HORYU-IV was developed by Kyushu Institute of Technology and it was released into LEO on the 17th of February 2016 at an altitude of 575km. The main mission is to acquire images of the electro-static discharges on dedicated solar panels. To demonstrate this advanced scientific technol- ogy, S-band communication subsystem was implemented onboard with transmitter data throughput of 100kbps and corresponding ground station (GS) was developed. The S-band GS was designed to achieve an effective data rate range from 38kbps to 100kbps. Before HORYU-IV launch, long distance (simulated 2600km) communication test was carried out and a resulting link margin of 20.2dB and reception data rate of 46kbps were obtained as expected. After HORYU-IV launch, during the first two months of operation, the average received data rate and link margin could not meet our mission requirements. The main anomalies that affected data reception were 1) HORYU-IV stabilization issue. Since the satel- lite was passively controlled, it took more than two months to be able to stabilize it and point the transmitter antenna on board to point to ground; 2) automatic Doppler correction could not be performed by the costume S-band receiver system. Therefore, the S-band ground station was modi- fied to meet mission requirements.

Key Words: S-band , operation, verification, HORYU-IV, ground station