HTIT series of Internet of things suite.

WIFI LoRa 32(433-470,868-915MHz) WIFI KIT 32  WIFI KIT 8 WIFI relay

LoRa introduction to spread spectrum technology:

LoRa is one of the LPWAN communications technologies,is a remote wireless transmission scheme based on spread spectrum technology adopted and popularized by Semtech company.It has the characteristics of long distance, low power consumption, multi-node and low cost.
At present, LoRa operates mainly in the global free band, including 433, 868, 915 MHz, etc.

 

LoRa network:

LoRa network is mainly composed of terminals(Built-in LoRa module)、Gateway(Or the base station)、Server和cloud。Application data can be transmitted in two directions.

LoRa应用

Wisdom city

LoRa technical points

Generally speaking,transmission rate, working frequency band and network topology are three main parameters that affect the characteristics of sensor network.The selection of transmission rate will affect the transmission distance and battery life of the system;the choice of working frequency band should compromise the design goal of frequency band and system;in FSK system, the choice of network topology is determined by the number of nodes required by transmission distance and the number of nodes required by the system.

LoRa integrates digital spread spectrum, digital signal processing and forward error correction coding technology with unprecedented performance.Previously, only those high grade industrial radio communications would fuse these technologies,with the entry of LoRa, the situation of embedded wireless communication has changed completely.

Forward error correction coding technologyIt’s to add some redundant information to the transmitted data sequence,in this way, the error code injected into the data transmission process is corrected at the receiving end.This technique reduces the need to create “self-healing” packets in the past and does well in addressing unexpected errors caused by multipath fading.Once the packet grouping is established and the forward error correction encoding is guaranteed to ensure reliability, these packets will be sent to the digital spread modulator.This modulator feeds each bit of packet data into a “spreader”, dividing each bit into a number of pieces.

Even if the noise is loud, LoRa can handle it.When the LoRa modem is configured, it can be divided into 64-4096 yards/bits,maximum spread spectrum factor can be used in 4096 yards/bit.In contrast, ZigBee can only be divided into 10-12 yards per bit.

By using the high spread spectrum factor, LoRa technology can transmit small volume data through a wide range of radio spectrum.In fact, when you measure through a spectrum analyzer, the data looks like noise, but the difference is that the noise is irrelevant and the data is correlated.Based on this, data can actually be extracted from the noise.The higher the spread factor, the more data can be extracted from the noise.In a well-functioning GFSK receiver, the minimum SNR (SNR) of 8dB requires a reliable demodulation signal.Using the method of configuring AngelBlocks, LoRa demodulates a signal with a signal-to-noise ratio of -20db, and the GFSK approach is 28dB, which corresponds to a wide range and distance.In an outdoor environment, the 6dB gap can double the original transmission distance.

Therefore, using LoRa technology, we can achieve a wide range of transmission range and distance with low emission power, which is exactly what we need.