gps antenna connection

[devil6600]

hi all,
i have a gps module which i have already interfaced with pc via max232 but still i need antenna connected to get lat/long from it, i just wanted to know that is it necessary to connect the antenna ground with module ground?
if you can see in the image attached, at the connector end there is a outer cover (golden) and inside that the main antenna wire. so is it necessary to connect the outer cover to ground? i have already tried connecting only the inside wire with module with no success.
kindly advice
thanks

 

[ckshivaram]

its the shield wire of antenna. it should be grounded properly to get the signals.... connect to GPS module / board ground...

 

[devil6600]

thanks for your response
i have connected the shield to the ground and inside antenna wire to the module antenna port. i am unable to get fix.
i get this string (@ 1hz) when i power up the module

$GPRMC,140220.175,V,2232.1536,N,11401.1938,E,,,,,,N*76
$GPGSV,1,1,01,13,,,31*78
$GPGGA,140221.173,2232.1536,N,11401.1938,E,0,00,50.0,32.18,M,0.00,M,,*67
$GPGSA,A,1,,,,,,,,,,,,,,,*1E

and after 2-3 minutes i get these strings

$GPRMC,140221.173,V,2232.1536,N,11401.1938,E,,,190411,,,N*7D
$GPGSV,3,1,12,13,36,237,31,30,02,092,,28,02,289,,24,37,168,*77
$GPGSV,3,2,12,23,22,198,,20,00,185,,19,57,016,,16,17,076,*79
$GPGSV,3,3,12,11,56,175,,08,16,324,,07,46,324,,06,18,042,*79
$GPGGA,140222.172,2232.1536,N,11401.1938,E,0,00,50.0,32.18,M,0.00,M,,*65
$GPGSA,A,1,,,,,,,,,,,,,,,*1E

i didn't found the matching connector for the antenna so i connected the shield of the antenna to ground with alligator clip and inside wire with a 24 AWG wire
kindly advice to make it work.

also, does antenna wire length have any effect on fix?

thanks

 

[horace1]

it looks as though you are getting valid NMEA messages

$GPGGA,140222.172,2232.1536,N,11401.1938,E,0,00,50.0,32.18,M,0.00,M,,*65

is 2232.1536 North latitude and 11401.1938 east Longitude
however the number of satelites is 0 so you probably have no signal

for details of NMEA messages see
NMEA data

buildings etc can effect the signal quality, we have buildings where we have to hang the antenna out of the window.

 

[ckshivaram]

keep it ON for 20 to 30 min and see whether gps is taking time to do a hot or warm start....

See how long it takes to be stable or you trigger warn or hot start at power ON..............

 

[devil6600]

thanks ckshivaram and horace1, i kept the module on for 20 minutes and i got the fix.
earlier i was switching it on for just 5-10 minutes.

 

[RCinFLA]

The picture you are showing is an amplified ceramic patch antenna with male MCM connector. This is common configuration. The LNA gain is typically 20 db to 30 db depending on model and cable length. It needs to be placed on at least 10 cm on a side ground plane.

It is 50 ohm RG174 cable needing femaie MCM connector on GPS receiver module. There are adaptors available if you have a different RF connector on your GPS receiver module.

Alligator clip connection for 1575 MHz won't do.

 

[ckshivaram]

in future if you dont use your GPS for more than 15 to 20 days then afterthat if you switch ON you may get all the parameters as zero.......

at that time dont panic.. the GPS has been reset.. allow it to be ON till its getrs new data.. it may take its own time....