RF Ranging with LoRa Leveraging RTL-SDRs and GNU Radio

Transcription

1 RF Ranging with LRa Leveraging RTL-SDRs and GNU Radi Wil Myrick September 20, 2018 GNU Radi Cnference 2018

2 Explring COTS, LRa, GNU Radi, and RF Ranging COTS Internet-f-Things (IT) transceiver technlgy prvides a useful set f features fr RF aided cmplementary Psitining, Navigatin, and Timing (PNT) Lng Range: Mre than 10km Lw Cst: IT transceivers are inexpensive Lw Pwer Cnsumptin: IT transceivers can perate fr many years Majrity f mdules lack access t PHY fr supprting PNT Leverage GNU Radi t prttype a LRa RF ranging Pythn blck withut requiring access t physical layer measurements frm the IT transceiver Leverage this LRa RF ranging blck as part f a lw cst experimental RF ranging system based n IT transceiver technlgy with lw SWAP-C SDRs PNT Sub-GHz Sftware Defined Radi (PUGS) 2

3 Lw Cst SDRs and IT RF Mdules RTL-SDR: LRa Sub-GHz Mdules: Extremely Inexpensive Tuning: 500 khz up t 1.75 GHz $21.00 USD Inexpensive 433 MHz, 868 MHz, and 915 MHz $40.00 USD 1PPM TCXO Max sampling rate is 2.4 Msps ENOB is ~7 bits USB Interface Bandwidths: 125 khz, 250 khz, and 500 khz 157 db maximum link budget +14 dbm high efficiency PA $30.00 USD Plut SDR: Inexpensive Tuning: 300 MHz up t 3.8 GHz Bandwidth: 200kHz t 20 MHz Max sampling rate is Msps 12-bit bit DACs and ADCs $99.00 USD LRa 2.4 GHz Mdules : Inexpensive Ranging Engine, Time-f-flight functin Bandwidths: 125 khz, 250 khz, 500 khz, and 1.6 MHz USB Interface dbm high efficiency PA 3

4 Cmpnents f PNT Sub-GHz SDR (PUGS) 3V3 Ulta-lw Nise switching regulatr LRa transceiver 32Mbit flash memry ESP32 Dual Cre Micrcntrller and WiFi/Bluetth 4.2 radi WS2812 RGB Multi-clr LED Internal WiFi and Bluetth Antenna External LRa antenna cnnectr Reset Switch RF Switch U. FL cnnectr Image curtesy f Image curtesy f 4

5 Cmpnents f PNT Sub-GHz SDR (PUGS) USB serial prt JST cnnectr fr LiP Battery Micrpythn USB t serial cnverter Raspberry Pi 3 Mdel B MicrSD card slt GLONASS GPS Pythn Accelermeter Image curtesy f Image curtesy f /raspberry-pi-3-mdel-b/ Images curtesy f 5

6 USB USB Lw SWAP-C Hybrid RF Ranging SDRs Master Slave 1 Wireless Transmissins f LRa Packets 2 Raspberry Pi 3 (RF Ranging Algrithms and Data) Raspberry Pi 3 (RF Ranging Algrithms and Data) 3 PUGS Nde Master LRa RF Ranging Algrithm Develpment GNU Radi LRa RF Ranging Pythn Blck PUGS Nde Slave PUGS Hybrid (Active/Passive) RF Ranging Setup based n LRa Transceiver Technlgy 6

7 GNU Radi Embedded Pythn Flw Graph PUGS Nde Master PUGS Nde Slave TDOA M TDOA S 7

8 Pycm IT Transceiver WiFi Bluetth LRa Cmpnents f PNT Sub-GHz SDR (PUGS) Raspberry Pi 3 (RPI 3) Features f PUGS RF Ranging prtcls written in Micrpythn Pythn based I/Q data capture scripts n RPI 3 RTL-SDR fr LRa Packet Capture GNU Radi Installatin with a mdified gr-lra OOT Pycm IT Pytrack Bard Multi-GNSS Receiver Accelermeter USB interface fr RPI3 GNSS Receiver RTL-SDR LRa Antenna (Passive) fr RTL-SDR LRa TX/RX Antenna 8

9 Explring RF Ranging and Time Transfer with PUGS PUGS Slave PUGS Master 9

10 Decupling RF Ranging Algrithms fr COTS ENSCO s Timing, Cmmunicatins, and Ranging Device (TCR-D) 1 One example f a Sub-GHz COTS Cmmunicatins Transceiver fr PUGS Narrwband RF Ranging (BW = 500 khz) Cmmunicatins Transceiver Cmmunicatins Transceiver Embedded System 2 Cmms Embedded System Interchangeable COTS Mdules RF Ranging Algrithms + SDR Ranging Embedded System Assured PNT with a Cell Phne IMU and Carrier Phase RF Measurements fr GNSS Denied Envirnments (JNC 2018) Wireless Synchrnizatin Apprach t Create Distributed Cherent Phased Arrays (JNC 2018) 3 RF Ranging Algrithms + SDR One example f a receive nly SDR fr Narrwband Sampling (Fs = 2Msps) 10

11 USB USB Experimental Operatin with PUGS Master Send Request fr Data Capture at Hpped Frequency Cmmunicatin Packet frm Master Reply Cmmunicatin Packet frm Slave Slave db Raspberry Pi 3 (RF Ranging Algrithms and Data) Master TDOA M Slave Raspberry Pi 3 (RF Ranging Algrithms and Data) Insert Spectrgram PUGS Nde Master PUGS Nde Slave 11

12 USB USB Experimental Operatin with PUGS Master Send Request fr Data Capture at Hpped Frequency Slave Cmmunicatin Packet frm Master Reply Cmmunicatin Packet frm Slave Raspberry Pi 3 (RF Ranging Algrithms and Data) Master TDOA S Slave db Raspberry Pi 3 (RF Ranging Algrithms and Data) PUGS Nde Master PUGS Nde Slave 12

13 Tw-way Ranging Experiments with PUGS Slave Master Leveraged Lw SWAP-C 2.4 GHz RF Ranging Transceiver t supprt PUGS Experimentatin MicrPythn based peratin f IT transceivers prvided rapid RF ranging prtcl explratin Hpped ver 26 frequencies in 900 MHz ISM Band RTL-SDR data capture at each PUGS fr RF ranging algrithm explratin based n pst prcessing analysis Transmitter perating level f PUGS at 5 dbm RF ranging measurements up t ~200 meters GPS measurements cllected n each PUGS 13

14 Tw-way Ranging Experiments with PUGS Std = 4.8m Mean = 112m Ttal Obs = 1368 Std = 4.8m Mean = 111m Ttal Obs =

15 Tw-way Ranging Experiments with PUGS Std = 5.3m Mean = 158m Ttal Obs = 1425 Std = 5.6m Mean = 158m Ttal Obs =

16 Tw-way Ranging Experiments with PUGS Std = 8.3m Mean = 197m Ttal Obs = 1368 Std = 7.8m Mean = 192m Ttal Obs =

17 Summary and Next Steps with GNU Radi LRa RF Ranging Pythn Blck with PUGS demnstrates the feasibility f < 10 meter level ranging with lw SWAP-C COTS IT transceivers and SDRs withut access t RF physical layer measurements LRa RF Ranging Pythn blck prvides a great experimental framewrk fr explring additinal PNT research tpics with respect t IT transceivers and lw cst SDRs Further GNU Radi Pythn blck develpment is planned based n Angle-f-Arrival algrithms in a distributed PUGS cnfiguratin 17

18 Questins? Wilbur L. Myrick, Ph.D. (703) Ideas t Reality