Introduction

Satellite technology is widely used for navigation, location tracking, and various other applications. Peoplesafe devices and mobile applications use GPS to determine a user's current location and utilise satellite networks to transmit that information and any emergency messages to its Alarm Receiving Centre to facilitate the dispatch of emergency services.

While satellite technology is generally reliable, several factors can affect its accuracy. This article explains the key environmental and technological elements that can influence the precision of your GPS location data and the reliability of your device's ability to communicate.

Factors Affecting GPS Accuracy

Environmental Obstructions

These obstructions are critical factors that can prevent your device from accurately getting a GPS position fix, and transmitting a message via satellite communication.

• Indoor Environments: GPS signals are weak and easily blocked by building materials like concrete, metal, and glass. This significantly reduces or eliminates signal reception indoors. Walls will also completely block or severely limit satellite message transmission.

• Dense Tree Canopies: Thick foliage absorbs and scatters GPS signals, weakening them and reducing the device's ability to calculate an accurate position.

• Terrain and Topography: Canyons, valleys, mountains, and steep hills can obstruct or reflect satellite signals, leading to inaccurate readings or signal loss.

• Urban Canyons (High-Rise Buildings): In urban environments, GPS signals can bounce off buildings, creating "multipath" errors. This occurs when a receiver receives multiple signals from the same satellite at slightly different times, leading to inaccurate position calculations.

Atmospheric Conditions

Ionospheric and Tropospheric Delays: The ionosphere and troposphere can cause delays in satellite signal transmission, affecting the accuracy of position calculations. These delays are influenced by factors like solar activity and weather patterns.

Time/Distance Since Last Use (Cold Start vs. Hot Start)

When a device with GPS or satellite communication capabilities is turned off for a long time, or if it travels a significant distance while powered down, it loses its stored satellite information.

• Cold Start: In this state, the device must start from scratch. It has to search the entire sky for all visible satellites and then download the full data set from them. This process can take several minutes—sometimes up to 10 or 15 minutes, especially in a sub-optimal location—before it can calculate a good position.

• Hot Start: If the device is used regularly and hasn't moved far, it retains this data. It only needs to quickly update the information from a few satellites, allowing it to get an accurate position (a "fix") in seconds.

Recommendation: If your device has been off for a long time or has travelled a significant distance whilst off, make sure to turn it on in an open area with a clear view of the sky and wait at least 5-10 minutes to ensure it has acquired a current and accurate position before you rely on it or go into an area where the signal will be obstructed.

Tips for Improving GPS Accuracy and Satellite Connectivity

Your safety device uses GPS to tell people where you are and a communication network (cellular or satellite) to send for help. Getting the most accurate location and ensuring your message is delivered is really important. Here's how to do it:

Getting the Best Position for Your Device

• Clear View of the Sky: The most important thing is to have a clear, open view of the sky. Move away from buildings, thick trees, or steep hills. Hold the device straight up, if you can, to ensure the best line of sight for both GPS acquisition and message transmission.

• Keep Things Out of the Way: Even small things can block the satellite signal, like your body, thick clothes, or metal.

• If you're in a car, try putting the device on the dashboard or near a window.

Knowing How Signals Work

• Inside is Bad: GPS signals don't work well indoors, and walls will completely block satellite message transmission. If you have to use your device inside, prepare beforehand, go to a window or, better yet, outside.

• Hills and Buildings Mess Things Up: Deep valleys, forests, and cities with tall buildings can block or confuse the signals. If you can, go to higher ground or an open area.

• Wait for the Best Fix: After you turn on your device, give it time to find its exact location. If the device has been off for a long time or has travelled whilst off (a 'cold start'), this can take several minutes as it needs to fully reacquire satellite data.

Follow Our Best Practices

Before going indoors or into areas where your device signal could be impacted, follow these steps to ensure the Peoplesafe Alarm Receiving Centre (ARC) has your up-to-date location:

1. Log a manual position: Log a manual position outside, with a clear view of the sky.

2. Record a voice memo: Record a voice memo stating your location and any risks associated with completing the task at that location.

3. Create an activity: Create a timed activity, recording your location and any risks associated with completing the task at that location.

Taking Care of Your Device

• Keep it Charged: A full battery helps your device work its best. Low batteries can sometimes affect the GPS and prevent proper message transmission.

• Test it Now and Then: Check your device in an open area to make sure it's working right. This helps you get used to using it and find any problems.

The Main Point

To ensure the most accurate location and reliable emergency message transmission, make sure your safety device has a clear, open view of the sky. By following these tips, you'll help make sure people can find you quickly if you need help.

Conclusion

Understanding the factors that affect GPS accuracy and satellite communication can help you interpret location data more effectively. By being aware of these limitations, you can take steps to improve accuracy and ensure reliable positioning in various environments.