From: Ken Johnson [johnson@mbari.org] Sent: Wednesday, January 11, 2012 12:12 PM To: Gene Massion Subject: FW: Request for Iridium Comm reliability info ************************************************** Kenneth S. Johnson Monterey Bay Aquarium Research Institute 7700 Sandholdt Road Moss Landing, CA 95039 831 775 1985 tel 831 775 1620 fax johnson@mbari.org http://www.mbari.org/chemsensor Check the Land/Ocean Biogeochemical Observatory at http://www.mbari.org/lobo Check the Periodic Table of Elements in the Ocean http://www.mbari.org/chemsensor/pteo.htm -----Original Message----- From: Rajan, Kanna Sent: Wednesday, March 26, 2008 3:34 PM To: swift@ocean.washington.edu Cc: Johnson, Ken Subject: Re: Request for Iridium Comm reliability info Dana, Thanks a million for that very quick response. I'd have been equally quick but got caught in the usual spate of unanticipated events here. With regards to the modem, we are likely to be sticking to the 9061 because we have it, has been tested and integrated in the past with our AUV and because we don't intend to have a sustained operations model but want to do one or more demonstrations. I was aware of the SBD approach and with the limitation of a 340 byte limit per packet which transforms to an email shore side. One additional reason we would likely not want to go the CSD route (and do correct me if I'm wrong) is that the circuit-switched approach requires a sustained connection with Iridium, which in less than optimal sea states with an AUV on the surface we're unlikely to get. The packet based approach would (in theory) be more robust to interference from what I understand, even if more expensive in the short run. Its unlikely we'll need RUDICS. regards -kanna On Mar 26, 2008, at 10:24 AM, Dana Swift wrote: > Hi Kanna, > >> I am looking for Iridium communication reliability figures (how often >> a connection times out, loss of data packets, packet size, >> throughput) for a typical float to communicate with shore. We would >> like to see if we can do 2Way comm using a 9601 modem we have >> currently installed on the vehicle. Essentially we're trying to >> understand how practical and under what conditions we can expect some >> decent results in terms of data exchange. Ken pointed me to your web >> site (http://flux.ocean.washington.edu/) but I wasn't able to discern >> any such reliability figures > > The Talladega 9601 transceiver has limited capabilities. It can > support only packet-switched data (ie., SBD-only)...and only small > packets. It > can not support circuit-switched data (CSD) which is required for > modem-modem or modem-rudics connections (that I use in our floats). > For the 9601, the maximum packet lengths are 205 bytes for mobile- > originated > transmissions and 135bytes for mobile-terminated transmissions. > For the > Daytona 9522, the SBD packet sizes are slightly under 2KB. > > Early-on in our iridium development work, I did some experimentation > with SBD (ie., packet-switched data). The prices have come down a bit > but, even now, SBD is still far too expensive for the amounts of data > that we transmit for each profile (ie., 60-100KB/profile). On a > per-byte basis, SBD is about 35-50 times more expensive than CSD data > in the context of our application. So we don't use the 9601 (or > SBD)...we use the Daytona (9522) which allows circuit-switched data > plus RUDICS. > > I have plenty of statistics and data regarding the use of iridium > circuit-switched data. However, I don't have any statistics or > information relevant to the Talladega 9601. > > -dds > -- > =================================================================== > = Dana D. Swift, Research Engineer Office: (206) 543-6697 = > = School of Oceanography Fax: (206) 685-3354 = > = University of Washington swift@ocean.washington.edu = > = Box 355351 OSB 325C = > = Seattle, WA 98195 = > = http://www.ocean.washington.edu/people/staff/swift/Swift.html = > =================================================================== >