ELF/VLF communication experiment by modulated heating of ionospheric auroral electrojet at EISCAT

Amplitude modulation high frequency (HF) radio waves at extremely low frequencies (ELF, 0.3–3 kHz) or very low frequencies (VLF, 3–30 kHz), heating the ionosphere, can nonlinearly modulate the auroral electrojet to produce ELF/VLF waves for long-distance communication. This paper presents the results of the first ELF/VLF communication experiments being conducted at Tromso, where the EISCAT HF facility is located. The ELF/VLF waves from the ionosphere are modulated by quaternary phase shift keying (QPSK) and used for communication. The ELF signals of 2,017 Hz at 20 and 100 bps, as well as VLF signals of 3,517 Hz at 20, 100, and 400 bps, received by a ground-based receiver (15 km away from the heater) were decoded, albeit with a high bit error rate (BER) for 3,517 Hz at 20 bps. With the decoding principle of QPSK, we attempted to find a solution to reduce the BER for future communication experiments. Based on the results of the ground experiment, the transmitted signals of 2,017 Hz at 20 bps were selected in the China Seismo-Electromagnetic Satellite (CSES) reception experiments. In a first, we demonstrate that ELF communication signals generated by the amplitude modulation heating of the ionosphere have been successfully received by the satellite and the ground-based receiver. These experimental results confirm that the ELF/VLF waves radiated by amplitude modulation heating of the auroral electrojet can be used for long-distance communication in future.