The ionospheric map delay is implemented as:
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def get_delay(self, rcv_pos, az, el, sat_pos, time, freq): |
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# To get a delay from a TEC map, we need to calculate |
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# the ionospheric pierce point, geometry described here |
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# https://en.wikipedia.org/wiki/Ionospheric_pierce_point |
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alpha, beta = get_alpha_beta(rcv_pos, el) |
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conv = LocalCoord.from_ecef(rcv_pos) |
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gamma = np.pi - alpha - beta |
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geocentric_alt = np.linalg.norm(rcv_pos) |
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ipp_dist = geocentric_alt*np.sin(gamma)/np.sin(beta) |
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ipp_ned = conv.ecef2ned(sat_pos)*(ipp_dist)/np.linalg.norm(sat_pos) |
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ipp_geo = conv.ned2geodetic(ipp_ned) |
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factor = 40.30E16 / (freq**2) * 10**(self.exp) |
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vertical_delay = self.get_TEC(ipp_geo, time) * factor |
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slant_delay = get_slant_delay(rcv_pos, az, el, sat_pos, time, freq, vertical_delay) |
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return slant_delay |
where the factor is 40.30E16 / (freq**2) * 10**(self.exp) , was this tested? Is the constant's exponent correct?
See https://iers-conventions.obspm.fr/content/tn36.pdf equations 9.14 to 9.41.
