GPS Technology Overview

Global Positioning System (GPS) and Assisted-GPS

• GPS is a satellite-based navigation system
• The system consists of 24 satellites in orbit
• The first satellite was launched in 1978
• The system was made available for civilian use in 1980
• GPS works 24 hours a day, in any weather condition, anywhere in the world
• The satellites orbit Earth at approximately 12,000 miles
• GPS signals transmit on two frequencies: L1 and L2

GPS Devices

• Handheld GPS devices are portable and can be carried or attached to backpacks, used for outdoor activities like hiking, camping, and geocaching
• In-car GPS devices are designed for vehicles, provide turn-by-turn directions, real-time traffic updates, and other features
• GPS watches are designed for athletes and fitness enthusiasts and can track distance, pace, and other workout metrics
• Aviation GPS devices are for pilots and aviation enthusiasts, providing real-time flight data including altitude, speed, and location
• Marine GPS devices are for boats and ships, providing navigational data such as depth, water temperature
• GPS trackers are small and portable, attached to vehicles, pets, or other objects. They track the location in real-time

How GPS Works

• GPS satellites circle the Earth twice a day in a precise orbit, transmitting signal information
• GPS receivers take this information and use it to calculate the user's exact location
• The receiver determines and displays the location on an electronic map

GPS Errors

• Signal reflection can occur when a signal bounces off objects like buildings or rocks
• Satellite shading can prevent the signal from working properly if satellites are not positioned at a wide enough angle
• A receiver's clock may not be as accurate as the satellites' atomic clocks, leading to timing errors in calculations

1G, 2G, 3G, 4G, 5G Mobile Communications

• Wireless is defined as "having no wires"
• Computer networks without physical connections use radio or microwaves for communication
• 1G technology was introduced in the 1980s and used analog signals; initial speed was up to 2.5kbps (limited to voice calls within a single city)
• 1G drawbacks: no security, poor reliability, poor battery life, large size, poor voice quality
• 2G uses GSM (global system for mobile communication), digital signals, and had a data speed up to 64kbps; enabled text messages, picture messages, and MMS
• 3G technology (introduced in the 2000s) increased bandwidth and data transfer rates; had a data speed from 144kbps to 2 Mbps; could support web-based applications, audio, and videos; had large capacities
• 3G drawbacks: expensive licenses, infrastructure challenges, high bandwidth requirements, expensive phones and large cell phones
• 4G (late-2000s) offered significantly increased data speed (100Mbps-1Gbps), mobile multimedia capability, global mobility, and integrated wireless solutions, known as mobile broadband everywhere
• 4G drawbacks: higher battery use, significant implementation challenges, costly equipment, and complex hardware
• 5G (late-2010s) is highly supportable to the WWW (wireless world wide web) and offers complete wireless communication with no or minimal limitations; has high capacity and high speed, supports high-quality data transmission and high-speed data transmission
• There are differences between 3G and 4G in bandwidth, use of broadband, technology, speed and data transfer rates.