Satellite Communications Navigation Difference: SATCOM vs GNSS

Satellite communications and satellite navigation both rely on spacecraft, but they do different jobs. Satellite communications (SATCOM) transfer information between users. Satellite navigation (GNSS, of which GPS is the best known system) broadcasts timing signals that a receiver uses to work out where it is. Defence lists satellite communications and position, navigation and timing as separate space mission sets. [1] This guide explains the satellite communications navigation difference in plain terms.

Keeping the two apart makes Defence news easier to follow, and it is useful when packing for a trip. A device that tells you where you are does not necessarily let you tell anyone else. A device that lets you send a message does not, by itself, tell you which way to walk.

What satellite communications do

The Australian Space Agency’s communications roadmap describes communication satellites as connecting us by using the electromagnetic spectrum to transfer information. Its examples include extending networks to connect families in regional Australia and coordinating planning and responses in the event of a national disaster. [2]

Defence’s space domain page gives a simple everyday example of satellite communications: staying connected with friends and relatives living overseas. [1] For the military, the roadmap notes that Defence uses satellite communications for the command and control of deployed sea, air and land forces. [2]

Put simply, the satellite is part of a link that carries information to and from people on the ground. The roadmap describes the ground segment as including antennas such as large dishes back on Earth. [2]

What satellite navigation (GNSS) does

Satellite navigation works differently. Training material from the United Nations International Committee on GNSS explains that a satellite with a known position transmits a regular time signal, and a receiver measures the signal’s transmission time. [3] With enough of these measurements, the receiver calculates its position.

What is GNSS?

Global navigation satellite system (GNSS) is the umbrella term. The Cyber and Infrastructure Security Centre names the United States’ GPS, Russia’s GLONASS, the European Union’s Galileo and China’s BeiDou, and explains that Australians access positioning, navigation and timing (PNT) services via GNSS constellations. [4] Providing position and time information is a different job from carrying your messages.

Defence’s space domain page uses satellite navigation in an everyday example too: navigating a road trip using a car’s GPS. [1]

The satellite communications navigation difference side by side

The orbit row is a general pattern, not a strict rule. The same roadmap notes that medium Earth orbit is increasingly used for communication satellites, and that low Earth orbit, with a maximum altitude of 2,000 km, can offer lower latency. [2]

Why Defence lists them as separate space mission sets

Defence’s space domain page says its space workforce will support the full suite of space mission sets. The list names satellite communications and position, navigation and timing as separate items, alongside space domain awareness, missile warning, satellite operations, space control, intelligence, surveillance and reconnaissance, and environmental monitoring. [1]

Separate mission sets reflect separate jobs, which is the satellite communications navigation difference Defence is drawing. For a general reader, the practical point is this: when a news story mentions a satellite communications project, it is about moving information, not about GPS. If you want to see how Defence organises services, commands and domains more broadly, our guide to the difference between military services, commands and domains explains the terms.

Check the date on satellite communications news

Australia’s military satellite communications plans have changed over time, so dates matter. On 4 November 2024, Defence announced that it had decided to cease its procurement activity with Lockheed Martin Australia for a single orbit, geostationary satellite communications system. Defence said it must instead prioritise a multi-orbit capability to increase resilience for the ADF, and that its current satellite communications capabilities support the organisation’s immediate needs. [5]

Plans in this area continue to develop, so when you read a news story about a SATCOM project, check its date and look for the latest official Defence statement. Treat any project details you read as accurate only for the date they were published.

Where satellite communications and navigation work together

The functions are different, but they are often combined. Geoscience Australia explains that SouthPAN uses ground stations to monitor satellite navigation signals, processing facilities turn that data into correction messages, and the messages are sent to an uplink station, which transmits them to a satellite in geostationary orbit for broadcast to users. Geoscience Australia says precise positioning from SouthPAN will offer accuracy at as little as 10 centimetres, a significant improvement on previous accuracy of 5 to 10 metres. [6] In that case, a satellite is used to deliver information that makes navigation more accurate.

Distress beacons are another example. The Australian Maritime Safety Authority explains that satellites listen from space for distress signals and notify the nearest ground station, and that if the beacon has GPS capability, a very accurate position may be transmitted with the alert. [7] Navigation tells the beacon where it is. The satellite relay gets that alert to search and rescue. AMSA describes beacons as being for when your life is in danger and you can’t get hold of emergency services by phone or radio. [7]

Plan for each job separately

For remote travel, think about communication and navigation as two separate questions. How will you call for help? How will you know where you are? Our road trip planning guide to emergency water, power and communication covers the communication side for longer journeys.

For navigation, a paper map and compass do not depend on any satellite. Military Shop’s compasses range includes the Silva Compass Field MS Compass, which its listing describes as an entry-level compass with a base plate with map measuring in mm and scales of 1:50,000 and 1:25,000. [8] Keep the map dry with something from the map cases range, and practise with both before you need them. Our guide to buying a compass has more on choosing one.

Know which tool does which job

Satellite communications move information. Satellite navigation provides position and time. That is the satellite communications navigation difference in two sentences. Defence treats them as separate mission sets, and civilian devices such as distress beacons show how they can work together without being the same thing. [1] [7]

When you plan your next trip, check that you have covered both questions. If your navigation backup needs attention, browse our compasses range and choose one that suits your experience.

Sources

1. Department of Defence | Space domain
2. Australian Space Agency | Communications Technologies and Services Roadmap 2021 to 2030 | December 2020
3. United Nations Office for Outer Space Affairs, ICG GNSS training (D. Manandhar, The University of Tokyo) | Basic GNSS Introduction, Applications and Low-Cost Receiver Systems | January 2022
4. Cyber and Infrastructure Security Centre, Department of Home Affairs | Factsheet for Critical Infrastructure: Positioning, Navigation and Timing | November 2024
5. Department of Defence | Defence to prioritise resilient satellite communications capability | 4 November 2024
6. Geoscience Australia | Southern Positioning Augmentation Network (SouthPAN) | page last updated 13 October 2026
7. Australian Maritime Safety Authority | How distress beacons work
8. Military Shop | Silva Compass Field MS Compass | SKU BN50289