Almanac Information

Almanac parameters

Parameter

Field in XML file

Definition

Units

SVID

SVID

Satellite ID (1 constellation of 36 satellites)

dimensionless

Δ(a 1/2)

aSqRoot 

Difference with respect to the square root of the nominal semi-major axis (29 600 km)

meters 1/2

e

ecc 

Eccentricity

dimensionless

δi

deltai 

Inclination at reference time relative to i0 = 56º

semi-circles*

Ω0

omega0 

Right ascension

semi-circles*

 .
Ω

omegaDot 

Rate of right ascension

semi-circles/s*

ω

Argument of perigee

semi-circles*

M0

m0 

Satellite mean anomaly at reference time

semi-circles*

af0

af0 

Satellite clock correction bias “truncated”

s

af1

af1 

Satellite clock correction linear “truncated”

s/s

IODa

iod 

Almanac Issue Of Data

dimensionless

t0a

t0a 

Almanac reference time

s

WNa

wna 

Almanac reference Week Number

week

SVstatus**

statusE5a

statusE5b

statusE1B

Satellite signal health status

dimensionless

* Note that the ‘semi-circle’ is not a SI unit but can be converted as: 1 semi-circle = π radian

** The F/NAV almanac transmitted by the E5a-I component contains the signal health status (E5aHS) coded on 2 bits. The I/NAV almanac transmitted by the E5b-I and E1-B components contains both signal health status (E5bHS) and (E1-BHS) coded on 2 bits each.