Advances in GNSS Equipment

Transcription

1 Advancs in GNSS Equipmnt Todd Humphrys With Input From: Thomas Pany, Brnhard Ridl IFEN, Carstn Strobr UFAF Larry Young, JPL David Munton, UT/ARL 2010 IGS Workshop, Nwcastl Upon Tyn

2 Q: What advancs in GNSS rcivr tchnology can th IGS xploit to improv its ntwork and products?

3 Outlin Rviw conclusions from Miami 2008 A look at commrcial rcivr stat-of-th-art Advancs in softwar rcivr tchnology DFE: Th final front-nd Th CASES rcivr Th IFEN/UFAF SX-NSR rcivr: Prformanc valuation Not all obsrvabls ar cratd qual Summary

4 Conclusions from Miami 2008 Many xcllnt commrcial RXs to choos from All major manufacturrs hav road maps toward all-in-viw capability Psudorang and phas masurmnt rror statistics ar htrognous and illdfind, impairing IGS products Softwar rcivrs show promis but hav not bn vttd

5 Th Supr Rcivr Tracks all opn signals, all satllits Tracks ncryptd signals whr possibl Wll-dfind, publicly disclosd masurmnt charactristics (phas, psudorang, C/No) RINEX 3.00 compliant Compltly usr rconfigurabl, from corrlations to tracking loops to navigation solution Intrnal cycl slip mitigation/dtction Up to 50 Hz masurmnts Intrnt rady; signal procssing stratgy rconfigurabl via intrnt Low cost

6 Th Ultra Rcivr Digital Storag Rx RF Front- End ADC RF Front- End RF Front- End Digital Storag Rx Rfrnc ADC Oscillator RF Front- End Digital Storag Rx Rfrnc ADC Oscillator Sampl Clock Digital Storag Rx Rfrnc ADC Oscillator Sampl Clock Mass Storag Sampl Clock Mass Storag Mass Storag Softwar Post-Procssing FFT-basd Acquisition Softwar Corrlators Tracking Loops, Data Dcoding, Obsrvabls Calculations Rfrnc Oscillator Sampl Clock Mass Storag

7 Commrcial Rcivr Offrings (2008) Sptntrio PolaRx3 Trimbl NtRS/NtR5 Lica GRX1200 Topcon NET-G3 7

8 Commrcial Rcivr Offrings (2010) Sptntrio GNRx1 Trimbl NtRS/NtR5/NtR8 Javad G3T Lica GRX1200+GNSS Topcon NET-G3 8

9 Rcivr Typ Distribution (Jun 2010)

10 Approaching th Supr Rcivr Excpt E5B, 216 channls Exampl Commrcial Rcivr: Javad G3T Tracks all opn signals, all satllits Tracks ncryptd signals whr possibl Wll-dfind, publicly disclosd masurmnt charactristics (phas, psudorang, C/No) Loop BW, updat rat configurabl RINEX 3.00 compliant Compltly usr rconfigurabl, from corrlations to tracking loops to navigation solution Intrnal cycl slip mitigation/dtction Up to 50 Hz Only masurmnts on G3T in IGS ntwork Intrnt rady; signal procssing stratgy rconfigurabl via intrnt (BOGI, Poland) Low cost Prformanc appars good ~$8k

11 Outlin Rviw conclusions from Miami 2008 A look at commrcial stat-of-th-art Advancs in softwar rcivr tchnology DFE: Th final front-nd Th CASES rcivr Th IFEN/UFAF SX-NSR rcivr: Prformanc valuation Not all obsrvabls ar cratd qual Summary

12 Rcall: Th Ultra Rcivr Digital Storag Rx RF Front- End ADC RF Front- End RF Front- End Digital Storag Rx Rfrnc ADC Oscillator RF Front- End Digital Storag Rx Rfrnc ADC Oscillator Sampl Clock Digital Storag Rx Rfrnc ADC Oscillator Sampl Clock Mass Storag Sampl Clock Mass Storag Mass Storag Softwar Post-Procssing FFT-basd Acquisition Softwar Corrlators Tracking Loops, Data Dcoding, Obsrvabls Calculations Rfrnc Oscillator Sampl Clock Mass Storag

13 Th ARL:UT Digitizing Front End

14 Th ARL:UT Digitizing Front End 1130 MHz 500 MHz span 1630 MHz (Fig. 1 of Wallnr t al., "Intrfrnc Computations Btwn GPS and Galilo," Proc. ION GNSS 2005)

15 Th ARL:UT Digitizing Front End 500 MHz bandwidth Singl RF signal path and ADC substantially liminats intr-signal instrumnt biass Tmpratur-stabilizd signal conditioning chain Opn-sourc dsign, as with GPSTk Dbut at ION GNSS 2010

16 UT/Cornll/ASTRA CASES SwRx

17 UT/Cornll/ASTRA CASES SwRx Dual-frquncy narrowband Compltly softwar rconfigurabl Antarctic dploymnt 2010 Spac dploymnt 2012 (as occultation snsor)

18 CASES Multi-Systm Rcivr Bank

19 Approaching th Ultra Rcivr Digital Storag Rx RF Front- End ADC RF Front- End RF Front- End Digital Storag Rx Rfrnc ADC Oscillator RF Front- End Digital Storag Rx Rfrnc ADC Oscillator Sampl Clock Digital Storag Rx Rfrnc ADC Oscillator Sampl Clock Mass Storag Sampl Clock Mass Storag Mass Storag Softwar Post-Procssing FFT-basd Acquisition Softwar Corrlators Tracking Loops, Data Dcoding, Obsrvabls Calculations Rfrnc Oscillator Sampl Clock Mass Storag

20 Approaching th Ultra Rcivr Mass Storag

21 Multicor GNSS Procssing Signal-typ lvl Low comm/sync ovrhad Poor load balancing Channl lvl Low comm/sync ovrhad Good load balancing Favors shard mmory architctur Corrlation lvl Dmonstratd 3.4x spdup on 4-cor Good load balancing machin with OpnMP Sub-corrlation lvl CASES post-procssing now 25x ral-tim Bods wll for ranalysis Good load balancing Highr comm/synch ovrhad Vry high comm/synch ovrhad

22 UFAF SwRx Evaluation (Carstn Strobr) Running sinc End 2007 Currnt Signals Frontnd Longst running tim without xtrnal rst Longst running tim with xtrnal rst GPS L1 C/A, L2C (CM+CL), L5 Giov A+B SBAS Fraunhofr, (IFEN possibl) >10 days >1 month Annotations: Extrnal rst dnots automatic rstart of th rcivr via script program Rfrnc station was on a productiv systm simultanously mploying monitoring algorithms -> priority was not only givn to long tim stability Currntly Glonass is in tst mod Ddicatd softwar rcivr rfrnc station (GPS L1, L2 only) intndd for long run stability is in tst phas Advantags Extnsiv data analysis possibl at masurmnt tim.g. instantanous monitoring for signal distortions with accss to low lvl masurmnts i.. signal sampl data Softwar rcivr is indpndnt from utilizd hardwar

23 UFAF SwRx Evaluation Dat DoY 170, Yar 2007 Horizontal scattr plot of final PDGPS adjustmnt at highst tmporal rsolution with bounding box (upward: north; right: astward). Analysis Softwar Masurmnts Numbr obsrvations (doubl diffrncs) Duration Data dltd du to cycl slips Standard dviation position PrPos GNSS Suit GPS L min 2% (for OEM 4 rcivr 1%) X 5.2mm Y 3.7mm Z 6.1mm

24 Oprational prformanc comparabl to NovAtl OEM 4 Coordinat tim sris of final PDGPS adjustmnt. Softwar rcivr at top, OEM IV at bottom.

25 UFAF SwRx Evaluation Drawbacks, suggstd dirctions Complx intraction btwn PC hardwar, working systm, additional applications and softwar rcivr.g.: USB accss is controlld by working systm (drivrs ) -> buffring ndd Additional applications starts unmant, procss tim consuming action.g. disk dfrag -> additional applications must b dltd or configurd too Short-tim intrnal procssing load paks du to frquntly simultanous xcution of xtnsiv tasks -> 2 stratgis: For rfrnc station no ral ral-tim ndd -> us alrady xisting buffring Adapt configuration to PC hardwar and us high powr hardwar Fr configurability lads to a big rror sourc givn by non optimal or wrong configuration -> in rfrnc station mod this is rlaxd du to fixd configuration

26 Outlin Rviw conclusions from Miami 2008 A look at commrcial stat-of-th-art Advancs in softwar rcivr tchnology DFE: Th final front-nd Th CASES rcivr Th IFEN/UFAF SX-NSR rcivr: Prformanc valuation Not all obsrvabls ar cratd qual Summary

27

28 Toward a Standardizd Carrir Phas and Psudorang Masurmnt Tchniqu Diffrnt rcivr manufacturrs us propritary (cod/carrir) masurmnt dfinitions Standard proposd by L. Young at last IGS workshop basd on th US patnt no. 4,821,294 (Thomas, Jr., Caltch) Goal: to hav stochastically indpndnt cod/carrir obsrvations with a wll undrstood obsrvation principl Us SX-NSR softwar rcivrs API for a prototyp implmntation

29 Carrir phas [cycls], dtrndd Illustration (Carrir Phas) 0.4 GPS C/A PRN13 Wk 1570, sc ~ , NavPort-2 Frontnd with OCXO 0.2 carrir tracking loop rror RINEX valu compnsation by corrlator modl phas rsidual phas (+/- pi/2) unwrappd rsidual phas total phas 2nd ordr polyfit Tim bfor RINEX poch [s] Vrification that corrlator basd obsrvations ar truly indpndnt Download: C++ sourc cod and xmplary data (GPS L1, Galilo E1/E5a) at

30 dtrndd Psudorang [m] Illustration (Psudorang) GPS C/A PRN13 Wk 1570, sc ~ , NavPort-2 Frontnd with OCXO modl PR rsidual PR total PR 2nd ordr polyfit RINEX valu Tim bfor RINEX poch [s]

31 Cod minus carrir psudorang [m] Evaluating th Exampl Cod minus carrir analysis shows that data is statistically indpndnt Discriminators cancl tim corrlation causd by th low bandwidth ( Hz) tracking loops Galilo E1 - PRN6 Phas discriminiator unwrapping togthr with FLL tracking givs valid carrir rangs Tim [s]

32 Summary Q: What advancs in GNSS rcivr tchnology can th IGS xploit to improv its ntwork and products? A1: Commrcial rcivrs ar approaching th Supr Rcivr : naring all-gnss-signals tracking, rconfigurabl, low-cost A2: 500-MHz digitizing opn-dsign front-nd capturs all currnt and plannd GNSS signals, substantially liminats intr-signal RX biass A3: 500-MHz front-nd + Multi-systm SwRx + Multi-cor procssing + data buffring Ultra Rcivr A4: SwRx prformanc comparabl to commrcial godtic RXs (but not yt as rliabl) A5: Rcivr APIs offr path for masurmnt standardization (.g., IFEN SX-NSR)