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3.4Ghz...why such a High freq.?!

Right at current, all wireless manufacturers are pushing the frequency of their products higher and higher into the Ghz range to achieve the throughput that modern software requires.
Because of this all wireless products have a short range (unless excessive power is applied which is illigal under the gov. regulations), and they all need LOS to be fully opperational.

This is my 2 cents worth (excuse the americanisum)
All wired networking runs off the ability to transmit power in the form of "+" and "-" volts in order to produce a pure binary stream. This runs off the mains which is AC current oscillating at 50Hz.
If (now PLEASE correct me if im horribly wrong) wired networks can achieve 10Mbps at 50Hz then why can a wireless network do the same at arround 50Hz. This would allow the signal generated to be reflected arround obsticals (thanks to the low wavelength of the wave) but also able to transmit large enough amounts of data.

Right That is the theory but im not 100% sure so please bare with it.
Any questions ask away
 
You just do not have the Bandwidth available at that frequency. If you want lots of Bandwidth and Broadband needs lots you have to go up in frequency. There is no way around that.
 
But Bandwidth is the ability to push though as many O's and 1's.
The more of them you can send the greater the file can be.
 
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Well my theory is flying out the window but i needed to air out an idea that was bugging me.
This is the situation, im thinking of connecting two PCs together. However there is no LOS and one is located about 20m below the other and 1 to 1.5Km max in distance.
any Ideas?
 
It is simply bandwidth and channels. You can fit many more channels and bandwidth per channel at higher frequencies.
 
Hi LAGGED and all,

I will try to explain a highly technical area in laymans terms...

It is all down to having enough waves to carry the information. At 50hz, you have 50 waves per second that could potentially carry information, but the absence of a cycle would be difficult to detect.

Digital information is often carried as presence of volts (1) and absence of volts (0). This is a Square Wave. A mathematician by the name of fourrier discovered that any waveform can be made up from sinewaves (50 hz mains is a sinewave). A square wave is made up of odd harmoonics (i.e. a 50hz square wave is made up from sine waves at 50hz (the fundamental), 150hz, 250hz, 350hz, 450hz...infinity at decreasing amplitudes. In practice only the first few of these harmonics are requires to carry the information.

For transmission by radio, this digital data is then used to modulate a carrier which must be of a sufficiently high frequency to carry the information. It turns out that a frequency of at least three times the highest frequency in the information is required.

This information is not confined to just a single frequency, but spreads out either side of the carrier frequency (A FM walkie-talkie uses a 12.5 khz channel to carry analogue speech information with a maximum frequency of 3khz). This can carry about data at 9600 baud in on direction.

To carry 1 megabit at VHF frequencies (30 MHz to 400MHz) would take most of the VHF band, leaving broadcasters (Such as Radio 1), the emergency services, taxis, the armed forces, radio amateurs to have to use other bands.

This is not quite true, because we can make the radio waves stay inside a wire and not radiate. This is how ethernet ADSL, ISDN and many other wired commnunications systems work.

Unfortuneately the do radiate a little, and the powerline transmission techniques being trialled are likely to impinge on the users of shortwave communications (such as yachts ocean liners in distress) by increasing the amount of noise that the receiving station must try to ignore when trying to receive the intended signal.

The whole issue of allocating bandwidth for wireless transmission is the subject of international law. The International Telecommunications Union has just finished a conference lasting over a month discussing the many isues required.

If you want to know more about radio propagation, may I suggest becoming a radio amateur (visit www.rsgb.org for more information) and then reading up and experimenting with data communications.

I actually learned much of this when studying for A-Level electronic systems in the late eighties.

Sorry if this was a bit long-winded, but I hope it answers your questions


Regards

Ellis
(Amateur Radio callsign G7SAI)
Just waiting for the UK government to implement the recent ITU resolution abandoning the need to learn morse code to use short-wave!
 
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