Advanced global navigation satellite system receiver design (797918), страница 2
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F-2F.3Achieved C/N0 ........................................................................................... F-4F.4Effective v. actual carrier to noise density ratio ........................................ F-5F.5Example implementation ........................................................................... F-5F.6Spectral analysis......................................................................................... F-6F.7PSK analysis .............................................................................................. F-7F.8Extension to BOC analysis ........................................................................
F-9G FPGA Correlator Registers ................................................................................G-1H Derivation of exact timing formulas for sine and cosine BOC..........................H-1H.1Direct analysis for sBOC(1,1) pulse .........................................................H-1H.2Direct analysis for cBOC(1,1) ...................................................................H-2IAltBOC(15,10) lookup table............................................................................... I-1LIST OF FIGURESFigure 3-1, Simplified conceptual spread spectrum system ........................................30Figure 3-2, L-Band GNSS frequency allocations ........................................................31Figure 3-3, Heritage GPS signal generation structure [Kaplan and Hegarty 2006] ....31Figure 3-4, C/A code generator ...................................................................................33Figure 3-5, Ideal autocorrelation of a PRN sequence ..................................................34Figure 3-6, Normalised autocorrelation of GPS C/A code ..........................................35Figure 3-7, Power spectral density of current GPS L1 signals: (unfiltered, 1W signalpower) ..................................................................................................................36Figure 3-8, Spreading waveforms and PSD of BPSK(1), BOC(1,1)-sine, BOC(2,1)sine and BOC(2,1)-cosine modulations ...............................................................40Figure 3-9, Power spectral density of future L1 GPS signals (unfiltered, 1W signalpower) ..................................................................................................................41Figure 3-10, L2(C) code signal generation ..................................................................42Figure 3-11, Power spectral density of future L5 GPS signal (unfiltered, 1W signalpower) ..................................................................................................................44Figure 3-12, Power spectral density of the Galileo E1 signals (1W signal power) .....47Figure 3-13, Power spectral density of the Galileo E6 signals (1W signal power) .....47Figure 3-14, Power spectral density of the Galileo E5 band (1W signal power) ........48Figure 4-1, PSK and BOC bandwidth definitions .......................................................51Figure 4-2, Power spectral density of a BOC(10, 5) signal with sine and cosine subcarriers..................................................................................................................52Figure 4-3, Matched filter equivalent to GNSS receiver .............................................52Figure 4-4, Autocorrelations of BOC(10, 5) signals: a) unfiltered b) 24MHzbandwidth.............................................................................................................55Figure 4-5, a) Autocorrelations of time delayed early, prompt and late PSK signals b)PSK discriminator curve ......................................................................................55Figure 4-6, BOC discriminator curves a) BOC(2×fC, fC) b) BOC(6×fC, fC) ................56Figure 4-7, BOC correlation functions with different sub-carrier phasing..................57Figure 4-8, BOC discriminator curves with different sub-carrier phasing ..................57Figure 4-9, Timing recovery model of PSK GNSS receiver .......................................60Figure 4-10, Representations of the PSK timing model functions ..............................60Figure 4-11, PSK receiver groups................................................................................62Figure 4-12, Sine and cosine BOC(fC, fC) discriminators with slope approximations.64Figure 4-13, Depiction of discriminator error induced by the presence of multipath .67Figure 4-14, Multipath error envelopes for wide PSK (TD = TC ) and narrow PSK(TD = TC 2) ..........................................................................................................68Figure 4-15, Multipath error envelopes of PSK-R(1) and BOC(1,1) signals( BOC )( PSK )TD = 2 × TS= TC....................................................................................69Figure 4-16, Multipath error envelopes for PSK-R(2) and BOC(1,1) signals( BOC )( PSK )TD = TS= TC..........................................................................................70Figure 4-17, Running average multipath error of PSK-R(2) and BOC(1,1) signals( BOC )( PSK )TD = TS= TC..........................................................................................70Figure 4-18, Multipath error envelopes for PSK-R(4) and BOC(2,1) signals (TD = TS )..............................................................................................................................71()()()Figure 4-19, Running average multipath error of PSK-R(4) and BOC(2,1) signals(TD = TS ) ..............................................................................................................71Figure 4-20, Multipath induced carrier phase error envelopes for PSK-R(4) andBOC(2,1) signals..................................................................................................72Figure 4-21, Running average carrier phase multipath error of PSK-R(4) andBOC(2,1) signals..................................................................................................72Figure 5-1, GNSS receiver block diagram...................................................................75Figure 5-2, PSK correlator structure............................................................................78Figure 5-3, Correlation profile of wII against code error (chips) and phase error(radians) ...............................................................................................................79Figure 5-4, PSK search correlation wSPSK ....................................................................80Figure 5-5, Serial GNSS signal search ........................................................................81Figure 5-6, Correlation power loss with frequency offset ...........................................82Figure 5-7, FFT signal detection principle ..................................................................83Figure 5-8, FFT of GPS C/A code signal ....................................................................83Figure 5-9, Square wave cosine function.....................................................................85Figure 5-10, Costas PLL discriminator characteristic .................................................85Figure 5-11, Dot product discriminator characteristic.................................................88Figure 5-12, BOC correlator using conventional PSK architecture ............................91Figure 5-13, Triangular cosine function ......................................................................92Figure 5-14, wII for BOC(2×fC, fC) against code error (chips) and carrier phaseerror(rads) ............................................................................................................93Figure 5-15, Single sideband search of BOC modulated signals.................................94Figure 5-16, Sub-carrier cancellation BOC search technique .....................................95Figure 5-17, Triangular sine function ..........................................................................96Figure 5-18, Magnitude envelopes of the wIII, wIQI and wSBOC correlations for aBOC(2×fC, fC) signal ............................................................................................97Figure 5-19, Comparison of PSK and BOC search correlations using the SCC searchtechnique: a) BOC(2×fC, fC) b) BOC(6×fC, fC).....................................................98Figure 5-20, BOC(6×fC, fC) discriminator curve..........................................................99Figure 5-21, Single-sideband BOC tracking..............................................................100Figure 5-22, Composite MGD discriminators for a BOC(2×fC, fC) signal ................103Figure 5-23, Acquisition example of MGD discriminators (BL = 1 Hz , C/N0 = 30 dBHz)......................................................................................................................104Figure 5-24, BOC(2×fC, fC) false-lock example with BJ gates ..................................106Figure 5-25, Worse case VE and VL count values for BOC(2×fC, fC) with uncorrelatedsignal to noise of 10 dB per correlation .............................................................107Figure 5-26, Worse case VE and VL count values for BOC(2×fC, fC) with correlatednoise samples, signal to noise of 10 dB per correlation.....................................108Figure 5-27, Acquisition example of BJ algorithm for BOC(2, 1) signal (BL = 1 Hz ,C/N0 = 30 dB-Hz, TD = TS).................................................................................108Figure 5-28, Zero crossings of a BOC(2×fC, fC) signal..............................................110Figure 5-29, Symmetric and asymmetric BOC(2×fC, fC) correlations, sub-carrier tocode offset =TS / 4 ..............................................................................................113Figure 5-30, Example jump to invalid tracking state, BOC(2,1), C/N0 = 24 dB-Hz,sub-carrier to code offset =TS / 4........................................................................114Figure 5-31, Depiction of asymmetric tracking bias .................................................115Figure 5-32, BJ comparison amplitude of BOC(2, 1) correlations against relativemultipath delays (in-phase carrier, central correlation peak tracking) ..............116Figure 5-33, BJ comparison amplitude of BOC(2, 1) correlations against relativemultipath delays (180° out of phase, central correlation peak tracking) ...........117Figure 6-1, General schematic of a coherent DE BOC receiver................................122Figure 6-2, Trapezoidal sine function........................................................................124Figure 6-3, wIII correlation with independent sub-carrier and code delay estimates .124Figure 6-4, wIIQ correlation with independent sub-carrier and code delay estimates TDC= TC ....................................................................................................................125Figure 6-5, wIQI correlation with independent sub-carrier and code delay estimates TDS= TS .....................................................................................................................125Figure 6-6, Example acquisition of the DE BOC receiver (BDLL = BSLL = 1 Hz , C/N0 =30 dB-Hz)...........................................................................................................129Figure 6-7, Corrected delay estimate of the DE BOC receiver .................................130Figure 6-8, Incoherent DE BOC receiver ..................................................................131Figure 6-9, Example incoherent acquisition ∆φ = 1 rad ...........................................133Figure 6-10, Simulations of PSK and DE BOC timing jitter with comparison to theory............................................................................................................................137Figure 6-11, Multipath error envelope of a conventional and DE BOC receiver,.....138Figure 6-12, Running average multipath error of a conventional and DE BOC receiver............................................................................................................................139Figure 6-13, Example acquisition of the DE BOC receiver with asymmetriccorrelation, .........................................................................................................140Figure 6-14, Loss of lock from 15 dB SNR (SGR filter)...........................................141Figure 6-15, Example of receiver SNR estimation of a slip in tracking....................142Figure 7-1, Giove-A satellite: a) at ESA for environmental testing b) on the launchpad......................................................................................................................147Figure 7-2, Baseline payload design for Giove-A [Falcone et al 2006]....................148Figure 7-3, MFUU for Giove-A.................................................................................148Figure 7-4...................................................................................................................150Figure 7-5, Simplified MFUU modulation architecture ............................................151Figure 7-6, Spectrum analyser plot of the Galileo BOC(15, 2.5) –cosine signal fromthe MFUU ..........................................................................................................152Figure 7-7, Bench IF signal generator .......................................................................153Figure 7-8, I Q plots for Galileo interplex modulated signals (m = 0.6155) .............155Figure 7-9, I Q plots for GPS interplex modulated signals (m = 0.66)......................156Figure 7-10, Interplex of 2*BOC(1,1) + BOC(10,5) IF signals ................................157Figure 7-11, AltBOC(15,10) IF signal.......................................................................158Figure 7-12, IF noise synthesis ..................................................................................159Figure 7-13, Histogram of 50,000 numbers from the multiplicative congruentialrandom number generator ..................................................................................160Figure 7-14, Histogram of quasi-Gaussian noise generator (15852 points) ..............160Figure 7-15, Spectrum analyser plot of BOC(1,1) from IF signal generator with nonoise.
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