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Re: LF: Re: Re: RE: Noise cancelling by using optic transmission of RX

To: <[email protected]>
Subject: Re: LF: Re: Re: RE: Noise cancelling by using optic transmission of RX signals
From: "Ken" <[email protected]>
Date: Tue, 29 Dec 2009 21:36:42 -0000
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If it is red then the optical wavelength is about 850nm, what you also need to know is the type of fibre on the sound card, i.e, multi mode or single mode. Multi mode fibre is usually 50/125 microns and single mode 9/125 microns, the first number is the core diameter, the second the overall fibre diameter, as you can see you do not want to try and launch a multi mode light source into a single mode fibre..

73s.
Ken.
M0KHW
----- Original Message ----- From: "John RABSON" <[email protected]>
To: <[email protected]>
Sent: Tuesday, December 29, 2009 9:31 AM
Subject: Re: LF: Re: Re: RE: Noise cancelling by using optic transmission of RX signals


Agreed we should be careful. My Creative Labs soundcard (external USB) has SPDIF optical connectors as well as electrical. The Optical Out connector emits a faint red light but I can't find any mention of safety in the user manual.

F5VLF

*********** REPLY SEPARATOR  ***********

On 18/12/2009 at 09:16 mal hamilton wrote:

Radio Amateurs BEWARE - Appliance Operators DO NOT TOUCH

G3KEV


----- Original Message -----
From: "Ken" <[email protected]>
To: <[email protected]>
Sent: Thursday, December 17, 2009 10:43 AM
Subject: LF: Re: RE: Noise cancelling by using optic transmission of RX
signals


Optical fibres are fine for transmission and remove all the problems of
interference and cross talk at a stroke, but please be careful and
observe
optical safety precautions when using lasers and other light sources. I
worked on optical systems for many years during my time with BT, and
optical
safety took priority over every thing else. All optical fibres need to
have
a perfect cleave on the ends, and the connectors  be absolutely clean, if
you are not launching into an optical connector then alignment will be a
problem, similarly at the receive end.


73.
Ken

M0KHW


----- Original Message -----
From: "Horst Stöcker" <[email protected]>
To: <[email protected]>
Sent: Thursday, December 17, 2009 9:01 AM
Subject: LF: RE: Noise cancelling by using optic transmission of RX
signals


In theory it's a good Idea which I had some weeks before without working
it
out.

Years before I also have made tests with FTA (free to air) optical
transmissions with a DL2CH-Transceiver and a TRX-Kit by Aatis which is
quite
much simpler.
Even with that it was no problem to link between two points about a few
meters.

In this case you should think about an IR-LED. Unfortunately, the Aatis
receiver has a photo transistor instead of a diode. But it should be no
great deal to modify that.

The problems with FTA optic transmission for this application are imho:
- You have to be sure, that no one can be injured by the laser beam,
especially at unattended operation.
- Think about how many hours/the beam has it's full power before becoming
much weaker.
- The optics must be kept clean. This could be a problem if the units are
out of reach.
- The units have to be mounted absolutely stable. For Example, on a
swinging
fibre rod you'll never bring a laser beam exactly to the rx area.

I bet, (FTA) optical transmission just changes one problem with a few
others.

But the transmission with optical cable seems interesting.

What type of cable do you suggest? I do not think, my TOS-Link cable
would
stand weather/UV and mechanical conditions outside for a long time.

Horst DO1KHS
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