Radio frequencies - How do they work?

[mekon]

I'm not up to speed with radio signal technicalities, so perhaps someone could explain this issue. Why can I walk anywhere in the house or garden with my (radio) wireless headphones and get a clear signal about 30 metres away, even through a wall? (I did this for test purposes, not usual usage)

Wireless LAN signals are so much more fragile (I'm really suffering with this at the moment :| even though the machines are 30cms apart), so I guess my question is what, other than building structure, has the biggest impact on signal strength?

I know they operate on a different frequency, and I've had my own WLAN (small scale, big deal) and managed wired systems for some time, but I'm hoping to glean some knowledge from those with some experience.

 

[Demo24]

Phones can if the frequencies are too close together. Just change what channel the router is on and see if that helps.

 

[spidey07]

It just another form of electromagnetic energy (waves) lower frequencies wavelength is longer and can penetrate materials easier depending on density/length. Higher frequencies like wifi are much higher and get obstructed and weakend/deformed easier. 802.11a is 5 ghz, 802.11b/g is 2.4 so guess which one has a bigger problem with penetration?

ps - 30 cms is TOO CLOSE for wireless. The antennas interfere with each other (well the waves actually interfere with each other because they are so strong because of being so close. As to what has the biggest impact on signal strength with wireless? Dense material like metal, even drywall weakens it. What's more important is signal strength relative to noise or your signal to strength ratio (SNR).

 

[So]

Imagine that your house is made of red tinted glass, and that your headphones' base station is a blue LED, but your router has a red LED. The red tinted glass will stop the router signals pretty quickly but the headphone signals not so much. Wour walls are essentially tinted glass for those frequencies. Also, the higher the frequency, the less the wave will bend around corners (which is why you can hear sound from around a corner but not see light around a corner).

 

[mekon]

That is awesome, I learned quite a lot from you all. I didn't explain myself clearly, in that the receiver is in the next room and the two offending machines are 30cms apart from each other but I now have something to work with and it makes sense. Thank you.

 

[spidey07]

If you're having wifi difficulty try the networking forum. There are many basic steps you can do - like don't "point" the antennas at each other, that is actually the weakest pattern and change channels to 1, 6, 11 to see what works best. That's still pretty darn close, try a little farther away.

 

[TecHNooB]

I got a question. When we're measuring the wavelength of something (light for example), what exactly is being measured to determine the wavelength? What is the 'amplitude' of light being measured to determine 1 wavelength?

 

[spidey07]

Originally posted by: TecHNooB
I got a question. When we're measuring the wavelength of something (light for example), what exactly is being measured to determine the wavelength? What is the 'amplitude' of light being measured to determine 1 wavelength?

The distance between the peaks, or more precisely the distance between when it crosses zero potential for the second time. Wikipedia should give you a good place to start.

linked for you, looks like a pretty good little article.
http://en.wikipedia.org/wiki/Electromagnetic_radiation

 

[ScottMac]

Originally posted by: TecHNooB
I got a question. When we're measuring the wavelength of something (light for example), what exactly is being measured to determine the wavelength? What is the 'amplitude' of light being measured to determine 1 wavelength?

Wave length is being measured to determine wavelength. The time and / or distance it takes to describe one cycle of the base signal. The signal is not always sinusoidal, though many / most tend to be.

Another factor to consider when talking about "radio waves" is the method of modulation i.e., how the information is encoded onto the basic RF energy. Some modulation methods are better for some purposes than others.

Modulation can be almost anything that can reliably change the character of the base frequency, such that it can be altered (modulated) and decoded (demodulated) reliably. The amplitude, the frequency (or more specific, the rate of the change in frequency), shifting frequency, tone groups ... nearly anything.