|
Posted by on June 14, 2005, 10:08 am
If you were Registered and logged in, you could reply and use other advanced thread options
Rubbish oh yes you are to elementary to understand wireless, poor guy.
Rolling code is of any use ONLY when the transmitted data is valid.
During Radio Frequency Interference (RFI) there is NO VALID
INFORMATION included ID.
What is your technical knowledge and what measurement tools do you
have beside your little wet finger in the wind?
Your professionals wet finger idiocy is coming from head to bottom!
RFI brain probe
\ /
____\/____
/ ___ ___ \
/ / @ \/ @ \ \
\ \___/\___/ /\
\____\/____/||
\Bottle/
|neck | Pro's in
/ \ Pissing
/ \ Contest
| \
| |
/ |
| ===. 10 mW
\ OO \ output
| | o power!
| / o
\_________/ o
|| || \___,,,__ /
|| || | WAS |O WAS = Wireless Alarm System
_||_||_ \_______/
The desire to not understand wireless alarm techniques
is far less intelligent than
the inability to understand them
wrote:
>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.
>
>
>>
>> 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
>>
>>
>
| 
XML site map