CN115395986A - Carrier communication module based on OFDM modulation - Google Patents
Carrier communication module based on OFDM modulation Download PDFInfo
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- CN115395986A CN115395986A CN202211032047.7A CN202211032047A CN115395986A CN 115395986 A CN115395986 A CN 115395986A CN 202211032047 A CN202211032047 A CN 202211032047A CN 115395986 A CN115395986 A CN 115395986A
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- 238000004891 communication Methods 0.000 title claims abstract description 34
- 230000008878 coupling Effects 0.000 claims abstract description 19
- 238000010168 coupling process Methods 0.000 claims abstract description 19
- 238000005859 coupling reaction Methods 0.000 claims abstract description 19
- 230000005540 biological transmission Effects 0.000 claims abstract description 8
- 238000001914 filtration Methods 0.000 claims abstract description 6
- 238000010586 diagram Methods 0.000 description 11
- 230000003321 amplification Effects 0.000 description 6
- 238000003199 nucleic acid amplification method Methods 0.000 description 6
- 238000005516 engineering process Methods 0.000 description 4
- 238000001228 spectrum Methods 0.000 description 4
- 239000003990 capacitor Substances 0.000 description 3
- 230000008054 signal transmission Effects 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B3/00—Line transmission systems
- H04B3/54—Systems for transmission via power distribution lines
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/69—Spread spectrum techniques
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- Cable Transmission Systems, Equalization Of Radio And Reduction Of Echo (AREA)
Abstract
A carrier communication module based on OFDM modulation comprises a carrier chip, an input filter circuit, a sending end filter circuit, a receiving end filter circuit, a coupling module and a power circuit, wherein the carrier chip is used for modulating and demodulating data; the input filter circuit is used for filtering interference signals outside the set frequency; the transmitting end filter circuit is used for amplifying power, preventing signal distortion and performing voltage limiting protection; the receiving end filter circuit is used for coupling the transmission system and the power line; the power supply circuit supplies power to the carrier chip. The invention greatly overcomes the problems of poor channel environment in the power line and noise interference of high-power electric appliance access, and enables signals to be stably transmitted in the power line.
Description
Technical Field
The invention relates to a carrier communication module based on OFDM modulation.
Background
The power line carrier communication technology is to realize signal transmission by using a power network. Compared with other wired communication technologies, the power carrier communication has many advantages in the field: firstly, the cable coverage is very wide, power lines are very common cable resources in various industrial or living application scenes, and the power carrier technology only needs to be applied on the basis of the power line resources. And secondly, the cost is lower, the power line is used as a communication medium in the power carrier communication technology, so that the existing power facilities can be fully utilized, the costs of rewiring and investment and transformation are saved, and more line investment is not needed to support communication.
However, the method is still limited by many problems, for example, the access of a high-power electrical appliance in a household power utilization scene can generate inevitable noise interference, and the power line itself is used as an infrastructure for transmitting electric energy, not a medium specially used for transmitting signals, and the channel environment is relatively severe.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention provides a carrier communication module based on OFDM, which mainly comprises the following five parts, wherein the carrier communication module is designed based on a spread spectrum communication chip ST7540, the chip not only comprises a plurality of modulation and demodulation modes, but also is internally provided with a power amplifier circuit to facilitate the subsequent circuit design of a user, the carrier communication module is connected to a 220V power grid through a power line to realize signal transmission, the working voltage is stabilized at about 9V, and a transformer module is adopted for direct current power supply; and a working mode in the spread spectrum chip and the whole communication flow are controlled by using a single chip microcomputer STM 8.
In order to solve the technical problems, the technical scheme of the invention is as follows:
a carrier communication module based on OFDM modulation comprises a carrier chip, an input filter circuit, a sending end filter circuit, a receiving end filter circuit, a coupling module and a power circuit, wherein the carrier chip is used for modulating and demodulating data; the input filter circuit is used for filtering interference signals outside the set frequency; the transmitting end filter circuit is used for power amplification, signal distortion prevention and voltage limiting protection; the receiving end filter circuit is used for coupling the transmission system and the power line; the power supply circuit supplies power to the carrier chip; when the carrier chip is in a receiving state, signals are input from the input pins through the coupling module, the input filter circuit and the receiving end filter circuit; when the chip is in a sending state, signals are output from the output pin and are transmitted to the power line through the sending end filter circuit, the input filter circuit and the coupling module, the input filter circuit and the receiving end filter circuit are sequentially connected in series to form a receiving branch, and the sending end filter circuit, the input filter circuit and the coupling module are sequentially connected in series to form a sending branch.
Further, the carrier chip is ST7540.
Still further, the input filter circuit is a filter circuit formed by a parallel resonance circuit, and interference signals outside the set frequency are filtered by setting a capacitor and an inductance value in the circuit.
An independent power amplification arithmetic unit PA is integrated in the ST7540 chip, a filter circuit at a sending end is a three-order low-pass filter designed based on the power amplification, a three-order active filter circuit is arranged at the sending end and consists of an RC low-pass filter circuit and a second-order Sallen-Key low-pass filter unit, so that signal distortion can be avoided, and a voltage-limiting protection effect is realized; the receiving end filter circuit is a passive filter circuit formed by passive devices and couples the transmission system with the power line.
The beneficial effects of the invention are as follows: the problems of poor channel environment in a power line and noise interference of high-power electrical appliance access are greatly solved, and signals can be stably transmitted in the power line.
Drawings
Fig. 1 is a system architecture diagram of a carrier communication module according to the present invention;
FIG. 2 is a schematic diagram of an input filter circuit according to the present invention;
FIG. 3 is a schematic diagram of a filter circuit at the transmitting end according to the present invention;
FIG. 4 is a schematic diagram of a filter circuit at the receiving end according to the present invention;
fig. 5 is a schematic block diagram of a carrier communication module based on OFDM modulation.
Detailed Description
The invention is further described below with reference to the accompanying drawings.
Referring to fig. 1 to 5, a carrier communication module based on OFDM modulation includes a carrier chip, an input filter circuit, a transmitting end filter circuit, a receiving end filter circuit, a coupling module, and a power circuit, where the carrier chip is used to modulate and demodulate data; the input filter circuit is used for filtering interference signals outside the set frequency; the transmitting end filter circuit is used for power amplification and simultaneously preventing signal distortion and performing voltage limiting protection; the receiving end filter circuit is used for coupling the transmission system and the power line; the power supply circuit supplies power to the carrier chip; when the carrier chip is in a receiving state, signals are input from the input pins through the coupling module, the input filter circuit and the receiving end filter circuit; when the chip is in a sending state, signals are output from the output pin and are transmitted to the power line through the sending end filter circuit, the input filter circuit and the coupling module, the input filter circuit and the receiving end filter circuit are sequentially connected in series to form a receiving branch, and the sending end filter circuit, the input filter circuit and the coupling module are sequentially connected in series to form a sending branch.
In this embodiment, a system architecture diagram of a carrier communication module is shown in fig. 1, and a main architecture of the carrier communication module includes the following five parts. First, the carrier communication module is designed based on the spread spectrum communication chip ST7540 described above. And secondly, the carrier communication module is connected to a 220V power grid through a power line to realize signal transmission, the working voltage is stabilized at about 9V, and a transformer module is adopted for direct current power supply. And a working mode in the spread spectrum chip and the whole communication flow are controlled by using a single chip microcomputer STM 8.
The schematic diagram of the internal input filter circuit of the power line carrier communication module is shown in fig. 2 and is composed of a parallel resonant circuit. Through the setting to electric capacity and inductance value in the circuit, can the filtering formulate the interference signal outside the frequency. With R L The resistance value of the circuit generated by the inductor connected in series in the circuit is represented, and the quality factor of the circuit is expressed as a function of the center frequency as follows:
since the dc impedance of the inductor is much smaller than the impedance of the resistor in the series circuit, the expression of the center frequency is simplified and the following results are obtained:
from the above expression, the quality factor Q of the filter circuit depends on R 1 And L 1 The larger the resistance value of the inductor is, the flatter the wave form of the resonance frequency output is, and the frequency selection characteristic is along with R 1 The value of (c) increases and becomes better.
A schematic diagram of a filter circuit at the internal transmitting end of the power line carrier communication module is shown in fig. 3. An independent power amplification arithmetic unit PA is integrated in the ST7540 chip, the filter circuit design is a three-order low-pass filter based on the power amplification design, and a three-order active filter circuit is arranged at the transmitting end. The filter consists of an RC low-pass filter circuit and a second-order Sallen-Key low-pass filter unit, and R is subjected to low-pass filtering 6 The arrangement of the transformer can amplify the direct current part of the signal, can avoid signal distortion and simultaneously plays a role in voltage limiting protection. As shown in fig. 2, the second-order Sallen-Key low-pass filter circuit has high input impedance and low output impedance, and has the advantages of easy gain adjustment and stable overall performance, and its transfer function expression is:
wherein,
meanwhile, the expression of the cut-off frequency of the unit is:
a schematic diagram of a filter circuit at a receiving end inside a power line carrier communication module is shown in fig. 4, and the filter circuit is a series resonant circuit and includes a linear transformer, a decoupling capacitor, an inductor and a capacitor. The filter circuit at the receiving end is a passive filter circuit composed of some passive devices, couples the transmission system with the power line, and is an important part of the system.
Fig. 5 shows a schematic block diagram of a carrier communication module based on OFDM modulation, which is a schematic block diagram of a carrier communication module during transmission and reception, respectively. When the chip is in a receiving state, signals are input from a specific pin through the coupling circuit, the input filter circuit and the input end filter circuit; when the chip is in a sending state, the signal is output from the specific pin and is transmitted to the power line through the sending end filter circuit, the input filter circuit and the power line coupling circuit.
The embodiments described in this specification are merely exemplary of implementations of the inventive concepts and are provided for illustrative purposes only. The scope of the present invention should not be construed as being limited to the particular forms set forth in the examples, but rather as being defined by the claims and the equivalents thereof which can occur to those skilled in the art upon consideration of the present inventive concept.
Claims (4)
1. A carrier communication module based on OFDM modulation is characterized by comprising a carrier chip, an input filter circuit, a sending end filter circuit, a receiving end filter circuit, a coupling module and a power circuit, wherein the carrier chip is used for modulating and demodulating data; the input filter circuit is used for filtering interference signals outside the set frequency; the transmitting end filter circuit is used for amplifying power, preventing signal distortion and performing voltage limiting protection; the receiving end filter circuit is used for coupling the transmission system and the power line; the power supply circuit supplies power to the carrier chip; when the carrier chip is in a receiving state, signals are input from the input pin through the coupling module, the input filter circuit and the receiving end filter circuit; when the chip is in a sending state, signals are output from the output pin and are transmitted to the power line through the sending end filter circuit, the input filter circuit and the coupling module, the input filter circuit and the receiving end filter circuit are sequentially connected in series to form a receiving branch, and the sending end filter circuit, the input filter circuit and the coupling module are sequentially connected in series to form a sending branch.
2. The OFDM modulation-based carrier communication module of claim 1, wherein the carrier chip is ST7540.
3. The OFDM modulation-based carrier communication module as claimed in claim 1 or 2, wherein the input filter circuit is a filter circuit formed by a parallel resonant circuit, and the filter circuit filters the interference signal outside a predetermined frequency by setting capacitance and inductance values in the filter circuit.
4. The carrier communication module based on OFDM modulation according to claim 2, wherein an independent Power Amplifier (PA) is integrated in the ST7540 chip, the filter circuit at the transmitting end is a third-order low-pass filter designed based on the power amplifier, and a third-order active filter circuit is provided at the transmitting end, and is composed of an RC low-pass filter circuit and a second-order Sallen-Key low-pass filter unit, so as to avoid signal distortion and achieve voltage-limiting protection; the receiving end filter circuit is a passive filter circuit formed by passive devices and couples the transmission system with the power line.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211032047.7A CN115395986A (en) | 2022-08-26 | 2022-08-26 | Carrier communication module based on OFDM modulation |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211032047.7A CN115395986A (en) | 2022-08-26 | 2022-08-26 | Carrier communication module based on OFDM modulation |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN115395986A true CN115395986A (en) | 2022-11-25 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202211032047.7A Withdrawn CN115395986A (en) | 2022-08-26 | 2022-08-26 | Carrier communication module based on OFDM modulation |
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| Country | Link |
|---|---|
| CN (1) | CN115395986A (en) |
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2022
- 2022-08-26 CN CN202211032047.7A patent/CN115395986A/en not_active Withdrawn
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Application publication date: 20221125 |