The Internet of Things (IoT) connects a steady information stream between the people and processes powering the world. Global Navigation Satellite Systems (GNSS) provide critical timing and positioning functions for device operations.
GNSS uses satellite technology to provide insight into connected devices’ geographic locations. GNSS is an inclusive term for the category of global systems, including:
- Global Positioning System (GPS)
- Globalnaya Navigazionnaya Sputnikovaya Sistema (GLONASS)
When more than one constellation is used simultaneously, the benefits of those systems combine for improved satellite coverage and overall performance.
In addition, the regional satellite-based augmentation systems (SBAS) assist the global systems:
- Wide Area Augmentation System (WAAS) in North and South America
- European Geostationary Navigation Overlay Service (EGNOS) in Europe
- GPS Aided GEO Augmented Navigation (GAGAN) in India
- MTSAT Satellite-Based Augmentation System (MSAS) in Japan
All are vital concerns to consider when choosing how many systems to utilize in IoT endeavors.
As global demand for connectivity increases, businesses can expect to see more integration of GNSS technologies. Which GNSS platforms are available today, and how do they differ?
4 GNSS Systems and Their Unique Features
GPS (United States)
While GPS and GNSS are often used interchangeably, GPS is the world’s most utilized satellite navigation system. It operates from 32 satellites across six orbital planes. Developed in the United States for military use, we now see GPS in-car navigation and business tagging in social media. A high-accuracy multifrequency GPS using Precise Point Positioning (PPP) or Real-Time Kinematic (RTK) techniques can identify spatial locations down to 10 centimeters or fewer.
Like GPS, GLONASS was designed during the 1970s as Russia’s military positioning system. Commercial applications (e.g., transmitting navigation positioning and weather broadcasts) started in the 1980s with the deployment of 24 satellites across three orbital planes.
Since 2000, China’s BeiDou Navigation Satellite System (BDS) has been on the rise to overtake GPS in global commercial usage. In its third generation, BeiDou claims to reach a millimeter-level accuracy that outperforms other systems.
Developed by the European Union in 2011, Galileo will consist of 30 satellites when it is fully operational (i.e., 24 working satellites with six spares). It provides a more accurate positioning service at higher latitudes than other GNSS systems by using over 24 satellites in six orbital planes. Galileo is currently providing emergency response services and making Europe’s roads and railways safe for everyone.
4 Benefits of Using Multiple Constellation GNSS Receivers at Once
Modern positioning and timing modules have evolved to take advantage of multiple GNSS constellations at once. Combining multiple satellite systems:
- Improves signal availability
- Gives operators more access
- Increases accuracy
Whether you’re navigating in a crowded city or a vast desert, multiple GNSS systems help you stay connected and centered while providing continuous positioning.
Industries and businesses can achieve the following benefits:
- Added Security
In the unlikely event that a satellite fails, GNSS receivers will automatically remove it from the navigation solution.
- Multiple Pathways
Access to multiple satellites increases visibility in regions with natural or artificial obstructions. (Urban canyons are created by tall, clustered buildings and can impact single-frequency GNSS accuracy.) This access improves Time to First Fix (TTFF), a measure of the time needed for a GNSS-connected device to determine its location from power-up.
- Future Proofing
Integrating multiple GNSS systems helps industries and businesses with future-proofing their products and services. Changes in each system mirror changes in the marketplace at varying rates.
- Increased Data Integrity
Galileo provides increased security features for multiple industries, including:
Layering multiple systems like Galileo with GPS casts a wider net in terms of reach and accuracy.
Evolution of Low-Power GNSS Solutions
Historically, GNSS receivers have consumed considerable amounts of power. The power consumption requirements have dropped dramatically over the last decade. Today’s GNSS receivers often have many configuration options, allowing users to manage power consumption and adapt functionality to specific use cases. The most challenging use cases for achieving a perfect balance between GNSS capabilities and power consumption include small IoT devices requiring near-continuous connectivity (e.g., pet or child trackers and smartwatches).
Devices that rely on multiconstellation GNSS tend to consume more power since they require more energy for seeking connections with various satellite signals. Because different GNSS constellations use varying frequency bands, receivers must use more power to track multiple sources.
4 Ways to Minimize GNSS Receiver Power Consumption
With any IoT device design, there are trade-offs when it comes to functionality and energy consumption. If your use case requires constant connectivity, the device won’t be able to go into a power-conserving sleep mode for long. While trade-offs remain a reality, there are opportunities to minimize GNSS receiver power consumption within a device.
- Selecting Components
Each component in the GNSS receiver can be selected with care to reduce overall power consumption. Including a backup battery can prevent situations in which power interruptions cause the receiver to reboot. Cold startups consume a significant amount of power. Having a backup battery to keep the receiver operational during outages allows the device to resume operation quickly and use less power. The oscillator is another component that can reduce or increase power usage. However, it must be chosen carefully based on the use case. If temperature fluctuations are possible in deployment (e.g., if the receiver will be in a logistics tracker on a ship or truck), choosing a temperature-controlled crystal oscillator (TCXO) might be wise. A TCXO reduces power while increasing receiver sensitivity. Other components that can affect power consumption include the real-time clock (RTC) and active antennas. Telit integrates RTCs and TCXOs for optimal performance in our GNSS receivers. This integration helps customers save time to market with a ready-to-use product.
- Reducing Update Rate to Utilize Power Save Modes
GNSS receivers might need to update their position once per second, hour or day depending on the use case. Ensuring the receiver’s update rate matches the use case needs allows operators to minimize power consumption and let devices enter Power Save Mode (PSM) between updates. Today’s GNSS receivers typically include at least one of these PSM options:
- Cyclic Tracking
Cyclic tracking PSM relies on a reduced-power tracking mode that does not seek new satellites. While not ideal for remotely deployed devices that rely on weak signals, this mode saves considerable power for receivers that enjoy strong, consistent satellite signals.
- On/Off Operation
The receiver can switch to a deep sleep mode (OFF) in this PSM, reducing power consumption. For devices that require check-ins once or twice per day, this is an excellent choice.
- Continuous Tracking
After an initial connection to check position, the receiver uses this mode to minimize power consumption while maintaining a continuous connection. This PSM is ideal for use cases requiring near-constant updates on position, such as sports or vehicle trackers.
- Cloud-Based Processing
Outsourcing complex computing processes to the cloud is another way for GNSS receivers to minimize power consumption at the end device. With a practice called snapshot positioning, the GNSS receiver carries out reception and processing tasks, but a cloud-based service calculates the actual position.
- Optimizing Power in Multiconstellation GNSS
Multiconstellation functionality increases accuracy and provides more continuous positioning updates, but there are trade-offs. When receivers track multiple GNSS constellations, they use more power — especially when different frequency bands are involved. One way to save energy while utilizing multiconstellation GNSS is by paying attention to which constellations your receivers will track depending on their location. Instead of tracking every available constellation, choose a few most likely to provide accurate positioning in the area where the devices are deployed. Try to minimize how many radio frequency (RF) bands the receivers will need to use.
Finding the Right Multi-Constellation Solutions for the Future
Telit offers many solutions for those curious about which services exist for utilizing signals from multiple GNSS constellations while minimizing power consumption. Telit is one of the few IoT companies delivering different combinations of multiple GNSS solutions for its customers. Test one of our GNSS modules in your application.
Editor’s Note: This blog was originally published on 6 March 2018 and has since been updated.