Freerunner as a mobile gateway -> shipping container

Ed Kapitein ed at
Tue May 24 14:44:33 CEST 2011



On 05/24/2011 02:42 PM, Ed Kapitein wrote:
> On 05/23/2011 07:24 PM, Phil Vandry wrote:
>> On Wed, May 18, 2011 at 03:19:16PM +0200, Eric Smith wrote:
>>> Main application here is in a sea shipping container.
>>> The key issues are RF communication (when in a GSM range of course) 
>>> and power management due to the long haul journey including journey 
>>> overland. Power supply has to be in the form of an additional battery.
>>> Technical issue is to have minimal size OS and to be low in power
>>> consumption.  And robust.
>> If you sleep and only wake up at intervals, you should anticipate some
>> difficulty acquiring a GPS signal every time you wake up. The GPS in
>> the Freerunner is really designed to make use of A-GPS and if you can't
>> do it because you are at sea and far from any network signal, it can
>> take a long time to get a position. We have sometimes seen it take over
>> 40 minutes to get a good fix (unit mounted on an aircraft glareshield).
>> -Phil
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> You could overcome the TTFF problem by using the agps software from [1]
> It loads the needed data from the gps chip and uses that the next time
> you power on the gps unit.
> I usually get a fix in 2 minutes.
> If you send the log data to a server via GPRS, you might want to use
> rsync with the --inplace option.
> The logs will only grow i suspect and i use this method of transferring
> the gps log from my car to my server at home,
> while driving.
> It also helps to chop the log files in smaller parts (+/- 2Mb per file)
> in case the GPRS connection is not that reliable, a resend
> will take less time.
> Roaming data can be expensive, so you might want to look at that too,
> with your mobile phone provider.
> Good luck with your project, and keep us posted about the
> successes/failures, we would like to learn from it.
> Kind regards,
> Ed
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