perturb Namespace Reference

Primary namespace for the perturb library, everything is in here. More...

Namespaces
namespace	sgp4
	An internal namespace containing the underlying SGP4 implementation.

Classes
struct	ClassicalOrbitalElements
	Classical Keplerian orbital elements. More...
struct	DateTime
	A basic and human readable representation of a point in time. More...
struct	JulianDate
	Represents a specific point in time on the Julian calendar. More...
class	Satellite
	Represents a specific orbital ephemeris for an Earth-centered trajectory. More...
struct	StateVector
	Represents the output prediction from SGP4. More...
struct	TwoLineElement
	Represents a pre-parsed TLE record. More...

Typedefs
using	Vec3 = std::array< double, 3 >
	Alias for representing position and velocity vectors.

Enumerations
enum class	Sgp4Error : int {   NONE = 0 , MEAN_ELEMENTS , MEAN_MOTION , PERT_ELEMENTS ,   SEMI_LATUS_RECTUM , EPOCH_ELEMENTS_SUB_ORBITAL , DECAYED , INVALID_TLE ,   UNKNOWN }
	Possible issues during SGP4 propagation or even TLE parsing. More...
enum class	GravModel { WGS72_OLD , WGS72 , WGS84 }
	Choice of gravity model / constants for the underlying SGP4 impl. More...
enum class	TLEParseError {   NONE , SHOULD_BE_SPACE , INVALID_FORMAT , INVALID_VALUE ,   CHECKSUM_MISMATCH }
	Possible errors when parsing a TLE. More...

Variables
constexpr std::size_t	TLE_LINE_LEN = 69
	Both lines of a TLE must be this length, for TLE constructors. More...

Detailed Description

Primary namespace for the perturb library, everything is in here.

See README for a brief intro to the main library types and basic usage.

Enumeration Type Documentation

GravModel

enum class perturb::GravModel

strong

Choice of gravity model / constants for the underlying SGP4 impl.

Corresponds to the gravconsttype type in perturb::sgp4. Generally, WGS72 is the standard choice, despite WGS84 being the newer and more accurate model. What is most important is that this is the exact same as the gravity model used to generate the TLE ephemeris. This can be confirmed from the source of your TLE data.

Sgp4Error

enum class perturb::Sgp4Error : int

strong

Possible issues during SGP4 propagation or even TLE parsing.

This is important in two places:

1. After construction of a Satellite, check Satellite::last_error for any issues with TLE parsing or SGP4 initialization.
2. Calling Satellite::propagate returns a perturb::Sgp4Error, indicating any possible issues with propagation.

If everything is all good, the value should be Sgp4Error::NONE. The errors Sgp4Error::MEAN_ELEMENTS to SGP4Error::DECAYED directly correlate to errors in the underlying SGP4 impl, from the comments of perturb::sgp4::sgp4. The additional Sgp4Error::INVALID_TLE is for issues with reading the TLE strings.

TLEParseError

enum class perturb::TLEParseError

strong

Possible errors when parsing a TLE.

Returned by TwoLineElement::parse after processing a TLE record string.

Postcondition

Errors (excluding NONE) are guaranteed to occur in definition order. Meaning that spaces are checked first, then invalid format, then invalid values, and lastly checksum. This allows you to assume, for example, that if there is a CHECKSUM_MISMATCH, then none of the previous errors occurred first, and so the invalid checksum is the only issue.

Enumerator
NONE	If no issues when parsing.
SHOULD_BE_SPACE	If there is a lack of space in the TLE.
INVALID_FORMAT	If general parsing was unsuccessfully.
INVALID_VALUE	If a parsed value doesn't make sense.
CHECKSUM_MISMATCH	If the checksum doesn't match.

Variable Documentation

TLE_LINE_LEN

constexpr std::size_t perturb::TLE_LINE_LEN = 69

constexpr

Both lines of a TLE must be this length, for TLE constructors.

The memory can and is accessed. Lines can be longer for verification mode, but that's for internal testing purposes only and doesn't pertain to general usage.