So all he needs is a PIC which will take the current location, output by
the GPS, and calculate the distance to a known set of points, triggering
an alarm when a trap is within .5km or something?

Since the distances are so small, one could even ignore the great circle
equations, and go straight to the square root of the sum of the squares
of the differences in latitude and longitude.  Could probably perform a
few tricks there as well using tables, or by alarming when both lat and
long are within one mile of the trap's lat and long.  Since the GPS only
updates every second, it'd have a full second to compare the current
position with the table of traps, which is plenty of time.

The hardest part, in fact, would probably be the serial reception and
NMEA parsing, and deciding how to store the trap coordinates.

Of course, it would be better to use APRS and a radar detector so you
could warn others of mobile speed traps you find as well.

-Adam

Nick Ray wrote:

>The system uses a database of known speed trap locations and alerts you when
>the GPS position nears one of them. There are one or 2 commercial systems
>availiable here in the UK, but I don't know accurate their data is.
>
>Useless for mobile traps though..
>
>>What is it that you plan on doing with the GPS?  How is the GPS supposed
>>to warn you of a speedtrap?
>>
>>-Adam
>>
>>APRS Mobiel wrote:
>>
>>>>>Hello to you all,
>>>>>
>>>>>My name is Bertus Living in Netherlands, retired
>>>>>
>>>>and
>>>>
>>>>>also a heavy hamradio user.
>>>>>
>>>>>Some time ago getting a idea to make speedtrap
>>>>>warning device with help using normal GPS
>>>>>receivers.
>>>>>
>
>--
>http://www.piclist.com hint: PICList Posts must start with ONE topic:
>[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads
>
>
>
>
>

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads