I think I may have found the answer to my own question :-) but I have a new question now, but I will put that in a new e-mail
... when LPL is doing its CCACheck routine and the energyindicator signals its .detected() event an "off" timer is started as a one shot with a lifetime of 100 ms (set in defaultLPL.h with a definition of DELAY_AFTER_RECEIVE 100. Assuming energy remained present in the Channel during this time the "off" timer would be restarted. Energy is detected but no packet was received this would simply cause a delay in the LPL routine. Regards Ben > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] Behalf > Of Murray, > Ben > Sent: 27 September 2007 11:18 > To: 'tinyos-help@Millennium.Berkeley.EDU'; 'David Moss' > Subject: [Tinyos-help] low power listening -- anomalous/random 100-200 > ms delay/skew? > > > (TinyOS 2.0.2; Micaz; mib510; Cygwin) > > I have left a number of motes running in low power listening > mode and have > observed that occasionally one or more of the motes' LPL-receive-check > experiences a sudden delay/shift of approximately 100 ms and shortly > thereafter a second sudden delay/shift of approximately > 100-120 ms. I am > not running any transmitters although 2.4 GHz is quite a popular > frequency... the first time I observed it two motes > experienced the delay at > the same time after three minutes of running, the second time > I observed it > a single Mote experienced the delay after approximately half > an hour, and > this morning one of the three motes I had left running had > experienced this > delay at some point overnight. One of the three motes > experienced this > delay in all three tests, one of the motes did not experience > the delay at > all, and the third Mote experienced the delay once in the > first test but not > again. When two motes experienced the delay, they > experienced it at what > appeared to be the same time and the delay was consistent > between them. > > Is there a built-in function within low power listening that > initiates a > timeout/delay-of-start with regards to the sleep interval > timer that lasts > approximately 100 ms, perhaps to cope with noisy channels or received > packets/suspected received packets? Signal detection as > opposed to a random > software/hardware error is because I have observed (using an > oscilloscope) > two motes undergoing the exact same delay at the exact same time. The > receive event is not triggered and therefore I assume that > this is some > function to deal with a suspected packet when energy is detected. > > Would it be a trivial matter for me to find this function > such that I could > add an event trigger so that I know every time that LPL > detects Channel > energy but subsequently does not receive a packet (assuming > this is what is > causing the delay). Perhaps something like "FalseReceive" - > this might > allow me to correct the timing within my programme whenever this delay > occurs. > > Also, if I could be directed to the exact function that would > be very useful > would as it might save me a lot of time trawling through code/editing > something incorrectly ;-) > > Many thanks > Ben > > ************************************************************** > ***************** > Please consider the environment before printing this email. > ************************************************************** > ***************** > This email and any files transmitted with it are intended > solely for the use of > the individual or entity to whom they are addressed and may > not be divulged to > any third party without the express permission of the > originator. Any views > expressed in this message are those of the individual sender, > except where the > sender specifically states them to be the views of Thales > Research & Technology > (UK) Limited. > ************************************************************** > ***************** > > _______________________________________________ > Tinyos-help mailing list > Tinyos-help@Millennium.Berkeley.EDU > https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/t inyos-help _______________________________________________ Tinyos-help mailing list Tinyos-help@Millennium.Berkeley.EDU https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
