Re: Frustration with X10 Powermid

[nobody@xxxxxxxxxxxx (Dave Houston)]

What part of "you need to keep the transmitter away from
fluorescents and direct sunlight" confused you? Your own statement,
"In the interior the LED was dark, but at points near the exterior or near
windows it glowed." should tell you something.

The Powermid system has two components, one receives IR (with carrier
modulation in the 38kHz ±5kHz range) and retransmits it as 418MHz RF. The
other receives 418MHz and retransmits it as IR (with a carrier in the
38-40kHz range). Both work in real time with no delays other than the
response times of their receivers and transmitters.

The one without the antenna is the IR-in/RF-out (transmitter) and the other
is the RF-in/IR-out (receiver). The receiver has an antenna for receiving
RF.

If the transmitter unit was sensitive to 418MHz RF, it would interfere with
itself so it is unlikely that your problems stem from RF in the 418MHz band.
It is even less likely to be RF interference from the highly used bands
above 430MHz.

When the transmitter LED is glowing, the unit is either receiving IR or EMI
(electro magnetic interference) in the 38kHz ±5kHz range or sunlight (which
has a lot of IR). You can verify this by taking the transmitter unit to a
darkened room, pointing an IR remote at it and pressing a button on the
remote. The LED will flicker on and off as the unit receives the IR. If you
have any RF remotes that use 418MHz, you can also verify that the LED (on
the transmitter) does not flicker when you press a button on the RF remote
but that the one on the receiver (with the antenna) does.

Aside from sensitivity to sunlight and EMI the Powermids work well. Aside
from sensitivity to sunlight and EMI most other remote extenders work almost
as well - many of them are merely Powermids in cognito which you can verify
by checking the FCC ID number (B4SST539) on the unit with the RF
transmitter.

While it's not an 802.11B device, the Global Caché GC-100 can be controlled
from a laptop/PDA if you have a way of going from 802.11B to 802.3 like a
wireless router or WAP.

km@xxxxxxxxxxxxxxxx wrote:

>I have done some new experiments.
>
>I decided to take the Powermid transmitter outside my apartment, and
>found that the LED glowed even brighter outside. I then drove it a few
>miles in each direction and got the same results consistantly. In my
>car I used an AC inverter to power it, but I also just plugged it into
>AC at various outdoor power sockets. The results were very consistant.
>
>I took it over to a nearby office building and tried it at various
>points in the building. In the interior the LED was dark, but at points
>near the exterior or near windows it glowed.
>
>In my aprartment there is no spot where the LED stays dark. It's a
>brick building constructed in the 1950's, which I presume has walls
>that provide less shielding  than the  the new office building.
>
>I don't know if there is something special in my area transmitting at
>418mhz, or if this is typical. My guess is that it's not that unusual,
>and that most people have better shielding. Even in my apartment the
>background LED glow does not cripple operation with most of my IR
>devices. I started into this because just  one of my IR controlled
>devices would not work either through the Powermid, or even directly
>when the Powermid transmitter was on. Most of the others work but are
>intermittent at times.
>
>Probably an unlucky device, poor shielding in the walls, and an unknown
>RF source painting the neighborhood.
>
>I have tried a Terk a year back which operates at 433mhz and it was
>similarly balky. It was a short test, and at the time I didn't test for
>background glow outdoors. Either that background is over the whole
>418-433 range, or these devices are not real discriminating by
>frequency.
>
>I was going to try a URC-9910, but I see its also at 433 which is
>discouraging. (Also they seem to be in very short supply).
>
>I really seem to be stuck. I wish someone would make an 802.11 device.
>That would allow generating the IR sequence from a laptop/pda as well
>as from a matched 802.11 repeater, and also work more reliably.