[Wireless serial port module quick selection guide] Communication frequency, chip, communication distance, power sensitivity, current air rate
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Introduction
Wireless module: a software and hardware module that transmits data via radio signals;
Serial port module: a software and hardware module that uses the serial port communication protocol to transmit data;
Wireless serial port module: a hardware and software module that uses serial port protocol for radio communication.
Key points for selecting serial port modules
01 Communication frequency
Communication frequency: the frequency of radio waves radiated outward by the wireless module when it is working;
The commonly used frequencies of wireless serial port modules can be roughly divided into 170MHz, 230MHz, 315MHz, 433MHz, 490MHz, 780MHz, 868MHz, 915MHz, 2.4GHz, etc.
In the use environment, choose modules with different frequencies according to your own environmental needs to avoid interference. At the same time, different frequencies have different characteristics in communication. For example, the 170MHz module has a lower frequency and a longer wavelength, so it has better communication effects in terms of signal penetration and diffraction capabilities than 868MHz and 2.4GHz modules.
02 Chip Solution
Chip solution: RF processing IC used in wireless serial port modules;
Different chips have different characteristics. Commonly used ones include SX1278, SX1276, SX1212, and SX1280 from "SEMTECH"; SI4463, SI4438, and SI4432 from "SILICON LABS"; and CC1110, CC1101, and CC1310 from TI.
Chips have different characteristics. Modules using different chip solutions also have their own characteristics in RF communication. For our users' selection, we can roughly estimate the performance differences and prices between modules from here.
03 Communication distance
Communication distance: One of the most core parameters of wireless modules. We choose the appropriate module according to the communication distance requirements we use. Wireless communication is affected by environmental factors, so we need to pay attention to the need to reserve a certain distance during module selection.
For example, if I need to pass 500 meters, then it is best not to choose a module with an index of 500 meters. At least choose one with an index of 600 meters or more. This way there is room to deal with environmental influences, which also ensures the adaptability and stability of the product.
04 Transmitting power and receiving sensitivity
Transmit power
Transmitting power: It is used to indicate the ability of the RF module to radiate radio wave signals outward; the transmitting power of the wireless serial port module also indicates the ability of the module to radiate radio waves outward. The greater the transmitting power of the module, the longer the communication distance will be under the same conditions, but its power consumption will also increase accordingly. This requires evaluation based on the product you are making.
The receiving sensitivity corresponds to the transmitting power. The transmitting power indicates the external radiation capability of the module, that is, the transmitting performance.
Receiving sensitivity
Receiving sensitivity: It indicates the receiving ability of the wireless module. Sensitivity is usually expressed as a negative value. It can be seen that the smaller the value corresponding to the sensitivity, the better the receiving performance.
For example, if the other parameters of the two modules are the same, the sensitivity of module 1 is -120dBm, and that of module 2 is -126dBm, then it means that the receiving performance of module 2 is better. Don't underestimate this 6dBm difference, in theory, this can make the communication distance of module 2 twice as far as that of module 1.
05 Transmitting current, receiving current, sleep current
Transmitting current: refers to the power supply current required by the module when transmitting;
This parameter is also very important for our choice, because some products can only provide a small amount of power, such as wearable devices, so you need to pay attention to this parameter when choosing a module. Usually the power supply capacity of the power supply is at least 1.3 times the transmission current.
Receiving current: the working current of the module in normal receiving state;
Sleep current: The working current when most functions of the module are not in use. This parameter is very important for users who make low-power products.
06 Air speed
The air rate here refers to the rate at which the radio frequency signal of the wireless module transmits the signal in the air;
The airspeed is related to the amount of data transmitted by the wireless module. The higher the airspeed, the greater the amount of data that can be transmitted per second by the wireless module.
For example, the remote controller of a drone needs to have a higher airspeed to ensure the transmission of a larger amount of data to control the flight. The higher the airspeed, the smaller the delay of wireless transmission;
Of course, the choice and setting of airspeed is not absolute. The larger the airspeed, the more suitable it is for us. This depends on the situation of our own products. At the same time, the higher the airspeed, the shorter the communication distance of the module will be to a certain extent. This also needs to be considered in combination with distance conditions, data volume, real-time and other issues.
07 Antenna interface type
I have previously written about the impact of antennas on the communication distance of wireless modules. Antennas are also crucial to wireless communication systems, so when choosing a module, you should also consider its antenna interface.
Commonly used interfaces are roughly divided into
- SMA
- IPEX
- Some modules also have onboard PCB antennas
This is also something we need to pay attention to when choosing products. The onboard PCB antenna has the advantages of small size and easy integration, but its communication distance is short. The antennas of SMA and IPEX interfaces are larger than PCB in terms of gain and volume.
08 Package type and size
Packaging and size: refers to the mechanical geometric dimensions of the module;
This indicator needs to be considered comprehensively in combination with the size and space requirements of the product itself.
The module packaging can be roughly divided into
Examples to illustrate the key points of selection
The following uses three tables as an example to illustrate the selection method of wireless modules
The three meters we often talk about are gas meter, electricity meter and water meter. Wireless meter reading is also widely used in life. So what should we pay attention to when choosing wireless modules in the three meters?
- First of all, wireless meter reading does not require a high amount of data transmission from the module, and the real-time requirements for the module are not too high. Therefore, from these two points of view, the selection of wireless modules does not require a very high airspeed.
- Secondly, when we look at the three-meter application, since they are all buildings, there are certain requirements for the penetration and diffraction performance of the module, such as 433MHz, 490MHz, etc.
- Then the power consumption of the wireless module in the three meters cannot be too high, so it is necessary to choose a module with appropriate power consumption. Finally, the volume restrictions of the three meters are mostly not high, so they can be considered comprehensively;
Summarize
In general, the selection of wireless modules is a comprehensive issue that we need to consider based on the performance requirements of our own products, design size and other aspects. Finally, I hope this article will help you choose a suitable module.
The above is all the content of this article. I hope it is useful to you. Thank you very much for taking the time to come here. Welcome to leave a message in the comment area and continue to pay attention to get more exciting content.
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