Receiver Operations

Receivers
Title	Receiver Operations
Author(s)	GMV
Level	Medium
Year of Publication	2011

Any GNSS receiver gathers

Operation modes

One thing most GNSS receivers have in common is how they operate in terms of processing chain, from reception of signals to solution outputs. Alhough their types, architectures, and applications may vary, the operations of receivers apply transversly:

RF stage: the first stage of a receiver comprises the antenna and front end, responsible for the RF processing chain.

Start-up: a receiver starts processing the samples from the RF stage in different ways, depending on the available a priori information.

Acquisition: the first step, in many cases, is the search for visible satellites that can be tracked and used in the computed solution.

Tracking: after the initial determination of the satellites to track, several signal processing algorithms are use to continuously track the satellite's motion relative to the user.

Lock detection: a receiver constantly performes decisions to assess the quality of the observables in terms of noise or uncertainty, and these decisions determine the probability of a given tracked signal being "lost". This decision can yield a loss of lock, and the receiver channel is free to process other signals (e.g. start acquisition for other satellites).

Solution output: when tracking is successfull for a large enough period of time, and for enough satellites, the navigation message can be decoded from each signal, and the extracted information is used to compute the best solution needed - in most cases, the user's PVT solution.