Leader in Differential GNSS Solutions Worldwide

Frequently Asked Questions

Below are answers to the questions we hear most frequently. If we have not addressed your specific question, please feel free to contact us.

 About OmniSTAR

What does OmniSTAR do?

OmniSTAR provides a worldwide corrections network which improves the accuracy of GPS positioning. We do this by monitoring the GPS constellation in real-time from over 100 reference sites, spread across the globe. A corrections stream is generated from this data and delivered to OmniSTAR-compatible receivers via geostationary satellite or over the Internet.

Customers purchase a subscription to the corrections stream for a fixed period and use the high accuracy positioning for everything from surveying and mapping applications to machine control and navigation.

How can OmniSTAR help my business?

OmniSTAR offers a variety of performance specifications allowing you to choose the best service for your particular application.

Please select a service or application from the above drop down menu to investigate further, or call your local OmniSTAR office to discuss how our corrections can help you.

 Service Availability

Where does OmniSTAR work?

Due to our global satellite coverage, OmniSTAR will work reliably across most land-based areas. Exceptions can be seen on our Coverage Maps

Within the OmniSTAR coverage area users must have a clear line of sight to the local OmniSTAR satellite.

Will my OmniSTAR receiver work anywhere?

Any OmniSTAR compatible receiver can be used within any coverage area. You will need to ensure it is set to the correct frequency of the local satellite and have a current/valid OmniSTAR subscription for that area.

How can I order a new subscription for a new area?

You can order a new subscription by calling one of the four regional OmniSTAR offices. At the time of your call, you will need your OmniSTAR ID/serial number to arrange payment. A member of the OmniSTAR Customer Care Team will send through the new subscription over your local satellite.

We also have a new online subscription management system for both resellers and end users. You will need to contact us to be set up with an account.

Click here for contact information for your regional office.

Do you have a Global Licence that I can use worldwide?

Yes, click here to contact your nearest OmniSTAR regional office for details.

Will my OmniSTAR work in near-shore areas or in bays?

OmniSTAR is a land-only system. The OmniSTAR User Agreement specifically prohibits use beyond the coastline.

For a range of offshore services, please contact Fugro Satellite Positioning.


How can I get an OmniSTAR subscription?

You will need to have an OmniSTAR compatible receiver to receive an OmniSTAR subscription. If you are unsure if your receiver is compatible please contact your nearest regional OmniSTAR office. Should your receiver be compatible, a member of our Customer Care Team will be able to set up your subscription within a matter of minutes (convergence times excluded).

How will I know when my current subscription will expire?

You will receive a renewal notice about 4-6 weeks before your subscription is due to expire advising you of your expiration date and the renewal process.

Some receivers will show the service “End Date” or “Expiration Date” on the display. If you are unsure how to find this, you can contact OmniSTAR and a member of our Customer Care Team will be able to look at our records and advise you of your expiry date.

What happens when my subscription expires?

This depends on the GPS receiver. Most will continue to output, but the data will be uncorrected. Some older receivers may stop outputting altogether.

Does OmniSTAR sell partial-year subscriptions?

Partial-year subscriptions are available in most areas. Contact your regional OmniSTAR office for details.

Can I purchase a subscription renewal ahead of time?

Yes, subscription renewals are simply added to your existing subscription date.

Can I subscribe after working hours?

Yes, in most regions, you can get a 24 to 72 hour subscription—at no cost—at night or during a weekend. At the end of this period you will need to subscribe through one of our Customer Care Team members to receive the full subscription period.

Can I subscribe over the Internet?

You are now able to subscribe your receiver for a 3-day trial on our website. Please Note: One receiver can only be subscribed to the 3-day trial twice in a lifetime.

We also have introduced new online subscription management systems for both resellers and end users but you will need to contact us to be set up with an account.

To find your local office, click here.

How do I obtain a subscription for a new area?

Call an OmniSTAR Regional office, be ready to give them your equipment serial number, arrange payment, and they will send the new subscription over your local satellite.

Is there a Global subscription that will allow me to work anywhere?

Yes, contact your nearest OmniSTAR regional office for details.To find your local office, click here.


What accuracy can I expect?

OmniSTAR’s services vary in accuracy from sub-metre, through decimetre, to centimetre grade. Further information on our offerings is available on the Services page.

When comparing OmniSTAR’s quoted accuracy against competitors it is important to ensure the same numbers are being compared. Accuracy may be described as a statistical term such as sigma-1 (the accuracy is achieved 67%of the time), sigma-2 (the accuracy is achieved 95% of the time) or “pass to pass”. OmniSTAR will always quote sigma-2accuracy; the highest quality measure of GPS performance

On which datum is OmniSTAR?

OmniSTAR uses ITRF2008 worldwide for all of its services with the exception of our OmnISTAR VBS service in North America, which is provided with the NAD83 datum.

Some DGNSS receivers are capable of outputting in a different datum to the corrections source. To confirm if your receiver supports this feature, consult the receiver documentation or contact your dealer.

Does averaging improve my position fix?

Averaging for periods greater than 24 hours can improve absolute accuracy. Due to the nature of differential corrections, averaging across shorter periods may not produce quality results.

Should I plan my work around the “best” times for GPS?

With a few exceptions, GPS is available 24-hours with a sufficient number of satellites for a good fix. If you run your GPS receiver with a 5-degree altitude mask and you are in a relatively open area, you should have good data around the clock. You may occasionally experience short periods of high DOP (Dilution of Precision) when certain GPS satellites are being moved or are down for maintenance. Those periods usually last for an hour or less and are repeatable for several days. If you are located on an urban or semi-urban area, your surroundings might block your line-of-sight to one or more GPS satellites, in which case you might want to plan your work around those times of the day that the maximum number of GPS satellites is visible on your location.

More tools and resources

Does it matter where I am relative to an OmniSTAR Base Station?

OmniSTAR XP, OmniSTAR GNSS and OmniSTAR G2 function globally and are not constrained by distance to a reference site. OmniSTAR VBS and OmniSTAR HP operate anywhere within our worldwide reference network, offering submeter and decimeter positioning in all but the most remote locations.

OmniSTAR CORS is currently only available to users in Tasmania.

What value should I use for my GPS Receiver’s “Altitude” or”Elevation””Mask”?

The OmniSTAR network outputs corrections for a 8 degree elevation mask. If the receiver is operating in a particularly “noisy” environment, or an area prone to multipath, then a higher elevation mask (8-10 degrees) may produce better results.


What is NMEA?

NMEA-0183 is one of the most commonly used receiver output formats. It reports a wide variety of information including time, position and velocity. It is a comma-separated text format (ASCII) and includes a number of different formats (or “sentences”) that provide different presentations of the information.

Configuring the correct NMEA output ensures your receiver can communicate with a machine guidance system, data logger or other third party device.

Further information is available on the NMEA Website.

How often will I get a fix from my GPS receiver?

Once initialized, the OmniSTAR engine in your receiver will produce positions at the maximum rate the device can sustain; from once a second to hundreds of reports per second. The OmniSTAR corrections stream only needs to update the state of the engine periodically. The receiver does not need to wait for a new corrections message to output a new position.

What is RTCM?

RTCM-104 is a GNSS data format used to supply corrections information to a receiver. OmniSTAR data is not broadcast in RTCM-104, but some receivers can supply an RTCM-104 stream generated from the OmniSTAR broadcast.

Further information on the RTCM-104 standard is available from their website.

Is OmniSTAR susceptible to interference?

Modern OmniSTAR receivers use an L-band satellite broadcast, and are more resilient than older models. Normal RF precautions should be used as certain cell phones, laptops or electric motors can cause interference if placed within a few feet of the antenna or receiver.

How does OmniSTAR compare to the Beacon Service?

OmniSTAR’s services are superior to Beacon Service in reliability, accuracy, coverage and customer support.

OmniSTAR uses a large worldwide network of reference sites, so the receiver’s accuracy does not diminish with distance as it can with a Beacon service. OmniSTAR VBS will easily outperform a distant beacon site, and OmniSTAR G2, OmniSTAR XP and OmniSTAR HP are an order of magnitude more accurate. OmniSTAR CORS can be up to two orders of magnitude more accurate.

OmniSTAR has proven reliability, with multiple redundancies to protect against an outage. If a Beacon transmitter fails it may be some time before it is available again.

We are proud to stand behind our product and offer 24/7 phone support to our customers to help with any issues they may encounter.

 Customer Service

Does OmniSTAR charge for customer Service?

OmniSTAR does not charge for customer service phone assistance. The customer service number is answered by a customer care representative 24 hours per day, every day. OmniSTAR customers will always get an answer to their request or question. Subscriptions are also available around the clock.

OmniSTAR customers will always get an answer to their request or question. Subscriptions are also available around the clock.

 OmniSTAR Network Datum

The continuous improvement of OmniSTAR’s DGNSS (Differential Global Navigation Satellite Systems) means that greater accuracies are now possible at longer distances from reference stations than ever before. OmniSTAR, operates a global network of reference stations; to maintain consistency, all the stations in the network are coordinated with reference to the International Terrestrial Reference Frame (ITRF).

The current datum for the OmniSTAR reference station network is ITRF2014.

For more information about datums, click on the arrows next to the topics below.

 Fixed and Dynamic Datums

The International Terrestrial Reference Frame, ITRF is an Earth Centred datum (i.e., with origin at the earth’s centre) and tied to the earth’s polar axis. Hence coordinates of all points on the earth’s surface slowly change over time as the continents drift in different directions. The ‘Epoch’ or time attached to an ITRF coordinate means these were the coordinates of the point on this specific day. ITRF is the standard datum used by the world’s scientific community, as it is the only system that ties together coordinates in different countries into one unified system.

The WGS-84 datum used by the GPS system itself is also regularly updated in order to minimise the difference between it and ITRF. The datums are now aligned to with in a few centimetres. Generally, for most non precision applications using GPS this error is of no consequence.

 Reference Station Coordinates

In any differential system the coordinates of the mobile or rover are in the same coordinate reference frame as that of the reference site(s), whether these are fixed sites on land or satellites in orbit. Because we use the ITRF, we need to regularly update the coordinates of the reference stations to compensate for the centimetre-level movements of the various tectonic plates on which they lie.

Although the reference stations move continually, the site positions are surveyed and updated every few months. This frequency keeps the reference stations positions with in a couple of centimetres of their true coordinates.

 Country-specific Information

For Australian users:

As discussed above in the “fixed vs. dynamic datums” section, WGS-84 coordinates differ from ITRF (current epoch) coordinates by a few centimeters. WGS-84 coordinates from a GPS receiver are also about 80 cm different from GDA94.

Most mapping in Australia has now moved from previous national datums such as AGD66 and AGD84 to GDA94. GDA94 is a fixed datum. It was arrived at by tying and fixing GDA94 to the ITRF reference frame on a specific date, as the datum is fixed or static a point coordinated with respect to GDA94 will continue to have the same coordinates over time irrespective of how the Australian land mass moves with respect to other continents.

For further details see http://www.ga.gov.au/geodesy/datums/cosys.jsp

Learn more about obtaining GDA94 coordinates.