readGLONASSNavigationRINEX: Read a RINEX navigation file for GLONASS satellites

In asteRisk: Computation of Satellite Position

Read a RINEX navigation file for GLONASS satellites

Description

RINEX (Receiver Independent Exchange Format) is one of the most widely used formats for providing data of satellite navigation systems. The RINEX standard defines several structured text file types, among which navigation files are used to distribute positional information of the satellites. The exact information provided in a RINEX navigation file varies for each satellite navigation system. This function reads RINEX navigation files for satellites of the GLONASS constellation, operated by Russia.

Usage

readGLONASSNavigationRINEX(filename)

Arguments

filename

Path to the GLONASS RINEX navigation file.

Value

A list with two elements. The first element, named header, is a list with the following elements:

rinexVersion	Version of the RINEX format used in the file
rinexFileType	Type of RINEX file
generatorProgram	Program used to generate the RINEX file
generatorEntity	Individual or organization that generated the file
fileCreationDateString	Date-time string indicating when the file was created
refYear	Reference year for system time correction
refMonth	Reference month for system time correction
refDay	Reference day for system time correction
sysTimeCorrection	Correction to system time scale to fine-tune GLONASS time to UTC in seconds. Since GLONASS time is linked to UTC, it should be a very small amount
leapSeconds	Leap seconds introduced since 1980. Useful to convert to GPS time
comments	Miscellaneous comments found in the header of the RINEX file

The second element is named messages, and it contains one element for each navigation message found in the RINEX file. Each of these elements is a list with the following elements that provide information about the position of the GLONASS satellite:

satelliteNumber	Slot number of the satellite within the GLONASS constellation. It can be converted to a PRN code by adding 37 to it
epochYearShort	Epoch year in 2-digit format. If lower than 80, the meaning should be taken as 20XX, while if larger than 80, it refers to 19XX.
epochMonth	Epoch month
epochDay	Epoch day
epochHour	Epoch hour
epochMinute	Epoch minute
epochSecond	Epoch second
ephemerisUTCTime	A nanotime object indicating the time corresponding to the reported position (ephemeris) in the present message. The time is in UTC, obtained by applying the individual clock bias of the particular satellite (clockBias field of each message) and the latest global GLONASS time bias with respect to UTC (sysTimeCorrection field of the header) to the uncorrected ephemeris time, given by the previous time fields. Corrections are performed as described in the GLONASS system specifications (https://russianspacesystems.ru/wp-content/uploads/2016/08/ICD_GLONASS_eng_v5.1.pdf)
clockBias	Clock bias (i.e., constant offset) that should be applied to the satellite time in order to obtain an even more accurate UTC time. In seconds
relativeFreqBias	Clock drift of the satellite clock that should be applied in combination with the time difference to the reference time in order to obtain an even more accurate UTC time. In seconds per second
messageFrameTime	Second of the UTC day when the message was transmitted
positionX	X coordinate of the position of the satellite in km, in the ITRF system of coordinates
positionY	Y coordinate of the position of the satellite in km, in the ITRF system of coordinates
positionZ	Z coordinate of the position of the satellite in km, in the ITRF system of coordinates
velocityX	X component of the velocity of the satellite in km/s, in the ITRF system of coordinates
velocityY	Y component of the velocity of the satellite in km/s, in the ITRF system of coordinates
velocityZ	Z component of the velocity of the satellite in km/s, in the ITRF system of coordinates
accelX	X component of the accel of the satellite in km/s, in the ITRF system of coordinates
accelY	Y component of the accel of the satellite in km/s, in the ITRF system of coordinates
accelZ	Z component of the accel of the satellite in km/s, in the ITRF system of coordinates
satelliteHealthCode	Code indicating the health of the satellite. 0 if healthy
freqNumber	Frequency number (k) of the GLONASS satellite. The two frequencies in MHz, f1 and f2, used by the satellite to transmit data can be calculated as follows: f1 = 1602 + k*9/16 and f2 = 1246 + k*7/16
informationAge	Age in days of the observation data used to generate the provided ephemeris

References

https://gage.upc.edu/gFD/ https://www.navcen.uscg.gov/pubs/gps/rinex/rinex.txt ftp://www.ngs.noaa.gov/cors/RINEX211.txt http://acc.igs.org/misc/rinex304.pdf https://russianspacesystems.ru/wp-content/uploads/2016/08/ICD_GLONASS_eng_v5.1.pdf

Examples

# The file testGLONASSRINEX.txt provided with the package includes 5 navigation
# messages from 4 GLONASS satellites

testGLONASSnav <- readGLONASSNavigationRINEX(paste0(path.package("asteRisk"), 
"/testGLONASSRINEX.txt"))
testGLONASSnav$header
testGLONASSnav$messages

asteRisk documentation built on Jan. 14, 2023, 5:07 p.m.