RE: C-Bus / IR / Bluetooth / WiFi / X-10 / Idratek / EIB

["Keith Doxey" <ukha@xxxxxxxxxxx>]

Hi Chris

> 'making a list of emc (electromagnetic compatibility) problems, 
so-far
> I have :
>
> * C-Bus dimmers blind X-10 dimmers, at least when in close-proximity
>

Probably due to the filtering employed by the C-Bus dimmers. EMC
compatability requires that equipment does not generate mains bourne
interference and is not suseptable to misoperation resulting from mains
bourne interference. Given that phase controlled dimming involves chopping
up the mains thereby causing loads of interference it is not unreasonable
to
expect that a manufacturer of such a product will go to great lengths to
resolve that problem.

X10 uses powerline communications as its data bus which means that it
DELIBERATELY PUTS INTERFERENCE onto the powerline. There are many pieces of
equipment that will cause problems with X10. Basically ANYTHING that uses a
switch mode power supply will either attenuate the X10 carrier or worse
totally obliterate it.

My advise would be to avoid X10 completely especially for a new
installation. For retrofit, many have no other option. Whilst my X10 has
been pretty good for the last 7 or 8 years (I only have a few modules)
there
have been times when it just gives up the ghost for seemingly no reason
whatsoever. My new laser printer is the latest culprit, had to fit a filter
to it.

> * compact fluorescent lamps of a certain age, within the same room,
and
> for a while soon after being switched-on, talk to the IR of my hi-fi
&
> persuade it to do things
>

Depends greatly on the IR receivers. As you have said in the past, your
Hifi
is quite old and probably uses a discrete IR photodiode with additional
circuitry to proces the signal. Modern IR Photodetector modules are tiny
little 3 pin devices that incorporate all the required circuitry. They are
exceptionally good at rejecting unwanted signals and will self adjust to
"remove" continuous signals that would normally interfere with
reception
although this does reduce the sensitivity a bit.

As Phil pointed out in another reply, this can affect IR repeates as well
but tend to be more of a problem with systems that will accept a wide range
of IR frequencies as the filtering cannot be as tight. The
"friendly"
receivers are designed for a more restricted IR frequency and can therefore
filter the signals much better.

IR protocols have also improved over the last few years and modern codes
are
much more resiliant to false decodes. Some early IR codes were very basic
with little or no error checking and as a result, if the received signal
looked something like it should then the equipment would respond. Because
modern devices have so many functions, the codes are now much more complex
and have better error checking.

I ALWAYS prefer a wired solution over one that doesnt use wires because it
tends to work 100% of the time and the only thing that will stop it is
physical damage.

Wireless (either RF or IR) solutions have their place in the overall scheme
of things but should not be seen as the preferred way. As RF devices become
more prevelent the radio spectrum will become congested and at best, data
rates will fall due to retransmission because of corrupion/collisions.

If you run out of bandwidth on a cable, adding "n" cables will
give you "n"
times the amount of bandwidth. The same isnt true for RF, the only ways are
release more radio spectrum or reduce RF power so "RF networks"
can be
closer together.

Hope that helps

Keith