YOW!!! Another information packed post (IPP). Maybe we could start a radio theory page on our new improved doc site? But what's "that broken matching network" mean? MS
David Moss wrote: > Manchester encoding. And CSMA. > > > > Manchester halves the throughput. Instead of 76.8 kbps, Manchester will > force your radio to transmit at 38.4 kbps. Getting rid of Manchester > may not be a simple task: it’s there to zero out the energy seen by a > receiver, so it can easily know that it’s receiving valid data. > > CSMA causes your transmitter to share the channel with other > transmitters, and the channel checks may be spaced relatively far apart > which dramatically decreases throughput. > > > > The CC1000 radio could be a really kick-ass radio if it were implemented > properly. The ability to easily enable/disable Manchester, CSMA, etc. > (among other things) would really improve its situation. The CC1000 > radio is much more energy efficient than the CC2420 radio, and can > transmit a lot farther than the CC2420 radio (but that broken matching > network on mica2’s and especially mica2dot’s really cause everyone > problems). It’s unfortunate so many people dismiss the CC1000 radio as > obsolete, when it could really outperform their radios in terms of > efficiency and range (not throughput). > > > > 29 bytes is only a software (and RAM) limitation. Increase it by doing > a CFLAGS+=-DTOSH_DATA_LENGTH=50 or something in your Makefile. Removing > unnecessary fields from the CC1000 header will decrease the > header:payload ratio and increase payload throughput. > > > > If you’re thinking about rolling your own hardware, you should really be > using CC1100 or CC2500 radios for any wireless application that doesn’t > require 802.15.4 compatibility: > http://docs.tinyos.net/index.php/CC1100/CC2500 > > > > -David > > > > > > > > > > > > ------------------------------------------------------------------------ > > *From:* [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] *On Behalf Of > *Edgar Charry > *Sent:* Monday, April 14, 2008 3:57 PM > *To:* [EMAIL PROTECTED]; Eric Keller > *Cc:* tinyos-help@millennium.berkeley.edu > *Subject:* Re: [Tinyos-help] Pumping up bandwidth - Mica2Dot/Mica2 > > > > Hi all, > > Thanks for your prompt replies. Unfortunately I that link didn't let me > through. > > In fact I am still trying to undestand them, as I wasn't aware of that > limitation of 33-50ms of the Mica2's! You are saying that the maximum > bandwidth my app should require is 0-25Hz so that I have a nice > reconstruction of my wave, due to HW limitations? > I knew that the CC1000 has a maximum bandwidth of 76.8kbps and of course > due to EEPROM readings/writings, CPU instructions, ADC's > measurements etc. this number should decrease. But I wasn't expecting a > final bandwidth of 30pckts/s!!! In fact, I thought there were problems > related to the TOSBase. > My app requirement need at least 100Hz (Mica2's transmission needed thus > 200 pckts/s), which is necessary to track a complete gait cycle using > acc and gyros with good definition. > > What is the most critical factor in the Mica2's that blow the > transmission rate so bad? Does this happen with the Mica2Dot too? Data > compression (sample with a higher freq, store in the RAM and then send > the whole bunch of bytes) has a limitation of 29 bytes due to TinyOS, > correct? > > Thanks guys for the good info. > Cheers, > Edgar Charry > >> Date: Mon, 14 Apr 2008 12:20:38 -0600 >> From: [EMAIL PROTECTED] >> To: [EMAIL PROTECTED] >> CC: tinyos-help@millennium.berkeley.edu >> Subject: Re: [Tinyos-help] Pumping up bandwidth - Mica2Dot/Mica2 >> >> Well, since people are quoting my second source messages, have a look at: >> http://www.etantdonnes.com/Motes/report_mica2/ >> (which seems to be down right now but will hopefully be back soon...). >> >> However my message speed/reliability measurements use only the standard >> GenericComm and TOS1 code. I think the OP was trying to fiddle timeouts >> and backoffs to speed things up further. Data mining of the help list >> should turn up some more useful advice in this respect. >> >> MS >> >> Eric Keller wrote: >> > There is a limit to how many packets you can send with a mica2 which > you are >> > at or above. You probably want to lower your bandwidth requirements > somehow. >> > See this message: >> > > https://www.millennium.berkeley.edu/pipermail/tinyos-help/2008-April/032464.html >> > >> > Eric >> > >> > >> > On Mon, Apr 14, 2008 at 4:59 AM, Edgar Charry <[EMAIL PROTECTED]> > wrote: >> >> Hi all, >> >> >> >> I am trying to pump my packet transmission up between a Mica2Dot and a >> >> Mica2 to at least 200Hz [pckts/s]. >> >> >> >> I've decreased the timer constant to a bottleneck of 33ms (30 > pckts/s) that >> >> pratically executes a round of ADC measurements and send the packet. >> >> Decreasing from this point doesn't give me more bandwidth. However, my >> >> packet is 14bytes long (the TinyOS header + just a couple of adc >> >> measurements + CRC). >> >> >> >> I suspect that this 33ms (parsed time stamps from XSniffer) are > limited to >> >> the TOSBase.nc on the Mica2. I suspect that the PLL of the Mica2 is >> >> listening through channels and is not locked to the transmitter's > one. Every >> >> loop thus should take 33ms. >> >> >> >> Actually, I haven't been through the CC1000 conf/mod components > though, but >> >> I reckon with your experience this can be solved easily. >> >> Cheers, >> >> Edgar Charry >> >> >> >> ________________________________ >> >> Explore the seven wonders of the world Learn more! >> >> _______________________________________________ >> >> 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 >> >> -- >> Platform: WinXP/Cygwin >> TinyOS version: 1.x, Boomerang >> Programmer: MIB510 >> Device(s): Mica2, MicaZ, Tmote >> Sensor board: homebrew >> >> _______________________________________________ >> Tinyos-help mailing list >> Tinyos-help@millennium.berkeley.edu >> https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help > > ------------------------------------------------------------------------ > > Explore the seven wonders of the world Learn more! > <http://search.msn.com/results.aspx?q=7+wonders+world&mkt=en-US&form=QBRE> > -- Platform: WinXP/Cygwin TinyOS version: 1.x, Boomerang Programmer: MIB510 Device(s): Mica2, MicaZ, Tmote Sensor board: homebrew _______________________________________________ Tinyos-help mailing list Tinyos-help@millennium.berkeley.edu https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
