## 2 Overview of SWARM IoT Constellation
### Capabilities of Constellation  
For the polar challenges, we created an automatic data and message transfer proposition using SWARM Technologies' low Earth orbit satellite constellation [26]. SWARM provides 150 small commercial cube satellites in the polar orbit at a 450-550 km altitude, where most orbits of Arctic regions and other parts of the Earth are covered. Two ground products can be used for two-way communication. The SWARM Eval Kit, which is a turnkey hardware platform for satellite data connectivity, includes a GPS patch antenna, a UFL-to-SMA cable, and a SWARM 14 wave VHF antenna that is tuned to SWARM's operating frequencies [27]. The SWARM IoT constellation, along with its Eval Kit and M138 modem, enables low-cost satellite communication for remote IoT applications. Below is an overview of the technical components and functionality:  
**SWARM IoT Constellation** (SWARM Technologies Inc., Mountain View, CA, USA): SWARM operates a network of low Earth orbit (LEO) satellites, providing global coverage for IoT data transmission. This constellation is designed for applications that require small data packets and low power consumption, such as remote sensing, asset tracking, and environmental monitoring. The system supports bi-directional communication, allowing both data reception and transmission from anywhere on Earth. This is especially valuable in remote areas where traditional terrestrial network coverage is unavailable. **M138 Modem** (SWARM Technologies Inc., Mountain View, CA, USA): The M138 modem is a compact low-power device designed for integration into third-party products. It is typically embedded into a printed circuit board (PCB) via an mPCIe interface. The modern enables sending and receiving data over the SWARM satellite network, which is particularly useful in industrial, agricultural, and tracking applications. Key components of the M138 modem include the following:  
* **GPS Module:** Used for location tracking;
* **VHF Radio**: For satellite communication;
* **ARM Cortex-M4 Processor**: Powers the modem's operations;
* **Sensors**: Include onboard GPS and a temperature sensor;
* **Connectivity**: Uses a 3.3 V serial UART for communication, simplifying integration into systems;
* **Low Power Modes**: Support various low-power operation modes that can be triggered by timers, GPIO signals, or serial commands. The customer can retrieve and deliver data using M138 via a REST API or Webhook to/from the SWARM cloud to user email and/or text messages using AWS. The frequency of the downlink is about 137-138 MHz, and that of the uplink is 148-150 MHz. **SWARM Eval Kit** (SWARM Technologies Inc., Mountain View, CA, USA): The Eval Kit allows developers to test and prototype applications with the SWARM network. It includes the M138 modem, a small display for user interaction, and a range of sensors for monitoring environmental data. One of the key benefits of the Eval Kit is its simplicity, enabling users to quickly prototype and deploy solutions for use in remote locations where traditional communication infrastructure is unavailable. The Eval Kit comes with everything you need to initiate satellite communication, including a tripod, a 9 W solar panel, batteries, and an integrated VHF and GPS antenna. The following kit was used to conduct all the experiments and has to be used to achieve the final research results. **Software Architecture**: The software stack for SWARM IoT systems typically involves integrating the modem into the user's existing hardware using a simple API to handle data transmission. The SWARM network provides a backend service supporting REST APIs or Webhooks for data retrieval. This means that developers can send data directly to a cloud platform (e.g., AWS, Slack, email), enabling easy integration into existing IoT ecosystems. **Data Transmission Protocols**: The SWARM network uses a low-bandwidth data protocol optimized for satellite communication. Data packets are transmitted over VHF frequencies: 137-138 MHz for downlink and 148-150 MHz for uplink.