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Tips and questions relating to the GPS modules from SFE
By fgcity
#44859
Hi everyone.

This is going to sound stupid but bare with me.

I have designed a PCB for the GE863 and by mistake or my own inelegance i have connected the TX, RX_Trace pins to the NMEA GPS serial port instead of the Binary ports.

and i can't change this, neither i can connect a line to those pins since the pins are under the module.

Can i get the GPS data in some other way from the standard Serial that controls the module? or configure the Control mode to give me the GPS data from the NMEA port i have connected?

I need any way possible to get the GPS data out of the module from the Standard Serial port of the module.

Please help out.
User avatar
By leon_heller
#44900
I don't think you can. I got the RxD and TxD pins the wrong way round on my first GE-863 prototype but that was easy to fix with a couple of track cuts and wires connecting to my MCU.

Leon
By velocet
#44950
Leon is right, if the connection is not made correctly then you can't get the data to the GSM\Python part of the device.

If you are unable to access the pads/tracks your only option is to pilot drill through the pads and cut the tracks. Then make your connections with wire.
By maokh
#44967
We had a small run of GE863 boards where the pads didnt quite bond right with the module. Got out the drill..some wire....annoying....but perfectly workable.
By fgcity
#44974
yeah, that's what i did.

What antennas for the GPS do you guys put on this module?

I have designed it with a patch antenna and an RF2370.

But i can't get any signal out of it. No lock.
By velocet
#44999
The patch antenna always give problems but its normally down to your 50ohm micro strip on your board. Dont have one? Then you have to use a 50ohm connector on the board or in the cable.

However I use the Sarantel helical antenna which has the 50ohm impedance built in and gives by far the best results for a wide range of applications.
By fgcity
#45047
50 ohm connector?
i make that ?

I have a strip on the other side of the antenna but i'm not sure it's 50 Ohm
By velocet
#45054
Dont forget we are talking about 50ohm impedance. NOT RESISTANCE.

If you were to connect the coax from your antenna to the PCB then you should have designed a 50ohm micro strip into the board.

OR have a ufl or mmx....... on the board.

If you have neither then you can put a connector in the coax.

A few pointers can be found if you search the forum.
By fgcity
#45057
i have a strip on my pcb leading from the reseption of the antenna (like on the datasheet)

but what is this connector you are talking about?

PS:
i also have a cercuit for the chip antenna that uses the RF2370 to boost the signal
By fgcity
#45083
So please help out.

I have never used a Chip antenna on a GPS.

Should i just connect the antenna directly to the module with no amplifying circuit?

Or should i use my RF2370 IC to amplify the signal ?

Also should i use the "supplied by the module" settings for the GPS antenna?

Another question: The controlled mode of the GE863 what data does it actually output? GGA ?

what would be the correct way to use the Chip antenna on this module ? And what should be my configuration ofr the module to get a GPS reading. Please if it's not too much trouble explain.
User avatar
By leon_heller
#45090
I use an amplified ceramic patch antenna.

Leon
By velocet
#45103
Sorry I may have confussed you a bit. If you are using a Chip antenna directly on the board then there will be no connector. Chances are you will still have to have the micro strip on the board. You will also have to tune the antenna - you need to have a good read of the data sheet.

You can also register with U-blox and find more information that may help.

My experience with Chip antenna was that to get good results the ground plane had to be so large it removed any advantages of having it.
By fgcity
#45105
how would i tune the antenna? (i have a microstrip on the PCB)

The GE863 doesn't have internal amplifier so my RF2370 cercuit should be there? or should i bypass to the antenna directly?
By velocet
#45116
You will have to refer to your antenna data sheet for tuning methods.

Normal setup is Antenna - LNA - GE863.
By fgcity
#45117
my antenna is from Sparkfun

how do i tune that ?
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