Automatic Dependent Surveillance-Broadcast (ADS-B) is a surveillance technology that uses position information broadcast by aircraft as a basis for surveillance. ADS-B technology can provide more timely, accurate and abundant information about aircraft. However, as a totally new surveillance method, before practically applied and operated, abundant tests and evaluations are necessary to validate the performance of ADS-B and guarantee the operational performance. On this background, we will evaluate performance of the ADS-B system. With the evaluation results, it would be much easier to determine whether and how to use ADS-B.

The following are the content of ADS-B data evaluation.

**The evaluation of accuracy**

By comparing ADS-B, radar and baseline position data at the same time, we can get the distance between synchronized ADS-B and baseline position data and the distance between synchronized radar and baseline position data. After counting the number of the messages falling into different distance interval, we get the distribution of distance about ADS-B and radar. Through this method, we can compare the accuracy performance of ADS-B with radar.

**The evaluation of Integrity**

Integrity of ADS-B reports is characterized by NUC (Navigation Uncertainty Category), of which the values are the integers from 0 to 9. According to relating ICAO standards, only if the NUC value of the ADS-B report is greater than 4, the report can meet the requirements of radar-like service. The number of ADS-B reports falling into different NUC values is counted to obtain the distribution of NUC.

**The evaluation of altitude**

By comparing the altitude track of ADS-B data with radar data at the same time interval, we can evaluate the ADS-B parameters such as continuity, altitude accuracy and so on.

**The evaluation of velocity**

By comparing the velocity track of ADS-B data with radar data at the same time interval, we can evaluate the ADS-B parameters such as continuity, velocity accuracy and so on.

**The evaluation of heading**

By comparing the heading track of ADS-B data with radar data at the same time interval, we can evaluate the ADS-B parameters such as continuity, heading accuracy and so on.

**The evaluation of Reliability**

By counting the time interval of the two successive messages about radar data and ADS-B data, we can get the distribution of the update interval about ADS-B and radar data. Then we can evaluate the update interval of ADS-B. Meanwhile, we also evaluate the relationship between the update rate of ADS-B data and the distance from aircraft to ground station.

**The evaluation of range**

By recording the max distance that ADS-B ground station can receive the ADS-B report, we can evaluate the range of surveillance data. Meanwhile, we can evaluate the surveillance rang at different flight levels.

**The evaluation of distance between radar and ADS-B data**

By comparing ADS-B with radar data at the same time, we can get the distance between synchronized ADS-B and radar data. Meanwhile, we observe the value of NUC and aircraft poison to evaluate whether the value of NUC and aircraft poison would influence the distance between radar and ADS-B.

**The evaluation of Coordinate (Lat and Lon) Error**

By comparing ADS-B, radar and baseline position data at the same time, we can get the Coordinate (Lat and Lon) Error between synchronized ADS-B and baseline position data and the Coordinate (Lat and Lon) Error between synchronized radar and baseline position data. Through this method, we can compare the Coordinate (Lat and Lon) Error of ADS-B with radar.