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34 lines
1.1 KiB
34 lines
1.1 KiB
#!/usr/bin/python
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from numpy import cos, exp, pi
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from .lib.coordinates import ecef2geodetic
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def saast(pos, el, humi=0.75, temp0=15.0):
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"""
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Function from RTKlib: https://github.com/tomojitakasu/RTKLIB/blob/master/src/rtkcmn.c#L3362-3362
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with no changes
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:param time: time
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:param pos: receiver position {ecef} m)
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:param el: azimuth/elevation angle {az,el} (rad) -- we do not use az
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:param humi: relative humidity
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:param temp0: temperature (Celsius)
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:return: tropospheric delay (m)
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"""
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pos_rad = ecef2geodetic(pos, radians=True)
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if pos_rad[2] < -1E3 or 1E4 < pos_rad[2] or el <= 0:
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return 0.0
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# /* standard atmosphere */
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hgt = 0.0 if pos_rad[2] < 0.0 else pos_rad[2]
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pres = 1013.25 * pow(1.0 - 2.2557E-5 * hgt, 5.2568)
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temp = temp0 - 6.5E-3 * hgt + 273.16
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e = 6.108 * humi * exp((17.15 * temp - 4684.0) / (temp - 38.45))
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# /* saastamoninen model */
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z = pi / 2.0 - el
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trph = 0.0022768 * pres / (
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1.0 - 0.00266 * cos(2.0 * pos_rad[0]) - 0.00028 * hgt / 1E3) / cos(z)
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trpw = 0.002277 * (1255.0 / temp + 0.05) * e / cos(z)
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return trph + trpw
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