Ah. I suspect that it is sending a continuous stream of packets with 0xaa. I don't know a way of fooling the cc2420 h/w into sending just preambles. It is a packet based interface so it doesn't do anything until you hand it a packet. There maybe a way around this by messing directly with control registers.
It has been a while since I looked at radio control registers and if i remember right it was for an older radio. I don't remember being able to mess with forcing a preamble. I'd suggest spending some quality time with the user manual for the cc2420. On Sun, Apr 25, 2010 at 5:11 PM, Kartik Siddhabathula < [email protected]> wrote: > 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]<http://mc/[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 >> >> >> _______________________________________________ >> Tinyos-help mailing list >> [email protected]<http://mc/[email protected]> >> https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help >> > > > > -- > Eric B. Decker > Senior (over 50 :-) Researcher > > > > -- Eric B. Decker Senior (over 50 :-) Researcher
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