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The GNSS integer ambiguities: estimation and validation

The GNSS integer ambiguities: estimation and validation

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Parameter distributions<br />

fˆx(x) probability density function of r<strong>and</strong>om variable ˆx<br />

f ˆx|ˆv(x|v) conditional probability density function of r<strong>and</strong>om variable ˆx<br />

ˆx ∼ N(x, Qx) r<strong>and</strong>om variable ˆx is normally distributed with mean x <strong>and</strong><br />

variance-covariance matrix Qx<br />

ˆx ∼ χ 2 (n, λ) r<strong>and</strong>om variable ˆx has χ 2 -distribution with n degrees of freedom<br />

<strong>and</strong> non-centrality parameter λ<br />

ˆx ∼ F (m, n, λ) r<strong>and</strong>om variable ˆx has F -distribution with m <strong>and</strong> n degrees of<br />

freedom <strong>and</strong> non-centrality parameter λ<br />

P (ˆx = x) probability that ˆx will be equal to the mean x<br />

P (ˆx = x|ˆv = v) probability that ˆx will be equal to the mean x conditioned on ˆv = v<br />

α false alarm rate or level of significance<br />

γ detection power<br />

Ambiguity resolution<br />

ˆx float estimate of x (= least-squares estimate)<br />

ˇx fixed estimate of x<br />

ˇɛ ambiguity residuals â − ǎ<br />

˜x best <strong>integer</strong> equivariant estimate of x<br />

¯x <strong>integer</strong> aperture estimate of x<br />

Ps, Pf , Pu probability of success, failure, <strong>and</strong> undecided respectively<br />

Ps,LS, Pf,LS <strong>integer</strong> least-squares success <strong>and</strong> fail rate respectively<br />

Sz<br />

pull-in region centered at the <strong>integer</strong> z<br />

sz(x) indicator function:<br />

sz(x) = 1 ⇔ x ∈ Sz, sz(x) = 0 otherwise<br />

ˆΩ squared norm of residuals of float solution:<br />

ˆΩ = êT G−1 ˆσ<br />

y ê<br />

2 float estimate of variance factor:<br />

ˆσ 2 ˇΩ<br />

ˆΩ = m−n−p<br />

squared norm of residuals of fixed solution:<br />

ˇΩ = ěT G−1 ˇσ<br />

y ě<br />

2 fixed estimate of variance factor:<br />

ˇσ 2 = ˇ Ri<br />

Ω<br />

m−p<br />

squared norm of ambiguity residuals:<br />

R1 = (â − ǎ) T G −1<br />

â (â − ǎ) = ˇ Ω − ˆ Ω<br />

R2 = (â − ǎ2) T G −1<br />

Ωz<br />

â (â − ǎ2)<br />

aperture pull-in region centered at the <strong>integer</strong> z<br />

Ω aperture space: Ω = ∪<br />

z∈Zn Ωz<br />

µ aperture parameter<br />

Notation <strong>and</strong> symbols xvii

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