The effect of sampling frequency and front-end bandwidth on the DLL - - PowerPoint PPT Presentation

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The effect of sampling frequency and front-end bandwidth on the DLL - - PowerPoint PPT Presentation

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The effect of sampling frequency and front-end bandwidth on the DLL code tracking performance Vi Vinh T T r ran, Thuan Nguyen, Nagaraj Shivaramaiah, Andrew Dempster Contents GNSS receiver model Local code generator and residual code

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Vi Vinh T r T ran, Thuan Nguyen, Nagaraj Shivaramaiah, Andrew Dempster

The effect of sampling frequency and front-end bandwidth on the DLL code tracking performance

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IG NSS SYMPOSIUM 201 6, UNSW, SYDNEY, AUSTRALIA 2

  • GNSS receiver model
  • Local code generator and residual code phase

estimation

  • Problem and motivation
  • Correlator output recalculation
  • DLL tracking error estimation
  • Experiment results

Contents

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GNSS receiver model

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Code generator and residual code phase estimation

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Conventional correlator

  • utput calculation
  • Autocorrelation output R(𝜐) = 1 βˆ’ 𝜐

π‘ˆ

𝑑 𝜐 ≀ π‘ˆ

𝑑

0 𝑓𝑓𝑓𝑓 π‘₯π‘₯𝑓π‘₯𝑓

  • Power spectral density

𝐻𝑑(𝑔)𝑄𝑄𝑄= π‘ˆ

𝑑𝑓𝑑𝑑𝑑2(πœŒπ‘”π‘ˆ 𝑑)

  • Correlation output:

R(𝜐) = ∫ 𝐻𝑑

𝛾𝑠/2 βˆ’π›Ύπ‘ /2

(𝑔)π‘„π‘„π‘„π‘“π‘˜2πœŒπœŒπœπ‘’π‘”

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Problems

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Problems

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Correlation output recalculation

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Correlation shapes

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DLL tracking error [1]:

πœπ‘‘

2 = πœπ‘£ 22πΆπ‘€π‘ˆ(1 βˆ’ 0.5πΆπ‘€π‘ˆ)

where: πœπ‘£ is variance of the unsmoothed TOA estimate from the discriminator πœπ‘‘ is variance of the smoothed TOA estimate from the discriminator BL is the noise filter bandwidth T is the integration time

[1] John W Betz and Kevin R Kolodziejski. Generalized theory of code tracking with an early-late discriminator part ii: noncoherent processing

and numerical results. IEEE T ransactions onAerospace and Electronic Systems, 45(4):1557–1564, 2009a

Conventional DLL tracking error estimation

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1

Conventional DLL tracking error estimation

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2

DLL tracking error re-estimation

  • DLL tracking error [2]:

πœπ‘‘

2 = 𝜏1 2 + πœπ‘£π‘‚ 2 2πΆπ‘€π‘ˆ(1 βˆ’ 0.5πΆπ‘€π‘ˆ)

where: πœπ‘£π‘‚ is the error part that is effected by the noise power 𝜏1 is the error part that is influenced by the sampling frequency πœπ‘‘ is variance of the smoothed TOA estimate from the discriminator

[2] Vinh T

. T ran, Nagaraj C. Shivaramaiah, Thuan D Nguyen, Eamonn Glenoon, W Cheong Joon, and Andrew G. Dempster. A generalized theory of the effect of sampling frequency on GNSScode tracking. Submitted to Aerospace and Electronic Systems, IEEE T ransactions on, 2016b

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3

Errors estimation

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DLL tracking error validation

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DLL tracking error re-estimation

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DLL tracking error versus sampling frequency and frontend band width

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DLL tracking error versus sampling frequency and frontend band width

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Experiment setup

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Experiment results

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Receiver Position Variation

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  • The more accurate correlation output and Delay

Locked Loop (DLL) code tracking error is proposed

  • The relation between the sampling frequency and

front-end filter bandwidth has a strong effect on the DLL jitter

  • The DLL tracking error is decreased while the

sampling frequency is increased and it is more efficient for weak signals ( CN0 < 30 dB-Hz ) if and

  • nly if the front-end bandwidth is fixed and much

smaller than the sampling frequency

Conclusions

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Thank you and Question ?