1. What is the difference between GPS and GNSS?
GPS is the Global Positioning System operated by the USA and is the most familiar and widely adopted satellite navigation system. GNSS (Global Navigation Satellite System) not only include GPS but also GLONASS (Russia), QZSS (Japan), Beidou (China) and Galileo (Europe) satellite navigation systems.
2. What are the benefits to the user of using GNSS?
When using GNSS instead of GPS, users are able to receive signals from more satellites from the various positioning satellite systems. In highly urbanized areas or areas with thick canopy, it often results in the ability to get signals from enough satellites to achieve positioning.
3. What are the benefits of using SiReNT?
Making use of data from SiReNT means a local base station is not necessary, reducing the hardware and manpower dependence of any positioning requirement. In addition, by using SiReNT, users are able to:
- achieve positioning, navigation and tracking information relative to national and international reference systems;
- achieve efficiencies and cost reductions in time and resources; and
- achieve reliability in the data.
4. What are the applications for GNSS?
GNSS can be used in three broad areas, namely positioning, navigation and tracking.
- Positioning: Control survey, geodetic survey, engineering survey, aerial photography, mapping and GIS data collection, etc.
- Navigation: Machine control, fleet management, asset tracking, vehicle navigation, emergency dispatch, etc.
- Tracking: Structural monitoring, geotechnical monitoring, tectonic plate movement monitoring, ionospheric study, integrated water vapor content studies, etc.
5. What are DGNSS, RTK and PP On-Demand?
DGNSS: Differential GNSS, provides sub-metre accuracy in real-time.
RTK: Real-Time Kinematic, provides centimeters accuracy in real-time.
PP On-Demand: Post Processing On-Demand, provides RINEX data for post processing to achieve millimeters accuracy. RINEX (Receiver INdependent EXchange Format) is an industry standard GNSS data storage format.
6. What are the accuracies that can be achieved?
Autonomous GNSS: From 5m and up
Differential GNSS: sub-metre accuracy
RTK: 3-5cm accuracy
PP On-Demand: 3-5mm accuracy
*Accuracies are also dependent on user’s equipment specifications as well as processing software used.
7. Do I need an accurate map to achieve high accuracy positioning with SiReNT?
SiReNT allows you to achieve positioning with high accuracy, precision and reliability. However you will need to plot these positions on a high accuracy map using the SVY21 map projection for referencing to the ground truths.
8. What if my GNSS receiver only collects data in WGS84?
WGS84 is a world reference frame which the SVY21 map projection is based on so they are compatible and interoperable.
9. How do I receive SiReNT DGNSS and RTK correction data in real-time?
SiReNT disseminates the DGNSS and RTK correction data via IP (Internet Protocol) and you will be able to receive the data stream through various wireless internet methods, e.g. 3G, LTE, WIFI, etc.
10. Is an internet connection all I need to receive SiReNT correction data stream?
Apart from that, you will need to have a valid SiReNT subscription account which will provide you with the Subscription ID and token required for logging in to the NTRIP caster on our server.
11. What is NTRIP?
NTRIP (Networked Transport of RTCM via Internet Protocol) streams GNSS data over the Internet. It is open sourced and free to use. The SiReNT servers run the NTRIP caster and the user devices need to run NTRIP clients to enable the connection to be made.
12. How would I know if my GNSS receiver has NTRIP?
You will need to check with your equipment’s distributor for its specifications.
13. What equipment models from which brands can I use SiReNT with?
As there are many such types of equipment that is compatible with SiReNT, please check with the equipment distributors for their specifications. Search the internet for keywords such as e.g. “GNSS Receivers Singapore”.
14. Can I use SiReNT with my latest state-of-the-art smart phone or tablet?
At the moment, there are no commercially available smart phones or tablets that have the capability to do differential correction with the build-in GPS/GLONASS chipset. There are NTRIP client applications that can receive differential corrections but the correction data can either be saved in the device or sent to a GPS/GNSS device via Bluetooth to achieve real-time differential corrections.
15. I encountered issues on logging in to my equipment using my account. What do I do?
Check your subscription ID and token format. Note: Your token is case sensitive. If you are unsure with your token, you can also reset it by logging in through SiReNT website on Sessions & Tokens under My Subscriptions menu. If the problem persists, please .
16. How far can I go when using SiReNT?
You can use SiReNT anywhere in Singapore.
17. Is SiReNT operating continuously?
Yes, SiReNT operates 24 hours a day, every day.
18. How can I validate my positioning results using SiReNT?
For real-time applications, you may start your survey on a known control point (e.g ISN). This ensures that your equipment, the settings in your equipment and SiReNT will provide the results you require. You may end the day of survey by measuring on a known point as well. New technology does not eliminate the need for good survey techniques.
19. Why am I unable to download certain RINEX data from PP-On-Demand?
PP-On-Demand only provides twelve months of RINEX data. In addition, Post-Processing data will only be available 1 hour after the end of the hourly-block requested time period. e.g. Data from 9am to 10am will only be available after 11am.
20. Can I find out the status of each SiReNT reference station while in the field?
Yes, the real-time statuses of SiReNT reference stations are available on the SiReNT website.
22. What is the IP address and port number for connecting to SiReNT?
The SiReNT IP address is 184.108.40.206 and the port number is 2101