Message-ID: <4CBF0DAF.8050806@g3ysx.org.uk>
Date: Wed, 20 Oct 2010 16:41:35 +0100
From: Stewart Bryant <stewart@g3ysx.org.uk>
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To: rsgb_lf_group@blacksheep.org
CC: Chris <c.ashby435@btinternet.com>
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Subject: Re: LF: Re: Re: Re: Re: Variometer
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On 20/10/2010 14:45, Chris wrote:
> Hi Mal,
> Yes, so I now understand, but it wasn't a 'full blown' repeater, as you
> say, more a remote RX like a grabber.

Exactly, it was an experimental system (MB7LF) that we ran for a while
and demonstrated at the HF convention, which received on 136KHz and did
a linear translation to 144MHz. This was use to overcome local RX
noise. We had a couple of real cases where local noise was a problem -
one at G3GRO who got huge ingress noise from a BT line to the local
hospital and the other was the HF Convention where noise from the
computer room wiped out 136KHz.

The service could be compared to a short range version of the modern
Internet grabbers, though it was much closer to a remote SDR because
you could tune the whole band remotely in parallel to other users.
However, it was deployed at a time when far fewer people had
Internet and the bandwidth available was much lower than it is today.

> Thing is, nobody had to use it if
> they didn't want to. Still can't see how it would attract 'pirates'.

It's didn't. The "pirate" thing was a storm in a teacup.

There was one event, one weekend, where someone did an experiment
involving a low power signal generator a small antenna and a morse
keyer to try the system out (unfortunately they accidentally had the
keyer is some strange mode that gave out random characters). They only
expected to get to Crawley, but got to Wales and were heard by Steve.
Once the problem was identified they shut down the experiment.

I can't remember who it was, but it was not one of the group that
deployed MB7LF.

- Stewart/G3YSX