Hi everyone,

I am trying to simulate a dynamic satellite constellation network using SatelliteToolbox. The goal is to use this network and integrate it with the QuNet package for benchmarking and performance analysis as a function of various parameter such as the satellite mesh density, ground node separation, number of users etc. The input to QuNet will be a graph, representing the simulated network at given point in time.

I am completely new to Julia so kind of stuck at the first phase still, trying to simulate the network to go with. This is what I have done so far, using TLE data of Starlink from this link,

https://celestrak.org/NORAD/elements/gp.php?GROUP=starlink&FORMAT=tle

```
using SatelliteToolbox
using Dates
# Load TLE data from a file
filename = "starlink.txt"
tles = read_tle(filename)
# Initialize an SGP4 propagator for each satellite
propagators = [init_orbit_propagator(Val(:sgp4), tle) for tle in tles]
# Define the time period for the simulation
start_time = DateTime(2023, 4, 26, 0, 0, 0)
end_time = DateTime(2023, 4, 26, 1, 0, 0)
time_step = Minute(180)
# Initialize the time array
time_array = collect(start_time:time_step:end_time)
# Initialize position and velocity arrays for each satellite
num_satellites = length(propagators)
sat_positions_eci = zeros(num_satellites, 3, length(time_array))
sat_positions_ecef = zeros(num_satellites, 3, length(time_array))
sat_positions_geodetic = zeros(num_satellites, 3, length(time_array))
sat_velocities = zeros(num_satellites, 3, length(time_array))
# Propagate the orbits for the entire simulation period using propagate_to_epoch!
for (i, t) in enumerate(time_array)
for (j, propagator) in enumerate(propagators)
tle = tles[j] # Access the TLE object for the current satellite
JD_t = Dates.datetime2julian(t)
r_eci, v_eci = propagate_to_epoch!(propagator, JD_t) # Using propagate_to_epoch! function
# Store ECI position and velocity data
sat_positions_eci[j, :, i] = r_eci
sat_velocities[j, :, i] = v_eci
# Convert ECI to ECEF
r_ecef = r_eci_to_ecef(r_eci, JD_t)
sat_positions_ecef[j, :, i] = r_ecef
# Convert ECEF to geodetic coordinates
lat, lon, alt = ecef_to_geodetic(r_ecef)
sat_positions_geodetic[j, :, i] = [lat, lon, alt]
end
end
# Now `sat_positions_eci`, `sat_positions_ecef`, and `sat_positions_geodetic` hold the position data for each satellite in ECI, ECEF, and geodetic coordinates, respectively
```

I am getting the following error from the code above,

MethodError: no method matching r_eci_to_ecef(::SVector{3, Float64}, ::Float64)

Can someone please correct my mistakes and possibly guide me to achieve what I am trying to do?

Thanks in advance!