28th Mar 2007, 3:17 pm
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New Member
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Join Date: Feb 2007
Posts: 3
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All of these portable players with built-in FM radios use the headphone cord plus the body of the player itself as two parts of the antenna. In order for the antenna to work well, it needs a "ground" - a role played by the chassis of the player.
Because the chassis is so small, it needs help - and this is usually in the form of "body coupling" - that is, the player usually resides in a pocket, while the headphone cords are dangling from ther user's head.
A simple experiment can demonstrate this: If you are in a location away from interference (not near your computer or other eletronic device) and tune in a weak, noisy station, its signal will almost always be noisier if you place the player on a table by itself rather than in a pocket: When you grab the player with your hand - and often when you put it in your pocket, the signal will often improve, as it has electric coupling (via capacitance) your body. (If you are near a source of interference like a computer or other electronic device, this demonstration won't work because all you'll be doing is showing how well your radio can pick up the interfering signal and not the radio station.)
If the signal that you are receiving is fairly weak, it will be more suscptible to minor changes in signal strength and you will want to improve the signal reaching the headphone cord as much as possible, so you would want to:
- Keep the player itself near your body - in a pocket, usually.
- Keep the headphone cords away from your body. Your body, being mostly water, does not make a very good antenna and can shield the signal.
One problem that can happen when trying to listen to a weak signal is if you have, for example, run the headphone cord inside your shirt: In this case It is against the body and cannot function as a good antenna. If you run it outside your shirt, for example, it may work better.
I have a pair of very nice, large headphones that sound really good, but they do not work well with the radio. Why? The cord is so long that I have to coil most of it up in my pocket and with most of the cord against my body, it loses most of the signal.
With the cheaper headphones, the shorter cord, are swinging around freely in space and works much better - but it is sometimes a nuisance as it can snag on things, such as when doing yardwork.
Another (somewhat unlikely) possibility is if you live very near the transmitter for a different station, that your receiver is being overloaded by that signal, drowning out the one that you are trying to listen to. If your are wearing your longer-corded headphones in a way to maximize signal, the receiver may be being overloaded - in which case, doing steps to worsen reception may actually improve things by preventing overload.
I hope that this helps.
CTMP3
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