Wireless communication is a kind of communication technology that utilizes the characteristic that electromagnetic wave signals can propagate in free space to exchange information. In recent years, from the convenient cell phone communication to the intelligent interconnected home system, and then to the era of Internet of Things (IoT) which is the "interconnection of everything", the wireless communication technology has shown its strong vitality and unlimited possibilities with its ubiquitous figure.
Sub-GHz is a wireless communication technology that works in the frequency band below 1 GHz. Due to its lower frequency and longer wavelength, Sub-GHz can achieve lower power consumption, longer transmission distance and more stable communication quality than wireless communication technologies such as Wi-Fi and Bluetooth that work in the 2.4 GHz frequency band, and is more suitable for applications in intelligent meter reading, industrial automation, street lighting and other low-power wide-area IoT networking scenarios. It is more suitable to be used in low-power wide-area IoT networking scenarios such as smart meter reading, industrial automation and street lighting.
What are the advantages of Sub-GHz wireless networking solutions?
Previously, due to the Sub-GHz networking solutions used in the communication mode is mostly limited to the framework of point-to-point communication, although the communication is convenient, but the function is relatively single, it is difficult to meet the demand for "interconnection" between multiple IoT devices. At the same time, LoRaWAN, Wi-SUN and other protocols provide powerful networking capabilities, but the protocols themselves have a high degree of complexity and require a certain cost of facilities, which limits their popularity.
Therefore, there is an urgent need for a Sub-GHz networking solution that can meet the basic networking communication requirements, but also has the characteristics of easy deployment, easy maintenance, and light weight. As a Sub-GHz wireless RF chip original manufacturer in China for twenty years, HOPERF can perfectly solve this market demand.
Taking its Sub-GHz wireless networking demonstration program as an example, the program supports the network structure of star topology and extended star topology, which not only has the characteristics of long transmission distance, but also can easily build a low-power wide-area Internet of Things composed of hundreds of terminal nodes.
Sub-GHz Wireless Networking Demonstration Scheme and its Network Topology
As shown in the figure above, in the HOPERF Sub-GHz wireless networking demonstration scheme, there are a total of one center node and nine terminal nodes (relay nodes can be added as appropriate when the transmission distance needs to be increased). At power-on, the network is first created by inputting AT commands (AT+FORMNET=<channel>,<PANID>) from the center node, followed by setting AT commands (AT+PJOIN=<duration>) that allow the terminal nodes to join the network within a specified period of time.
Each terminal node can be networked with the center node by inputting AT commands (AT+JOINED=<channel>,<PAN ID> or AT+JOINSLP=<channel>,<PAN ID>), which is easy to use without programming. In addition, terminal nodes that have been successfully networked with the center node will automatically store the connection information and will be automatically networked with the center node the next time they are turned on, which is convenient and fast.
Sub-GHz Wireless Networking Demonstration Solution
When a terminal node is connected to the network, it can be configured as "working" or "sleeping" mode by entering the corresponding AT command (AT+JOINED=<channel>,<PAN ID> or AT+JOINSLP=<channel>,<PAN ID>) according to the actual requirements. "mode or "sleep" mode.
In "Work" mode, the terminal node will remain active and communicate with the control center in real time, which is suitable for smoke alarms, weather monitoring stations and other networking scenarios that require continuous monitoring. If the terminal node needs to withdraw from the network, enter the AT command (AT+LEAVE), and the terminal node will erase the connection information stored with the center node.
For example, in the field of building automation, due to the high building walls, Sub-GHz wireless networking demonstration solution can perfectly play its own advantages of long-distance transmission and strong ability to penetrate the wall, to provide a solid guarantee for real-time bidirectional communication between the smoke alarms (terminal nodes) on each floor and the control center, and to protect the safety of the building.
Under the "sleep" mode, the terminal node will regularly transmit temperature, air pressure and distance data to the control center according to its own sensing function at a set reporting time, and the terminal node will only be woken up briefly when it transmits to the control center, while remaining in a dormant state during the rest of the time, which can greatly improve the battery life of the terminal node. node's battery life.
For example, in the field of large-scale smart meter reading, by adopting the Sub-GHz wireless networking solution, the appropriate reporting time can be set for each household water/electricity/gas meter (terminal node), and the data information of water/electricity/gas consumption can be transmitted to the control center at regular intervals, which greatly simplifies the manpower cost of the electric power company in reading the meter, and improves the efficiency of the energy utilization.
In addition, after successful networking, the terminal nodes and the center node can upload data manually in addition to uploading data by themselves, just by entering AT commands (AT+SEND=<Length>,<Payload string>).
Product Recommendation: High Performance Sub-GHz RF Transceiver Module RFM23A020
RFM23A020 is a high-performance, highly integrated, cost-effective with support for long-distance communication wireless RF transceiver module, supports a wide voltage input from 1.8V to 3.8V, and provides a number of general-purpose IOs, which allows a high degree of freedom for multi-faceted development. In addition, the RFM23A020 boasts a transmit power of up to 20dBm, which greatly enhances the link performance of the application.
RFM23A020 Typical Application Circuits
RFM23A020 Product Features
- Superior anti-jamming ability, suitable for complex interference environment scenario use
- Operating frequency: 868MHz, 915MHz
- Modulation: OOK, (G)FSK, (G)MSK, OQPSK
- Voltage range: 1.8V to 3.8V
- Receive sensitivity: -118dBm @868MHz, 2.4kbps, GFSK
- Transmit Current: 77mA @20dBm, 868MHz, 73mA @20dBm, 915MHz
- Receiving current: 5mA
It is worth mentioning that RFM23A020 adopts DSSS technology, which has super anti-jamming capability and is especially suitable for use in complex interference environments, making it an ideal solution for Sub-GHz "Internet of Things" applications such as smart home, security, lighting, building automation and metering.
Looking ahead, with the continuous popularization and deepening of IoT applications, we believe that Sub-GHz wireless communication technology will surely play an important role in more fields and bring more convenient, intelligent and green experiences to our lives.
