Crate swiftnav

swiftnav is a library that implements GNSS utility functions to perform position estimations. The data used by swiftnav typically comes from GNSS receiver chips as raw observation and ephemeris data. swiftnav is more of a “bring your own algorithm” library, it provides a bunch of functionality that is useful when processing raw GNSS data, but it provides only limited position estimation capabilities. Each module encompasses a single set of functionality, and they are meant to be pretty self-explanatory for developers familiar with GNSS processing.

GNSS systems are used to estimate the location of the receiver by determining the distance between the receiver and several satellites. The satellites send out precisely timed periodic messages and the receiver measures the delay of those messages. Knowing the location of the satellites at the time of transmission and the delays of the messages the receiver is able to determine the location of itself in relation to the satellites.

swiftnav does not provide any functionality for communicating with receivers made by Swift Navigation, or any manufacturer. libsbp is the library to use if you want to communicate with receivers using Swift Binary Protocol (SBP).

Time

Time is a very important aspect of GNSS. swiftnav defaults to representing all times as GPS times. It provides the ability to manipulate GPS time stamps, as well as means to convert a GPS time stamp into various other time bases (GLONASS time, UTC, MJD).

Coordinates

Several different coordinate types have representations and the ability to convert between them. Earth centered earth fixed (ECEF), Latitude longitude and height (both in radians and degrees), and Azimuth and elevation coordinates are available.

Ephemeris

Decoding and evaluation of broadcast ephemeris for all major GNSS constellations is made available. You are able to calculate the satellite position at a particular point in time in several different coordinates.

Troposphere and Ionosphere

Two major sources of signal error in GNSS are the troposphere and ionosphere. swiftnav provides the ability to decode and use the broadcast Klobuchar ionosphere model. An implementation of the UNM3m troposphere model is also provided.

Single epoch position solver

A simple least squares position solver is also included. This allows you to get an approximate position with GNSS measurements from a single point in time. It uses a least squares algorith, so no state is maintained between solves. This can be used to seed your own position estimation algorithm with a rough starting location.

Modules

coords

Coordinates and conversions

edc

Error detection code

ephemeris

Decoding and evaluation of satellite ephemeris

geoid

Geoid height calculation

ionosphere

Ionosphere delay calculation

navmeas

Raw GNSS measurement representation

reference_frame

Geodetic reference frame transformations

signal

Signal identifiers

solver

Single epoch PVT solver

time

Time handling

troposphere

Troposphere delay calculation