[aprssig] NMEA output GPS or compass?
Greg D
ko6th.greg at gmail.com
Sat Jun 30 01:15:17 EDT 2018
One can pick up a Garmin GPS-III on eBay for about $20. Serial
interface built-in, but with the round connector. It includes a
magnetic compass, and switches to it when not moving, at least for the
internal display - not sure what happens to the serial data strings.
Greg KO6TH
John Gorkos wrote:
> 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).
>
> de AB0OO
>
> 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
>> 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
>> <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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>>
>> --
>> K1FZY (WA4TPW) SK 9/29/37-4/13/15
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