# SP3
[](https://crates.io/crates/sp3)
[](https://github.com/georust/rinex/actions/workflows/rust.yml)
[](https://docs.rs/sp3/)
[](https://crates.io/crates/sp3)
[](https://github.com/georust/rinex/sp3/blob/main/LICENSE-APACHE)
[](https://github.com/georust/rinex/sp3/blob/main/LICENSE-MIT)
SP3 Precise GNSS Orbit files parser.
SP3 is specifid by [IGS](https://igs.org/products/#orbits_clocks).
The parser only supports Revisions C & D at the moment and rejects revisions A & B.
## Getting started
Add "sp3" to you cargo file
```toml
[dependencies]
sp3 = "1"
```
Parse an SP3 file
```rust
use crate::prelude::*;
use rinex::prelude::Constellation;
use std::path::PathBuf;
use std::str::FromStr;
let path = PathBuf::new()
.join(env!("CARGO_MANIFEST_DIR"))
.join("data")
.join("ESA0OPSRAP_20232390000_01D_15M_ORB.SP3.gz");
let sp3 = SP3::from_file(&path.to_string_lossy());
assert!(
sp3.is_ok(),
"failed to parse ESA0OPSRAP_20232390000_01D_15M_ORB.SP3.gz : {:?}",
sp3.err()
);
let sp3 = sp3.unwrap();
/*
* Test general infos
*/
assert_eq!(sp3.version, Version::C);
assert_eq!(sp3.data_type, DataType::Position);
assert_eq!(
sp3.first_epoch(),
Some(Epoch::from_str("2023-08-27T00:00:00 GPST").unwrap())
);
assert_eq!(sp3.nb_epochs(), 96, "bad number of epochs");
assert_eq!(sp3.coord_system, "ITRF2");
assert_eq!(sp3.orbit_type, OrbitType::BHN);
assert_eq!(sp3.time_system, TimeScale::GPST);
assert_eq!(sp3.constellation, Constellation::Mixed);
assert_eq!(sp3.agency, "ESOC");
assert_eq!(sp3.week_counter, (2277, 0.0_f64));
assert_eq!(sp3.epoch_interval, Duration::from_seconds(900.0_f64));
// browse SV positions
for (epoch, sv, (x, y, z)) in sp3.sv_position() {
}
// browse SV clock
for (epoch, sv, clock) in sp3.sv_clock() {
}
```
## File Merge
Merge files together, for example to create a context spanning 48 hours
```rust
let folder = PathBuf::new()
.join(env!("CARGO_MANIFEST_DIR"))
.join("data");
let sp3_a = folder.clone()
.join("ESA0OPSRAP_20232390000_01D_15M_ORB.SP3.gz");
let sp3_b = folder.clone()
.join("ESA0OPSULT_20232320600_02D_15M_ORB.SP3.gz");
let sp3 = SP3::from_file(&sp3_a.to_string_lossy())
.unwrap();
let sp3_b = SP3::from_file(&sp3_b.to_string_lossy())
.unwrap();
let sp3 = sp3_a.merge(sp3_b);
assert!(sp3.is_ok());
```
## Position Vector Interpolation
Interpolate SV position at desired Epoch.
In order to preserve the high (+/- 1mm precision) for SP3 datasets,
we recommend using at least an interpolation order of 9 for typical SP3 files
with 15' epoch intervals.
The current implementation restricts the interpolatable Epochs at
[tmin, tmax] = [(N +1)/2 * τ, T(n-1) - (N +1)/2 * τ],
both included, where N is the interpolation order, τ the epoch interval, and T(n-1)
the last Epoch in this file.
Refer to the online API for more information
```rust
use sp3::prelude::*;
use rinex::sv;
use std::str::FromStr;
use std::path::PathBuf;
use rinex::prelude::Sv;
let path = PathBuf::new()
.join(env!("CARGO_MANIFEST_DIR"))
.join("data")
.join("ESA0OPSRAP_20232390000_01D_15M_ORB.SP3.gz");
let sp3 = SP3::from_file(&path.to_string_lossy())
.unwrap();
let epoch = Epoch::from_str("2023-08-27T00:00:00 GPST")
.unwrap();
let interpolated = sp3.interpolate(epoch, sv!("G01"), 11);
assert!(interpolated.is_none(), "too early in this file");
let epoch = Epoch::from_str("2023-08-27T08:15:00 GPST")
.unwrap();
let interpolated = sp3.interpolate(epoch, sv!("G01"), 11);
assert!(interpolated.is_some());
let (x, y, z) = interpolated.unwrap();
// demonstrate error is still sub cm
assert!((x - 13281.083885).abs() * 1.0E3 < 1.0E-2); // distances are expressed in km in all SP3
assert!((y - -11661.887057).abs() * 1.0E3 < 1.0E-2);
assert!((z - 19365.687261).abs() * 1.0E3 < 1.0E-2);
```