# Multi-Signal GNSS & the Curious Case of Galileo E24: Part 1

DevFeed: [Multi-Signal GNSS & the Curious Case of Galileo E24: Part 1](<https://devfeed.tech/articles/multi-signal-gnss-the-curious-case-of-galileo-e24-part-1-36555.md>)

Original publisher: [Read original article](<https://berthub.eu/articles/posts/the-curious-case-of-galileo-e24/>)

Published: 2020-07-18T07:07:23Z

Content type: article

Language: en

Sources: [Bert Hubert's writings](<https://devfeed.tech/sources/bert-hubert-s-writings.md>)

Topics: [systems](<https://devfeed.tech/topics/systems.md>)

Tags: [engineering](<https://devfeed.tech/tags/engineering.md>), [equipment](<https://devfeed.tech/tags/equipment.md>), [gnss](<https://devfeed.tech/tags/gnss.md>), [phones](<https://devfeed.tech/tags/phones.md>), [signal](<https://devfeed.tech/tags/signal.md>), [standard](<https://devfeed.tech/tags/standard.md>)

## AI overview

This article investigates why Galileo satellite E24 was reported as being 1.5 meters off while phones and other positioning equipment showed no problems. It introduces multi-frequency GNSS and explains how ionospheric delays affect satellite-distance measurements.

## Source excerpt

GPS, GLONASS, Galileo, BeiDou (Global Navigational Satellite Systems, GNSS) are miracles of engineering. And within any complex system hide surprises and unsuspected complications. In this post I go over how we resolved an odd observation: that everyone (including major institutions) reported that one of the Galileo satellites (E24) appeared to be off by 1.5 meters, while actual positioning equipment (like phones) showed no problems at all. Through the explanation, we'll casually learn a thing or two about the cool concept of multi-frequency GNSS.