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Message-ID: <594397.37559.qm@web87016.mail.ird.yahoo.com>
Date: Thu, 17 Dec 2009 12:59:37 +0000 (GMT)
From: Sam <jewell@btinternet.com>
To: "rsgb_lf_group@blacksheep.org" <rsgb_lf_group@blacksheep.org>
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Subject: Re: LF: Re: RE: Noise cancelling by using optic transmission of RX signals
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I have a small number of ex equipment semiconductor quantum well semicondu=
ctor lasers (1550nm) and PIN diodes on PCB cards. These are pigtailed with=
 single mode fibre terminated in FC connectors. The cards have an FC bulkh=
ead adaptor so that they can be connected together to form a short one-way=
 radio over fibre link. These are modern (current) devices and capable of=
 carrying radio over fibre from DC to about 2.0 - 2.4GHz. This would form=
 a high performance, but short, fibre link (antenna isolator), but with ac=
cess to some SM fibre with FC connectors the link could be up to 100km lon=
g, depending on a number of factors!
These are offered for a small donation to the Bawdsey remote receiver proj=
ect, plus postage. Contact me off list if you are interested. I must stres=
s that I am unable to provide further assistance in setting up the fibre=
 optic links or devices. You are on your own!
Relevant optical safety, using lasers, needs to be observed.
Sam@g4ddk.com

73 de Sam








On 17 Dec 2009, at 10:43, "Ken" <ken.h.wright@btinternet.com> wrote:

Optical fibres are fine for transmission and remove all the problems of in=
terference 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 opti=
cal safety took priority over every thing else. All optical fibres need to=
 have a perfect cleave on the ends, and the connectors  be absolutely clea=
n, 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 St=F6cker" <horst.stoecker@web.d=
e>
To: <rsgb_lf_group@blacksheep.org>
Sent: Thursday, December 17, 2009 9:01 AM
Subject: LF: RE: Noise cancelling by using optic transmission of RX signal=
s


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 transmi=
ssions 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 me=
ters.

In this case you should think about an IR-LED. Unfortunately, the Aatis re=
ceiver has a photo transistor instead of a diode. But it should be no grea=
t 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, espec=
ially 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 swingi=
ng 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 othe=
rs.

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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