Hello! from Pioneer 10
Now this is line of sight communications! NASA reports they've picked up a signal from Pioneer 10, now 7.3 billion miles from Earth, 78 times the distance from the sun to our planet. The power of the received signal? A billionth of a trillionth of a watt. This points out why power in the high frequency radio bands, such as cellular or point to point microwave, is usually secondary in importance to having both radios within sight of each other. If one radio isn't fairly close to line of sight, and five watts won't make the connection, well, fifty watts probably won't help. To make the point, if the antenna on board Pioneer wasn't facing Earth then a thousand watts would do nothing, the energy would simply be on its way to another part of the galaxy. As radio frequencies get higher, as they approach visible light frequencies, their waves act more and more like light; you can focus and direct that energy in a narrow fashion. Picture a flashlight and its directed beams, that's how to imagine radio waves at higher frequencies. Here's was the URL for the well illustrated NASA story:
http://science.nasa.gov/headlines/y2001/ast03may_1.htm?friend
734 external links here at privateline.com? That's the current total. I've put in these links so that people can go further with their learning. But now they've become a big problem, too many of them expire too soon, leaving people disappointed when links to sites and pages I've recommended don't work. Some people estimate 3% of the links on the web die every month. So in a year more than a third of this site's external links will no longer operate. What's worse is that many sites kill pages, not just move them. So good telecom information is lost. In the future I will start archiving pages here, with a link back to the originating site. I don't want to infringe on copyrights but I also don't want the information to disappear.