This section to be removed in light of latest ETSI guidelines and dealt with in covering LS.
12 Expected ETSI actions
This section to be removed in light of latest ETSI guidelines and dealt with in covering LS.
Annex A:
FMCW Radar - Technical Details
Fixed infrastructure radar are typically frequency modulated continuous wave [FMCW] transceivers, with an associated signal processing system. The radar itself measures power in range bins, at incremental steps from the antenna. These are sampled and processed, before being presented to a Tracking process.
The Tracker is sophisticated, following the movement of numerous objects over time, against pre-registered behavioural conditions. However, it is the business rules is a subsequent processing stage to the tracker that ultimately make sense of the radar data for the system users.
Figure 2 Radar signal processing chain
A.1.1 Underlying FMCW radar and tracking technology
For traffic applications, a typical radar sensor has a maximum useful detection range coverage of 500 metres in radius, and is typically mounted 5 metres above the street level.
Inside the radome, an antenna of 2 degree beamwidth in azimuth and a spread beam in elevation spins around 360 degrees in 2 seconds, so any one point within the sensor coverage is revisited every 500 ms.
During the rotation, 900 azimuth measurements are taken sweeping in 1 ms and typically 600 MHz bandwidth, though other bandwidth usage is configurable. The measured range resolution achieved is 0.25 m. The radar collects signal power in range and bearing and sends these data over an Ethernet interface to a remote processing unit [RPU].
Hosted on the RPU, a software tracking package excludes the measurements of static infrastructure – known as clutter – and then detects moving targets with the radar field of view using a dynamic threshold process [CFAR]. Once a target has been detected a multi hypothesis algorithm associates its movements in order to generate a track. Each track has information on it location (range and bearing), speed, direction of travel and size of the object. Based on the track properties and behaviour, specific alarms can then be generated according to the operators needs
.
Figure 3 Typical modulation scheme for a fixed infrastructure radar
