Help with Venus GPS evaluation board

GPS/GNSS Development Boards
1

I just hooked up the Venus GPS-09133 eval board over USB and am having trouble getting any signal at all from the satellites, even outdoors. This is what I usually get from the serial port:

$GPGGA,193130.000,0000.0000,N,00000.0000,E,0,00,0.0,0.0,M,0.0,M,0000*64

$GPGSA,A,1,0.0,0.0,0.0*30

$GPRMC,193130.000,V,0000.0000,N,00000.0000,E,000.0,000.0,010210,N*7D

$GPVTG,000.0,T,M,000.0,N,000.0,K,N*02

Occasionally it’ll hold on to a satellite for a few minutes and sync up the clock, but it has never gotten enough for a position fix, even after letting it run for 8 hours. I’m using the GPS-00177 antenna. Moving the antenna around does affect the SNR, so I don’t think the antenna connector is defective. Any advice?

2

What exactly are you using to power this board and what are you using to connect it to the computer? You are powering it with 3.3v, right? Are you sure your supply provides enough current? The module and the antenna will take about 90mA when getting a first fix.

Also, what way do you have the antenna aiming? The ceramic part with the dot on it should be pointing up. What you place the antenna on will also affect how well this module performs (i.e. if you are working on a metal desk, try moving it off of that or putting a piece of cardboard between the desk and the module.

You should be testing this module with a clear view of the sky too, from building my own module I have found it is possible to get a lock indoors, but not with the venus module and antenna you are using.

3

Thank you for your helpful response. I’ll see if I can find a place to test it with a less obstructed view. The module is powered by a LD1117V33 regulator (800 mA max). The output measures about 3.275 V with the GPS running. The serial output goes through a SparkFun FTDI breakout board. They share data and ground but not power.

I have tried orienting the antenna a few different ways but generally dot down. I’ll place it with dot up from now on. Would a different antenna give it a stronger signal?

4

Ah! Your antenna is upsidedown. Turn it around and it will work MUCH better. You want the flat plane with the dot to be pointed straight up with as clear a view of the sky as your project allows.

Your power supply provides sufficient current, but just to be sure, are you using filtering capacitors? With gps and other rf components you want the power supply to have as little ripple as possible.

5

Thank you very much for your help. With better antenna orientation and more patience it does eventually get a position fix.