Article 6: Design of multi-functional intelligent trunk following control system | undergraduate graduation design - [Key Technology - positioning technology related data (UWB WiFi Bluetooth)]

bluetooth

• At present, the positioning accuracy of this technology is very poor , bluetooth 5.0 And previous versions use RSSI Signal strength to locate distance , It is difficult to achieve accuracy above meter level , If you want to position the angle , A directional antenna is required . There are two ways , Always two Bluetooth modules , The orientation of the directional antenna is different , The signal source angle is calculated according to the signal strength ratio received by the antenna ; Another method is to add a rotating mechanism to the antenna , It is similar to the radar rotation scanning method to find the direction with the strongest signal . The positioning accuracy can also be improved according to the networking of multiple devices , But the practicality is not very good . So the current positioning of this method is not ideal , No follow-up products .

• Future Bluetooth 5.1 After technology matures , There will be a chance . bluetooth 5.1 Support antenna array , Antenna array receiving RF The signal has phase difference , The distance and angle of the signal source can be calculated according to the phase difference . From Bluetooth 5.1 Newly published technical standards , The positioning accuracy can reach CM Level , The angle accuracy can reach 5 Within degrees . At present, the Bluetooth technology alliance has announced Bluetooth 5.1 standard , No product has been launched yet , According to the progress rule of semiconductor devices , Generally, the market is expected to launch mature mass-produced Bluetooth after two years 5.1 Chip or module , It's still quite anticipated . But from its principle , bluetooth 5.1 Not perfect , There is a multipath reflection problem , If the indoor space is not large or there are columns around , Metal and other electromagnetic wave emitters will reflect the signal of the signal source in multipath , Finally, the signal received by the antenna comes from multiple directions , It will cause positioning error .

Read a text Bluetooth 5.1 AoA Arrival angle location service implementation principle
​

WIFI

be based on ESP32 Of WiFi-RSSI location
adopt ESP866 Of RSSI Value ranging detailed tutorial
​

UWB

millet UWB One finger Technology （ video ）
【UWB location 】 - DWM1000 Simple experience of module debugging - 1
【UWB location 】 - DWM1000 Simple experience of module debugging - 2
【UWB location 】 - DWM1000 Simple experience of module debugging - 3
DW1000 Way of learning （ One ） -------- Use DW1000 send data
​

DW1000 UWB Data manual of transceiver chip for free download

• DW1000 Is a fully integrated single-chip ultra wideband （UWB） Low power low cost transceiver IC, accord with IEEE802.15.4-2011. It can be used in two-way ranging or TDOA positioning systems , Take the positioning accuracy as 10 Cm of assets . It also supports up to 6.8
  Mbps Transmit data at the same rate
• DW1000 Is a fully integrated low-power single chip CMOS RF transceiver integrated circuit , accord with IEEE802.15.4-2011 UWB standard .DW1000 By an analog front end （ Contains a receiver and a transmitter ） And a digital backend （ Interface with off chip host processor ） form .TX/RX The switch is used to connect the receiver or transmitter to the antenna port . Temperature and voltage monitors are provided on the chip. The receiver consists of an RF front end , The front end amplifies the received signal in a low noise amplifier , Then it is directly converted down to baseband . The receiver is for broadband 、 Linearity and noise figure are optimized . This makes every supported IEEE802.15.4-2011
  UWB All channels can be down converted with minimum additional noise and distortion . The baseband signal is demodulated , The received data is obtained by SPI To the main controller .　　 By applying the digitally encoded transmission data to the analog pulse generator , Generate a transmission pulse sequence . The pulse train is up converted by the double balanced mixer to the carrier generated by the synthesizer , And focus on the allowed IEEE802.15.4-2011 One of the UWB On the channel . The modulated RF waveform is amplified before transmission from an external antenna . Integrated circuits have on-chip one-time programmability （OTP） Memory . This memory can be used to store calibration data , Such as Tx Power level 、 Crystal initial frequency error adjustment and range accuracy adjustment . These adjustment values can be automatically retrieved when needed . See the first 5.14 section . When the on-chip voltage regulator is disabled , Normally open can be used （AON） The memory is reserved in the lowest power operation state DW1000 The configuration data . This data will be automatically uploaded and downloaded .DW1000
  AON Memory usage is configurable .DW1000 The clock scheme is based on three main circuits ： Crystal oscillator 、 Clock PLL and RF PLL . The on-chip oscillator is designed to use an external crystal in 38.4 Working at megahertz . If there is a properly stable clock elsewhere in the user's system , Then you can use external 38.4 The megahertz clock signal replaces the crystal . The 38.4 The megahertz clock is used as two on-chip PLL The reference clock input of . The clock PLL（ Expressed as CLKPLL） Clock required to generate digital back-end processing signals . The RF PLL generates a down converted local oscillator for the receiving chain （LO）, Generate up converted local oscillator for the emission chain （LO）. Provide an internal 13
  kHz oscillator , For sleep state . Host interfaces include slave only interfaces for device communication and configuration SPI. A lot of MAC function , Include CRC Generate 、CRC Check and receive frame filtering .

DWM1000 Module introduction

• be based on DecaWave company-developed DW1000 chip , compatible IEEE802.15.4-2011 Protocol ultra wideband wireless transceiver chip
• It is mainly used in real-time positioning system （RTLS） And the development of wireless sensor networks , This includes agriculture , Building control , Factory automation , Medical care , Security and warehousing industries .

​

Ultra wide band DWM1000 modular brief introduction

• DWM1000 Module is based on Decawave company DW1000 Ultra wideband transceiver module designed by chip . The module integrates the antenna and all RF circuits 、 Power management and clock circuit . This module can be used in TWR or TDOA In the positioning system , Used to locate the target , Its accuracy can be less than 10cm; And the module supports up to 6.8Mbps Data transfer rate
• Technical data
  •  accord with IEEE802.15.4-2011 UWB standard ;
  •  Support from the 3.5GHz To 6.5GHz Of 4 RF bands ;

 The output power of the transmitter is programmable and controllable ;
 Fully coherent receiver , Maximize the use of distance , High accuracy ;
 Its design complies with FCC（ The Federal Communications Commission ）&ETSI（ European Telecommunications Standards Association ）UWB Spectrum standard ;
 The power supply is 2.8V~3.6V;
 low power consumption ;
 The data transmission rate is 110kbps,850kbps,6.8Mbps Three models ;
 The maximum packet length is 1023 byte , Meet the application requirements of high data exchange ;
 Integrate MAC Support function
 Support two-way ranging and TDOA location ;
 The host interface is SPI;
 23mmx13mmx2.9mm Of 24 Needle side Castle shaped package （side castellation package）.