79 lines
3.5 KiB
Rust
79 lines
3.5 KiB
Rust
//! Interference and carrier-to-interference computation.
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//!
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//! A wanted signal rarely arrives alone. This crate combines the wanted
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//! carrier with one or more interfering carriers and with noise, and reports
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//! the ratios that decide whether the wanted link is usable.
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//!
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//! The figures computed here are:
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//!
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//! - The carrier to interference ratio, over one interferer or several.
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//! - The carrier to noise plus interference ratio, which is what a receiver
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//! actually sees, because it cannot separate the two.
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//! - The equivalent noise temperature of an interferer, which lets an
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//! interference contribution be folded into the link budget as if it were
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//! noise.
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//!
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//! Interference from a second satellite sharing the same frequency is
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//! described by the angle between the two satellites as seen from the ground
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//! station. The receive antenna has a sidelobe response in that direction,
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//! and the ratio of the interferer's power to the wanted power follows from
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//! the two gains and the two path losses. This crate takes the two gains as
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//! inputs, so it composes with the pattern models in `apsis-antenna`.
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//!
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//! Source: the definitions of carrier to interference and carrier to noise
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//! plus interference, and the practice of expressing interference as an
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//! equivalent noise temperature, are standard in satellite link design and
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//! appear for example in the ITU-R Handbook on Satellite Communications.
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//!
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//! ```
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//! use apsis_interference::{Interferer, carrier_to_interference, combine};
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//! use apsis_rf::{Decibel, Power};
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//!
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//! let wanted = Power::from_dbw(-130.0).expect("finite");
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//! let interferer = Interferer {
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//! power: Power::from_dbw(-140.0).expect("finite"),
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//! };
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//!
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//! // One interferer ten decibels below the carrier leaves a C/I of 10 dB.
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//! let ratio = carrier_to_interference(wanted, &[interferer]).expect("valid");
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//! assert!((ratio.db() - 10.0).abs() < 1e-9);
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//!
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//! // Combining with noise can only lower the result.
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//! let combined = combine(ratio, Decibel::from_db(15.0)).expect("valid");
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//! assert!(combined.db() < ratio.db());
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//! ```
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//!
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//! 干扰与载干比计算。
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//!
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//! 有用信号很少独自到达。本 crate 把有用载波与一个或多个干扰载波以及噪声
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//! 合并，并报告决定该有用链路是否可用的各比值。
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//!
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//! 此处计算的数字是：
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//!
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//! - 载干比，对一个或若干干扰源。
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//! - 载波与噪声加干扰之比，这是接收机实际所见，因为它无法把二者分开。
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//! - 某干扰源的等效噪声温度，它使干扰贡献可以像噪声一样折算进链路预算。
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//!
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//! 来自共享同一频率的第二颗卫星的干扰，由自地面站看两颗卫星之间的角描述。
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//! 接收天线在该方向上有旁瓣响应，而干扰源功率与有用功率之比由两个增益与
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//! 两个路径损耗得出。本 crate 把两个增益作为输入，故它与 `apsis-antenna`
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//! 中的方向图模型可组合。
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//!
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//! 出处：载干比与载波噪声加干扰比的定义，以及把干扰表达为等效噪声温度的
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//! 做法，都是卫星链路设计中的标准内容，例如见于 ITU-R Handbook on Satellite
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//! Communications。
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#![forbid(unsafe_code)]
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#![deny(missing_docs)]
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mod ratio;
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pub use ratio::{
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InterferenceSummary, Interferer, carrier_to_interference, carrier_to_interference_single,
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carrier_to_noise_plus_interference, combine, equivalent_noise_temperature,
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interference_to_noise_ratio, summarise, total_interference,
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};
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pub use apsis_core::constant::BOLTZMANN;
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pub use apsis_rf::{Decibel, Power};
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