Hi Eric,

Sorry, there seems to be some confusion! Let me phrase my question properly:

I want to implement a deceptive jammer. Details of the deceptive jammer are as 
follows:

Deceptive jammer: Instead of sending out random bits, the deceptive jammer 
constantly injects regular packets to the channel without any gap between 
sub-sequent packet transmissions. As a result, a normal communicator will be 
deceived into believing there is
a legitimate packet and will be duped to remain in the receive state. For 
example, in TinyOS, if a preamble is detected, a node remains in the receive 
mode, regardless of whether that node has a packet to send or not. Hence, even 
if a node has packets to send,
it cannot switch to the send state because a constant stream of incoming 
packets will be detected. Further, we also observe that it is adequate for the 
jammer to
only send a continuous stream of preamble bits (0xAA in TinyOS) rather than 
entire packets.

I read this in a paper and am curious just like you that how some one can just 
send a preamble.

Thanks,
Kartik
--- On Sun, 4/25/10, Eric Decker <[email protected]> wrote:

From: Eric Decker <[email protected]>
Subject: Re: [Tinyos-help] how to ensure to send only the preamble and not the  
message
To: "Kartik Siddhabathula" <[email protected]>
Cc: "TinyoS help" <[email protected]>
Date: Sunday, April 25, 2010, 6:52 PM

why on earth do you want to do that?
Also what preamble are you talking about?  The preamble on the radio?  the 
cc2420 preamble?
If so you can't do that.  My understanding is the radio will start to transmit 
the preamble if it has something to transmit and after it has done the CCA,
clear channel assessment.  In other words if there is nothing to transmit it 
won't transmit the preamble.
Catch 22.
But maybe you are trying to do something else.  In which case, phrasing your 
question in a more consise, clearer manner would really help you get an answer 
for the question you are seeking answers to.

So what exactly are you trying to do?

On Sun, Apr 25, 2010 at 2:46 PM, Kartik Siddhabathula 
<[email protected]> wrote:

Hi All,

I am using tinyos-2.x and telosb motes. I just want to send the preamble and 
not the complete message. Does anyone has any idea how I can do it?


Thanks in advance,
Kartik









      
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Eric B. Decker
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