We are working on a custom board with the DW1000 embedded on it, on our new batch, we implemented a LNA on Rx path to improve range as described in APS004: Increasing the Range of DW1000 Using LNA.A TXCO is also added to increase accuracy and finally we also added a switch before the LNA to allow the use of an external antenna.
There is our design of the DW1000:
And the design of the ant path with the LNA and external antenna selector:
On the PCB we made the antenna path to 50 ohms from the dw1000 to the internal or external antenna to respect the needed impedance.
On software side, we activated the REG:26:00 – GPIO_MODE – GPIO Mode Control Register to the mode 01: The pin operates as the EXTRXE output. as described in the application note APS004.
We also measured the switches to be sure the selection is correct for the Rx through the LNA and the Tx directly to the antenna.
We try to do some tests to measure the range between two beacons that transmit and receive data of maximum of 116 octets with some UWB signal configuration, with internal + LNA and with external antennas. We also measure the power input of the DW1000 module to see if the voltage is constant and in the range of the nominals value for the module. All our tests seems correct and we don’t have the tools to measure the RF signals.
The most working configuration used is:
UWB configuration : ================= Channel : 1 Data rate : 850 K PRF : 16 MHz Preamble length : 128 PAC size : 8 SFD length : 16 SFD timeout : 69697 SYS_CFG : FFEN : 0 FFBC : 0 FFAB : 0 FFAD : 0 FFAA : 0 FFAM : 0 FFAR : 0 FFA4 : 0 FFA5 : 0 HIRQ_POL : 1 SPI_EDGE : 0 DIS_FCE : 0 DIS_DRXB : 1 DIS_PHE : 0 DIS_RSDE : 0 FCS_INIT2F : 0 PHR_MODE : 0 DIS_STXP : 1 RXM110K : 0 RXWTOE : 0 RXAUTR : 1 AUTOACK : 0 AACKPEND : 0 CHAN_CTRL : TX CHAN : 1 RX CHAN : 1 DWSFD : 1 RXPRF : 1 TNSSFD : 1 RNSSFD : 1 TX_PCODE : 2 RX_PCODE : 2 TX_FCTRL : TFLEN : 12 TFLE : 0 TXBR : 1 TR : 1 TXPRF : 1 TXPSR : 1 PE : 1 TXBOFFS : 0 SFD/LENGTH : 16 AGC_CTRL/TUNE1 : 8870 AGC_CTRL/TUNE2 : 2502A907 AGC_CTRL/TUNE3 : 35 DRX_CONF/TUNE0b : 6 DRX_CONF/TUNE1a : 87 DRX_CONF/TUNE1b : 20 DRX_CONF/TUNE2 : 311A002D DRX_CONF/TUNE4H : 28 RF_CONF/RXCTRLH : D8 RF_CONF/TXCTRL : 5C40 TX_CAL/PGDELAY : C9 FS_CTRL/PLLTUNE : 1E FS_CTRL/PLLCFG : 9000407 LDE/CFG1 : D LDE/CFG2 : 1607 LDE/REPC : 5998 EXTRXE : Enable TX POWER 0 : 12.50 + 1.00 = 13.50 dB TX POWER 1 : 15.00 + 1.00 = 16.00 dB TX POWER 2 : 15.00 + 4.00 = 19.00 dB TX POWER 3 : 15.00 + 7.00 = 22.00 dB
we also tried to change some parameters and also the best config given by Decawave for long range operations
and also these configuration:
Only channel 1 and 4 are working, channel 2 work very baddly all others channel doesn’t work at all.
We tried those antennas as external antennas:
UWB Isometric Helical Antenna (working frequencies: 2,4 GHz to 5,8 GHz;power: 5W;gain: 3,5 dBi;impedance: 50Ω):
Antenna UWB 3.1WHz-9GHz omnidirectional (power: 5W;gain: 3,5 dBi;impedance: 50Ω):
Directionnal UWB antenna (working frequencies: 1,4 ~ 10,5 GHz;power: 10W;gain: 7dBi; impedance: 50Ω):
With those antennas, the ranging is very lowm:
- indoor: 4/5 meters for all antennas with the best found UWB configuration and less with other configurations
- outdoor LoS: 1/2 meters for the Helical and omnidirectional antennas and 5/6 meters with the directional one with the best found UWB configuration and less with other configurations
With the internal antenna, the range is very poor only few centimeters and some messages are missing on best found UWB configurations and some configurations doesn’t work at all.
We also tested to do cross test with internal and external antennas but the results are the same very poor ranging.
Do you have any lead or clue to what is going wrong with our design and/or if we forgot to set some registers to make it works well as expected (100Meters+ announced 300M on the DWM1000 module without LNA ??? )
Thanks you in advance for you reading time and your help, I am available if you need more details to help us analyze our desing.