Christian, Antonio Thank you for your information. According to my experiments, this time interval before sending packets is nor preamble neither CCA check (see https://www.dropbox.com/s/d5gxspydumhxcnt/wave4.bmp). Because: 1- I set transmission power to the lowest level (1). The voltage drop in the photo shows the sending period. The power consumption before sending period is more, so it can not be preamble because preamble is supposed to be transmitted at the same transmission power (i.e. 1). Right? 2- I changed MAX_CCA parameter and I found that in the waveform.
So, I would say that this short period before sending packet is the time interval when the radio listens to career to find out whether it is free or not. IOW, it's for avoiding conflict. Right? How can I reduce its length? Farzad On 04.02.2013 17:37, Christian Haas wrote: > On 02/04/2013 04:15 PM, Farzad Samie wrote: >> Hi Christian >> Perfect! It works now. And it will not go to receive more after >> transmission. >> But there is still a question; According to the signal value in image >> below, it sounds that the sender will listen to the channel to check >> whether it is free or not. It senses career first, and then send the >> packets. Is it the reason of this signal's behavior? If yes, can we >> reduce the time interval of listening to channel before transmission? >> https://www.dropbox.com/s/9bwa4quu68z7561/wave2.bmp > > > You are using TinyOS LPL, so that signal can either be the preamble > (packets beeing repeated for setLocalWakeupInterval(whatever time you > are using)) or the CCA check for MAX_LPL_CCA_CHECKS cycles due to the > periodic wake-up. > > You might take a look at > > http://telematics.tm.kit.edu/publications/Files/466/publication_466.pdf > > for more abut energy measurements an LPL. > > Regards, > Christian > _______________________________________________ Tinyos-help mailing list [email protected] https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
