“Radio waves” transmit music, conversations, pictures and data invisibly through the air, often over millions of miles — it happens every day in thousands of different ways! Even though radio waves are invisible and completely undetectable to humans, they have totally changed society. Whether we are talking about a cell phone, a baby monitor, a cordless phone or any one of the thousands of other wireless technologies, all of them use radio waves to communicate.
Here are just a few of the everyday technologies that depend on radio waves:
- AM and FM radio broadcasts
- Cordless phones
- Garage door openers
- Wireless networks
- Radio-controlled toys
- Television broadcasts
- Cell phones
- GPS receivers
- Ham radios
- Satellite communications
- Police radios
- Wireless clocks
The list goes on and on… Even things like radar and microwave ovens depend on radio waves. Things like communication and navigation satellites would be impossible without radio waves, as would modern aviation — an airplane depends on a dozen different radio systems. The current trend toward wireless Internet access uses radio as well, and that means a lot more convenience in the future!
The funny thing is that, at its core, radio is an incredibly simple technology. With just a couple of electronic components that cost at most a dollar or two, you can build simple radio transmitters and receivers. The story of how something so simple has become a bedrock technology of the modern world is fascinating!
There are few situations more terrifying than being trapped underground with no visible means of escape. Miners risk being caught in this situation every day they go to work. In the United States, the Mine Safety and Health Administration establishes guidelines and safety measures that help minimize the chance of a disaster. But sometimes that’s not enough.
According to the Bureau of Labor Statistics, the fatality rate for miners in 2007 was 24.8 per 100,000 people employed. Only the collective industries of agriculture, fishing, forestry and hunting had a higher fatality rate. Not every fatality was the result of a collapsed mine. An equipment failure or poor safety habits can also end in tragedy. Miners may encounter dangerous gases like methane as they move underground, too.
One of the biggest challenges in mine safety is communication. It’s difficult to create a network that works well underground. Most radio waves can’t penetrate rock — you need to have a line of sight between the two transmission points. That’s not feasible for most mining operations. A strong communications system underground could help reduce mining accidents and increase the effectiveness of rescue operations.
A wireless radio network would be a key component of an effective communications system. Using radio waves, miners could remain in contact with surface operations. Sensors hooked up to a wireless radio network could send back environmental information to the base of operations, alerting team leaders to potentially hazardous situations before an accident can happen. And with the right tracking system, leaders could keep tabs on where miners are within the mine. In the event of an accident, leaders could determine who was in the area at the time.
Wireless technology is pervasive — you can find hotspots in airports and coffee shops. Some cities have rolled out municipal wireless networks. You might think that every mine in the world would have them, too. But remember: Radio waves have a hard time penetrating through solid rock. When you design a wireless radio network for a mine, you have to take that into account. We’ll look at two of the most common approaches to implementing a wireless radio network in a mine.
First, we’ll focus on a system with a funny name: the leaky feeder.
