the design of the control circuit and significantly shortens the delay of instruction transmission and decoding.

[0051] In order to analyze the beneficial effects of the present application on switching speed, the following logical relationship can be constructed. Assume that the total frequency switching time of the system is T total In the prior art, its switching time T total,prior is mainly composed of serial instruction transmission time T command and filter tuning time T tune , that is: T total,prior = T command + T tune .

[0052] And in the embodiment of the present application, its switching time T total,new is mainly composed of control logic transmission delay T control and RF switch establishment time T switch , that is: T total,new = T control + T switch . In the above formula, T command is the time required to complete a serial instruction sending and parsing, usually in the order of milliseconds (ms); T tune is the time required for the tunable filter to stabilize to the new frequency point, also in the order of milliseconds (ms). And T control is the transmission delay of digital logic level, usually in the order of nanoseconds (ns); T switch is the on-off establishment time of modern RF switches, usually in the order of nanoseconds (ns) to microseconds (μs). It can be understood that T command >> T control and T tune >> T switch , therefore, the total switching time T total,new of the embodiment of the present application is much smaller than T total,prior of the prior art, thus realizing ultra-fast frequency switching and meeting the demand of modern communication systems for high frequency hopping rate.

[0053] In step S303, the input signal is filtered by the corresponding SAW filter branch in the SAW filter array via the selected path of the radio frequency switch. Different SAW filters correspond to different frequency bands (such as 1400 MHz, 1480 MHz, etc.), filter signals, filter specific frequency bands, and suppress out-of-band interference.

[0054] The SAW filter array in the present application is composed of a plurality of SAW filters with different center frequencies connected in parallel. In the present embodiment, the array can specifically include six SAW filters, the frequency bands of which are connected to each other or partially overlap, and together cover the entire working frequency band of 1.3 GHz to 1.8 GHz. For example, the six filters can cover 1300 MHz-1400 MHz, 1380 MHz-1480 MHz, 1460 MHz-1560 MHz, 1540 MHz-1640 MHz, 1620 MHz-1720 MHz, and 1700 MHz-1800 MHz, respectively. When the radio frequency switch selects one path, only the specific frequency band signal corresponding to the branch can pass through, and signals of other frequency bands are effectively suppressed.

[0055] As a preferred solution, the SAW filter has excellent out-of-band suppression and far-end suppression performance. In the preferred aspect, in the present embodiment, the out-of-band suppression capability of each SAW filter at the edge of its passband (for example, at the frequency points of 1.28 GHz and 1.82 GHz) is preferably not less than 29 dBc. When the out-of-band suppression performance is lower than this value, the system is easily disturbed by strong signals in adjacent channels during frequency switching, resulting in an increase in communication error rate. Therefore, controlling the out-of-band suppression to be above 29 dBc can ensure that the system still has high communication reliability in a complex electromagnetic environment.

[0056] Further, the far-end suppression of the SAW filter at the second harmonic frequency 2f0 is preferably not less than 40 dB. When the far-end suppression is insufficient, the harmonics generated by the system itself or strong far-end interference signals from the outside may be mistaken for valid signals, affecting the communication quality. Keeping the far-end suppression capability above 40 dB can effectively filter out such interference and improve the purity of the signal.

[0057] In addition, the insertion loss of the SAW filter is preferably controlled to be below 3 dB. Excessive insertion loss will significantly attenuate the power of the useful signal, reducing the signal-to-noise ratio of the receiver. Controlling the insertion loss to a lower level helps to maintain the link budget and ensure the communication distance and quality. At the same time, the SAW filter used in the present application has good temperature stability.

[0058] As a preferred scheme, the temperature drift coefficient of the center frequency is less than 50ppm / ℃, which ensures the accuracy and stability of the frequency of the device in a wide temperature working range (for example, -40℃ to +85℃).

[0059] In step S304, the signal filtered by the surface acoustic wave filter branch is output through the radio frequency switch. Since the surface acoustic wave filter has good out-of-band suppression characteristics, the target signal of 1.3G-1.8G frequency band is very clean after being processed by each filter. Thus, the frequency switching and filtering of the signal can be efficiently completed in a small space, which greatly improves the signal quality, improves the space utilization, and reduces the development cost. Due to the high selectivity of the SAW filter, the output signal is the purified target frequency band signal, and the out-of-band noise and interference has been greatly reduced. The signal can be sent to the downstream amplification, demodulation and other radio frequency links for further processing.

[0060] It can be understood that, by using the miniaturized packaged SAW filter array to replace the bulky conventional frequency hopping filter, and combining with the high-integration radio frequency switch, the physical size and PCB area of the overall scheme are significantly reduced, and the space utilization is improved.

[0061] Meanwhile, the 28V power supply module which is easy to introduce high-frequency noise is abandoned, and a standard low-voltage DC power supply (for example, 3.3V or 5V) is used to supply power for the control circuit and the radio frequency switch, which fundamentally eliminates the noise interference introduced by the power supply ripple, and ensures the stability and reliability of the filtering performance. The entire system uses 3.3V or 5V low-voltage power supply, and the power supply circuit is simple and does not need additional noise filtering design. All surface acoustic wave filters and radio frequency switches use 0402 or 0603 surface-mounted components, which can be densely arranged on a small PCB, and a very high space utilization is achieved.

[0062] In summary, the application adopts miniaturized packaged acoustic surface filter array and high-integration radio frequency switch to replace bulky traditional frequency hopping filter, greatly reduces system volume, and provides reliable guarantee for device miniaturization. The acoustic surface filter itself has high selectivity and good out-of-band suppression characteristics (such as out-of-band suppression of 1.28G / 1.82G frequency point reaches 29dBc, and far-end suppression at 2f0 reaches 40dB), and through array design, high-performance continuous frequency band coverage is achieved, which significantly improves system anti-interference ability and signal quality. At the same time, according to the design of the application, complex frequency synthesizer, FPGA control circuit and 28V power supply module are omitted, which simplifies the system architecture, significantly reduces the hardware complexity, power consumption and overall cost. Through the radio frequency switch, different fixed filter paths are directly selected, and the switching speed is only determined by the switching time of the radio frequency switch, which can reach microseconds, which is much faster than the tuning speed of the traditional filter, and meets the ultra-fast frequency hopping requirement. Low-voltage power supply is adopted to avoid the introduction of power supply noise, and the system works more stably and reliably.

[0063] Based on this, the application successfully solves the technical bottlenecks of traditional frequency hopping system in space, performance, speed and cost through flexible frequency switching, efficient signal processing, miniaturized packaging design and high cost-effective implementation mode, and provides an ideal solution for the new generation of compact and high-performance frequency modulation communication equipment.

[0064] Although the present application has shown and described several embodiments of the present application, it will be apparent to those skilled in the art that many modifications, changes and substitutions can be made thereto without departing from the spirit and scope of the present application. It is to be understood that various alternatives to the embodiments of the application described herein can be employed in practicing the present application.

Claims

1. A frequency-modulated communication system based on an array of surface acoustic wave filters, characterized in that, The application relates to a frequency hopping communication system, comprising: a surface acoustic wave filter array module, which comprises a plurality of parallelly connected surface acoustic wave filter branches with different center frequencies, each of which comprises at least one SAW filter; a radio frequency switch module, one radio frequency switch of which is used for receiving a wideband radio frequency signal and its output end is connected with the input ends of the plurality of surface acoustic wave filter branches, and another radio frequency switch of which is connected with the output ends of the plurality of surface acoustic wave filter branches one by one and its output end is used for outputting a filtered wideband radio frequency signal; a control module, which is used for sending parallel digital logic level control signals to the radio frequency switch module according to a preset frequency hopping sequence or external instruction, so as to select a signal path corresponding to a target frequency, and make the wideband radio frequency signal pass through the selected surface acoustic wave filter branch for filtering processing.

2. The frequency-modulated communication system based on an array of surface acoustic wave filters according to claim 1, characterized in that, The surface acoustic wave filter array module comprises a plurality of SAW filters, the passband ranges of which are connected with each other or partially overlapped, and the entire working frequency band of the system is covered.

3. The frequency-modulated communication system based on an array of surface acoustic wave filters according to claim 2, characterized in that, The entire working frequency band of the frequency modulation communication system is 1.3GHz to 1.8GHz.

4. The frequency-modulated communication system based on an array of surface acoustic wave filters according to claim 3, characterized in that, The surface acoustic wave filter array module comprises six SAW filters, and the covered frequencies of the six SAW filters are 1300MHz to 1400MHz, 1380MHz to 1480MHz, 1460MHz to 1560MHz, 1540MHz to 1640MHz, 1620MHz to 1720MHz and 1700MHz to 1800MHz.

5. The acoustic surface filter array based frequency modulation communication system of claim 1, wherein, The out-of-band rejection capability of the plurality of surface acoustic wave filter branches at the edges of the respective passbands is not less than 29dBc.

6. The frequency-modulated communication system based on an array of surface acoustic wave filters according to claim 5, characterized in that, The far-end rejection capability of the plurality of surface acoustic wave filter branches at a second harmonic frequency is not less than 40dB.

7. The acoustic surface filter array based frequency modulation communication system of claim 1, wherein, The insertion loss of the plurality of surface acoustic wave filter branches is less than 3dB.

8. The acoustic surface filter array based frequency modulation communication system of claim 1, wherein, The center frequency temperature drift coefficient of the plurality of surface acoustic wave filter branches is less than 50ppm / deg C.

9. The acoustic surface filter array based frequency modulation communication system of claim 1, wherein, The surface acoustic wave filter array module is integrated and packaged in a miniaturized package.

10. A frequency switching method applied to the frequency modulation communication system based on the surface acoustic wave filter array as claimed in any one of claims 1 to 9, characterized by, The application relates to a frequency hopping communication system, comprising: acquiring a wideband radio frequency input signal; a control module, which is used for sending a channel selection control signal to the radio frequency switch module according to a preset frequency hopping sequence or external instruction, so as to select a specific signal path; the wideband radio frequency input signal enters corresponding surface acoustic wave filter branches in the surface acoustic wave filter array through the path selected by the radio frequency switch for filtering processing; the signal filtered by the surface acoustic wave filter branches is output through the radio frequency switch.

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