Prev: IIR design / FDATool?
Next: Fast Coarse Spectrum Analysis of Sound Samples in Java
From: fisico32 on 8 Aug 2010 22:38
Hello Forum,

I friend of mine company was using free space laser links to connect
building to building. Now they use radio waves. The radio antenna are
pretty small.

Is there a real advantage in using laser (optical frequencies) instead of
radio frequencies?

Can we achieve faster modulations with lasers than RF and a much larger
data rate?

Laser are used in fibers in wavelength division multiplexing: the same as
frequency division multiplexing, we can cram more channels each one with a
large bandwidth) together without having them interfere....

But in the case of a single channel (link bldg to bldg) can lasers achieve
super bandwidths?
thanks
fisico32
From: Robert Miles on 8 Aug 2010 22:45

"fisico32" <marcoscipioni1(a)n_o_s_p_a_m.gmail.com> wrote in message
news:POWdnanAxdmu98LRnZ2dnUVZ_oSdnZ2d(a)giganews.com...
> Hello Forum,
>
> I friend of mine company was using free space laser links to connect
> building to building. Now they use radio waves. The radio antenna are
> pretty small.
>
> Is there a real advantage in using laser (optical frequencies) instead of
> radio frequencies?
>
> Can we achieve faster modulations with lasers than RF and a much larger
> data rate?
>
> Laser are used in fibers in wavelength division multiplexing: the same as
> frequency division multiplexing, we can cram more channels each one with a
> large bandwidth) together without having them interfere....
>
> But in the case of a single channel (link bldg to bldg) can lasers achieve
> super bandwidths?
> thanks
> fisico32

I'd expect you to have more transparency problems with lasers.

Lasers can theoretically achieve higher bandwidths, but you may
have problems with the bandwidths of the components used to
translate from electrical signals to light and back.

Robert Miles


From: Jerry Avins on 8 Aug 2010 23:28
On 8/8/2010 10:38 PM, fisico32 wrote:
> Hello Forum,
>
> I friend of mine company was using free space laser links to connect
> building to building. Now they use radio waves. The radio antenna are
> pretty small.
>
> Is there a real advantage in using laser (optical frequencies) instead of
> radio frequencies?
>
> Can we achieve faster modulations with lasers than RF and a much larger
> data rate?
>
> Laser are used in fibers in wavelength division multiplexing: the same as
> frequency division multiplexing, we can cram more channels each one with a
> large bandwidth) together without having them interfere....
>
> But in the case of a single channel (link bldg to bldg) can lasers achieve
> super bandwidths?
> thanks
> fisico32

Lasers don't propagate well in rain, snow, and fog.

Jerry
--
Engineering is the art of making what you want from things you can get.
�����������������������������������������������������������������������
From: Eric Jacobsen on 9 Aug 2010 00:58
On Sun, 08 Aug 2010 21:38:43 -0500, "fisico32"
<marcoscipioni1(a)n_o_s_p_a_m.gmail.com> wrote:

>Hello Forum,
>
>I friend of mine company was using free space laser links to connect
>building to building. Now they use radio waves. The radio antenna are
>pretty small.
>
>Is there a real advantage in using laser (optical frequencies) instead of
>radio frequencies?
>
>Can we achieve faster modulations with lasers than RF and a much larger
>data rate?
>
>Laser are used in fibers in wavelength division multiplexing: the same as
>frequency division multiplexing, we can cram more channels each one with a
>large bandwidth) together without having them interfere....
>
>But in the case of a single channel (link bldg to bldg) can lasers achieve
>super bandwidths?
>thanks
>fisico32

Yes, the main advantage to free-space optics is the potential for
higher bandwidth (and higher throughput) than is possible with RF
transmission, as well as higher immunity from interference.

But there are a lot of downsides, too, which is why a lot of people,
like your friend, may switch to RF instead. Some of the downsides,
like susceptibility to weather interfering with the link, have already
been mentioned.




Eric Jacobsen
Minister of Algorithms
Abineau Communications
http://www.abineau.com
From: Steve Pope on 9 Aug 2010 03:32
Eric Jacobsen <eric.jacobsen(a)ieee.org> wrote:

>Yes, the main advantage to free-space optics is the potential for
>higher bandwidth (and higher throughput) than is possible with RF
>transmission, as well as higher immunity from interference.

A huge advantage is low probability of intercept.

Interference can happen though... if your two platforms and the sun
are collinear.

Steve
 |  Next  |  Last
Pages: 1 2
Prev: IIR design / FDATool?
Next: Fast Coarse Spectrum Analysis of Sound Samples in Java