Virtual radar- Emulating long range ARSRs with ADS-B

One of the main values of utilizing automatic dependent surveillance - broadcast (ADS-B) data for air traffic control is that it provides greatly improved coverage as well as improved accuracy. As with all technology advances and deployments, especially in the National Airspace System (NAS) domain, there is a long transition time when the old and new systems must work together. The goal of the virtual radar is to provide ADS-B data in a way that completely emulates the characteristics of the current physical radars such that any automation system receiving the data will not have to be modified. Some of the issues that must be addressed include accuracy differences, conversion from cartesian GPS coordinates to polar range-azimuth coordinates, update frequency, providing a conversion of the of the ADS-B data to common digitizer (CD) beacon messages, generating the beacon real time quality control (BRTQC) and search real time quality control (SRTQC) messages as well as the radar status messages. Update frequency has unique issues to be resolved in the fact that the timing of the ADS-B reports may not correspond with the time that virtual radar beam may have hit the target. This issue of time registration will be investigated and the approaches to solving them discussed. The test and validation of virtual radars may require some new procedures and test tools to adequately insure the accuracy and correct operation. The benefits of virtual radars are exciting as they allow all of the benefits of ADS-B, improved coverage, and accuracy, and less maintenance without having to wait for upgraded automation systems.