My code is in a combination of "C" and x86 assembly language.

It uses a serial data stream received from a Trimble GPS, which is _not_ is
NMEA format.

Unfortunately, it uses a library provided by Trimble to decode said
datastream (into uncompressed binary records), which I am not allowed to
distribute.

Similar technology could be used to handle NMEA data.

Bob Ammerman
RAm Systems
(contract development of high performance, high function, low-level
software)

----- Original Message -----
From: M. Adam Davis <adavis@UBASICS.COM>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: Wednesday, October 04, 2000 9:17 AM
Subject: Re: [PIC]-data recorder project-guidance needed.


> Hmmm...  Perhaps one might be able to let the code (or algrithm) loose?
>
> A GPS datalogger is one of my next steps in toying with the surplus
trimble GPS
> board I have.
>
> -Adam
>
> Bob Ammerman wrote:
> >
> > I wrote some compression code to store GPS fixes using a delta encoding
> > scheme.
> >
> > I was able to store fixes in full precision at one second intervals for
> > something on the order of 6 bytes per fix.
> >
> > Was _very_ sneaky code though!
> >
> > Bob Ammerman
> > RAm Systems
> > (contract development of high performance, high function, low-level
> > software)
> >
> > ----- Original Message -----
> > From: Peter L. Peres <plp@ACTCOM.CO.IL>
> > To: <PICLIST@MITVMA.MIT.EDU>
> > Sent: Tuesday, October 03, 2000 3:08 PM
> > Subject: [PIC]-data recorder project-guidance needed.
> >
> > > imho unless your device can teleport you should use sigma-delta
encoding
> > > of each 'next' datum and full records from time to time (like every 10
> > > minutes or such). If your encoding scheme is reasonably good then you
can
> > > use RLL encoding (compression) on the delta records (assuming that the
car
> > > runs on constant speed and direction most of the time), to achieve
some
> > > eye-popping compression gains. There are more shortcuts available, the
> > > question is, how large is your budget (time) and how much can the
thing
> > > cost.
> > >
> > > good luck,
> > >
> > > Peter
> > >
> > > --
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> > >
> > >
> >
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