dop module

Dillution of Precision (DOP) calculations and interface with NavData.

dop._calculate_enut_matrix(derived)[source]

Calculate the ENU and Time Matrix from elevation and azimuth. Each row is [d_e, d_n, d_u, 1] for each satellite.

Parameters:

derived (gnss_lib_py.navdata.navdata.NavData) – NavData instance containing received GNSS measurements for a particular time instance, contains elevation and azimuth angle information for an estimated location.

Returns:

enut_matrix – Matrix of ENU and Time vectors of size (num_satellites, 4).

Return type:

np.ndarray

dop._safe_sqrt(x)[source]

Safe square root for DOP calculations.

Parameters:

x (float) – Value to take the square root of.

Returns:

y – Square root of x, or NaN if x is negative.

Return type:

float

dop.calculate_dop(derived)[source]

Calculate the DOP from elevation and azimuth (ENU).

Parameters:

derived (gnss_lib_py.navdata.navdata.NavData) – NavData instance containing received GNSS measurements for a particular time instance, contains elevation and azimuth angle information for an estimated location.

Returns:

dop – Dilution of precision, with DOP type as the keys: “HDOP”, “VDOP”, “TDOP”, “PDOP”, “GDOP”.

Return type:

Dict

dop.calculate_enu_dop_matrix(derived)[source]

Calculate the DOP matrix from elevation and azimuth (ENU).

Parameters:

derived (gnss_lib_py.navdata.navdata.NavData) – NavData instance containing received GNSS measurements for a particular time instance, contains elevation and azimuth angle information for an estimated location.

Returns:

dop_matrix – DOP matrix of size (4, 4).

Return type:

np.ndarray

dop.get_dop(navdata, **which_dop)[source]

Get DOP from navdata.

Parameters:

  • navdata (gnss_lib_py.navdata.navdata.NavData) – NavData instance containing received GNSS measurements for a particular time instance, contains elevation and azimuth angle information for an estimated location. Instance of the NavData class which must include at least gps_millis, el_sv_deg, and az_sv_deg

  • which_dop (dict) –

    Dictionary of which dop values are needed. Default is HDOP and VDOP.

    Note that the dop matrix output is splatted across entries following the behavior below:

    [[EE, EN, EU, ET],
 [NE, NN, NU, NT],
 [UE, UN, UU, UT],
 [TE, TN, TU, TT]]  (16 values in 2D array)

    is stored as:

    [EE, EN, EU, ET,
     NN, NU, NT,
         UU, UT,
             TT] (10 values in 1D array)

    recognizing that the dop matrix is symmetric.

Returns:

dop_navdata – Dilution of precision data along with the relevant time stamp.

Return type:

gnss_lib_py.navdata.navdata.NavData

dop.get_enu_dop_labels()[source]

Helper function to get the DOP labels.

Returns:

dop_labels – List of strings for the DOP labels.

Return type:

list

dop.parse_dop(dop_matrix)[source]

Calculate DOP types from the DOP matrix.

Parameters:

dop_matrix (np.ndarray) – DOP matrix in ENU coordinates of size (4, 4).

Returns:

dop – Dilution of precision, with DOP type as the keys: “HDOP”, “VDOP”, “TDOP”, “PDOP”, “GDOP”.

Return type:

Dict

dop.splat_dop_matrix(dop_matrix)[source]

Splat the DOP matrix into a 1D array. Note that the dop matrix output is splatted across entries following the behavior below:

[[EE, EN, EU, ET],
 [NE, NN, NU, NT],
 [UE, UN, UU, UT],
 [TE, TN, TU, TT]]  (16 values in 2D array)

is stored as:

[EE, EN, EU, ET,
     NN, NU, NT,
         UU, UT,
             TT] (10 values in 1D array)

recognizing that the dop matrix is symmetric.

Parameters:

dop_matrix (np.ndarray) – DOP matrix in ENU coordinates of size (4, 4).

Returns:

dop_splat – DOP matrix splatted into a 1D array of size (10,).

Return type:

np.ndarray

dop.unsplat_dop_matrix(dop_splat)[source]

Un-splat the DOP matrix from a 1D array. Note that the dop matrix output is unsplatted across entries following the behavior below:

[EE, EN, EU, ET,
     NN, NU, NT,
         UU, UT,
             TT] (10 values in 1D array)

is unsplatted to

[[EE, EN, EU, ET],
 [NE, NN, NU, NT],
 [UE, UN, UU, UT],
 [TE, TN, TU, TT]]  (16 values in 2D array)

recognizing that the dop matrix is symmetric.

Parameters:

dop_splat (np.ndarray) – DOP matrix splatted into a 1D array of size (10,).

Returns:

dop_matrix – DOP matrix in ENU coordinates of size (4, 4).

Return type:

np.ndarray