There is growing demand for Global Positioning System (GPS) receivers that enable small satellites to achieve attitude and orbit control, orbital transfers, and end-of-life deorbiting.
In this article we provide a gentle primer to the topic of selecting a GPS receiver for a smallsat mission and give an overview of some of the navigation and positioning products making waves in the global marketplace for space.
In the next few chapters we take a brief look at how GPS receivers work and discuss what key performance characteristics need to be taken into account when selecting a product for your operation. If you would instead like to skip down to view the product listings, please click here.
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Please note that this aspect of the supply chain has recently been undergoing a number of changes with new suppliers and products coming to market - we will therefore keep this post updated over time with new product and service information. To stay up to date, please consider bookmarking this page and subscribing to our weekly newsletter at the link below.
Selecting the most appropriate GPS for a CubeSat or a small satellite can be a tricky challenge.
Rapid growth of the NewSpace sector has led to greater use of modular components and several manufacturers are now producing GPS receivers as independent products. Selecting the right GPS receiver is important for ensuring the ease of operations of your satellite.
In this article, we look at some of the factors that should be taken into account to make this decision. We also provide an overview of a number of GPS receivers on the market, all of which are listed on the satsearch platform to help you select the best option.
GPS receivers are ubiqitous in many ground-based applications, from large-scale industrial transport navigation systems to fitness trackers and smartphones. However, using GPS receivers in space is a much more challenging task compared to normal terrestrial use.
Most terrestrial applications use Commercial Off The Shelf (COTS) components designed for specific operations and featuring typical characteristics needed for ground-based use. The difference between such uses and space-based GPS is not just in the components used but also in the software embedded, as GPS receivers made for terrestrial use typically are not tuned to accommodate the large variations in the received signal Doppler frequencies that are usually the case with satellites orbiting the Earth.
Aside from such technical limitations there are also regulatory issues such as the requirements set by the International Traffic on Arms Regulations (ITAR) which do not allow GPS receivers to provide navigation outputs after they exceed the ITAR limits of 60,000 feet and 1,000 knots. Therefore, GPS receivers often come with export control restrictions that depend on the end-user requirements. Be sure to check with the suppliers if they are able to actually serve you before considering testing a particular GPS receiver at the design stage.
Despite the limitations GPS receivers have been shown to be very useful for a range of in-orbit processes such as:
- Precise orbit determination
- Onboard time synchronization and geocoding of payload information
- Autonomous orbit control and maneuver planning
- Spacecraft formation flying
- Onboard attitude determination
Key performance criteria
Now that you’re armed with the knowledge of what a GPS receiver needs to do you can make an informed decision from the available products, based on your required performance characteristics.
Some of the potential key specifications and performance criteria to evaluate for each product are:
- Number of channels
- Number of antennae
- Position accuracy
- Velocity accuracy
- Update rate
- Power consumption
- Time-To-First-Fix (TTFF)
These provide a snippet of the technical details that are necessary to evaluate as part of your selection process. In addition, there are the typical criteria for any major purchase such as; cost, delivery time, supplier reputation and location (particularly regarding any export controls, as mentioned above), contract details and maintenance conditions to take into account.
Finally, it’s important to note that selection of a GPS receiver for your satellite is an iterative process, as is the case for virtually every other component of your overall system.
GPS receivers on the market
Below we have listed several GPS receiver products that are currently available.
Please note that this list will be updated when new products are added to the global marketplace for space - so please check back for more.
The GNSS200 Global Navigation Satellite System (GNSS) receiver is a low mass, low power GNSS receiver for use in (small) satellites. It is designed specifically for use in CubeSat platforms, and it can also be used in conjunction with the iADCS-series of attitude determination and control systems as well as the iACS series of attitude control systems. It offers a multi-constellation output, and the standard version is delivered with a TTL UART output. It is designed to work either with active or passive antennae (to be defined at the time of ordering) and outputs NMEA-compatible data as standard. It is possible to qualify the units for use in larger satellites as well.
The NewSpace Systems NGPS-01-422 Receiver is a 12-channel hardware-based receiver which utilises a well-established GPS chipset. This GPS chipset has been successfully flown by a number of organisations over many years. Targeted towards low-cost SmallSat constellations, it has been adapted for space altitude and velocity through the use of custom software modifications.
NGPS-03-422 receiver fits the CubeSat form factor. An active GPS patch antenna can also be provided with the receiver. Additionally, the GPS circuitry at the heart of the receiver can also be deployed as a single mezzanine board to accompany the NewSpace Systems CubeSat attitude control system board or as a standalone boxed or unboxed version for cubesats.
Meisei Electric’s GPS receiver uses low cost COTS hardware and is QZSS- and GPS-receivable. Software processing by CPU and FPGA with the flexibility to meet individual needs is available. Positioning of the spacecraft is achieved regardless of the attitude by dual-channel antenna.
The GPS-601 Satellite GNSS Receiver and GNSS-700 by SpaceQuest
The GPS-601 Satellite GNSS Receiver is a 120 channel GNSS receiver that tracks GPS, GLONASS, Galileo, and BeiDou. The GPS-601 contains an improved core and an expanded interface card which improves the components’ available features, accuracy, and compatibility, while still relying on the foundation of a space-qualified and proven design.
The GNSS-700 Series Satellite GNSS Receiver is an upgraded version of Space Quest’s GPS12-V1. It contains an improved core and an expanded interface board that improves the unit’s functionality, accuracy and compatibility, while still relying on the foundation of a space qualified and proven design.
Edit: 30 January 2020 - this listing was updated to add details of the GNSS-700 Series Satellite GNSS Receiver.
The GPSRM 1 utilizes a NovAtel® OEM719-series high-performance 555-channel space-grade GNSS receiver to provide accurate position, navigation and timing (PNT) information. Full access to the entire NovAtel OEM7 API is provided via a selectable 3.3V LVTTL serial interface, along with PPS and VARF outputs. SupMCU provides telecommands and telemetry via SCPI over I2C, as well as both Vinti7 and SGP4 orbit propagators (OPs). The OEM719’s microUSB port is available at all times; it is primarily used in conjunction with NovAtel Connect software in a development environment and to update OEM719 firmware.
The Phoenix GPS receiver is a 12-channel single-frequency receiver specifically designed for high-dynamics and space applications. The receiver is based on Zarlink’s advanced GP4020 baseband processor, which results in a small size and low power consumption. In combination with DLR’s proprietary firmware, the receiver offers precision measurements for advanced navigation applications as well as robust tracking, even under extreme dynamics. Three specific receiver versions (Phoenix-S/- XNS and Phoenix-HD) are offered to optimally support both orbital and ballistic missions.
The SGR-Ligo is SSTL’s miniaturised Space GNSS (Global Navigation Satellite System) Receiver that supports the Cubesat PC-104 standard. The SGR-Ligo is low mass, low power and delivers position, velocity and time to Low Earth orbit satellites. It uses radiation tolerant core components and supports both dual antennae and 24+ channels capable of tracking GPS L1 signals, with options for GLONASS G1 and Galileo E1 signals. The SGR-Ligo supports multiple interface standards including UART, CAN and I2C, and can be powered from either 3V3 or 5V spacecraft buses. The SGR-Ligo also supports the use of passive antennas for even lower power requirements.
The SGR-05P is a miniaturised single antenna space GPS receiver that provides position, velocity and time in an OEM configuration for the tightest integration requirements on professional small satellites. The SGR-05P comprises the GPS receiver “engine” from within the SGR-07, and makes use of the host’s regulated power supply and TTL interfaces. The integrator must account for power, EMC, latch-up protection and shielding against radiation, resulting in a highly compact solution.
Measuring 60 millimeters by 100 millimeters, the OEM4-G2L is designed to meet the increasing need for smaller systems. At just 56 grams, this receiver offers many advanced features, including two serial ports supporting speeds of up to 230,400 bits per second, a USB port, and a configurable PPS output and event mark inputs. The OEM4-G2L is also ideal for power-conscious applications, consuming less than 1.6 Watts typically.
WARPSPACE claims that its GPS receiver is the smallest and lightest GPS module in the world. The product is just 24.1 x 20.2 x 7.5mm and weighs 3g. It provides a 5-pin header interface and a position accuracy of 2.5m, while operating at a voltage of 3.3V and power of 45mA. The WARPSPACE GPS Receiver also supports GPS, GLONASS, QZSS, WAAS, EGNOS, MSAS, and GAGAN GNSS systems.
The Venus838FLPx-SPC is a high performance, low cost, single chip GPS receiver targeting CubeSat, small satellite, and micro satellite space applications. It offers very low power consumption, high sensitivity, and best in class signal acquisition and time-to-first-fix performance. Venus838FLPx-SPC contains the necessary components of a complete GPS receiver, including GPS RF front-end, GPS baseband signal processor, 0.5ppm TCXO, 32.768kHz RTC crystal, RTC LDO regulator, and passive components.
It takes up only 100mm2 PCB footprint. Dedicated massive-correlator signal parameter search engine within the baseband enables rapid search of all the available satellites and acquisition of weak signal. An advanced track engine allows weak signal tracking and positioning in harsh environments. Venus838FLPx-SPC is low cost, easy to use, minimizes RF layout design issues.
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