Radio

Ham, Broadcast and Internet radio

Fascinating!

Posted by Tom on January 20, 2008
Posted in: Astronomy, Radio.

Early this morning (01/20/08) I took part in a fascinating radio test, the HAARP – LWA Moon Bounce Experiment It was an attempt to detect high frequency (~7MHz) radio waves reflected from the Moon using regular amateur radio receivers and antennas.

I was quite skeptical of the possibility but still got myself out of bed at 0630z (0030 am CST) to see for myself. The experiment was to last for two hours, one hour on 6.7925MHz and the next hour on 7.4075MHz. Fellow hams will notice that these frequencies are just below and above the 40 meter amateur band, an extremely low frequency for Moon bounce.

The tests consisted of 2 seconds of transmission followed by 3 seconds of silence with this pattern repeated for one hour on each frequency. Since the round-trip travel time for the signal to reach the Moon and return is about 2-1/2 seconds, the echo should occur in the silent period. You can read the other details of the experiment at the link above.

The bottom line: Even with my modest antenna (a multi-band vertical) I was able to hear the signal returning. Not strong, but easily audible. I was really surprised when I first heard the echoes. Even with the transmitter putting out 3.6 megawatts of RF power, I felt it was an amazing feat.

I’ve submitted my report to the people at HAARP and I’m pleased to have made even a tiny contribution to the experiment.

Internet Radio

Posted by Tom on February 20, 2007
Posted in: Music, Radio, Technology.

FM25B Most of you know what Internet radio is. For those who don’t, it’s simply radio programming transmitted over the Internet as a stream (rather than a download like a podcast). Usually, but not always, the programming is associated with a normal broadcasting station and mirrors their on-air content.

The benefits of Internet radio are several:

  • Variety: You can listen to programming outside of your normal radio range. I regularly listen to stations in Los Angeles, Duluth, Boston, Houston and Colorado Springs. There are even Internet Radio stations in countries all around the world.
  • Time Shifting: For network or syndicated programming you can listen at different times due to time-zone shifting or station schedules. Often on weekends I don’t get up in time for the NPR Weekend Edition but I can catch it from stations in the Mountain or Pacific time zones.
  • Quality: Many stations stream high quality audio – much better than you get on an AM signal and often better than a distant FM signal.
  • Freedom: If you live in an area where your local stations all have crappy programming you can find something more to your liking somewhere else. Since our local public radio stations imploded recently, I’ve been getting my radio fix from a wide range of stations. There is an all folk music station I listen to in Boston, a station that carries Old Time Radio programs on the weekend, and several stations with unique local programming. I’m still looking for one that streams Dr. Demento!

Of course the downside is you can’t do this in the car. You are not, however, tied to your computer to listen to Internet radio. With a low-powered FM stereo transmitter (I purchased the FM25B kit from Ramsey Electronics) you can listen anywhere in your house. Ramsey and other manufacturers have a number of models in a wide price range.

With the FM25B connected to my PC and using a simple wire antenna, not only can I listen to Internet radio anywhere in the house, but in the garage, out on the deck or when out working in the yard.

It’s perfectly legal within FCC Part 15 regulations though if you get interference complaints you must change your operation to eliminate them.

Podcasts

Posted by Tom on October 9, 2006
Posted in: Radio, Technology.

Over the last year or so I’ve gotten interested in podcasts – on demand audio programs which usually focus on a single theme or subject. Gradually my list of subscribed podcasts has grown to almost 9 hours of listening per week! Right now I concentrate on current technology news or astronomy related podcasts.

If you are not familiar with podcasting you can look at this Wikipedia article. There are thousands of podcasts on almost any conceivable subject and the numbers are growing exponentially. If you have some special interest, no matter how obscure, just Google for – podcast “your interest” – and I bet you’ll find at least one, probably more, related podcast.

The name podcast tends to make many people think that you must have an Apple iPod to listen to podcasts. This is absolutely not true. Anyone with a computer can listen to podcasts – you don’t need a special mp3 player, though that does allow you to listen while on the go. You don’t even need to have a special program like Apple iTunes to download podcasts. Nearly all podcasters have multiple ways to download their shows.
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