[aprssig] NMEA output GPS or compass?
jgorkos at gmail.com
Fri Jun 29 17:10:24 EDT 2018
So, does it just want GPHDT? Putting together a microprocessor that
reads a 3DOF compass sensor and outputs the NMEA sentence once per
second is an Arduino-101 project. Hardest part would be getting the
signal levels correct going to the back of the LD-250. The entire thing
would fit in an altoids tin (but shouldn't... you know... the whole
magnetic field sensor doesn't like that).
On 6/29/18 13:41, david vanhorn wrote:
> 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
> <mailto: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
> 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
> > though, so if the vehicle is moving, they are "smeared" across the
> > It's only really useful while moving if the strikes are converted to
> > absolute rather than relative coordinates, and then the image is
> > 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>
> > <mailto: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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