# Data Analysis of the TK-1G Sounding Rocket Installed with a Satellite Navigation System
## 2 Overview  
On 3 July 2015, a flight experiment on the rocket sonde installed with new satellite navigation system was conducted in Alxa Left Banner, China. As a director in charge of the data processing, the author had first-hand experience of the experiment and thus gained access to relevant data. Figure 1 shows the state of the rocket before launching.  
The meteorological rocket detection system consists of four sub-systems: the meteorological rocket, the rocket sonde, the ground launch system (as well as the ground signal receiving station), and the data processing software with the rocket sonde at its core. After the launch, the rocket will take the rocket sonde near the top of the trajectory, and then the rocket ejection separation system will ignite, separating it from the main body of the rocket. Under air dynamic pressure, the parachute will be inflated to provide lift within a few seconds, carrying the sonde slowly and stably. During the process, atmospheric temperature will be measured by the temperature sensor and atmospheric pressure by the pressure sensor. All such figures will then be transmitted to ground receiving stations via transmitters and processed by data processing systems before the data related to atmospheric temperature, pressure, and density can be finally obtained. In addition, records of the falling trajectory of the parachute collected by means of the COMPASS (stands for Chinese Compass (BeiDou) Navigation Satellite System)/GPS positioning module can offer relevant readings of the wind direction and speed.  
Figure 1: Pre-launch preparation.  
The rocket was launched at 6:30 a.m. During its flight, the rocket presented a smooth trajectory and the rocket sonde worked well. The COMPASS/GPS positioning module did not lose lock in condition of large acceleration during take-off or separation stage. The receiving system on the ground was able to gather the whole data during the entire process of rocket exploration. The experiment achieved the intended purpose and the rocket sonde with satellite-navigation system successfully realized 60-20 km positioning.  
The coordinates of the launch site are \(105^{\circ}36^{\prime}27^{\prime\prime}\) E, \(38^{\circ}45^{\prime}28^{\prime\prime}\) N, with a height of 1429.8 m above sea level; the specified launch direction is \(299^{\circ}\), and standardized theoretical launching elevation of the trajectory is \(81.5^{\circ}\).  
Three receiving stations are set up in this experiment. Station 1, equipped with portable ground automatic weather station to monitor real-time surface wind, locates at 150 m to the left of the launch site. Station 2 and 3 are situated approximately 6 km and 12 km, respectively, to the rear side of the launch site.  
A balloon (750 g) was released one hour before launching, carrying a GPS sonde to detect the atmospheric condition between the ground and a height of 16 km. The wind data of the ground, 6 km and 11 km was used for correction of the rocket's flight trajectory. The trajectory angle of elevation was adjusted to \(82.3^{\circ}\), and the azimuth angle was adjusted to \(296^{\circ}\) after the wind correction. The rocket sonde was started to load the ephemeris 17 min before launching.