Oxford Technical Services (OxTS) has launched precision time protocol (PTP) master functionality on all of its next-generation inertial navigation systems (INS).
PTP is a network-based time synchronization protocol used to synchronize all clocks throughout a computer network. It is used in many industries, but most notably in finance to synchronize transactions, mobile-phone tower transmissions and subsea acoustic arrays.
Time synchronization
In many commercial organizations, millisecond-level device synchronization as offered with network time protocol (NTP) is sufficient. However, in surveying and automotive testing environments where there is more than one clock source (lidar and inertial navigation systems, or INS, for example), final results can suffer from time drift if millisecond — and not microsecond — synchronization is used.
Time drift becomes relevant as soon as you introduce more than one data acquisition system working in parallel. This is because each system will have its own timing error, and over time this error will grow and create drift.
For surveyors, time drift can negatively impact point clouds by making object recognition difficult, subsequently leading to blurring and double vision.
For automotive engineers, when running campaigns, analysis of events within your data may be misaligned, making the analysis more difficult and/or less efficient.
Stamp out time drift
To stamp out time drift, it is important to use the most accurate clock source available.
A key component of an INS is the GNSS receiver. The GNSS receiver acquires data, including timing information, directly from multiple GNSS constellations (GPS, GLONASS, BeiDou and Galileo). The GNSS receiver, coupled with the inertial measurement unit within the INS, allows users to benefit from the centimeter-level position accuracy that is so important in surveying and automotive testing environments.
These satellite systems house the most accurate time source possible — atomic clocks — meaning that devices connected to a network that includes an INS can take advantage of this time source owing to the GNSS receiver within the INS.
Simpler setup for lidar use
By migrating from a traditional PPS hardware set-up, which involves connecting and wiring multiple cables, to a PTP setup, which is essentially an Ethernet “plug-and-play” solution, users can also make day-to-day use of the equipment simpler and more efficient.
PTP enabled network. (Image: OxTS)
Without PTP – using PPS setup. (Image: OxTS)
This much-improved hardware setup allows surveyors and automotive test engineers to be up and running in a much shorter time frame than previously possible.
Adding value to the automotive industry
The addition of PTP also adds value for automotive users. With cars-under-test incorporating multiple sensors (lidars, cameras, etc.), synchronizing all that data can help support accurate analysis after the test is complete.
OxTS is continuing to develop its PTP solution by working on PTP slave functionality and improving the configuration process, which will provide greater flexibility in typical automotive setups that use data acquisition (DAQ) for larger sensor networks.
Summary
PTP as a time synchronization method is becoming more popular, particularly in the lidar industry, with manufacturers such as Ouster and Hesai enabling PTP on their sensors.
The shorter “time to survey” gives customers a much-enhanced user experience, and the higher quality final output on offer means that many users will demand their sensors are PTP-compatible before considering them for their projects.
Manufacturers of complimentary sensors, such as INS, need to build the capability into their product sets to allow them to be fit for the future.
Various OxTS INS are available to use PTP, including the new xNAV650, the company’s new small, lightweight and affordable INS for applications where payload size and weight matter. Learn more about the xNAV650 INS.
Users can also find out more about OxTS and its range of PTP-enabled devices by visiting its dedicated landing page, OxTS PTP-enabled INS devices.
Image: OxTS