11:00 〜 13:00
[PEM12-P05] Observation of ionospheric irregularity by using scintillation of beacon and NOAA satellite signals
キーワード：電離圏擾乱、ビーコン、ソフトウェアラジオ
The ionosphere plays an important role as a communication path between a ground-ground and satellite-ground. The irregularity of the plasma density in the ionosphere is often generated from a few tens of kilometers to a few meters. Notably, irregularities on the scale of hundreds of meters to a few kilometers cause fluctuation in the radio wave transmitted from the Global Navigation Satellite System (GNSS) satellites. Previous studies presented small-scale ionospheric irregularities were generated by cascading of the large-scale irregularities. Therefore, it is important to observe large (few km) scale irregularities simultaneous with small (100 m-few km) scale irregularities.
We receive the VHF (150 MHz) and UHF (400 MHz) beacon signals transmitted from Low Earth Orbit satellites by receivers based on the software-defined radio (SDR) to derive the total electron content (TEC) and amplitude variation of the signal. Since the beacon signals are efficiently scintillated by the few km scale irregularities, we plan to install the satellite beacon receiver to observe the scintillation and conduct a simultaneous observation with the GPS receivers from high to low latitude regions. We developed a SDR-based beacon receiver based on the GRBR (GnuRadio Beacon Receiver) and installed at Electronic Navigation Research Institute, Chofu, Tokyo (35.68 N, 139.56 E).
Since most of the beacon satellites are aging, the number of satellites transmitting the beacon signals are decreasing and the intensities of signal become weak. To increase the observation opportunity, we have also developed a receiver for the signal of the American National Oceanic and Atmospheric Administration (NOAA) series of weather satellites. The NOAA satellites transmits frequency modulated (FM) signals at 137 MHz. The time series of the amplitude of the FM signals are extracted to derive the amplitude scintillation. The opportunity of scintillation observations will be roughly doubled, although TEC cannot be derived from NOAA signals.
We started the observation of NOAA satellites from September 2021. We will describe our system and present observation results of NOAA satellites. The results are compared with the ROTI (rate of TEC index) map which represents the existence of ionospheric irregularities. Future distribution plan our system will be discussed. As a next step, the system will be installed at Ishigaki Island (24.4N, 124.1E, 19.7 Mag. Lat.) where equatorial plasma bubbles are often observed. Simultaneous observations with all-sky airglow imagers and GNSS scintillation receivers will provide knowledge of ionospheric irregularities development associated with plasma bubbles.
We receive the VHF (150 MHz) and UHF (400 MHz) beacon signals transmitted from Low Earth Orbit satellites by receivers based on the software-defined radio (SDR) to derive the total electron content (TEC) and amplitude variation of the signal. Since the beacon signals are efficiently scintillated by the few km scale irregularities, we plan to install the satellite beacon receiver to observe the scintillation and conduct a simultaneous observation with the GPS receivers from high to low latitude regions. We developed a SDR-based beacon receiver based on the GRBR (GnuRadio Beacon Receiver) and installed at Electronic Navigation Research Institute, Chofu, Tokyo (35.68 N, 139.56 E).
Since most of the beacon satellites are aging, the number of satellites transmitting the beacon signals are decreasing and the intensities of signal become weak. To increase the observation opportunity, we have also developed a receiver for the signal of the American National Oceanic and Atmospheric Administration (NOAA) series of weather satellites. The NOAA satellites transmits frequency modulated (FM) signals at 137 MHz. The time series of the amplitude of the FM signals are extracted to derive the amplitude scintillation. The opportunity of scintillation observations will be roughly doubled, although TEC cannot be derived from NOAA signals.
We started the observation of NOAA satellites from September 2021. We will describe our system and present observation results of NOAA satellites. The results are compared with the ROTI (rate of TEC index) map which represents the existence of ionospheric irregularities. Future distribution plan our system will be discussed. As a next step, the system will be installed at Ishigaki Island (24.4N, 124.1E, 19.7 Mag. Lat.) where equatorial plasma bubbles are often observed. Simultaneous observations with all-sky airglow imagers and GNSS scintillation receivers will provide knowledge of ionospheric irregularities development associated with plasma bubbles.