We are in the age of rapid Robot proliferation, where it’s a race to deliver your unique robot functionality to your customers. To that end, engineers should not be wasting their time on the design elements that don’t necessarily differentiate their products, such as the operating system, sensor modules, camera modules, etc. Most developers are not. That said, the traditional Global Navigation Satellite System positioning implementation is an external antenna connected to an internal receiver module via a length of cable. That can often result in sub-optimal results when cm-level performance is required, for reasons described below. Calian provides a different partitioning model that combines the antenna and the receiver, to connect to the rest of system over a digital serial link: a Smart GNSS Antenna.
Cm-level precision requires significant care to ensure that the low power signals from the antenna reach the receiver without being too impaired to allow for the receiver to make the phase comparisons needed for PPP-RTK or RTK corrections. The right antenna does the job of cleaning up near band communication interference such as WiFi and cellular, as well as being resilient to multipath and even purposeful jamming. Calian’s eXtended Filtering (XF) antenna technology attenuates near band frequencies, and Calian Accutenna dual feed patches and Calian filar helical elements are multipath resilient (to a point). However, no matter how pristine the signal output from the antenna, it still needs to get to the receiver, and that is where the real trouble begins. System generated noise from high-speed buses, on-board electronics, RF transmitters and lidar systems etc. are a direct threat to the low power signal from the antenna. When presenting a GNSS antenna over an extended cable to the receiver, it is an expansive window for unanticipated frequencies to be induced on the GNSS signal, interfering with the ability of receivers to converge to GNSS fix and maintain fix.
Integrating the antenna with the receiver and connecting the Smart GNSS Antenna/Appliance to the system over a serial digital interface (RS-232, RS-422, USB) virtually eliminates the exposure to this “last meter” noise problem. The connection between the antenna and the receiver is controlled, with no variation based on a robots mechanical design; optimizing gain and providing proper noise shielding on a short and consistent signal path. It has the added benefit of reduced proximity to system noise sources via the noise immune digital serial interface.
Calian has a broad line of cm-level capable Smart GNSS Antennas, presenting the native GNSS receiver programming interface to the system for maximal compatibility with existing platform drivers for GNSS receivers such as the u-blox F9 series. Calian has also developed a ROS2™ driver for the products.
The Smart Antenna line up has a comprehensive set of variants to suit different applications; from the TW5384 L1/L2 Smart Antenna (Fixed mount, Base or Rover, with Moving Base Precise Heading functionality integrating Calian’s ceramic patch Accutenna and the u-blox ZED-F9P dual band high performance GNSS receiver) to the TW5790 L1/L2 Smart Antenna (surface mount, Rover, with built in IMU, integrating Calian’s ceramic patch Accutenna and the u-blox ZED-F9R dual band high performance GNSS receiver and the NEO-D9S receiver for PointPerfect PPP-RTK corrections on L-Band). There are also extremely lightweight low power helical Smart Antennas (e.g. HCS885XF L1/L5 Smart Helical Antenna that integrates Calian’s Helical antennas with u-blox’s NEO-F9P), and a powerful SmartChoke version incorporating Septentrio’s Mosaic X5 receiver that can be set up as a permanent Continually Operating Reference Station Base to generate private network RTK corrections. The dual band Smart GNSS Antennas work with RTK corrections from a local private base, or from commercial services such as PointPerfect PPP-RTK, Swift Navigation’s Skylark RTK or Point One Navigation’s Polaris RTK.
There are SDK packages for each antenna (e.g. SDK for the TW5790) that provide serial to USB connectors (for non-USB antenna variants) to easily connect to a PC, TruPrecision Evaluation software and complementary trials for PointPerfect, Polaris and Skylark.
Please do reach out for any questions you may have.
Gordon Echlin,
Director, Business Development Smart Antennas/PNT Systems, GNSS