When choosing personal safety devices for your organisation, one of the main decisions you will need to make is whether to get satellite devices or cellular devices. Both have their advantages and disadvantages so are suitable in different situations. Here are the main things you need to know.
Cellular devices need to communicate with cellular towers on the ground to send messages and data back to the main system. Those towers are operated by cellular networks.
The problem is it is impossible to have enough towers to give 100 percent coverage - you will know this from using your mobile phone as the signal can reduce to nothing, even in large and populated cities.
This problem of cellular tower coverage is exacerbated in remote areas. This is because individual cellular towers only work in a small geographical area. In addition, the quality of coverage they offer is impacted by the general surroundings, i.e. buildings or hilly and mountainous terrain can reduce the quality of the signal - or block it completely.
It is simply not financially feasible for cellular networks to install towers in remote locations. Therefore, when you use a cellular-based personal safety device, you may encounter coverage issues. Those issues will be more prevalent the more remote your workers are.
This makes satellite devices the best choice in remote locations as they don't need to be close to a tower or any other structure on the ground. Instead, they communicate directly with satellites which then forward the data to the main system on land.
Wider Geographical Access
Almost all cellular solutions will be restricted to the cellular networks in their target countries. For example, if you purchase a cellular personal safety device in Australia, it will probably only work in Australia or New Zealand as it is only compatible with the cellular networks in those countries.
As satellite devices communicate directly with satellites in the sky, they are operational over a much larger geographical area. For example, a device purchased in Australia will work in much of Asia too. It is not worldwide coverage, but it is much more extensive than a cellular solution.
Line of Sight
So long as a cellular device has a connection with a cellular tower, it will work, regardless of the location of the user. This includes when the user is inside.
A satellite device is not as flexible, however, as it requires line of sight to the sky (and the satellite). In other words, the device must be able to "see" the satellite to connect to it and send data. This requirement can be restrictive in some situations, including working indoors or underground.
Satellite devices require a lot more power to use than cellular devices. As a result, battery life is not normally as long with a satellite device as it is with a cellular device.
Most high-quality satellite personal safety devices have features that make the battery last longer to mitigate the power problem. This includes sending data in batches - for example, sending data every 10 minutes rather than every two minutes. Another feature that is often used is to stop sending updates when the user stops moving.
Even with these features, however, battery life is more of an issue with satellite devices than with cellular.
Satellite solutions are more expensive to purchase than cellular. Even more importantly, the data transfer costs for satellite systems are more expensive - significantly more expensive, in fact.
The best satellite devices will have features to reduce the cost of use. This includes sending data in periodic batches rather than in real-time to reduce the amount of data sent overall. You will still pay a lot more to use a satellite personal safety device than a cellular device, though.
Frequency and Consistency of Data Transmission
The above two points highlight features of many satellite personal safety devices that help to save battery life and reduce costs. Those features have a significant negative side effect, however. Sending data in periodic batches and implementing power saving features like pausing updates when the user is not moving means messages are less frequent and, in some situations, less consistent. This can delay the alerting of crossing a geofence and updated location of the user.
Summary - Satellite or Cellular?
Cellular personal safety devices are cheaper to buy, less costly to run, and they have better battery life than satellite equivalents. In addition, they more flexible in regular use as they don't require a direct line of sight to send data or messages.
All this, however, must be put in context. While the above are all significant benefits, they are pointless if the user is in a location that doesn't have cellular coverage. In these locations, satellite devices are the only option as they are the only solution that provides a reliable means of communication.