SIM 908 Unknown Location GPS Problem

Hi

I am developing a tracking system using your SIM908 modules. Previously we have used the SIM508 and SIm548C modules. The problem i'm facing is that when i send the "AT+CGPSSTATUS?" command via the serial port, i get the response "+CGPSSTATUS: Location Unknown" and "AT+CGPSINF=0" gives message "0,0.000000,0.000000,0.000000,20101010000641.000,0,2,0.000000,0.000000 OK". The debug/GPS port of the module (pin 15,16) give a continuous High value no NMEA info even though i have sent the "AT+CGPSOUT=255" AT command. My firmware revision number is "Revision:1137B01SIM908M64_ST_DTMF_JD_EAT". I have connected the GPS_VANT_IN to 4.0 volts as i'm using an active antenna with a 3-5 volts range. The GPS_VANT_Out pin is unconnected. Please help me in resolving this issue, as it is very important for us.
Awaiting your prompt reply.

Regards

Omar Khan

- - - Updated - - -

Please also suggest the most suitable GSM and Active GPS antenna for SIM908 Module.

First of all, you must send AT+CGPSPWR=1 and AT+CGPSRST=1. These commands power on and reset the GPS section on your module. If every thing is ok, then after a few seconds there is a continous string like this:
$GPGLL,3544.139224,N,05126.176682,E,092115.000,A,A*52
$GPGSA,A,2,08,26,17,,,,,,,,,,2.24,2.00,1.00*0E
$GPGSV,4,1,14,28,73,333,22,08,60,058,42,26,56,299,29,17,44,172,25*7A
$GPGSV,4,2,14,07,27,099,23,15,16,318,,11,15,073,20,05,12,244,23*77
$GPGSV,4,3,14,01,09,090,,19,06,036,,13,03,152,,10,00,197,*78
$GPGSV,4,4,14,04,,,22,27,,,24*7B
$GPRMC,092115.000,A,3544.139224,N,05126.176682,E,0.000,111,300612,,,A*7C
$GPVTG,111,T,,M,0.000,N,0.000,K,A*12
$GPZDA,092115.000,30,06,2012,,*5C

the module's default baudrate is 115200 bps.
vahideh

Hi, everybody
When I send: AT+CGPSSTATUS? and AT+CGPSINF=32
SIM908 return in different times:
1: +CGPSSTATUS: Location Unknown
32,000000.000,V,0.000000,N,0.000000,E,0.00,0.00,000000,,E,A
2: +CGPSSTATUS: Location 2D Fix
32,102443.000,A,2058.493712,N,10545.750240,E,0.03,0.00,290912,,E,A
3: +CGPSSTATUS: Location 3D Fix
32,080800.000,A,2058.486497,N,10545.762744,E,0.00,0.00,260912,,E,A
Help me, explain:
Location Unknown and "V" (warning) is don't get location, so can SIM908 return: Location 2D Fix & Location 3D Fix and "V"?-> can i get this location if it has "V".
Are Location 2D Fix and Location 3D Fix diffenrent about location (2D - "A,2058.493712,N,10545.750240,E" and 3D - "A,2058.486497,N,10545.762744,E" ) ?

Thank!

Help, show me!!!!!!!

I am using SIM908 for vehicle tracker, I have used active antenna 3-5 volt for GPS and was working fine, but today suddenly the GPS VANT-INT pin and GPS ANT pin show short and there is no GPS location retrieved.
Please tell me the reason as soon as possible.