Hi Jinkyu, If you want to go the GPS way, and have a scenario where a good GPS signal is available to you, you could use the PPS signal that is provided by most GPS receivers.
This is a pulse-per-second signal, the edge for which is guaranteed to have a jitter no less than 1us (typically). To get the event time stamp in microsecond numbers however, you should wire the PPS signal to a hardware counter that runs off a decently calibrated high frequency crystal. You can then get event timestamps by reading the absolute time in seconds from the GPS and the fractional part in microseconds from the hardware counter. If you're adventurous, you could design (or use) a frequency multiplier that uses a PLL to lock a low-stability high-frequency 1MHz clock to the high-stability low-frequency 1Hz PPS signal. This will result in (ideally) a high-stability high-frequency clock that you can then wire to a counter. Hope that helps, Zainul. On Sat, Aug 15, 2009 at 7:39 AM, Jinkyu Koo<k...@purdue.edu> wrote: > Thanks for the comments, Alan and Thomas. > > Wiring or powerful amplifier would be a good solution. > However, in my scenario, distance between two nodes sometimes reaches > several tens of miles, > which makes it difficult to use such an approach. > > So I am wondering if there is any equipment that can measure the time of > event in micro-second order precision, > and can be synchronized with some standard clock. > For example, I imagines a device made by mixing an oscilloscope and > GPS-receiver :) > If I can secure two such devices, I will be free from physical distance. > > Thanks, > Jinkyu > > Alan Marchiori wrote: >> On Fri, Aug 14, 2009 at 11:19 AM, Thomas Schmid<thomas.sch...@gmail.com> >> wrote: >> >>> No, what Jinkyu tires to do is to evaluate the precision of FTSP over >>> a whole network. One possibility would be to have your beacon node use >>> a power amplifier like this one: >>> >>> http://focus.ti.com/docs/prod/folders/print/cc2591.html >>> >>> This would extend the range of your beacon compared to other nodes, >>> increasing the probability that more nodes will hear it. However, >>> depending on your distances and the accuracies that you look at, you >>> might want to incorporate time of flight into your precision >>> measurements. >>> >>> Cheers, >>> >>> Thomas >>> >> >> I see; you could also use some form of backchannel communication for >> syncornization. Possibly even just a wire supplying a 1 pulse per >> second tied to an interrupt input. >> _______________________________________________ >> Tinyos-help mailing list >> Tinyos-help@millennium.berkeley.edu >> https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help >> > > -- > Ph.D. Student > School of Electrical and Computer Engineering > Purdue University, West Lafayette > > Office: EE338 & MSEE280 > Cell: 1-765-337-1704 > E-mail: k...@purdue.edu > > > _______________________________________________ > Tinyos-help mailing list > Tinyos-help@millennium.berkeley.edu > https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help > _______________________________________________ Tinyos-help mailing list Tinyos-help@millennium.berkeley.edu https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
