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Tips and questions relating to the GPS modules from SFE
By amcleod
My brand new GS407 (uBlox 5) can't seem to find any satellites.

I've connected it to a uBlox Adapter from DIYdrones, powered it with 5v, and using the 4-wire (-,+,Tx,RX) headers I've connected to my computer with an FTDI cable. u-Center is receiving various $GPTXT messages from the unit, but apparently nothing else. I'm not getting any data on the Receiver Status window (other than "No Fix" in red for Fix Mode).

The u-Center Troubleshooting section only tells you how to troubleshoot u-Center, not the GPS module itself. I am a novice with this type of unit, and don't know what to try next.

Any suggestions greatly welcome!
By fll-freak
Stupid question: Are you outside with a view of the sky? GPS only works if it has a clear view of the satelites! Automotive glass, low-e building glass, moisture (like in tree leaves) will all degrade a signal. Structural materials (metals and woods) from a building act as a pure block.

Less stupid question: How long did you wait for a fix? A virgin GPS may take 10-20 minutes to get a fix.

Even Less stupid question: What type of antenna do you have and need? My very old uBlox modules (1980 vintage) needed an amplified antenna. You had to pass the antenna LNA power supply voltage on a seperate pin. If yours is the same check the antenna supply. If your unit needs an active antenna make sure that is what you have.
By sylvie369
(Double-checking with my GPS...)

Okay, the satelites are still up there, at least numbers 9, 14, 15, 18, 21, 24, 26 and 27.
By amcleod
fll-freak wrote:Stupid question: Are you outside with a view of the sky?
I tried it by the window, I stuck it OUT the window on a long pole, and I went out and sat on the driveway with a laptop on a starry night and tried there. Zip.
By fll-freak
So I checked the actual datasheet and found your unit has a built in helical antenna. That kind of removed my lesser stupid questions.

Since you are getting serial coms, you must have at least 3.3 volts and the multitudes of grounds connected as well as the tx from the unit. You do have all the grounds connected right?

Do you have the filter caps installed as shown in the reference design?

I do not think the battery backup is needed, but do you have that connected?

Cold start is listed as 29 seconds. That is very fast. The military units I use take many minutes to get to full capability. So you were outside for more than 29 seconds?

We have had problems with a unit when most of the satelites were down low to the horizon. Our radome masked these satelites and we would not get a lock. Do you happen to live in the bottom on a deep canyon?

uBlox has an PC application you can use to start looking at things like signal levels and satelites in view. Time to start with that application.
By amcleod
Good news -- it works!

The GS407 is connected to/powered through this unit. I was powering it at 5v but I increased to 8v. Then I took it outside and did a cold start. It acquires 7 satellites in 36 seconds and gave me a 3D fix.

Now, if I take it inside and place it by the window, it can still see four satellites and give a fix.

Thanks to those who made helpful suggestions!
By devangel77b
Why do you have to power it with 8V?
I thought the uBlox 5 chip only wants 3.3 V absolute max.
The DIYdrones board has an onboard battery and regulator, but the SparkFun breakout does not.

I have the same problem - I am able to "talk" to the GPS fine but it sees no satellites and doesn't know what time it is. Other GPS devices get fixes just fine in the same spot, and in uBlox microcenter I am able to change all the settings; I just don't get a fix after 30 minutes of waiting.
By CubicEE
I have the same problem but I'm not willing to power the 3.3V part from 5V since the datasheet from ublox specifies 3.6V as the absolute max for the supply voltage, so what can I do to fix this?
By CubicEE
It turns out that the voltage being supplied was actually 3V at the GPS. Adjusting this to 3.3V and ensuring that it was 3.3V at the GPS receiver allowed me to get a fix.
By Enrique
I have the same problem with this unit. I see messages coming in in u-center but it does not see any satellites.
I waited for over 30 minutes but still nothing.
Do I need to update firmware or something?
Any suggestions?