Feature: Satellites


• Delivery: allows the receiver to get corrections via the Internet or L-band satellite; however, protocols and formats vary from provider to provider;


• Business model: subscriptions such as prepaid, pay-per-use, fl eet-contract or receiver bundles are available at diff erent costs, with telecom networks off ering packages of corrections bundled with other value-added services. However, as various service providers use


diff erent correction formats and protocols, there’s yet no standardisation to consolidate all the various delivery mechanisms. T is makes it challenging for users to receive, decode and start using the corrections data. For Internet communication, NTRIP


(specifi cally for GNSS), MQTT (IoT) or even custom protocols are being used. T ere is also variability in the data format of the corrections themselves, with versions like SSRZ, SSRC and SPARTN, in addition to the standard SSR (PPP-RTK) and RTK corrections.


Navigating the corrections maze Septentrio designs and manufactures multi-frequency multi-constellation GPS/ GNSS positioning technology, and it has established the Agnostic Corrections Partner Program, allowing users to select the service that serves their systems best and to easily connect it to a receiver with a high degree of positioning accuracy and reliability. T is program off ers several advantages:


Figure 1: Corrections deliver the information needed by the receiver for high positioning accuracy


Figure 2: Correction-agnostic receivers allow users the fl exibility to select the correction service which best fi ts their needs. External CPU is required to host service decoding libraries


1. Bridges the challenges and complexities posed by various interfaces, protocols and formats between service providers;


2. Provides documentation and open- source sample libraries on GitHub for easy connection to the service of choice;


3. Enables connection of services to high- performance GNSS receivers, known for positioning availability and reliability due to a high degree of security and resilience against GNSS jamming and spoofi ng; 4. Ensures continuous support and


GNSS positioning is subject to errors caused by GNSS satellites and ionosphere. Correction services send information which helps the receiver compensate for these errors


stability from Septentrio, with up-to date documentation. In contrast to the classical model of being


locked to a specifi c correction service with a certain receiver, a correction-agnostic receiver allows users to access the correction service that is most suitable for their application; see Figure 2. An external CPU is required to host service decoding libraries and format conversion code, which allows the connection to a particular corrections service.


www.electronicsworld.co.uk July/August 2024 49


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