Re: 4 . Wireless alarm systems INTERFERING sources>

[Crash Gordon® <NONE@xxxxxxxx>]

You have to understand that Paul (the RFI nutjob) is a wacko. He doesn't =
even understand what he is copy/pasting.

He bought some piece of crap wireless alarm system YEARS ago and it =
didnt work...who knows what the truth is...he may have even broken it =
putting it in...whatever.=20

Yah RFI exists. Is it a big problem with modern wireless alarm systems? =
No, if it was no one would buy or install them. Do problems occasionally =
arise, probably...but so do problems with broken wires, bad switches, =
blown fuses, shorted sirens.

Bottom line...Paul is wacko.

"Dr. Phred" <fred.spearey@xxxxxxxxxxxxx> wrote in message =
news:42799911.9090506@xxxxxxxxxxxxxxxx
> I'm new here but I'd like a chance to voice an opinion. RFI is=20
> everywhere on this planet and is ceated by just about everything on =
and=20
> surrounding this planet. It is true, RFI is real, but if it was really =

> all that much of a problem almost anything electronic wouldn't work. =
RFI=20
> is transmitted thought the air (radiated) and though wires =
(conducted).=20
> This is simple elementary knowledge. Anything electrical can generate=20
> it, have you ever tried to listen to a radio when the wife vacuums?, =
or=20
> tried to use a CB when sun spot activity is high. It can cause =
concerns.=20
> But it is in no way as bad as I have some people talk about in this=20
> group. If a product was so suseptible to RF that it wouldn't work, the =

> UL or FCC wouldn't give it their approval. I can hardly believe that a =

> grown man would spend hundreds of hours campaining about the pitfalls =
of=20
> wireless alarm simply because he probably had an install go bad in the =

> past that he couldn't resolve. There are literally millions of =
wireless=20
> alarm system in the world and if they were so unreliable as to fail=20
> every time someone shaved next door, I'm sure the manufactures would=20
> have been driven out of business years ago. I have only discovered a =
few=20
> wireless problems that have become a mystery to resolve. I have found =
as=20
> many strange quirks with wired systems, some resulting from RFI( yes,=20
> they can suffer from that too). All I can say is, I'm not a fan of air =

> cooled engines, but I didn't spend my life trying to run Volkswagon =
out=20
> of business. I hope that these people realize that as they waste their =

> lives whining about the BIG RFI problem, they're only creating more =
with=20
> each key stroke...
>=20
> -pull@shoot wrote:
> > What type of signals are able to produce RFI (Radio Frequency
> > Interference) on Wireless Alarm Systems and will jeopardize they're
> > operation?
> >=20
> > Not all Radio Frequency (RF) transmitters are able to generate RFI,
> > they have to be in accordance to certain rules described hereafter.
> >  Find here with more detail the list of Radio Frequency (RF)
> > transmitter sources generating RFI mentioned here above:
> >=20
> > 1. RF transmitters operating "ON" the Wireless Alarm Systems
> >    frequency.
> >    This is the most annoying RFI, it require only a very low power =
to
> >    do so (in my REAL case, 1 milliWatt was enough);
> >=20
> > 2. RF transmitters "SATURATING" the input stage of the Wireless =
Alarm
> >    Systems RF receiver
> >    A transmitter "close" to the operating frequency may have enough
> >    power to saturate the RF receiver input stage.
> >    This signal overrides the normal incoming RF sensor signals.
> >    This can happen with permanent installed RF transmitter stations =
or
> >    temporary operated (CB, Radio Ham, ++) mobile or fix.
> >=20
> > 3. RF transmitters causing "INTERMODULATION"
> >    "In gross" its the mix of two signals that result in an on
> >    the frequency signal of the Wireless Alarm Systems due to the
> >    non-linearity of wireless RF receiver input stage.
> >    It can be defined as a beat tone generated by two signals where
> >    the mixed beat part is on the Wireless Alarm operating frequency.
> >    Realize that quite a fair amount of combinations may produce
> >    that sort of RF signal.
> >=20
> > 4. "HARMONICS" of a RF transmitters falling in the Wireless receiver
> >    frequency bandwidth.
> >    All transmitters generate harmonics, those harmonics have to
> >    be suppressed (EMC requirement) to a certain degree,
> >    nevertheless there are still attenuated harmonics and when you
> >    have to deal with a powerful RF transmitter they may still be
> >    sufficient to "muzzle" the RF receiver sensor inputs of the
> >    Wireless Alarm Systems.
> >=20
> > 5. a RF transmitter signal not directly on the frequency who is "NOT
> >    ATTENUATED" enough by the RF "receiver bandpass filters".
> >    The RF receiver's use already since approx. 20 years SAW filters.
> >    Those filters attenuate the beside the frequency incoming =
signals,
> >    however those signals are still coming true in an attenuated =
manner
> >    but they may be of a sufficient amplitude to "interfere" the RF
> >    receiver sensor inputs.
> >=20
> > 6. RF transmitters on the IF (intermediate frequency)
> >    Modern wireless receivers use frequency conversion techniques
> >    who uses and IF stage to narrow the bandwidth (easier on lower
> >    frequencies).
> >    One drawback with them, if the IF frequency is not attenuated
> >    enough by the input stage, a RF transmission on that frequency =
will
> >    pass and generate RFI.
> >=20
> > As you see there is a quite some impressive number possible of RF
> > transmitter sources that may generate RFI on Wireless Alarm System
> > receivers.
> >  The major problem being that specific RFI avoidance techniques, =
used
> > in military and by similar instances, are not affordable for =
wireless
> > alarm systems even if the FCC (or like instances) would allow this
> > type of avoidance techniques in wireless alarm systems.
> >=20
> >  RFI is expectedly most of the time (and lucky enough) of the
> > involuntary nature and not persistent but in the meanwhile the =
system
> > is deaf and when it comes to security realize how easy it is to have =
a
> > Wireless Alarm Systems disturbed... dead.
> >  Silent key, NO ALARM, NO DETECTION.
> >=20
> > Paul
> >=20
>