# A Magnetotelluric Signal Acquisition and Monitoring System Based on a Cloud Platform
## 1 Introduction  
Conducting geophysical research requires a large amount of effective data [1], so geophysical instruments that can efficiently acquire data play a crucial role in the geophysical industry. They provide geophysical researchers and engineers with the means to obtain information about the Earth's internal structure, surface features, and environmental conditions [2]. Geophysical instruments are key in exploring oil, natural gas, minerals, and water resources, while also offering tools for in-depth research into the Earth's internal structure and crustal movements [3, 4]. The magnetotelluric (MT) method [5], proposed in the early 1950s, is a geophysical technique that uses natural alternating electromagnetic fields to study underground electrical structures. Its exploration depth varies with the frequency of the electromagnetic field, ranging from tens of meters to hundreds of kilometers. In the traditional MT instrument market, companies like Canada's Phoenix, Germany's Metronix, and the USA's EMI dominate globally [6]. In the past, geophysical instrument control systems were mainly based on personal computers and Windows operating systems, using wired communication. However, with advancements in communication technology, the field has gradually shifted towards portability and lightweight designs. The new generation of control systems, centered around handheld devices and smartphones, uses wireless communication, marking the beginning of a more flexible and convenient era for instrument control systems. This transformation is expected to improve operational convenience, enhance mobility, and make geophysical instruments more adaptable to different environments and scenarios. Smartphones, as control terminals, have brought many conveniences to people's lives. With the widespread adoption of Android smartphones, more control systems have focused on Android platforms. Existing smartphone applications in the geophysical field mainly fall into two categories: educational and data-sharing applications, and control programs for acquisition systems [7; 8; 9; 10]. In 2018, [PERSON] et al. developed an Android application capable of monitoring multiple electromagnetic receivers simultaneously [11]; in 2020, [PERSON] et al. designed an Android-based monitoring program for wireless microseismic stations [12]; in 2021, [PERSON] et al. developed a wireless microseismic acquisition control system with Android-based control software [13]; and in 2024, [PERSON] et al. designed a landslide monitoring data acquisition application based on the Android platform [14]. In 2024, the broadband complex resistivity measurement system for rocks and ores designed by [PERSON] et al. was equipped with an Android platform for monitoring and control [15]. Over the past decade, advancements in wireless communication, computer technology, new materials, and electronics have profoundly influenced the development of geophysical instruments [16; 17; 18]. The development of geophysical wireless communication systems has undergone a leap from traditional wired transmission to modern intelligent networking. Early cable-dependent wired systems (e.g., seismic stations) were limited by deployment costs and scope, and data-based real-time performance was poor. With the progress of wireless technology, short-range radio frequency (e.g., ZigBee) has realized local networking since the 1980s; satellite communications (e.g., Iridium, Beidou) broke through the bottleneck of polar monitoring at the beginning of the twenty-first century, but there was a problem of high latency; this problem was solved after 2010 when the popularization of 4G/5G mobile communications was achieved. At the same time, efficient data transmission has introduced the Internet of Things and cloud platforms into geophysical wireless communication systems.