The Whistler Catcher Thin: An Advanced VLF Reception System Based on the Whistler Catcher Pi

The Whistler Catcher Pi is a VLF Reception System that captures the VLF spectrum up to 48 kHz using a VLF Active Antenna, Audio Injector Stereo soundcard, GNSS receiver, and a Raspberry Pi running vlfrx-tools software. The system has the ability to capture science-grade VLF data using common off the shelf components. It can timestamp with GNSS accuracy, remove mains hum, automatically capture natural radio events like dawn chorus and whistlers, automatically record amplitude and absolute phase of Navy VLF transmitters to detect SIDs and GRBs, calculate the Time of Group Arrival of sferics, record EbNaut transmissions from VLF amateurs, and many more. It was installed in December 2021 and is still in continuous operation, having captured over 100 whistlers, detected hundreds of SIDs, and an EbNaut transmission at 8.270 kHz from DL3JMM in Germany. Having built on this success, we propose the Whistler Catcher Thin, a VLF reception system that can capture spectrum up to 96 kHz utilizing the same VLF Active Antenna, Behringer UMC202HD USB Audio Interface, and Dell Wyze 5070 Thin Client. The added processing power and higher sample rate from these low cost components lend well to a low cost network of these VLF reception systems for DASI2, adding observations to simultaneous HF and magnetometer observations. With a network of at least six systems, the HamSCI lightning location network can be realized.