benn686@hotmail.com wrote:

>Theres several low power GPS receivers out there (ex. Trimble's Lassen
>iQ), but aside from the hardwre interfacing to it what else is
>required?
>
>Ive never used or owned anything with GPS, just figured it would be a
>neat project, but is gps data free, just hook up an antenna and go?  Or
>does it require some kind of existing account for authentication?

I just ordered a Polstar GPS mouse which looks interesting.
Slightly bigger size than a usual external GPS antenna and it supplies
direct TTL as well as RS232 serial I/O. An add-on cable came with it
to connect it to a USB port (no external power needed). Price about 70
Euro (90 USD) incl shipping.

Is anybody familiar with a Polstar GPS mouse? The manual claims power
consumption is only 120mW in "tracking mode". Power can be 5-9V DC,
which would mean only 24mA at 5V. That seems hard to believe.

Joop

On 2 Mar 2005 16:29:07 -0800, benn686@hotmail.com wrote:

>Theres several low power GPS receivers out there (ex. Trimble's Lassen
>iQ), but aside from the hardwre interfacing to it what else is
>required?

You probably want a unit that outputs NMEA 0183 "sentences" (formatted
ASCII text). Google for "GPS NMEA 0183" for loads of info. Fairly simple
to interface with.

>Ive never used or owned anything with GPS, just figured it would be a
>neat project, but is gps data free, just hook up an antenna and go?  Or
>does it require some kind of existing account for authentication?

The antenna, front end, and signal processing are often all in a single
package for consumer units, although systems with separate antennas are
available.

If you're shopping around, also look for systems that support DGPS and
WAAS as well as, perhaps, a dual frequency system that can take
advantage of the L2C signal as it is implemented.

Just getting a lat/lon position may become boring pretty quickly unless
you have a set of charts/sectionals to plot positions on. If you need
maps to go with it, the DeLorme "Street Atlas USA" product will
interface with NMEA 0183 units as well as their own USB-powered GPS
gadget. They have a topo product as well and there are other, similar
products. http://www.delorme.com/streetatlasusa/

-- 
Rich Webb   Norfolk, VA

Jim Stewart wrote:
> benn686@hotmail.com wrote:
> 
>> Theres several low power GPS receivers out there (ex. Trimble's Lassen
>> iQ), but aside from the hardwre interfacing to it what else is
>> required?
>>
>> Ive never used or owned anything with GPS, just figured it would be a
>> neat project, but is gps data free, just hook up an antenna and go?  Or
>> does it require some kind of existing account for authentication?
> 
> 
> All you need is sky.  No authentication for
> commercial GPS.  

Confirmed. Most GPS widgets have a 4800 or 9600 baud serial ouput using 
either proprietary binary or NMEA (ASCII) protocol.

Get or configure for NMEA protocol for easiest implementation. Google 
NMEA for protocol definition.

With my limited programming skills it was a day's work to code a simple 
app to show current position.

>Doesn't work well in buildings though.

Also confirmed ;-)

Chris.

benn686@hotmail.com wrote:
> Theres several low power GPS receivers out there (ex. Trimble's Lassen
> iQ), but aside from the hardwre interfacing to it what else is
> required?
> 
> Ive never used or owned anything with GPS, just figured it would be a
> neat project, but is gps data free, just hook up an antenna and go?  Or
> does it require some kind of existing account for authentication?

All you need is sky.  No authentication for
commercial GPS.  Doesn't work well in buildings
though.

Theres several low power GPS receivers out there (ex. Trimble's Lassen
iQ), but aside from the hardwre interfacing to it what else is
required?

Ive never used or owned anything with GPS, just figured it would be a
neat project, but is gps data free, just hook up an antenna and go?  Or
does it require some kind of existing account for authentication?