A shortwave broadband frequency selection method

Abstract

This invention relates to the field of shortwave communication technology and discloses a shortwave broadband frequency selection method. This invention utilizes a collaborative mechanism of narrowband detection signal and broadband noise floor monitoring to enable traditional narrowband shortwave equipment to achieve accurate frequency selection for 12kHz / 24kHz broadband communication without hardware upgrades. This method combines narrowband signal-to-noise ratio evaluation with broadband spectrum analysis to ensure optimal communication quality for the selected frequency in both narrowband and broadband ranges. It effectively solves the problem that traditional narrowband frequency selection cannot adapt to broadband services, and also possesses advantages such as environmental adaptability, high computational efficiency, and strong compatibility, significantly improving the reliability and economy of shortwave broadband communication.

Description

Technical Field

[0001] This invention relates to the field of shortwave communication technology, and in particular to a shortwave broadband frequency selection method. Background Technology

[0002] Shortwave communication, also known as high-frequency (HF) communication, uses electromagnetic waves in the frequency range of 1.6MHz to 30MHz for wireless communication. Traditionally, shortwave communication is mostly used for narrowband communication (typically 3kHz bandwidth), providing data transmission rates of tens to thousands of bits per second for transmitting signaling, messages, voice, and small files. In recent years, with the development of shortwave technology and equipment, shortwave communication has moved towards broadband, providing higher bandwidth (such as 12kHz or 24kHz bandwidth) and faster data transmission rates to meet the transmission needs of large files, images, faxes, and other services. However, due to the specific characteristics of shortwave products in terms of users, application scenarios, and application scope, the process from technological breakthroughs to product development, small-batch trials, and mass production generally takes several years or even more than a decade. Therefore, users often continue to use a large number of older devices. Given the relatively long lifespan of shortwave products, how to leverage existing user products to keep pace with technological advancements and maximize their performance has become a major concern for both shortwave product suppliers and users.

[0003] Traditional narrowband shortwave communication equipment (such as shortwave radios and shortwave channel controllers) is designed for shortwave narrowband (3kHz) service transmission. Due to hardware limitations, it cannot provide shortwave broadband (12kHz or 24kHz) service transmission capabilities, but the hardware generally has shortwave broadband reception capabilities. Therefore, it can be upgraded to have shortwave broadband reception capabilities through broadband software modifications. However, shortwave wireless communication is greatly affected by factors such as season, daytime, environment, distance, and ionosphere. Therefore, selecting a high-quality, real-time available shortwave frequency is crucial to improving shortwave broadband service capabilities.

[0004] Current narrowband frequency selection methods generally utilize shortwave narrowband communication equipment to directly perform narrowband frequency selection based on real-time detection of the 3kHz shortwave narrowband channel. The receiver evaluates the signal-to-noise ratio (SNR) of the transmitter's signal and then feeds the result back to the receiver, allowing both parties to select the optimal transmit / receive frequency with the best SNR. The specific process is as follows: Figure 1 As shown. While the 3kHz frequency selected by narrowband frequency selection is optimal for narrowband communication, it doesn't necessarily guarantee optimal communication over the 12kHz or 24kHz wideband range. If one or more strong interference signals exist outside the 3kHz range but within the 12kHz or 24kHz range, communication over the entire 12kHz or 24kHz wideband range will be relatively poor. Specifically, as shown... Figure 2 As shown.

[0005] Therefore, there is an urgent need for a shortwave broadband frequency selection method to quickly and accurately select a frequency that can achieve good communication quality in both the 3kHz and 12kHz / 24kHz ranges when using traditional narrowband shortwave communication equipment. Summary of the Invention

[0006] This invention provides a shortwave broadband frequency selection method to overcome the shortcomings of existing technologies.

[0007] This invention provides a shortwave broadband frequency selection method, implemented based on shortwave radio station A and shortwave radio station B, the method comprising:

[0008] Send first narrowband detection signals of different frequencies from shortwave radio station A to shortwave radio station B;

[0009] Based on the first narrowband detection signals at different frequencies, the signal-to-noise ratio and noise floor are evaluated at different frequency points using shortwave radio station B, and the optimal broadband frequency fx in the direction from shortwave radio station A to shortwave radio station B is selected.

[0010] The second narrowband detection signal at different frequencies is transmitted from shortwave radio station B to shortwave radio station A. The second narrowband detection signal at different frequencies includes the second narrowband detection signal at the broadband optimal frequency fx.

[0011] Based on the second narrowband detection signals at different frequencies, the signal-to-noise ratio and noise floor are evaluated at different frequency points using shortwave radio station A, and the optimal broadband frequency fy in the direction from shortwave radio station B to shortwave radio station A is selected.

[0012] According to a shortwave broadband frequency selection method provided by the present invention, the signal-to-noise ratio evaluation includes the following steps:

[0013] Based on narrowband detection signals of different frequencies, the signal-to-noise ratio at different frequency points is obtained;

[0014] Based on the signal-to-noise ratio (SNR) of different frequency points, filter out frequency points whose SNR is not within the preset SNR range;

[0015] Based on the signal-to-noise ratio, the filtered frequency points are sorted in descending order. The sorted frequency points are then used for subsequent noise floor monitoring within a preset bandwidth range.

[0016] According to the present invention, a shortwave broadband frequency selection method is provided, wherein the preset bandwidth range is 12kHz or 24kHz.

[0017] According to the present invention, a shortwave broadband frequency selection method includes the following steps for noise floor monitoring:

[0018] Based on narrowband detection signals of different frequencies, the noise floor monitoring index data of different frequency points within the preset bandwidth range are obtained;

[0019] Based on the noise floor monitoring data of different frequency points within the preset bandwidth range, the optimal broadband frequency is selected from different frequency points using preset screening conditions.

[0020] According to a shortwave broadband frequency selection method provided by the present invention, the noise floor monitoring index includes any one of the following or any combination thereof: average noise floor, noise floor spectrum, and interference signal amplitude.

[0021] According to a shortwave broadband frequency selection method provided by the present invention, the step of selecting the optimal broadband frequency from different frequency points based on noise floor monitoring index data of different frequency points within a preset bandwidth range and using preset screening conditions includes:

[0022] Based on the noise floor monitoring data of different frequency points within the preset bandwidth range, the frequency point with the lowest average noise floor, the flattest noise floor spectrum, and no interference signals exceeding the preset amplitude range is selected from the sorted frequency points and taken as the optimal broadband frequency.

[0023] According to the present invention, a shortwave broadband frequency selection method includes the following steps for noise floor monitoring:

[0024] Based on narrowband detection signals of different frequencies, and taking the real-time detection frequency as the center, perform multiple consecutive Fourier transforms (FFTs) within a preset bandwidth range to obtain the average value and variance of the shortwave signal energy within the preset bandwidth range centered on that frequency.

[0025] Based on the average energy of shortwave signals at different frequencies, the different frequencies are sorted in ascending order.

[0026] Different frequency points are selected based on the variance of shortwave signal energy. The frequency point with the highest variance that meets the preset conditions is selected first and is then used as the optimal broadband frequency.

[0027] According to the present invention, a shortwave broadband frequency selection method is provided, wherein the preset condition is that the variance is the lowest or the variance is within a preset variance range.

[0028] A shortwave broadband frequency selection method provided by the present invention further includes the following steps:

[0029] By sending a response from shortwave radio station A to shortwave radio station B on the broadband optimal frequency fx, it notifies shortwave radio station B that its broadband optimal frequency is fy.

[0030] By sending a response from shortwave radio B to shortwave radio A on the optimal broadband frequency fy, the frequency selection of shortwave radio A is successfully completed.

[0031] The shortwave broadband frequency selection method provided by this invention has at least the following beneficial effects:

[0032] 1. Improved compatibility and cost-effectiveness

[0033] By employing a collaborative mechanism of narrowband detection signals and broadband noise floor monitoring, traditional narrowband shortwave communication equipment (such as 3kHz bandwidth radios) can achieve precise frequency selection for 12kHz / 24kHz broadband communication without hardware upgrades. This effectively solves the technical bottleneck of older user-side equipment being unable to adapt to broadband services, significantly extends the service life of existing equipment, and reduces the hardware costs of broadband upgrades.

[0034] 2. Broadband communication quality assurance

[0035] This innovative approach combines narrowband signal-to-noise ratio (SNR) assessment with noise floor monitoring within a preset bandwidth: initial channel quality screening (SNR filtering and ranking) is achieved through multi-frequency narrowband detection, and broadband spectrum analysis based on FFT transform (multi-dimensional evaluation of average noise floor, spectral flatness, interference signal amplitude, etc.) dynamically selects the frequency point with the optimal variance as the broadband center frequency. This ensures that the selected frequency has optimal communication stability in both the 3kHz narrowband and 12kHz / 24kHz broadband ranges, avoiding broadband frequency band interference problems caused by narrowband frequency selection in traditional methods.

[0036] 3. Adapting to environmental changes

[0037] By adopting a bidirectional detection mechanism (independent frequency selection for shortwave radio stations A→B and B→A) and introducing real-time broadband noise floor monitoring indicators, it can dynamically adapt to shortwave channel-specific interferences such as ionospheric changes and multipath effects, significantly improving frequency selection robustness in complex electromagnetic environments.

[0038] 4. Optimized operational efficiency

[0039] By quickly filtering low-quality frequency points within a preset signal-to-noise ratio range and prioritizing the selection of high-potential frequency bands for broadband analysis using a sorting algorithm, the computational complexity is significantly reduced compared to full-bandwidth scanning, enabling minute-level rapid frequency selection to meet the real-time requirements of scenarios such as emergency communications.

[0040] 5. Standardized expansion capabilities

[0041] The defined noise floor monitoring index system (average noise floor, spectral flatness, etc.) and screening conditions can be flexibly configured, supporting different broadband standards such as 12kHz / 24kHz, providing technical expansion space for the future evolution of higher bandwidth shortwave communication. Attached Figure Description

[0042] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0043] Figure 1 This is a flowchart illustrating an existing narrowband frequency selection method.

[0044] Figure 2 This diagram illustrates a scenario where one or more high-energy interference signals exist outside the 3kHz range and within the 12kHz or 24kHz range in an existing narrowband frequency selection method.

[0045] Figure 3 This is a flowchart illustrating a shortwave broadband frequency selection method provided by the present invention.

[0046] Figure 4 This is a schematic diagram of noise floor monitoring in a shortwave broadband frequency selection method provided by the present invention. Detailed Implementation

[0047] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, embodiments of this invention, and should not be construed as limiting the invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention. In the description of this invention, it should be understood that the terminology used is for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0048] Traditional shortwave radios refer to wireless communication within a 3kHz bandwidth as narrowband communication, which was the primary wireless communication method used by traditional shortwave radios. With advancements in shortwave wireless communication technology and the increasing demand for high-bandwidth communication, shortwave gradually introduced 12kHz or 24kHz bandwidth wireless communication technologies, known as shortwave broadband communication. Higher bandwidth provides higher transmission rates, but places higher demands on the quality of shortwave wireless channel conditions. This manifests as a higher signal-to-noise ratio and better noise floor in the 12kHz or 24kHz bandwidth, ensuring high-speed and stable signal transmission for subsequent broadband services at these frequencies.

[0049] The core idea of ​​this invention is to sort the frequencies based on their connectivity and signal-to-noise ratio by narrowband detection of real-time signals between two shortwave radio stations at different frequencies, perform secondary screening based on broadband noise floor monitoring among multiple preferred frequencies, and finally select the optimal frequency suitable for broadband communication.

[0050] Figure 3 This is a flowchart illustrating a shortwave broadband frequency selection method provided by the present invention.

[0051] See Figure 3The present invention provides a shortwave broadband frequency selection method, implemented based on shortwave radio station A and shortwave radio station B, and the method may include:

[0052] The first narrowband detection signal of different frequencies is sent sequentially from shortwave radio station A to shortwave radio station B.

[0053] Based on the first narrowband detection signals at different frequencies, the signal-to-noise ratio and noise floor are evaluated at different frequency points using shortwave radio station B, and the optimal broadband frequency fx in the direction from shortwave radio station A to shortwave radio station B is selected.

[0054] The second narrowband detection signal at different frequencies is transmitted from shortwave radio station B to shortwave radio station A. The second narrowband detection signal at different frequencies includes the second narrowband detection signal at the broadband optimal frequency fx.

[0055] Based on the second narrowband detection signals at different frequencies, the signal-to-noise ratio and noise floor monitoring of different frequency points are performed using shortwave radio station A, and the optimal broadband frequency fy in the direction from shortwave radio station B to shortwave radio station A is selected.

[0056] By sending a response from shortwave radio station A to shortwave radio station B on the broadband optimal frequency fx, it notifies shortwave radio station B that its broadband optimal frequency is fy.

[0057] By sending a response from shortwave radio B to shortwave radio A on the optimal broadband frequency fy, the frequency selection of shortwave radio A is successfully completed.

[0058] In one embodiment, signal-to-noise ratio evaluation includes the following steps:

[0059] Based on narrowband detection signals of different frequencies, the signal-to-noise ratio at different frequency points is obtained;

[0060] Based on the signal-to-noise ratio (SNR) of different frequency points, filter out frequency points whose SNR is not within the preset SNR range;

[0061] Based on the signal-to-noise ratio, the filtered frequency points are sorted in descending order. The sorted frequency points are then used for subsequent noise floor monitoring within a preset bandwidth range, which can be either 12kHz or 24kHz.

[0062] In one embodiment, noise floor monitoring includes the following steps:

[0063] Based on narrowband detection signals of different frequencies, noise floor monitoring index data at different frequency points within a preset bandwidth range are obtained. The noise floor monitoring index includes any one of the following or any combination thereof: average noise floor, noise floor spectrum, and interference signal amplitude.

[0064] Based on the noise floor monitoring data of different frequency points within the preset bandwidth range, the frequency point with the lowest average noise floor, the flattest noise floor spectrum, and no interference signals exceeding the preset amplitude range is selected from the sorted frequency points and taken as the optimal broadband frequency.

[0065] See Figure 4 The receiving shortwave radio station received three narrowband frequency-selective probe signals at frequencies f1, f2, and f3, respectively, and the signal-to-noise ratio (SNR) of each signal was above the required frequency selection threshold. Assuming the frequency selection requirement is to find the optimal frequency with a 12kHz bandwidth, noise floor monitoring was performed on each of the three frequencies, analyzing noise floor data over a 12kHz bandwidth (6kHz to the left and right of each frequency). If the average noise floor is the lowest, the noise floor spectrum is the flattest, and there are no interference signals exceeding a certain amplitude within the 12kHz bandwidth, then that frequency is determined to be the optimal frequency for the 12kHz bandwidth. Figure 4 As shown, there are high-energy interference signals near frequency f1, and frequency f2 has a significantly lower noise floor than frequencies f1 and f3. Therefore, frequency f2 is selected as the optimal frequency for a 12kHz bandwidth.

[0066] In one embodiment, noise floor monitoring includes the following steps:

[0067] Based on narrowband detection signals of different frequencies, and taking the real-time detection frequency as the center, perform multiple consecutive Fourier transforms (FFTs) within a preset bandwidth range to obtain the average value and variance of the shortwave signal energy within the preset bandwidth range centered on that frequency.

[0068] Based on the average energy of shortwave signals at different frequencies, the different frequencies are sorted in ascending order.

[0069] Different frequency points are screened according to the variance of shortwave signal energy. The frequency points with the lowest variance or variance within the preset variance range and the highest ranking are selected first and are taken as the broadband optimal frequency.

[0070] The calculated average energy value and variance can be used to comprehensively reflect the "average noise floor, noise floor spectrum, and interference signal." The average energy value reflects the level of the "average noise floor"; the lower the average value, the lower the average noise floor. The energy variance reflects the "noise floor spectrum and interference signal"; the lower the energy variance, the flatter the noise floor spectrum within that frequency band, indicating the absence of significant interference signals. Conversely, a higher energy variance indicates an uneven noise floor spectrum within the frequency band, suggesting the high likelihood of interference signals.

[0071] The shortwave broadband frequency selection method proposed in this invention has several technical advantages: First, the method adopts an innovative mechanism combining narrowband detection and broadband monitoring, enabling existing narrowband communication equipment to support 12kHz / 24kHz broadband communication without hardware modifications, significantly improving equipment compatibility and reducing upgrade costs; second, by comprehensively utilizing narrowband signal-to-noise ratio evaluation and FFT-based broadband spectrum analysis technology, it ensures that the selected frequency points provide optimal communication quality in both narrowband and broadband ranges; third, the bidirectional detection design and real-time monitoring function effectively cope with environmental interference such as ionospheric changes, enhancing the system's environmental adaptability; in addition, the optimized frequency selection algorithm significantly improves frequency selection efficiency and enables rapid response; finally, the standardized monitoring index system provides a good technical foundation for future bandwidth expansion.

[0072] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0073] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A shortwave broadband frequency selection method, implemented based on shortwave radio station A and shortwave radio station B, characterized in that, include: Send first narrowband detection signals of different frequencies from shortwave radio station A to shortwave radio station B; Based on the first narrowband detection signals at different frequencies, the signal-to-noise ratio and noise floor are evaluated at different frequency points using shortwave radio station B, and the optimal broadband frequency fx in the direction from shortwave radio station A to shortwave radio station B is selected. Selecting the optimal shortwave broadband frequency involves the following steps: Based on narrowband detection signals of different frequencies, and taking the real-time narrowband detection frequency as the center, perform multiple consecutive Fourier transforms within a preset bandwidth range to obtain the average value and variance of the shortwave signal energy within a preset bandwidth range centered on that frequency. Based on the average energy of shortwave signals at different frequencies, the different frequencies are sorted in ascending order. Different frequency points are selected based on the variance of shortwave signal energy. The frequency point with the highest variance that meets the preset conditions is selected first and is then used as the optimal broadband frequency. The second narrowband detection signal at different frequencies is transmitted from shortwave radio station B to shortwave radio station A. The second narrowband detection signal at different frequencies includes the second narrowband detection signal at the broadband optimal frequency fx. Based on the second narrowband detection signals at different frequencies, the signal-to-noise ratio and noise floor monitoring of different frequency points are performed using shortwave radio station A, and the optimal broadband frequency fy in the direction from shortwave radio station B to shortwave radio station A is selected. The shortwave radio has a narrowband bandwidth of 3kHz, and the preset bandwidth range is 12kHz or 24kHz.

2. The shortwave broadband frequency selection method according to claim 1, characterized in that, Signal-to-noise ratio (SNR) evaluation includes the following steps: Based on narrowband detection signals of different frequencies, the signal-to-noise ratio at different frequency points is obtained; Based on the signal-to-noise ratio (SNR) of different frequency points, filter out frequency points whose SNR is not within the preset SNR range; Based on the signal-to-noise ratio, the filtered frequency points are sorted in descending order. The sorted frequency points are then used for subsequent noise floor monitoring within a preset bandwidth range.

3. The shortwave broadband frequency selection method according to claim 2, characterized in that, Background noise monitoring includes the following steps: Based on narrowband detection signals of different frequencies, the noise floor monitoring index data of different narrowband detection frequency points within the preset bandwidth range are obtained; Based on the noise floor monitoring data of different narrowband detection frequencies within a preset bandwidth range, the optimal broadband frequency is selected from different narrowband detection frequencies using preset screening conditions.

4. The shortwave broadband frequency selection method according to claim 3, characterized in that, The noise floor monitoring indicators include any one or any combination of the following: average noise floor, noise floor spectrum, and interference signal amplitude.

5. The shortwave broadband frequency selection method according to claim 1, characterized in that, The preset conditions are minimum variance or variance within a preset variance range.

6. The shortwave broadband frequency selection method according to any one of claims 1-5, characterized in that, It also includes the following steps: By sending a response from shortwave radio station A to shortwave radio station B on the broadband optimal frequency fx, it informs shortwave radio station B that its broadband optimal frequency is fy.

7. The shortwave broadband frequency selection method according to claim 6, characterized in that, It also includes the following steps: By sending a response from shortwave radio B to shortwave radio A on the optimal broadband frequency fy, the frequency selection of shortwave radio A is successfully completed.

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