Hi,
I am downloading GPS Almanacs from U.S. Coast Guard Navigation Center web site to inject into the modem using nrf_modem_gnss_agps_write(). Below is current almanac for one satellite:
******** Week 197 almanac for PRN-01 ********
ID: 01
Health: 000
Eccentricity: 0.1223945618E-001
Time of Applicability(s): 589824.0000
Orbital Inclination(rad): 0.9890724625
Rate of Right Ascen(r/s): -0.8114623721E-008
SQRT(A) (m 1/2): 5153.605957
Right Ascen at Week(rad): -0.1638998176E+001
Argument of Perigee(rad): 0.938111269
Mean Anom(rad): -0.1604865606E+001
Af0(s): 0.2212524414E-003
Af1(s/s): -0.3637978807E-011
week: 197
I cannot map ioda member of nrf_modem_gnss_agps_data_almanac struct to any field in the YUMA (or SEM AL3).
Below is the mapping I have worked out:
| nrf_modem_gnss_agps_data_almanac Member | YUMA Field |
| sv_id | ID |
| wn | week |
| toa | Time of Applicability |
| ioda | ??? |
| e | Eccentricity |
| delta_i | Orbital Inclination |
| omega_dot | Rate of Right Ascen |
| sv_health | Health |
| sqrt_a | SQRT(A) |
| omega0 | Right Ascen at Week |
| w | Argument of Perigee |
| m0 | Mean Anom |
| af0 | Af0 |
| af1 | Af1 |
I understand that nrf_modem_gnss_agps_data_almanac expects certain values to be in semi-circle and not radians, and am using YUMA format just as a sample, due to it being easier on the eyes compared to SEM AL3.
Could you please advise what is ioda exactly, and how can it be calculated / deducted from GPS Almanac information?
Kind Regards,
Iman
