[aprssig] NMEA output GPS or compass?

[david vanhorn]

The GPS really would add nothing to the system.  Their map is static.


On Fri, Jun 29, 2018 at 11:52 AM, John Gorkos <jgorkos at gmail.com> wrote:

> I'm a little late to this, but what input is the LD-250 looking for?
> If it's straight NMEA with GPHDT sentences, why not just build your own
> little device to do that?  Seems to me, you could do the whole thing for
> about $80:  a $10 Atmega µProcessor like a trinket, a $15 triple-axis
> accelerometer board with a LSM303DLHC chip on it, and a $40 GPS board
> with NMEA out.  Throw in a $10 level converter to get the output signals
> up to "true" RS-232 levels, and put a little glue code in there to
> generate the GPHDT sentence and mix it with the NMEA stream from the
> GPS, and put it all in a nice little box with a power plug on it.
>
> Heck, send me $80 and give me a week, and I'll send you the box.  I've
> got everything I need sitting here on my test bench.
>
> John Gorkos
> AB0OO
>
> On 6/29/18 10:27, david vanhorn wrote:
> > Thanks all.
> >
> > I am going to hold off till I find a fluxgate compass.  The GPS route
> > would "work" but this thing has enough issues already.
> >
> > The Boltek LD-250 is " Long Range detection Designed for mobile use in a
> > moving vehicle with a GPS or Compass connected " (From their web site)
> > However..
> >
> > Their software doesn't work with any known map program.
> > The unit sends strike information as bearing and distance relative to
> > the front side of the sensor.
> > If you add a compass, the strikes are rotated accordingly.
> > The strikes are not converted to anything like an object at a coordinate
> > though, so if the vehicle is moving, they are "smeared" across the map.
> >
> > It's only really useful while moving if the strikes are converted to
> > absolute rather than relative coordinates, and then the image is rotated
> > and panned accordingly to the vehicle rotation and motion.
> > I could easily live without an actual map
> >
> > The GPS wouldn't give me workable heading data when not moving, and the
> > LD-250 doesn't give useful data while I am moving..
> >
> > With a compass, at least I could park in whatever direction works, and
> > I'd get a display rotated so that it's oriented north up.
> >
> > It's a fixed location instrument in a mobile package.   The only plus is
> > that it doesn't require a full PC with PCI slot to run.
> >
> > Basically, in the 10 years since I last used it, the half-assed
> > implementation of their software hasn't improved at all.   I need it to
> > be at least 3/4 assed. :)
> >
> > It would be really cool if some working mobile app/program whatever
> > could be trained to hear their data and plot it on a working map.
> >
> >   $WIMLI,<ddd>,<uuu>,<bbb.b>*<cs><cr><lf>
> >
> > <ddd> - corrected strike distance 0-300 miles
> >   <uuu> - uncorrected strike distance 0-300 miles
> > <bbb.b> - bearing to strike 000.0-359.9 degrees
> >        <cs> - checksum in hex
> >    <cr> - carriage return
> >    <lf> - line feed
> >
> >
> >
> > http://www.boltek.com/manual-ld-250.pdf
> >
> > On Thu, Jun 28, 2018 at 7:25 AM, david vanhorn <kc6ete at gmail.com
> > <mailto:kc6ete at gmail.com>> wrote:
> >
> >
> >     I'm reactivating an old project, and I would like to find an NMEA
> >     output GPS unit like the old Garmins with their four pin connector,
> >     or a compass with similar output.
> >
> >     What I've seen in compasses are crazy expensive ($500), and GPS
> >     units seem to all be USB output now if they have any external data
> >     connection at all.
> >
> >     What I absolutely need at a minimum is a compass or GPS with an NMEA
> >     output. The system has NMEA+ NMEA-, +12V power to compass/GPS and
> >     ground.  If it's a GPS unit, I would prefer some sort of simple
> >     "puck" style unit rather than something with a display and buttons
> >     to misconfigure.
> >
> >     Any sources coming to mind?
> >
> >
> >     --
> >     K1FZY (WA4TPW) SK  9/29/37-4/13/15
> >
> >
> >
> >
> > --
> > K1FZY (WA4TPW) SK  9/29/37-4/13/15
> >
> >
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> >
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-- 
K1FZY (WA4TPW) SK  9/29/37-4/13/15
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