What is wrong with this GPS data?

hai

This is my GPS out.The unit is placed in a outward projected concrete beam(only 1 meter) near a window of my room.Seems sattelites are not accessable. Clarify.

My room is in the second floor of a building .How can I manage?



$GPGSA,A,1,,,,,,,,,,,,,,,*1E
$GPGSV,2,1,08,23,00,000,,31,00,000,,03,00,000,,24,00,000,*74
$GPGSV,2,2,08,07,00,000,,20,00,000,,21,00,000,,10,00,000,*76
$GPRMC,004845.0,V,0000.00000,N,00000.00000,E,,,010100,,,N*7B
$GPGGA,004847.0,0000.00000,N,00000.00000,E,0,00,,-00018,M,,,,*15
$GPGSA,A,1,,,,,,,,,,,,,,,*1E
$GPGSV,2,1,08,23,00,000,,31,00,000,,03,00,000,,24,00,000,*74
$GPGSV,2,2,08,07,00,000,,20,00,000,,21,00,000,,10,00,000,*76
$GPRMC,004847.0,V,0000.00000,N,00000.00000,E,,,010100,,,N*79
$GPGGA,004847.0,0000.00000,N,00000.00000,E,0,00,,-00018,M,,,,*15
$GPGSA,A,1,,,,,,,,,,,,,,,*1E
$GPGSV,2,1,08,23,00,000,,31,00,000,,03,00,000,,24,00,000,*74
$GPGSV,2,2,08,07,00,000,,20,00,000,,21,00,000,,10,00,000,*76
$GPRMC,004848.0,V,0000.00000,N,00000.00000,E,,,010100,,,N*76
$GPGGA,004849.0,0000.00000,N,00000.00000,E,0,00,,-00018,M,,,,*1B
$GPGSA,A,1,,,,,,,,,,,,,,,*1E
$GPGSV,2,1,08,23,00,000,,31,00,000,,03,00,000,,24,00,000,*74
$GPGSV,2,2,08,07,00,000,,20,00,000,,21,00,000,33,10,00,000,*76
$GPRMC,004849.0,V,0000.00000,N,00000.00000,E,,,010100,,,N*77

picstudent

It doesn't look like you have received any data from the GPS satellites ..
Assuming that the receiver and antenna work correctly, try to angle the antena so it looks at the locations higher than 1500-2000km above the Equator ..
Close to the wall of the building you are in you may have simply nothing ..
You need to have at least two satellites in view to produce something and three to have steady data ..

Regards,
IanP

IanP said:

It doesn't look like you have received any data from the GPS satellites ..
..at least two satellites in view to produce something and three to have steady data ..

Regards,
IanP

Click to expand...

Thanks for the info.

My unit in now placed by the side of the outer wall of a buiding,So as you mentioned one side may be blank.

How you people are doing expiriments like these ? by placing the GPS module on open ground?

Like my present trial position ,through a projection from a window is not a option to 'see' satellite?

Please give some details how you operate on similer test conditions.

with regards
picsudent

Without help from other instruments, you will be stepping like a "blind" ..
For comparison, it is handy to have another GPS receiver, such as simple hand-held Garmin, which gives you current satellite constellation and displays number of satellites in view ..

Try to use one of table from: **broken link removed** to find out what satellite coverage you may have ..

Also, keep in mind that sometimes it takes several minutes for a receiver to start working, especially if it is fired for the first time ..

And, if you are sure that electrically speaking everything is sound, take this GPS receiver with a battery and a laptop and go somewhere out to open space ..

Regards,
IanP

It doesn't look like to fix 3D position, but It contacted the few satellite.

How much time passed from power up?

You allow some minutes to get position fix from the Cold Boot

Picstudent said:

This is my GPS out.The unit is placed in a outward projected concrete beam(only 1 meter) near a window of my room.Seems sattelites are not accessable. Clarify.

Click to expand...

GPS doesn't work indoors. Period.

visioneer said:

It doesn't look like to fix 3D position, but It contacted the few satellite.

How much time passed from power up?

You allow some minutes to get position fix from the Cold Boot

Click to expand...

Hai
I have waited for some 15 minits after power on.

With the present position it will not get 180 degree clearence to the sky. One side is a wall.


With regards

picstudent

Even with half sky available, it should work. Assuming you are using an active antenna, check if your antenna is properly powered, check the power requirements (required voltage). Also, make sure your power supply is a good one, noise injected into GPS module through the power pins is not a good idea. Make sure the RF cable is in good shape (eventually change the antenna for comparison).

/pisoiu

pisoiu said:

Even with half sky available, it should work. Assuming you are using an active antenna, check if your antenna is properly powered, check the power requirements (required voltage). Also, make sure your power supply is a good one, noise injected into GPS module through the power pins is not a good idea. Make sure the RF cable is in good shape (eventually change the antenna for comparison).

/pisoiu

Click to expand...

Thanks for the reply.

My antena seems to be a passive one connected permentently to GPS unit by 5 cm soldered cable. Both are placed side by side in my own pcb.

Here is the output now.

$GPGGA,071819.5,0000.00000,N,00000.00000,E,0,01,,-00028,M,,,,*1B
$GPGSA,A,1,,,,,,,,,,,,,,,*1E
$GPGSV,2,1,08,09,90,027,35,26,00,000,,14,00,000,,15,00,000,44*74
$GPGSV,2,2,08,24,00,000,,04,00,000,,23,00,000,,10,00,000,*73
$GPRMC,071819.5,V,0000.00000,N,00000.00000,E,,,130506,,,N*74

Only some data appears in GPGSV string which is not there when the unit is indoors.
I am also have doubts about power supply factor.I am using power through a wire which is 10 meters long. I have used some decoupling capacitors and zener in the board .Supply is only 3.08 volts now.datasheet says 3.0to 3.65 volts.

Please suggest the best power supply arrangement.

I have tried by connecting a 1.5*2 drycell pack ~3.3 volt also.The same result.

he antena and GPS came in a single pack.I just opened it and soldered it .No chance for the antena or connection get damaged mechanically.

The board which holds GPS is having a MAX232 and associated circuitary and supply close to that.Any effects from that?

Please provide possible suggessions .I am in Dead lock!

with regards
picstudent

With regards
picstudent

I think you shouldn't worry about supply voltage as 3.08V is within the rated limits ..

08 in the GSV string would indicate that you have 8 satellites in view .. that is more than you need ..

Just playing devil's advocate: maybe there is a command that you need to send to this unit to activate it ???

Regards,
IanP

Example (signal not acquired): $GPGGA,235947.000,0000.0000,N,00000.0000,E,0,00,0.0,0.0,M,,,,0000*00
Example (signal acquired): $GPGGA,092204.999,4250.5589,S,14718.5084,E,1,04,24.4,19.7,M,,,,0000*1F

Example (signal not acquired): $GPGSV,1,1,01,21,00,000,*4B
Example (signal acquired): $GPGSV,3,1,10,20,78,331,45,01,59,235,47,22,41,069,,13,32,252,45*70

Click to expand...

IanP said:

Just playing devil's advocate: maybe there is a command that you need to send to this unit to activate it ???

Regards,
IanP

Click to expand...

Thanks a lot

This is exactly something Which I have been thinking for the past one hour.
(Great men think alike)
Something must be there to start it. That company has got less details (At least for me)in their datasheet.

Will struggle with that now.

Thanks a lot

picstudent