RE: Fw: X-10 - UK vs. US

["Kevin Hawkins" <lists@xxxxxxx>]

Historically various countries managed their own radio spectrum
allocations. Only quite recently have these bodies worked well together to
try and provide some matching space for devices around the world - eg
802.11
, Bluetooth etc. Historically we ended up with this sort of problem with
418Mhz in the UK and 433Mhz in Europe and 310Mhz in the USA. The UK has now
adopted 433 as well.  However things are really tight, for example the
Amateur Radio 70cm band is right on top of this frequency and it is only a
secondary user to another major network. 310 Mhz in the UK could (will) be
used by someone. All these devices contribute to the 'radio noise floor'
that is experienced everywhere nowadays - this makes very weak signals
inaudible - the ones the radio enthusiasts love from far flung places of
the
world.
Now normally there's no problem - the aerials are small and
inefficient and the receivers very insensitive. But in some cases it causes
problems - if you are close to the official user for example. In such a
dispute you would be at fault. You could be disturbing their reception or
they could be blocking your receivers. This has manifested itself with
instances like people who lived close to transmitters being unable to
unlock
their cars with radio keyfobs etc.
A big concern is in security systems. I had a Chub wireless system
that constantly went into tamper because a local signal was blocking the
sensors - it was unuseable, constantly alarming when set. In your specific
case where you are using a radio PIR if this was being used in any critical
application I would caution against imports - however for basic operation
it's going to work obviously - although it will be illegal as such. In fact
the RF PIR you refer to is such a basic device that it would never form
part
of a sensible security system I feel - but as a remote signalling device
you
can't beat it at that cost.
Just one more point - the European regulations on the purity of the
transmissions from 433 Mhz devices , and the selectivity and adjacent noise
immunity of the receivers is much more stringent than the US regulations on
310Mhz - that is also why 433 costs more. The US can allow this as
physically they have such huge open space in comparison to European
population density. Ironically as so much is crammed into 433 and 418 here
-
the frequencies are really congested and 310 may be clearer. All these
frequencies with the limited designs of the X10 products can suffer
interference over several hundred metres - although their operational
distances are much less 30m or so.

110 V US X10 devices can be operated in the UK with a step down
autotransformer or by capacitively coupling a normal transformer. You need
110V appliances and light bulbs though - the latter can be bought from most
electrical wholesalers eg City Electrical etc. There are mod sites to
convert 110V modules to 220V although I can't recommend this - and UK
prices
are a lot better now. It's usually the features that drive me to consider
this rather than the prices. I had a 110V ring for some lighting/sockets in
my previous house.

K

> -----Original Message-----
> From: etj_webster [mailto:etj_webster@xxxxxxx]
> Sent: 02 September 2003 11:52
> To: ukha_d@xxxxxxx
> Subject: Re: Fw: [ukha_d] X-10 - UK vs. US
>
> --- In ukha_d@xxxxxxx, Gareth Cook <g@u...> wrote:
> > All my X10 PIRs are US RF based, and I use a US X10 receiver into
a
> > Maplins stepdown special.
> >
> > Works a treat.
> >
> > G.
> >
>
> Hi,
>
> I'm new on here and will post my 'newbie' post in a moment.
> I thought I'd post in response to this first though.
>
> I asked a question about precisely this (i.e. using US RF modules
> (310Mhz) in the UK (which are normally 433Mhz) on the uk selfbuild
> list around 45 minutes ago ;-p
>
> These pirs are _very_ cheap in the US compared to here, even when you
> factor in postage.
> Okay, so they aren't officially approved, but are there any
> interference problems ?
>
> How easy is it to modify US 110v modules to run on 240v (I recall
> seeing an article on this some time ago, but forget where).
>
> Cheers,
>     John.
>
>
>
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