Data sending method and system based on FFSK modulation

Abstract

The invention relates to a data sending method and system based on FFSK modulation, and the method comprises the steps: taking a single period with a higher characteristic frequency in 1 / 0 logic of FFSK modulation as a modulation period of single data, and aligning the sending time of a single data signal with a lower characteristic frequency to the modulation period of the single data; calculating the least common multiple of the modulation period of the single data and the sampling period of the audio data to obtain the multiple x of the corresponding single modulation period; carrying out one-time complete sampling by every x 1 / 0 logics, traversing output logics of all 1 / 0 combinations, and storing results into the MCU; and during data transmission, the MCU takes every x bit data as a group and takes the 1 / 0 output logic stored in advance for transmission. Compared with the prior art, a plurality of complete logic 1 / 0 of the FFSK can be completely sent under the condition that the minimum number of sampling periods is found, corresponding data are stored in the MCU in advance, real-time calculation in the running process is not needed, the requirement of the MCU is lowered, and the running efficiency of the MCU is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of wireless data transmission, and in particular to a FFSK sending data processing method. Background Art

[0002] According to the railway industry standard TB / T3052-2002, wireless data transmission uses FFSK modulation, with a characteristic frequency of "1" of 1200Hz and "0" of 1800Hz. The audio data sampling frequency of conventional train radio stations is generally 8kHz, such as Figure 1 As shown, when one wants to directly send a single FFSK logic 1 / 0, it is found that a complete FFSK logic 1 / 0 cannot be sent in an integer number of sampling cycles.

[0003] The existing technical solution is generally to splice y1=sin(1200*π*t) and y2=sin(1800*π*t) in real time according to the transmitted data and then send them continuously. The amount of calculation is large and generally a microprocessor (MCU) with floating point budget function is required to achieve fast real-time calculation, which has high requirements for the processor. Summary of the invention

[0004] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and provide a method for processing FFSK transmission data at a sampling frequency that is not a multiple of the FFSK modulation characteristic frequency.

[0005] The purpose of the present invention can be achieved by the following technical solutions:

[0006] As a first aspect of the present invention, a data transmission method based on FFSK modulation is provided, the steps comprising:

[0007] A single cycle with a higher characteristic frequency in the 1 / 0 logic of FFSK modulation is used as the modulation cycle of a single data, and the transmission time of a single data signal with a lower characteristic frequency is aligned to the modulation cycle of the single data;

[0008] Calculate the least common multiple of the modulation period of a single data and the audio data sampling period, and obtain the corresponding multiple x of the single modulation period;

[0009] Perform a complete sampling for every x 1 / 0 logics, traverse the output logic of all 1 / 0 combinations of complete sampling, and store the results in the MCU;

[0010] When transmitting data, the MCU groups every x bits of data and uses the 1 / 0 output logic stored in advance to send them.

[0011] As a preferred technical solution, the characteristic frequencies of the 1 / 0 logic in the FFSK modulation include: 1200 / 1800 Hz, 1200 / 2400 Hz and 2400 / 4800 Hz.

[0012] As a preferred technical solution, the sampling frequency of the audio data includes 8KHz.

[0013] As a preferred technical solution, the data transmission rate includes: 1200 bit / s, 2400 bit / s or 4800 bit / s.

[0014] As a preferred technical solution, when the waveform at the end of a group of 1 / 0 output logic changes from positive to negative, a negative number is taken for subsequent 1 / 0 data.

[0015] As a preferred technical solution, if the transmitted data is not a multiple of x, 0 is added to the end of the transmitted data.

[0016] As a second aspect of the present invention, a data transmission system based on FFSK modulation is provided, comprising:

[0017] The minimum number of sampling cycle calculation modules uses the single cycle of the signal with lower characteristic frequency logic in the 1 / 0 logic of FFSK modulation as the modulation cycle of a single data; aligns the sending cycle of another single data signal with higher characteristic frequency logic to the modulation cycle of a single data; calculates the least common multiple of the modulation cycle of a single data and the sampling cycle of the audio data, and obtains the corresponding multiple x of the single modulation cycle;

[0018] Output logic traversal module: perform a complete sampling every x 1 / 0 logics, traverse the output logic of all 1 / 0 combinations and store the results in the MCU;

[0019] When transmitting data, the MCU takes x bits of data as a group and uses the 1 / 0 output logic stored in advance to send it.

[0020] As a preferred technical solution, the data transmission rate includes: 1200 bit / s, 2400 bit / s or 4800 bit / s;

[0021] The sampling frequency of the audio data includes 8KHz.

[0022] As a preferred technical solution, when the waveform at the end of a group of 1 / 0 output logic changes from positive to negative, the MCU takes a negative number for subsequent 1 / 0 data.

[0023] As a preferred technical solution, if the transmitted data is not a multiple of x, 0 is added to the end of the transmitted data.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] The present invention aligns the modulation and signal transmission cycle of a single data of 1 / 0 logic in FFSK modulation, and can completely transmit several complete logical 1 / 0 of FFSK by finding the minimum number of sampling cycles, and at the same time stores the corresponding data in advance in the MCU, so that the MCU no longer needs floating-point operation function, reducing the requirements of the MCU. In addition, since all 1 / 0 transmission situations are traversed, there is no need for real-time calculation during operation, and directly using the data stored in advance also improves the operation efficiency of the MCU. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic diagram of 1200 / 1800Hz at 8kHz sampling rate;

[0027] Figure 2 It is a structural schematic diagram of the present invention;

[0028] Figure 3 It is a schematic diagram of the traversal of the present invention;

[0029] Figure 4 It is a structural schematic diagram of the present invention; DETAILED DESCRIPTION

[0030] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0031] Example 1

[0032] As one implementation of the present invention, this embodiment provides a FFSK data transmission method, such as Figure 2 As shown, it includes the following steps:

[0033] Step S1, using the signal period of the higher characteristic frequency in the "1 / 0" logic as the modulation period of a single data, and multiplying the signal period of the other lower characteristic frequency by the multiple a of the difference between the characteristic frequencies of the two, and aligning the transmission duration of the single data signal to the modulation period of the single data;

[0034] Calculate the least common multiple of the modulation period of a single data and the sampling period of the audio data T = 1 / f, as shown in the following formula:

[0035]

[0036] By calculation, the multiples x of a single modulation period and the multiples y of the audio data sampling period can be obtained;

[0037] Step S2, therefore, every x logic 1 / 0 can achieve one complete sampling, traverse and calculate all possible 1 / 0 combinations, obtain the complete 1 / 0 output logic, and store the result in the MCU;

[0038] Step S3: When transmitting data, every x bits are grouped together and the 1 / 0 output logic stored in advance is used for transmission; if the transmitted data is not a multiple of x, 0 is added to the end of the data.

[0039] In particular, when the waveform at the end of a set of 1 / 0 output logic changes from positive to negative, the subsequent 1 / 0 data needs to be negative to achieve a smooth transition of the waveform.

[0040] Example 2

[0041] This embodiment provides an example of processing data sent using FFSK modulation with a characteristic frequency of "1" of 1200 Hz and "0" of 1800 Hz at a common radio station sampling frequency of 8 kHz:

[0042] 1) Calculate the least common multiple of a 1200Hz single cycle, a 1800Hz half cycle, and an 8000Hz sampling cycle, as shown in the following formula:

[0043]

[0044] 2) By calculation, we can get x=3, x=20;

[0045] 3) The calculation results are as follows Figure 3 As shown, at the 3rd cycle of 1200Hz and the 4.5th cycle of 1800Hz, the zero crossing coincides at the 20th cycle of 8000Hz;

[0046] 4) A complete sampling can be achieved with every 3 logic 1 / 0, and all possibilities are traversed and calculated. The result is as follows Figure 4 As shown, the sample code for the calculation is as follows:

[0047]

[0048]

[0049] 5) When outputting 000, 011, 101, and 110, please note that the subsequent data needs to be negative to achieve a smooth transition of the waveform;

[0050] 6) Finally, when transmitting data, send every 3 bits as a group. If it is not a multiple of 3, add 0 at the end.

[0051] The implementation scope of the present invention is not limited to the sampling frequency of 8KHz, and can also be implemented by the same calculation method at different sampling frequencies;

[0052] The implementation scope of the present invention is not limited to the characteristic frequency 1200 / 1800 Hz, but is also applicable to 1200 / 2400 Hz and 2400 / 4800 Hz, etc. When calculating the least common multiple, the least common multiple is calculated based on a single cycle of 1200 Hz, two cycles of 2400 Hz, and the audio data sampling cycle;

[0053] The implementation scope of the present invention is not limited to the transmission rate of 1200 bit / s, but is also applicable to 2400 bit / s and 4800 bit / s.

[0054] Example 3

[0055] As another implementation manner of the present invention, this embodiment further provides a system using the data transmission method based on FFSK modulation as described in the above embodiment, specifically comprising:

[0056] The minimum number of sampling cycle calculation modules uses the single cycle of the signal with lower characteristic frequency logic in the 1 / 0 logic of FFSK modulation as the modulation cycle of a single data; aligns the sending cycle of another single data signal with higher characteristic frequency logic to the modulation cycle of a single data; calculates the least common multiple of the modulation cycle of a single data and the sampling cycle of the audio data, and obtains the corresponding multiple x of the single modulation cycle;

[0057] Output logic traversal module: perform a complete sampling every x 1 / 0 logics, traverse the output logic of all 1 / 0 combinations and store the results in the MCU;

[0058] When transmitting data, the MCU takes x bits of data as a group and uses the 1 / 0 output logic stored in advance to send it.

[0059] The data transmission rate includes: 1200 bit / s, 2400 bit / s or 4800 bit / s;

[0060] The sampling frequency of the audio data includes 8KHz.

[0061] Specifically, when the waveform at the end of a group of 1 / 0 output logic changes from positive to negative, the MCU takes a negative number for subsequent 1 / 0 data.

[0062] Specifically, if the transmitted data is not a multiple of x, 0 is added to the end of the transmitted data.

[0063] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A data transmission method based on FFSK modulation, characterized in that the steps include: A single cycle with a higher characteristic frequency in the 1 / 0 logic of FFSK modulation is used as the modulation cycle of a single data, and the transmission time of a single data signal with a lower characteristic frequency is aligned to the modulation cycle of the single data; Calculate the least common multiple of the modulation period of a single data and the audio data sampling period, and obtain the corresponding multiple x of the single modulation period; Perform a complete sampling for every x 1 / 0 logics, traverse the output logic of all 1 / 0 combinations of complete sampling, and store the results in the MCU; When transmitting data, the MCU groups every x bits of data and uses the 1 / 0 output logic stored in advance to send them.

2. The data transmission method based on FFSK modulation according to claim 1, characterized in that: The characteristic frequencies of the 1 / 0 logic in the FFSK modulation include: 1200 / 1800 Hz, 1200 / 2400 Hz and 2400 / 4800 Hz.

3. The data transmission method based on FFSK modulation according to claim 1, characterized in that: The sampling frequency of the audio data includes 8KHz.

4. The data transmission method based on FFSK modulation according to claim 1, characterized in that: The data transmission rate includes: 1200 bit / s, 2400 bit / s or 4800 bit / s.

5. The data transmission method based on FFSK modulation according to claim 1, characterized in that: When the waveform at the end of a group of 1 / 0 output logic changes from positive to negative, the subsequent 1 / 0 data is negative.

6. The data transmission method based on FFSK modulation according to claim 1, characterized in that: If the transmitted data is not a multiple of x, 0 is added to the end of the transmitted data.

7. A data transmission system based on FFSK modulation, characterized in that: include: The minimum number of sampling cycle calculation modules uses the single cycle of the signal with lower characteristic frequency logic in the 1 / 0 logic of FFSK modulation as the modulation cycle of a single data; aligns the sending cycle of another single data signal with higher characteristic frequency logic to the modulation cycle of a single data; calculates the least common multiple of the modulation cycle of a single data and the sampling cycle of the audio data, and obtains the corresponding multiple x of the single modulation cycle; Output logic traversal module: perform a complete sampling every x 1 / 0 logics, traverse the output logic of all 1 / 0 combinations and store the results in the MCU; When transmitting data, the MCU takes x bits of data as a group and uses the 1 / 0 output logic stored in advance to send it.

8. The data transmission system based on FFSK modulation according to claim 7, characterized in that: The data transmission rate includes: 1200 bit / s, 2400 bit / s or 4800 bit / s; The sampling frequency of the audio data includes 8KHz.

9. The data transmission system based on FFSK modulation according to claim 7, characterized in that: When the waveform at the end of a set of 1 / 0 output logic changes from positive to negative, the MCU takes a negative number for subsequent 1 / 0 data.

10. The data transmission system based on FFSK modulation according to claim 7, characterized in that: If the transmitted data is not a multiple of x, 0 is added to the end of the transmitted data.

Images