A sophisticated satellite-based system allows pinpointing a person’s location in a dangerous, isolated situation on land or sea. It thus hopefully speeds their subsequent rescue in many cases. This final part looks at the next generation of system satellites and some ideas for a similar lunar system. The MEOSAR satellites The most recent enhancement to […]
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Satellite-based search-and-rescue, Part 3: Space segment and satellites
A sophisticated satellite-based system allows pinpointing a person’s location in a dangerous, isolated situation on land or sea. It thus hopefully speeds their subsequent rescue in many cases. Cospas-Sarsat uses three types of satellites: low-Earth orbit search-and-rescue (LEOSAR), medium-Earth orbit search-and-rescue (MEOSAR), and high-altitude geosynchronous orbit search-and-rescue (GEOSAR satellites). There are five LEOSAR, seven GEOSAR, […]
Satellite-based search-and-rescue, Part 2: Ground segment and transmitter beacons
A sophisticated satellite-based system allows pinpointing a person’s location in a dangerous, isolated situation on land or sea. It thus hopefully speeds their subsequent rescue in many cases. Over one million emergency beacons are in use worldwide, all operating at 406 MHz (with some exceptions, called out below). Cospas-Sarsat does not manufacture or sell beacons. […]
Satellite-based search-and-rescue, Part 1: The overall system
A sophisticated satellite-based system allows pinpointing a person’s location in a dangerous, isolated situation on land or sea. It thus hopefully speeds their subsequent rescue in many cases. You’ve undoubtedly seen or read stories about someone miraculously recused at sea or in some relatively uninhabited, remote part of the Earth, without a way to call […]
Reaction wheels ensure satellites maintain the right attitude: Part 2
Electrically driven reaction wheels use conservation of angular momentum to keep a satellite pointed in the right direction, eliminating the need for fuel-powered and limited thrusters. Part 1 was an introduction to reaction wheel basics. This part continues the investigation into their performance and construction. Physics and analysis Although the basic principle of reaction wheels […]
Reaction wheels ensure satellites maintain the right attitude: Part 1
Electrically driven reaction wheels use conservation of angular momentum to keep a satellite pointed in the right direction, eliminating the need for fuel-powered and limited thrusters. Orbiting satellites usually must maintain a precise and stable orientation for various reasons: to keep their cameras or radar pointed at their Earth targets or to keep their telescopes […]
Saving energy with MCU power management
MCU low-power features such as built-in energy harvesting help optimize applications where long battery life is important. Masamitsu Muratani, Renesas The spectacular growth of the Internet of Things (IoT) is driving the need for devices that are smarter, faster, and can last for long periods on small and inexpensive batteries. To meet such requirements, Renesas […]
How to extend, boost and repeat Wi-Fi signals
Since the U.S. Federal Communications Commission (FCC) limits Wi-Fi transmitter power, it’s often necessary to increase the range of Wi-Fi signals using some signal boosting/extending technology. But transmit power is only half of the equation. Wi-Fi connections are always bidirectional and symmetrical. When working to extend Wi-Fi signals, the bidirectional nature of the connection is […]
The basics of Wi-Fi security and encryption
Wi-Fi security has significantly improved over the years from initially being more aspirational than real until today, where Wi-Fi 6 security is considered to be on a par with the security of 5G telephony. This FAQ will answer several questions related to Wi-Fi security and encryption: What’s the difference between WEP, WPA, WPA2, and WPA3? […]
What to consider when selecting a Wi-Fi antenna
Antennas are a critical part of the link budget in all wireless communications applications, including Wi-Fi. In addition to the numerous antenna performance and link budget issues in wireless communications, there are general architectural challenges. The architectural options are the focus of this FAQ, including; long-distance versus local Wi-Fi and the use of directional vs. […]
