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

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 phase estimation • Problem and motivation • Correlator output recalculation • DLL tracking error estimation • Experiment results 2 IG NSS SYMPOSIUM 201 6, UNSW, SYDNEY, AUSTRALIA

GNSS receiver model | 3 IG NSS SYMPOSIUM 201 6, UNSW, SYDNEY, AUSTRALIA

Code generator and residual code phase estimation | 4 IG NSS SYMPOSIUM 201 6, UNSW, SYDNEY, AUSTRALIA

Conventional correlator output calculation • Autocorrelation output R( 𝜐 ) = � 1 − 𝜐 𝑑 𝜐 ≤ 𝑈 𝑑 𝑈 0 𝑓𝑓𝑓𝑓 𝑥𝑥𝑓𝑥𝑓 • Power spectral density 𝑑 𝑓𝑡𝑡𝑡 2 ( 𝜌𝑔𝑈 𝐻 𝑡 ( 𝑔 ) 𝑄𝑄𝑄 = 𝑈 𝑑 ) • Correlation output: 𝛾 𝑠 / 2 ( 𝑔 ) 𝑄𝑄𝑄 𝑓 𝑘2𝜌𝜌𝜐 𝑒𝑔 R( 𝜐 ) = ∫ 𝐻 𝑡 −𝛾 𝑠 / 2 | 5 IG NSS SYMPOSIUM 201 6, UNSW, SYDNEY, AUSTRALIA

Problems | 6 IG NSS SYMPOSIUM 201 6, UNSW, SYDNEY, AUSTRALIA

Problems | 7 IG NSS SYMPOSIUM 201 6, UNSW, SYDNEY, AUSTRALIA

Correlation output recalculation | 8 IG NSS SYMPOSIUM 201 6, UNSW, SYDNEY, AUSTRALIA

Correlation shapes | 9 IG NSS SYMPOSIUM 201 6, UNSW, SYDNEY, AUSTRALIA

Conventional DLL tracking error estimation DLL tracking error [1]: 2 = 𝜏 𝑣 2 2𝐶 𝑀 𝑈 (1 − 0.5 𝐶 𝑀 𝑈 ) 𝜏 𝑡 where: 𝜏 𝑣 is variance of the unsmoothed TOA estimate from the discriminator 𝜏 𝑡 is variance of the smoothed TOA estimate from the discriminator B L 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 | 1 IG NSS SYMPOSIUM 201 6, UNSW, SYDNEY, AUSTRALIA 0

Conventional DLL tracking error estimation | 1 IG NSS SYMPOSIUM 201 6, UNSW, SYDNEY, AUSTRALIA 1

DLL tracking error re-estimation DLL tracking error [2]: • 2 = 𝜏 1 2 + 𝜏 𝑣𝑂 2 2𝐶 𝑀 𝑈 (1 − 0.5 𝐶 𝑀 𝑈 ) 𝜏 𝑡 where: 𝜏 𝑣𝑂 is the error part that is effected by the noise power 𝜏 1 is the error part that is influenced by the sampling frequency 𝜏 𝑡 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 | 1 IG NSS SYMPOSIUM 201 6, UNSW, SYDNEY, AUSTRALIA 2

Errors estimation | 1 IG NSS SYMPOSIUM 201 6, UNSW, SYDNEY, AUSTRALIA 3

DLL tracking error validation | 1 IG NSS SYMPOSIUM 201 6, UNSW, SYDNEY, AUSTRALIA 4

DLL tracking error re-estimation | 1 IG NSS SYMPOSIUM 201 6, UNSW, SYDNEY, AUSTRALIA 5

DLL tracking error versus sampling frequency and frontend band width | 1 IG NSS SYMPOSIUM 201 6, UNSW, SYDNEY, AUSTRALIA 6

DLL tracking error versus sampling frequency and frontend band width | 1 IG NSS SYMPOSIUM 201 6, UNSW, SYDNEY, AUSTRALIA 7

Experiment setup | 1 IG NSS SYMPOSIUM 201 6, UNSW, SYDNEY, AUSTRALIA 8

Experiment results | 1 IG NSS SYMPOSIUM 201 6, UNSW, SYDNEY, AUSTRALIA 9

Receiver Position Variation | 20 IG NSS SYMPOSIUM 201 6, UNSW, SYDNEY, AUSTRALIA

Conclusions • 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 only if the front-end bandwidth is fixed and much smaller than the sampling frequency | 21 IG NSS SYMPOSIUM 201 6, UNSW, SYDNEY, AUSTRALIA

Thank you and Question ? | 22 IG NSS SYMPOSIUM 201 6, UNSW, SYDNEY, AUSTRALIA