Setup procedure for GPS module from Simcom

Hi,

I am using a GPS module from Simcom.
My Problem is that the $GPRMC message always give "V" which means unvalid data.
I checked in the same place with Garmin GPS 12 XL and it works fine.

Is there any setup procedure for the GPS module?

Is there any referance documents for the SiRF Formate as I studdid the NMEA 0138 only and need to study SiRF too.

Salam
Hossam Alzomor
www.i-g.org

Re: GPS module Problem

Hossam,

I have a few suggestions to try.

1) Are you using the correct antenna for the GPS unit?
Some units come with attached patch antennas, some
need an external active antenna.

2) Are you waiting enough time for the unit to find the
location, especially if this is a cold-start? I don't know
about your unit, but years ago I had a problem with a
new GPS module outputting the 'V' flag, along with a
location about 600 miles away. This turned out to be the
last valid location, which I traced back to the location of
the factory that manufactured the unit. A cold start,
especially when the unit is moved far away from the last
valid location, can take several minutes to lock on. I think
this old unit may have taken up to 45-60 minutes before
it knew where it was when doing a cold-start.

I've also found that when doing such a cold start, it is
best to take the unit out in the open where it can get a
clear view of the sky and all available satellites. Once I
got a valid lock, then I brought it inside to work on (where
it could only "see" a few satellites through a window).

Re: GPS module Problem

Hai

1. Place the unit in a open space and try.
2. Look the datasheet for any possible command like "start tracking"
3. check antena connectors or replace antena.
4. replace GPS unit.


Two GPS units like this almost wasted my 2 weeks. Finally I realised they were faulty.



All the best.
picstudent

Re: GPS module Problem

check the dc voltage on antenna
you need 3v for active antenna

GPS module Problem

check the dc voltage on antenna
you need 3v for active antenna