@@ -56,10 +56,12 @@ Once the tracking has been carried out, **monitoring** will make it possible **t
#### _Few things we need before the calculation process:_
First of all, a ground segment is needed to provide additional information and services that are not available from the space segment alone. Overall, the ground segment plays a critical role in ensuring the overall performance and functionality of the GNSS system.
First of all, a ground segment is needed **to provide additional information and services** that are not available from the space segment alone. Overall, the ground segment plays a critical role in **ensuring the overall performance and functionality** of the GNSS system.
Then, <spandir="">the user segment plays a critical role in enabling GNSS applications and services, it is the end-user's device that makes the **position**, **velocity** and **time information available to the user.**</span>
@@ -108,7 +110,6 @@ This phenomenon is problematic because it is difficult to model and eliminate. A
The satellites of the GNSS system are equipped with **several atomic clocks**; however, **their high accuracy has a limit.** The corrections for the offset of the clocks are transmitted in the "navigation message". These corrections are calculated by reference ground stations and are used to compensate for the continuous deviation of the clocks. The uncertainty in the receiver clock, which is much less accurate since it is not an atomic clock, is considered an additional unknown, hence the need for at least four satellites.
