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 […]
Automobile Hands-Off Detection, Part 4: Capacitive solutions
Cars with lane-keeping assistance (LKA) also are mandated to have a hands-off detection (HOD) function; there are several ways to meet this challenging requirement. Despite the BOM advantages of torque-based HOD, it has performance issues. Capacitive-based sensing is a viable alternative approach. Capacitive sensing for HOD monitors the driver’s grip on the steering wheel by […]
Automobile Hands-Off Detection, Part 3: Torque solutions
Cars with lane-keeping assistance (LKA) also are mandated to have a hands-off detection (HOD) function; there are several ways to meet this challenging requirement. The previous part of this article discussed the need for hands-off (or on) detection (HOD) and its connection to the lane-keeping assistance feature in today’s cars. This part will look at […]
Automobile Hands-Off Detection, Part 2: Requirements
Cars with lane-keeping assistance (LKA) also are mandated to have a hands-off detection (HOD) function; there are several ways to meet this challenging requirement. Where does “hands-off detection” (HOD) come into the picture? (Note: “hands-off detection” is sometimes spelled out as “hands-on detection;” fortunately, the acronym is the same either way.) It is a feature […]
Automobile Hands-Off Detection, Part 1: Basic issues
Cars with lane-keeping assistance (LKA) also are mandated to have a hands-off detection (HOD) function; there are several ways to meet this challenging requirement. Today’s cars are packed with all sorts of functions, features, and attributes that didn’t exist – or need to – just a few years ago. Whether for driver and passenger convenience, […]
Is Li-Fi “To Be” or “Not To Be”? Part 3 – Status
Optical wireless communications in the form of “Li-Fi” is a technical alternative to RF-based Wi-Fi with distinct strengths and weaknesses. Part 2 of this article looked at Li-Fi attributes and building blocks. This part looks at Li-Fi system-level issues and offers a perspective on Li-Fi’s present market acceptance. Q: Can I use Li-Fi today? A: […]
