Test your wireless alarm equipment on interference sensitivty
Petem
or just on your piece of garbage?
i do use lot of power when transmiting with my ham radio transceiver all
year long...
i creat RFI (radio frequecy interference) ,on a day to day basis and i dont
have any trouble with my dsc power 832 with 900mhz spead spectrum device...
my system can detect rf jam and lost of device signal..( i did test those
option cause i removed a faulty transmiter and while it was in my truck
cause it was under warenty and i was bringing it to my dealer i received a
call from the wife saying that system was in trouble,in a matter of minute
after i left the house....)
Before asking other to perform test that you never made on a real system
do it yourself of shute up
"Paul i don't read" <ma...@aol.com> wrote in message
news:70ahivcrjc9ebcflr...@4ax.com...
> The continuing insults of so called pro's force me to react and show
> that Radio Frequency Interference (RFI) exist and muzzle ALL wireless
> alarm system, YOURS TO (even the latest product/sold systems).
> Nothing in a reasonable priced, batery powered general public system
> can avoid RFI, military systems for instance can.
>
> WARNING:
> This is a "perfect" professional group who has no fear to say
> (assorted with insults) that what i mention is wrong.
> I have no fear to publish the means to TEST and FAIL YOUR wireless
> alarm systems from the OUTSIDE in order to proof the most evident
> facts known by real data communication pro's but those last are
> apparently not present in this group.
>
> You like to TEST the reliability of your wireless alarm system?
> - You like to find-out that a transmitter can muzzle the receiver
> and fail your entire detection system?
> - You like to find-out if your system is really equipped with some
> kind of RFI detection circuit (like some pretend)?
>
> Well, purchase for a few boxes a transmitter "operating on" your
> wireless alarm frequency and look at the show..
> http://www.mipot.com/ or http://www.aurel.it/
> Have a authority certified RF transmitter circuit from them who can be
> used to test YOUR wireless alarm system.
>
> Happy testing, your system is RFI fail safe according to so called
> pro's, just make sure it is...
>
> Paul
>
Martin
I had major RFI problems with a wired alarm system, it was all blamed on a
local radio amateur (which I don't believe!); the wireless system I replaced
it with has worked perfectly.
"Petem" <pe...@nospam.com> wrote in message
news:wY5Wa.3578$s_6....@weber.videotron.net...
William Allen Scheer
news:bgblqi$i9i$1...@titan.btinternet.com...
>
> I had major RFI problems with a wired alarm system, it was all blamed on a
> local radio amateur (which I don't believe!); the wireless system I
replaced
> it with has worked perfectly.
It would be helpful to know the brand/model of teh equipment which failed,
and also what you replaced it with.
Petem
> local radio amateur (which I don't believe!); the wireless system I
replaced
> it with has worked perfectly.
>
that could be possible....
I was creating problem on a dsc pc 3000 with the fire zone...(my back door
friend)
I had to put a capacitor in parallel of the smoke detector to stop the fire
trouble to trigger all the time
but I never had any trouble with my 900 MHz wireless smoke
detector...Strange! LOL!!!!!!!!!!
Robert L. Bass
a hard-wired system.
Many years ago we installed a Z1100e hard-wired alarm that used to false
late at night -- usually around the same time of night -- once or twice a
week. The installation was a small liquor store in a strip mall (no,
Graham; not *that* kind) in Simsbury, CT. I replaced the motion detector on
the zone that was falsing. No change. Then I replaced the cable and ran it
via another route. Same thing. Finally I pulled some shielded cable. No
improvement.
One night we called in the alarm and the dispatcher said there was already
an officer on premises. Hmm. I called back and asked the dispatcher if the
officer had just used his portable. Sure enough, he had keyed up to report
he was shaking doors in the mall as was his habit and about 30 seconds later
the alarm went off.
The next day I went out and checked everything in the system. The motion
detector was a fairly reliable unit for its day. Everything looked right.
I asked the proprietor if he'd had any work done since we installed the
alarm. Sure enough, he'd had the water heater replaced. In the process the
plumber had installed some PVC where the line had previously been all
copper. Out panel was grounded to the water pipe since the building's
ground rod had been conveniently buried under asphalt by the paving
contractor. I ran a new ground lead and all was well.
I've never been overly fond of wireless but there are issues with hard-wired
systems on occasion, too.
Regards,
Robert
=============================>
Bass Home Electronics, Inc
2291 Pine View Circle
Sarasota · Florida · 34231
877-722-8900 Sales & Tech Support
941-925-9747 Fax
941-232-0791 Wireless
Nextel Private ID - 161*21755*1
http://www.bass-home.com
=============================>
AlarmReview
anything. If it's false, please provide proof that it's false:
Subject: Re: Nuisance of MOST pro's when it boilsdown to Wireless unreliability
Date: 2003-01-21 06:37:21 GMT
NOTICE:
The original post WAS NOT posted by Jim, so please do not reply to the message.
It was posted by Paul Rampelbergh of Belgium.
Paul has been attempting for some time to convince people that wireless alarm
systems can be routinely blocked by RFI. He used the example that his wireless
headphone caused his wireless alarm system to be useless. This is his opinion
that he has every right to express.
Now Paul, this is MY opinion:
1.You made an allegation regarding wireless alarm systems, however you provided
no proof to your claim.
2. You repeatedly refused to provide basic information on the system and
headphone so that others can attempt to simulate the problem.
3. You have made exaggerated claims about your engineering background, only to
have that proven false.
4. When someone disagreed with your claims, they reported that you flooded
their e-mail with message after message on the subject and refused to stop.
5. You discover that many on alt.security.alarm had you filtered, you started
forging headers so that you could get around their filters.
6. You continually repost relies to your post so it looks like others are
responding when they are not.
7. You once before attempted to make a claims in post regarding flight
simulators only to have the manufacture refute you statements.
8. When you find yourself up against a wall regarding your rants, you move to
another NG, like this one, to attempt to get your message across
9. Since your reputation precedes you, you have resorted to forging headers to
make it seem that others are posting the information when it's you.
10. You are a certifiable mental case.
Now, here's the deal. I know it probably wouldn't mean anything to you, but if
there is any shred of competency in your brain, you would seriously consider
this. You stop posting this garbage about wireless and I'll not post what I've
found out about you. Just so you know I'm real, here's three bits of the
information:
1- At the age of 14, your school recommended that you receive a psychological
exam after you were accused of asking girls for a sample of their feces.
2- When you were applying for a position with the Communication Directorate,
your written test only had 8 correct answers out of 100, the lowest score ever
recorded. Even wannabe engineers scored at least 20 right. You made
challenges based on assumptions that had no basis in electronics.
3- You were twice arrested in France (1998) & (2001) for indecent acts You were
warned and released in the 1998 after you made a solicitation for sex to a
transvestite (ref: 98-454048-G-12), and ordered to pay a fine in the 2001
incident (ref: M01-000862-G-06) involving a male in a public restroom.
So Paul, which way do you want to go?
Do you continue your rants and raves, becoming the biggest nuisance in years,
or do you "debate" the issue like a rational individual using your own headers
without forgeries? Remember, the amount of information gathered on Paul
Rampelbergh, born 9/23/1971, who resides at 29 Heldenlaan 1970 Wezenbeek-Oppem
Belgium, Phone number 02) 7311850, Identity card # 77GR937488, Passport #
85236028341, could be the subject of much unwanted attention. FYI, your visa
to visit Singapore expires in May, seems you can't get a technical company to
sponsor your visit.
Robert L. Bass
You got all this [snipped] information on someone named Paul Ramplebergh
fairly easily. Suppose some teenage hacker who enjoys stirring up a bunch
of folks in a newsgroup (like this one for example) got that same
information. Suppose that teenager was actually just a troll living in
upstate New York or somewhere else in the USA. All he'd have to do is spoof
some ISP in Belgium and start posting under the name of a hapless character
named Paul Ramplebergh...
Do you recall the line in the movie, Eraser where Arnold says,
"Congratulations. You've just been erased?" Well, congratulations, you've
just been trolled and not by Paul Ramplebergh but by some American kid who
is much smarter (though not necessarily more deranged) than most of the guys
who constantly argue with him.
Now, to make things even funnier from the perspective of the troll, you
threaten to expose this Belgian guy who in all likelihood doesn't even own a
PC if the American troll doesn't stop annoying you by posting the same RFI
rant for the next two to three millennia. Care to guess whether the troll
will now acquiesce?
hooferi
news:cQCdne-cEce...@giganews.com:
> A little food for thought...
>
> You got all this [snipped] information on someone named Paul
> Ramplebergh fairly easily. Suppose some teenage hacker who enjoys
> stirring up a bunch of folks in a newsgroup (like this one for
> example) got that same information. Suppose that teenager was
> actually just a troll living in upstate New York or somewhere else in
> the USA. All he'd have to do is spoof some ISP in Belgium and start
> posting under the name of a hapless character named Paul
> Ramplebergh...
>
> Do you recall the line in the movie, Eraser where Arnold says,
> "Congratulations. You've just been erased?" Well, congratulations,
> you've just been trolled and not by Paul Ramplebergh but by some
> American kid who is much smarter (though not necessarily more
> deranged) than most of the guys who constantly argue with him.
Oh brother.
You get trolled daily, ten times daily sometimes Basshole.
What does that make you?
>
>
Mark Leuck
"Robert L. Bass" <rober...@comcast.net> wrote in message
news:cQCdne-cEce...@giganews.com...
> A little food for thought...
>
> fairly easily. Suppose some teenage hacker who enjoys stirring up a bunch
> of folks in a newsgroup (like this one for example) got that same
> information. Suppose that teenager was actually just a troll living in
> upstate New York or somewhere else in the USA. All he'd have to do is
spoof
> some ISP in Belgium and start posting under the name of a hapless
character
I should think he would have given up long ago assuming its someone playing
around. Our nutcase friend here thinks he's on a mission
> Do you recall the line in the movie, Eraser where Arnold says,
> "Congratulations. You've just been erased?" Well, congratulations,
you've
> just been trolled and not by Pual Rxxxxxxxxxxh but by some American kid
who
> is much smarter (though not necessarily more deranged) than most of the
guys
> who constantly argue with him.
You seemed to have no problems replying to the guy a few months ago several
times
Petem
"Paul" <slam...@aol.com> wrote in message
news:jcujiv0slgm90j41n...@4ax.com...
> Not all Radio Frequency (RF) transmitters are able to generate RFI,
TOTALLY FALSE!!! All radio transmiter produce RFI
as soon a radio trasnmit it will make armonics..if you had any modulation to
it it will even make more.
if you overmodulate it will produce more in a very fast and unpredictable
way...
get your story straight and go learn a bit....
> they have to be in accordance to certain rules described hereafter.
> What type of signals are able to produce RFI (Radio Frequency
> Interference) on Wireless Alarm Systems and will jeopardize they're
> operation?
> RF Transmitters operating:
> - ON the wireless frequency
> - Saturating the receiver
> - Intermodulation
> - Harmonics
> - Falling in the receiver bandpass
> - On the IF frequency
> - and more...
> In essence the problems caused by interference is the fact that by no
> way two (or more) systems can use simultaneously the same frequency.
Mark Leuck
"Mark Leuck" <m..leuck@comcast.net> wrote in message
news:EbnWa.37383$Ho3.5495@sccrnsc03...
>
> "Robert L. Bass" <rober...@comcast.net> wrote in message
> news:cQCdne-cEce...@giganews.com...
> > A little food for thought...
> >
> > You got all this [snipped] information on someone named Pual
Rxxxxxxxxxxh
> > fairly easily. Suppose some teenage hacker who enjoys stirring up a
bunch
> > of folks in a newsgroup (like this one for example) got that same
> > information. Suppose that teenager was actually just a troll living in
> > upstate New York or somewhere else in the USA. All he'd have to do is
> spoof
> > some ISP in Belgium and start posting under the name of a hapless
> character
> > named Pual Rxxxxxxxxxxh...
In my opinion he should also seek professional help for his irrational and
impulsive nature, to think someone actually wants to spend 2 years droning
on and on in this newsgroup, emailing dozens of people countless times
without ANY proof at all the problem exists and without ANY attempt at
getting the information from modern system manufacturers
Instead of blaming himself for his own stupidity in buying a piece of shit
system like the one on this page which ANY rational THINKING person would
have known was JUNK (I mean look at the thing) he walked in, looked at it on
the counter and said "I'd like to buy that sir" then has to wonder why it
doesn't work like it should.
http://www.jr-international.fr/modules.php?name=Boutique&itm_ref=1845
He chooses to foolishly cut down the entire wireless industry which he knows
nothing about, its enough to drive a man to get arrested for doing obscene
things in public restrooms I tell ya
(I had another reason to post this, just didn't want to do it to the person
himself)
:)
Robert L. Bass
> impulsive nature, to think someone actually wants to spend 2 years droning
> on and on in this newsgroup, emailing dozens of people countless times
Phew! For a moment I thought you were describing Jiminex.
> Instead of blaming himself for his own stupidity in buying a piece of shit
> system...
You're still assuming that (1) he's actually from Belgium; (2) he actually
had the alleged alarm; and (3) there ever was a problem with headset. I
suspect the whole story is a frankism -- (an assinine story made up on the
spot for the sake of stirring up the rabble).
> He chooses to foolishly cut down the entire wireless industry
> which he knows nothing about...
Maybe he doesn't care a Whitt about wireless alarms. Maybe he just gets his
jollies by making a bunch of people get upset over his comments. That *is*
one of the classic definitions of a USENET troll.
> its enough to drive a man to get arrested for doing obscene
> things in public restrooms I tell ya
You've been spending *way* too much time chatting with Graham. :^)
AlarmReview
>its a natural radio effect that two systems
>can't operate on the same frequency.
So you're saying that multiple transceivers unitizing Motorola Type I/II cannot
transmit on the same frequency simultaneously and still maintain independent
communications?
So you're saying that two UHF-FM Public Safety transceivers with CTCSS encoders
and decoders can't transmit simultaneously and still maintain independent
communications?
So you're saying that two wireless devices using the AMWD protocol can't
operate on the same frequency and still maintain independent data flow?
So you're saying that two cameras operating on ISM band 2.831 GHz cannot
operate on the same frequency and still maintain independent images?
>You are from the begin just to unqualified
>in electronic radio communication to
>provide ANY explanation
Since you made several factual errors in your many statements, exactly what is
your "expertise" in wireless communications? What do you do for a living?
>Learn radio wave techniques and it may
>help you to understand the most basic and elementary radio reception
>techniques.
I was about to suggest the same thing for you.
>I asked for Manufacturer data on the
> wireless data loop, none available.
Paul, you know that's a big lie! The information is available either through
the manufacture or the USPTO. You're back to your old mirrors game. You can't
claim the info isn't there simply because you have not asked for it. By your
rationale, Napoleon never existed because you never met him. Come on Paul,
show little maturity! How about telling us who you have contacted and were
refuse the information.
>You just have to purchase a cat in a box
>and rely on unqualified low level
>electricians.
But we should take the word of a retrieval clerk who works in the Office of
Infrastructure Improvements? Let's face it, a "low level electrician" is a
more reliable source than a guy who pulls maps showing where sewer lines are
located. Wouldn't you agree?
>Well, well, this shows once more your
>intellectual level,
>Who do you think to influence with such
>stupid remarks?
But you never denied that they are true.
Poor Paul.
Robert L. Bass
> operating at 433MHz.
> What is your proof that modern systems can avoid that kind of
> disturbance? Impossible to avoid it, its external to the equipment and
> not under control, its a natural radio effect that two systems can't
> operate on the same frequency.
> on new systems?
Hmm. Notice how improved his grammar is above. In the next paragraph he
slips back into pidgin English. This guy *definitely* has English as his
primary language. He's almost certainly an American kid.
> You are from the begin just to unqualified in electronic radio
> communication to provide ANY explanation on how ALL new systems can
> avoid RFI, again, impossible. Learn radio wave techniques and it may
Frank Olson
yourself, Robert... and you continue to do so, then step back when you get
burned. "Stirring the rabble" with Bassisms, and "BassSpeak" is your
specialty...
--
Frank E. Olson
http://www.alt-security-alarms.com
Free listings for qualified industry professionals, dealers & suppliers.
Please visit the unofficial web site to view FAQ and participant
information.
"Robert L. Bass" <rober...@comcast.net> wrote in message
news:AP6dnYlJ2tU...@giganews.com...
hooferi
>> My wireless alarm system was disturbed with a wireless headphone
>> operating at 433MHz.
>> What is your proof that modern systems can avoid that kind of
>> disturbance? Impossible to avoid it, its external to the equipment and
>> not under control, its a natural radio effect that two systems can't
>> operate on the same frequency.
>> HOW do you know that Radio Frequency Interference (RFI) has no effect
>> on new systems?
>
> Hmm. Notice how improved his grammar is above. In the next paragraph he
> slips back into pidgin English. This guy *definitely* has English as his
> primary language. He's almost certainly an American kid.
My primary language isn't English, basswipe, and yet I speak it far better
than you..
hooferi
>> In my opinion he should also seek professional help for his
>> irrational and impulsive nature, to think someone actually wants to
>> spend 2 years droning on and on in this newsgroup, emailing dozens of
>> people countless times without ANY proof at all ...
>
> Phew! For a moment I thought you were describing Jiminex.
>
>> Instead of blaming himself for his own stupidity in buying a piece of
>> shit system...
>
> You're still assuming that (1) he's actually from Belgium; (2) he
> actually had the alleged alarm; and (3) there ever was a problem with
> headset. I suspect the whole story is a frankism -- (an assinine
> story made up on the spot for the sake of stirring up the rabble).
>
>> He chooses to foolishly cut down the entire wireless industry
>> which he knows nothing about...
>
> Maybe he doesn't care a Whitt about wireless alarms. Maybe he just
> gets his jollies by making a bunch of people get upset over his
> comments. That *is* one of the classic definitions of a USENET troll.
So, by that definition, you are a troll
Frank Olson
"hooferi" <c...@w.w.w.> wrote in message
news:bgin53$c4l$4...@blackhelicopter.databasix.com...
Richard
says...
> The continuing insults of so called pro's force me to react and show
> that Radio Frequency Interference (RFI) exist and muzzle ALL wireless
> alarm system, YOURS TO (even the latest product/sold systems).
> Nothing in a reasonable priced, batery powered general public system
> can avoid RFI, military systems for instance can.
>
> WARNING:
> This is a "perfect" professional group who has no fear to say
> (assorted with insults) that what i mention is wrong.
> I have no fear to publish the means to TEST and FAIL YOUR wireless
> alarm systems from the OUTSIDE in order to proof the most evident
> facts known by real data communication pro's but those last are
> apparently not present in this group.
>
content has already degenerated considerably. Please do not hurl insults
at each other, it archives absolutely nothing.
Wireless systems ARE unreliable from the point of view that
communication between the base station(s) and the sensors CAN be
interrupted.
All good base stations are able to detect loss of communication (as
separate from just RFI) and all good panels can be programmed to respond
to this in a proactive manner.
For your information, we use wide band white noise generators to test
wireless failure detection and response programming which do the job
perfectly.
As a policy we will NEVER install new wireless systems, simply because
they are susceptible to jamming, RF jam detection is mandatory and
thanks to poor legislation most systems share frequencies with other
common stuff.
This post is my opinion, and the opinion of my current employer and
every employer I have worked for. If you disagree with it, feel free to
say so in a calm and professional manner.
Marc
philosophy if someone wants to get into your place bad enough, they are
going to bypass any alarm system regardless if its wired of wireless.
Granted wireless might be a little easier, but if someone wants your stuff
bad enough, they will find a way.
"Richard" <rubbish@/dev/null.com> wrote in message
news:MPG.199b50774...@news.gen.net.uk...
Richard
@hotmail.com says...
> I cant even believe im going to put in my 2 cents, but I've alwyas had the
> philosophy if someone wants to get into your place bad enough, they are
> going to bypass any alarm system regardless if its wired of wireless.
> Granted wireless might be a little easier, but if someone wants your stuff
> bad enough, they will find a way.
>
a commercial building by deploying internal and external armour to the
point at which 'wants your stuff bad enough' becomes 'but not that
much'. The hard part is making the decision as to what constitutes 'too
hard' as opposed to expensive overkill.
If you wanted to go a little lighter on the ironwork, you then a good
route is to deploy internal immobilisers, such as sonic bombs at two per
room on opposing walls (<15sqm) which certainly adds some 'but not that
much', or, If you don't mind the cost of refueling and a rather lengthy
delay getting back in then fog and/or gas is a good way to go especially
if locally triggered.
There are enough low (/no) security premises in the country that once
you start making it hard and problematic, crooks aren't interested
anymore. (IMO)
Marc
"Richard" <rubbish@/dev/null.com> wrote in message
news:MPG.199bafd8a...@news.gen.net.uk...
Richard
slam...@aol.com says...
<snip>
>
> >Wireless systems ARE unreliable from the point of view that
> >communication between the base station(s) and the sensors CAN be
> >interrupted.
> >
> >All good base stations are able to detect loss of communication (as
> >separate from just RFI) and all good panels can be programmed to respond
> >to this in a proactive manner.
>
> Can you explain how RFI is typical detected and what is the delay
> before eventual alarm? How and why is false alarm avoided?
RFI is detected when packeted data from the remote sensors is
supplimented with additional crap (like cordless phones, etc) Providing
the forign signal makes it through the demodulator/pll and is in the
appropriate format to be discriminated by the decoder.
This is seperate from RF JAM, which is detected when the packet stream
is corrupted and/or the base looses contact with (more than one, a
significant percentage, or all, depending on system) of its remote
units.
Most good wireless base stations ignore RFI, but respond actively to RF
JAM. As an example (one I've done today), a DSC 4020 with 2 wireless
zone base stations. An RF JAM condition whilst the partition is armed
results in an alarm condition after 60 seconds. It is reported to the
central station, but ignored when the partition is unarmed.
>
> >For your information, we use wide band white noise generators to test
> >wireless failure detection and response programming which do the job
> >perfectly.
>
> Well, i don't know if a noise generator is able to test really all RFI
> conditions.. I can agree with you that it is one mean to upset the
> wireless system.
The noise generator produces random (white) noise at a specific
frequency and modulation, and can then spread across a band of
frequencies as controled from knobs on the front. It can transmit up to
4w. For example, I'd set it to 432Mhz at 1w and spread to 434Mhz, FM
modulated to shaft a DSC base station (which it does quite nicely). The
base station is completely shafted until the noise generator is turned
off. Standing right next to the base station, at power below 0.09w the
base station can still see its remotes, any higher and it looses them
and reports a JAM.
>
> >As a policy we will NEVER install new wireless systems, simply because
> >they are susceptible to jamming, RF jam detection is mandatory and
> >thanks to poor legislation most systems share frequencies with other
> >common stuff.
>
> Poor legislation, well yes and no..
>
> Yes: Some devices, like my wireless headphone where certified and
> allowed to operate on the wireless alarm frequency who is
> assigned to burst operation. Its a stupid mistake from
> administrative authorities and to my opinion, it can't be
> protected to occur by law because it requires a technical
> judgement of the type of transmission..
433 is a unlicensed domestic consumer frequency that all sorts of crap
uses. Wireless alarms were quite late on the scene with 433.
>
> NO: Its impossible to provide a secured individual frequency,
> none are available, to crowded.
Maybe.
Wireless security systems SHOULD NOT be using generic frequencies like
433, that's just dumb. There are additional frequencies available and
for £120 per year anyone can apply and be granted a license to use an
alternative frequency.
> If it was possible to have individualized frequencies:
> - Who will cover the cost involved to control and secure
The DTI does for their £120 per year per license.
I think the problem is that Security Pro's don't use wireless in general
and as such no one (that matters) really cares. I believe that almost
all wireless systems are targeted at the 'domestic' market which makes
manufacturers use frequencies like 433.
Marc
"Richard" <rubbish@/dev/null.com> wrote in message
news:MPG.199c82efd...@news.gen.net.uk...
> for Ł120 per year anyone can apply and be granted a license to use an
> alternative frequency.
>
> > If it was possible to have individualized frequencies:
> > - Who will cover the cost involved to control and secure
> The DTI does for their Ł120 per year per license.
Richard
slam...@aol.com says...
> On Thu, 7 Aug 2003 16:39:13 +0100, Richard <rubbish@/dev/null.com>
> wrote:
>
> >> >Wireless systems ARE unreliable from the point of view that
> >> >communication between the base station(s) and the sensors CAN be
> >> >interrupted.
> >> >
> >> >All good base stations are able to detect loss of communication (as
> >> >separate from just RFI) and all good panels can be programmed to respond
> >> >to this in a proactive manner.
>
> >> Let me pickup on that one.
> >> Can you explain how RFI is typical detected and what is the delay
> >> before eventual alarm? How and why is false alarm avoided?
> >
> >RFI is detected when packeted data from the remote sensors is
> >supplimented with additional crap (like cordless phones, etc) Providing
> >the forign signal makes it through the demodulator/pll and is in the
> >appropriate format to be discriminated by the decoder.
>
> collisions between alarm sensors (burst, asynchronous) and as such
> detected to be RFI?
In Polled systems, there are no frequency collisions because the sensors
response in sequence as the base polls them.
For non-polled (one way) systems, good transmitters will read the
ambient RF prior to raising a carrier and as such aviod transmission
collisions. This does however make them more suspeptable to jamming.
Cheaper transmitters do on occasion transmit simultaneously which would
cause the base station to either receive the packet as corrupted (if its
smart) or not be able to decode the signal (even if it makes it through
the demodulator) and perhaps detect it as RFI.
>
> >This is seperate from RF JAM, which is detected when the packet stream
> >is corrupted and/or the base looses contact with (more than one, a
> >significant percentage, or all, depending on system) of its remote
> >units.
>
> In light of my above remark, how long has the RFI detection feature to
> be setup before it may give useless alarms?
>
Depends on system and programming. If an RFI condition is present for
more than 60 seconds, the system should report it. (as seperate from RF
JAM)
> >Most good wireless base stations ignore RFI, but respond actively to RF
> >JAM. As an example (one I've done today), a DSC 4020 with 2 wireless
> >zone base stations. An RF JAM condition whilst the partition is armed
> >results in an alarm condition after 60 seconds. It is reported to the
> >central station, but ignored when the partition is unarmed.
>
> 60 seconds, you are kidding.. burst + unsynchronized signals.. false
> alarms yes, RFI no.
No. RF JAM is a feature of base stations that are able to maintain
communication with remotes, this communication is polled (either
intelligently) or by transmission of a carrier. 60 seconds is a long
time to loose a remote which should be making every effort to respond to
the base. The possible scenarios are
1. Its blown up
2. Its been destroyed physically
3. Its being jammed
Whilst in an armed state, all three should generate an alarm condition.
For wireless remotes that are unimportant you could assign them to a
reduced priority zone and setup a cross zone delay so that if the
unimportant one by itself fails, trouble is indicated, if more than one
unimportant remote, or any other zone then alarm. Just depends on how
much effort you want to put into the programming, and how much the
customer is going to pay. I guess we're back to "don't use wireless" :)
>
> >> >For your information, we use wide band white noise generators to test
> >> >wireless failure detection and response programming which do the job
> >> >perfectly.
> >>
> >> Well, i don't know if a noise generator is able to test really all RFI
A white noise generator is a tool specifically designed to generate
Interference. Its the ideal tool.