Re: 28. New readers, RF intruders in wireless alarm systems

["Roger" <rumble@xxxxxxxxxxxxxxxxx>]

What total rubbish! You do not understand rolling code or its true purpose.
And as for the rest of it...delays - what a joke. You make me laugh you
really do. Anyone reading this diatribe should simply ignore it. Take it
from me that the guy doesn't know what he's talking about.


<-pull@shoot> wrote in message
news:ojdpa11eadvtap4nkqvo5krfkaivipittb@xxxxxxxxxx
>
> Radio Frequency (RF) intruders.
>
> The whole RF spectrum is divided and regulated by international
> committees who define the allowances on each frequency.
> The Wireless Alarm Systems have free multi user "shared" frequencies
> assigned with no waranty that it is free for communication at any
> requested time.
> Keeping in mind that only one operator can transmit on the same
> frequency at the same time, a protocol is laid-out to circumvent the
> shared frequency restrictions.
> Each user has to respect some transmission rules like:
> - Limit the transmit power;
> - Each transmission has to have an identifier;
> - transmit in a BURST transmission mode,
> to mention the most essentials.
>
> Limited transmission power.
> By limiting the transmission power the signal reception range is
> reduced and by consequence the possible mutual interference on that
> frequency.
>
> Personal identifier (ID).
> As multiple users uses the same frequency and in order to retrieve
> only the information belonging to hiss personal system, each user
> identifies themselves during hiss transmission with a unique ID.
> Some transmitters uses ID rolling codes, the code changes each time in
> order to make sure that at repetition he has a unique ID.
> Realize that sometimes this rolling code may not be unique, the
> individual receivers have to keep trace of the temporary intruder ID
> in order to retrieve only hiss data.
> This requires multiple transmission/reception attempts before true
> validation of the corresponding ID and by consequence causes a
> reception DELAY.
>
> Burst transmission.
> Burst transmission is one way to circumvent mutual interference.
> Each transmitter sends hiss data information during a small period of
> time hoping that the frequency is unoccupied while he transmits.
> When two or more transmissions occur at the same time, interference
> is generated and the receivers are disturbed, they can't decode the
> data information.
> This is not a real problem, the transmission is repeated several time
> with the hope that at some time during the repetitions the frequency
> is free.
> This require multiple transmission/reception attempts before data is
> passing true, by consequence this causes a reception DELAY of the data
> involved.
>
>
> The whole burst transmission protocol has restrictions, the burst
> length and repetition rate, the number of possible systems and
> different types using the same frequency and more..
>
> Now, back to the header, intruders.
> As described above, the validity of data transmission of all
> transmissions using the shared frequency spectrum are depending on the
> respect of the burst transmission requirement/principle.
> If one, lets call them INTRUDER, uses a different protocol and
> transmits without the respect of the burst principles, the whole
> frequency utilization goes bingo in the distance range of hiss
> transmitter.
> That's the case during Radio Frequency Interference (RFI).
>
> Hope this clarifies a little the wireless alarm system shared
> frequency operation fragility.
>
> NOTE: I don't mind if "so called professionals" explain it in a
>      better and more detailed way but it never happened...
>      Criticism is easy, explaining instead...
>
> Paul
>
>