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https://github.com/rx14/predict.cr
Satellite prediction library for crystal using the sgp4 model
https://github.com/rx14/predict.cr
crystal satellite satellite-prediction sgp4
Last synced: 12 days ago
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Satellite prediction library for crystal using the sgp4 model
- Host: GitHub
- URL: https://github.com/rx14/predict.cr
- Owner: RX14
- License: mit
- Created: 2016-12-05T00:58:00.000Z (almost 8 years ago)
- Default Branch: master
- Last Pushed: 2020-04-13T11:31:45.000Z (over 4 years ago)
- Last Synced: 2024-10-04T21:33:25.734Z (about 1 month ago)
- Topics: crystal, satellite, satellite-prediction, sgp4
- Language: C++
- Homepage:
- Size: 62.5 KB
- Stars: 17
- Watchers: 4
- Forks: 2
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
# predict.cr
Predict is a satellite prediction library for crystal using the sgp4 model.
The model used is the updated combined sgp/sdp4 model from the celestrak website.
Predict can track the latitude, longitude and altitude of satellites, and also calculate look angles (azimuth, elevation, range) from an observer on the earth's surface.
## Installation
Add this to your application's `shard.yml`:
```yaml
dependencies:
predict:
github: RX14/predict.cr
version: 0.1.3
```
## Usage
```crystal
require "predict"
# All values truncated to 4 decimal places for readability
# Parse TLE
tle = Predict::TLE.parse_three_line <<-TLE
ISS (ZARYA)
1 25544U 98067A 16339.72355294 .00003337 00000-0 58323-4 0 9990
2 25544 51.6456 287.6667 0006011 291.2532 140.8410 15.53794284 31519
TLE
# Inspect TLE data
tle.name # => "ISS (ZARYA)"
tle.catalog_number # => 25544
tle.mean_motion # => 15.5379
# Create satellite from TLE, this initialises the orbital model
satellite = Predict::Satellite.new(tle)
# Create a prediction from the TLE
time = Time.new(2016, 12, 5, 12, 0, 0)
satellite_position, satellite_velocity = satellite.predict(time)
satellite_position # => Predict::TEME(@x=3815.7998, @y=1932.0874, @z=5261.6006)
# Predict ground track
satellite_position.to_lat_long_alt(time) # => Predict::LatLongAlt(@latitude=0.8913, @longitude=2.3062, @altitude=415.4529)
# Predict look angles from an observer (200m altitude)
observer = Predict::LatLongAlt.from_degrees(52.9, -2.24, 200.0)
observer.look_at(satellite_position, time) # => Predict::LookAngle(@azimuth=0.50118495648349193, @elevation=-0.55812612380797122, @range=7501.0178628601843)
# Predict next pass time
start_time, end_time = satellite.next_pass(at: observer, after: time)
start_time # => 2016-12-05 16:23:55
end_time # => 2016-12-05 16:32:29
# And the one after that...
start_time, end_time = satellite.next_pass(at: observer, after: end_time)
start_time # => 2016-12-05 17:58:46
end_time # => 2016-12-05 18:09:15
```
## Development
SGP4 is bound as a static library in src/predict/ext. Use `make` with the optional make variables `release=true` or `debug=true` to build the static library. Make sure you run the specs and formatter before sending PRs.
Useful reading material on sgp4 and coordinate systems is http://celestrak.com/columns/.
## Contributing
1. Fork it ( https://github.com/RX14/predict.cr/fork )
2. Create your feature branch (`git checkout -b feature/foo`)
3. Commit your changes (`git commit`)
4. Push to the branch (`git push origin feature/foo`)
5. Create a new Pull Request
## Contributors
- [RX14](https://github.com/RX14) - creator, maintainer