Re: Somewhat funny stuff

["ABLE1" <royboynospam@xxxxxxxxxxxxx>]

More input on motion detector effecting a wireless laptop.  It is a strange
world we live in.


>I covered it with a biscuit tin lid today, and the problem immediately
>vanished.  I happend to spot a workman installing more of them and told him
>to remove it.  He said therew as absolutely no way it could be causing that
>problem, but I persuaded him to remove it while a continuous ping was on
>the screen of a wireless laptop.  It could clearly be seen that as soon as
>he unplugged it, everything worked, and when he put it back, packets
>disappeared.  He told me it used microwaves, but couldn't tell me the
>frequency (although he thought it was meant to be substantially higher than
>2.4GHz).  All of the detectors throughout the building look identical, but
>only this one appeared to cause problems.  Perhaps it was faulty and was
>oscillating at half the correct frequency?
>
> The whole of the new corridor still hates higher numbered channels for no
> apparent reason.  Channel 1 works perfectly, channel 6 works with older
> laptops but not new ones(?!) and channel 11 works with nothing.  There is
> only that one transmitter in range there, so who knows what's going on!


"ABLE1" <royboynospam@xxxxxxxxxxxxx> wrote in message
news:5TLgl.174890$9i5.49254@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
> Found this discussion over at alt.electronics.  Those Brits are all the
> rage some times.
> Kinda enjoyed the read and thought I would share.
>
>
>
> We have a wireless network at work which appears to have gone downhill
> since the workmen installed PIRs for the burglar alarm.  One of them in
> particular appears to cause dropped packets the closer a laptop is to it.
> Is this possible??  It's not a wireless PIR as far as I know, as I can see
> some leftover cable he was using which is a multicore (about 10 cores)
> type similar to phone systems, so I assume this is for the signal aswell
> as power.  The person in that office swears blind that there were
> absolutely no problems until the PIR was installed above her desk, and now
> when I check, about 60% of the packets are being dropped.  Moving her
> laptop to the opposite side of the room it drops only 5% of packets.  PIRs
> used to just pick up infrared of your bodyheat, but I think now they are
> also motion sensors?  Perhaps this means they are sending out a signal and
> bouncing it off you?  Perhaps this could interfere with wireless
> networking?
>
> --
>> You can now get ones that use microwave detection as well as PIR, they
>> are called "Dual PIR" sensors:
>
>> 10.5GHz for the microwave
>>
>> A normal PIR sensor would not cause any issues like this as they are
>> passive.
>>
>> You can simply swap a Dual PIR for a normal PIR no probems.
>
> Good point, I'll just tell them to put in a passive in any rooms with
> problems if I can prove it's that.
>
> We've always had detectors though and never had problems, so maybe it's
> faulty?  Or the new ones are on a different band.  If it's using 2.4GHz,
> in my opinion it's wrong.  Using the same band as wireless networks in an
> office is just plain stupid.
>
>> Sensors only need a 4 conductor cable, two for power (12V), two for the
>> contact.
>
> Odd that they left a bit of approx 10 core cable then (and that was the
> only thing they were fitting at the time).  Unless it uses a different
> core for each type of detection?
>
> A normal PIR sensor would not cause any issues like this as they are
> passive.
>
> You can simply swap a Dual PIR for a normal PIR no probems. Sensors
> only need a 4 conductor cable, two for power (12V), two for the
> contact.
>
>> ---
>> If its PIR it shouln't.
>>
>> PIR is Passive Infra Red, and it's body heat which triggers the sensor,
>> not anthing the device transmits.
>>
>
> I'm not sure if it's PIR or not.  Aren't a lot of them nowadays
> multifunction?
>
>> Maybe the wiring is affecting the strength of the RF field areound where
>> she sits.
>
> The wiring?  It shouldn't have that strong a field from its wiring surely?
>
> The effect is as such: within about 2-3 metres the network is unusable.
> The next 2-3 metres it works most of the time.  After that it's almost
> perfect.
>
>
>