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Tips and questions relating to the GPS modules from SFE
By barragan
#41196
I am unable to get a lock with it, solid red at any location.
What do I need to do to return it and get a new one (I have modified the cable). (number at the bottom is 400866)

Thanks for the help.
By busonerd
#41205
Hi,

Two things to check before you return it;

1 - Is your power supply clean?

2 - Have you waited 12 minutes with it exposed at some area? It can take up to 12 minutes to acquire almanac data at first power on.

Cheers,

--David Carne
By birbal
#134645
Hi!

I have the same problem. I never tried before any project with the EM-406A module, so I'm completely beginner in this area.
However I made a simple project with the EM-406A, Arduino Uno and an 16 LCD Display to see if I can get any data outside because my first attempt to use close to my window and watching the serial port was unsuccessful. I left it outside, in my garden for 30 min and the LED is stil blinking with no sign of lock. What can I do?

Thanks,

Birbal
By alex2wr
#134695
Hello guys,

I new to this forums and electronics, but I'm looking forward to learn.

I just got a Netduino, a GPS shield and a EM-406A to make my first project and so far I'm figuring things out except that I cannot make the GPS to lock on satellites.

In regards to my setup and what I've done:

1. Power through laptops USB port.
2. GPS module next to my window where my phone locks on 8 satellites
3. I have let the GPS on for over 12 minutes
4. The GPS is attached to GPS shield with 2-sided tape.


Here's the GPS sentense I'm getting:
$GPGGA,014445.417,,,,,0,00,,,M,0.0,M,,0000*54
$GPGSA,A,1,,,,,,,,,,,,,,,*1E
$GPRMC,014445.417,V,,,,,,,171011,,,N*48
$GPGGA,014446.430,,,,,0,00,,,M,0.0,M,,0000*52
$GPGSA,A,1,,,,,,,,,,,,,,,*1E
$GPGSV,1,1,00*79
$GPRMC,014446.430,V,,,,,,,171011,,,N*4E
$GPGGA,014447.417,,,,,0,00,,,M,0.0,M,,0000*56
$GPGSA,A,1,,,,,,,,,,,,,,,*1E
$GPRMC,014447.417,V,,,,,,,171011,,,N*4A
$GPGGA,014448.417,,,,,0,00,,,M,0.0,M,,0000*59
$GPGSA,A,1,,,,,,,,,,,,,,,*1E
$GPRMC,014448.417,V,,,,,,,171011,,,N*45
$GPGGA,014449.430,,,,,0,00,,,M,0.0,M,,0000*5D
$GPGSA,A,1,,,,,,,,,,,,,,,*1E
$GPRMC,014449.430,V,,,,,,,171011,,,N*41
$GPGGA,014450.417,,,,,0,00,,,M,0.0,M,,0000*50
$GPGSA,A,1,,,,,,,,,,,,,,,*1E
$GPRMC,014450.417,V,,,,,,,171011,,,N*4C
$GPGGA,014451.417,,,,,0,00,,,M,0.0,M,,0000*51
$GPGSA,A,1,,,,,,,,,,,,,,,*1E
$GPGSV,1,1,00*79


Some of my questions:

1. Should I use UART or DLINE?
2. I don't understand what the "Solder Jumper" does, can someone tell me if I need to solder it?

Your help is greatly appreciated,

Alex,
By ezflyr
#134705
birbal wrote:Hi!

I have the same problem. I never tried before any project with the EM-406A module, so I'm completely beginner in this area.
However I made a simple project with the EM-406A, Arduino Uno and an 16 LCD Display to see if I can get any data outside because my first attempt to use close to my window and watching the serial port was unsuccessful. I left it outside, in my garden for 30 min and the LED is stil blinking with no sign of lock. What can I do?

Thanks,

Birbal
Hi Birbal,

What do you mean by 'no sign of lock'??? According to the EM-406A datasheet, the LED indicator is on solid (no flashing) when there is no valid position, and it is flashing when a position fix been established. That is exactly the way the one on my work bench is operating.

What have you got attached to the EM-406A serial port? Are you trying to read the port directly with a computer, or are you trying to read the data with a micro-controller?? If you are connecting it to a computer, you need an interface chip between the two like a MAX232 IC. If you are connecting to a micro, one thing to be aware of is that although the EM-406A is powered at 5V, the serial output (TxD) output swing is only 0V to 2.85V. On many micros, the RxD input is a Schmitt trigger, and the 2.85V is not enough to trigger the input. What you need to do is add a simple buffer between the EM-406A and the micro to boost the voltage level up to 0 to 5V.

I hope this helps!

John
By ezflyr
#134706
alex2wr wrote:Hello guys,

I new to this forums and electronics, but I'm looking forward to learn.

I just got a Netduino, a GPS shield and a EM-406A to make my first project and so far I'm figuring things out except that I cannot make the GPS to lock on satellites.

In regards to my setup and what I've done:

1. Power through laptops USB port.
2. GPS module next to my window where my phone locks on 8 satellites
3. I have let the GPS on for over 12 minutes
4. The GPS is attached to GPS shield with 2-sided tape.


Here's the GPS sentense I'm getting:
$GPGGA,014445.417,,,,,0,00,,,M,0.0,M,,0000*54
$GPGSA,A,1,,,,,,,,,,,,,,,*1E
$GPRMC,014445.417,V,,,,,,,171011,,,N*48
$GPGGA,014446.430,,,,,0,00,,,M,0.0,M,,0000*52
$GPGSA,A,1,,,,,,,,,,,,,,,*1E
$GPGSV,1,1,00*79
$GPRMC,014446.430,V,,,,,,,171011,,,N*4E
$GPGGA,014447.417,,,,,0,00,,,M,0.0,M,,0000*56
$GPGSA,A,1,,,,,,,,,,,,,,,*1E
$GPRMC,014447.417,V,,,,,,,171011,,,N*4A
$GPGGA,014448.417,,,,,0,00,,,M,0.0,M,,0000*59
$GPGSA,A,1,,,,,,,,,,,,,,,*1E
$GPRMC,014448.417,V,,,,,,,171011,,,N*45
$GPGGA,014449.430,,,,,0,00,,,M,0.0,M,,0000*5D
$GPGSA,A,1,,,,,,,,,,,,,,,*1E
$GPRMC,014449.430,V,,,,,,,171011,,,N*41
$GPGGA,014450.417,,,,,0,00,,,M,0.0,M,,0000*50
$GPGSA,A,1,,,,,,,,,,,,,,,*1E
$GPRMC,014450.417,V,,,,,,,171011,,,N*4C
$GPGGA,014451.417,,,,,0,00,,,M,0.0,M,,0000*51
$GPGSA,A,1,,,,,,,,,,,,,,,*1E
$GPGSV,1,1,00*79


Some of my questions:

1. Should I use UART or DLINE?
2. I don't understand what the "Solder Jumper" does, can someone tell me if I need to solder it?

Your help is greatly appreciated,

Alex,
Hi Alex,

I don't know anything about the 'GPS Shield', but I am familiar with the EM-406A, and since you are receiving data from the module, I don't think it's a configuration problem with the shield. It just sounds like the GPS has just not had the conditions/opportunity to obtain a good position fix! If you look at the $GPGSV message, the third field ("00") indicates that no satellites are in view. I would take the laptop and the shield outside as far away from any obstructions (trees, buildings, etc.) and let it sit for a good 1/2 hour and see what happens. you can watch the $GPGSV message for any changes.

There are a couple of things that make a GPS require a lot of time to get a position fix. One is not being switched on in a long time, and two is moving the GPS module a long distance while off. The GPS module has a database of satellite positions in time, and has an expectation of what satellites it should see based on it's position. If the database is very outdated (the module has been off for a long time), or if the position assumption is wrong (the module was moved), the module needs to go into a search mode to find it's current position, and rebuild the database.

Hope this helps!

John
By birbal
#134729
John Morley wrote: What do you mean by 'no sign of lock'??? According to the EM-406A datasheet, the LED indicator is on solid (no flashing) when there is no valid position, and it is flashing when a position fix been established. That is exactly the way the one on my work bench is operating.
Hi John!

Thank you very much for your reply. I don't know why I understood the other way around. I just download the datashet and indeed it says that LED Flashing: Position fixed. Which I obtain pretty fast.

So then I have a problem with my software. Like I said before I'm using Arduino and I'm watching the serial monitor thrugh this board. I will research more about the software then.

Thank you very much!

Birbal
By birbal
#134732
Hi Again!

After hours of research and try different version of software I finally found a version wich can get all the NMEA data and finally is working. Now I can alterate this software to accomplish exactly what I'm looking for.

Thanks again John for your answer! I don't know how I get the impression that the blinking led means there is no lock. Anyway is pretty amaizing coz I get signal very easy and fast indoor and there is no need to aproach my window.
By alex2wr
#134739
John Morley wrote: Hi Alex,

I don't know anything about the 'GPS Shield', but I am familiar with the EM-406A, and since you are receiving data from the module, I don't think it's a configuration problem with the shield. It just sounds like the GPS has just not had the conditions/opportunity to obtain a good position fix! If you look at the $GPGSV message, the third field ("00") indicates that no satellites are in view. I would take the laptop and the shield outside as far away from any obstructions (trees, buildings, etc.) and let it sit for a good 1/2 hour and see what happens. you can watch the $GPGSV message for any changes.

There are a couple of things that make a GPS require a lot of time to get a position fix. One is not being switched on in a long time, and two is moving the GPS module a long distance while off. The GPS module has a database of satellite positions in time, and has an expectation of what satellites it should see based on it's position. If the database is very outdated (the module has been off for a long time), or if the position assumption is wrong (the module was moved), the module needs to go into a search mode to find it's current position, and rebuild the database.

Hope this helps!

John
Hello John,

Thank you for your feedback, I went ahead and tried to go out to an open area with and waited 45 minutes and still no lock.

Regarding the GPS Shield, this is what I meant http://www.sparkfun.com/products/10710

Is it possible the GPS is broken?

Thanks again
By ezflyr
#134747
alex2wr wrote:
John Morley wrote: Hi Alex,

I don't know anything about the 'GPS Shield', but I am familiar with the EM-406A, and since you are receiving data from the module, I don't think it's a configuration problem with the shield. It just sounds like the GPS has just not had the conditions/opportunity to obtain a good position fix! If you look at the $GPGSV message, the third field ("00") indicates that no satellites are in view. I would take the laptop and the shield outside as far away from any obstructions (trees, buildings, etc.) and let it sit for a good 1/2 hour and see what happens. you can watch the $GPGSV message for any changes.

There are a couple of things that make a GPS require a lot of time to get a position fix. One is not being switched on in a long time, and two is moving the GPS module a long distance while off. The GPS module has a database of satellite positions in time, and has an expectation of what satellites it should see based on it's position. If the database is very outdated (the module has been off for a long time), or if the position assumption is wrong (the module was moved), the module needs to go into a search mode to find it's current position, and rebuild the database.

Hope this helps!

John
Hello John,

Thank you for your feedback, I went ahead and tried to go out to an open area with and waited 45 minutes and still no lock.

Regarding the GPS Shield, this is what I meant http://www.sparkfun.com/products/10710

Is it possible the GPS is broken?

Thanks again
Hi Alex,

Yes, that is always a possibility, but I've found that modern electronic components are quite reliable, and the problem is often found elsewhere!

Can you measure the voltage between pin 1 and pin 2 on the GPS connector? It should be +5V. It appears that the Arduino board is supplying this voltage, and it's worthwhile to check that it is what you expect!

Where are you located? If you are in the USA, I'd be happy to look at your GPS module for you. I've got a EM-406A connected to a PIC micro, and a 8X2 LCD display. It would be easy to swap your module into my project, and see if it works with a known good circuit!

Thanks,

John
By alex2wr
#134751
John Morley wrote:
Hi Alex,

Yes, that is always a possibility, but I've found that modern electronic components are quite reliable, and the problem is often found elsewhere!

Can you measure the voltage between pin 1 and pin 2 on the GPS connector? It should be +5V. It appears that the Arduino board is supplying this voltage, and it's worthwhile to check that it is what you expect!

Where are you located? If you are in the USA, I'd be happy to look at your GPS module for you. I've got a EM-406A connected to a PIC micro, and a 8X2 LCD display. It would be easy to swap your module into my project, and see if it works with a known good circuit!

Thanks,

John
Hello John,

Thank you for your help and your interest on helping.

I did measure it last night using the onboard analog in channels but I don't remember what I was getting. When I get home tonigth, I will check again and post it.

I'm in OH and I wouln't mind sending you the unit, as I'm running out of time to make this work. I'm making this data logger for a race motorcydle to record engine parameters during a race so that I can adjust air fuel ratio to its optimal and the race is next weekend, 10.29.11 so I'm hoping to have this ready by then.

As mentined above, I'll check the voltage of TX and RX pins on the GPS shield when I get home tonigh and post the results. I'll also get the unit ready to ship tomorrow.

PM me you address to have it ready tomorrow.

I appreciate you help,

Alex,
By alex2wr
#134788
alex2wr wrote:
John Morley wrote:
Hi Alex,

Yes, that is always a possibility, but I've found that modern electronic components are quite reliable, and the problem is often found elsewhere!

Can you measure the voltage between pin 1 and pin 2 on the GPS connector? It should be +5V. It appears that the Arduino board is supplying this voltage, and it's worthwhile to check that it is what you expect!

Where are you located? If you are in the USA, I'd be happy to look at your GPS module for you. I've got a EM-406A connected to a PIC micro, and a 8X2 LCD display. It would be easy to swap your module into my project, and see if it works with a known good circuit!

Thanks,

John
Hello John,

Thank you for your help and your interest on helping.

I did measure it last night using the onboard analog in channels but I don't remember what I was getting. When I get home tonigth, I will check again and post it.

I'm in OH and I wouln't mind sending you the unit, as I'm running out of time to make this work. I'm making this data logger for a race motorcydle to record engine parameters during a race so that I can adjust air fuel ratio to its optimal and the race is next weekend, 10.29.11 so I'm hoping to have this ready by then.

As mentined above, I'll check the voltage of TX and RX pins on the GPS shield when I get home tonigh and post the results. I'll also get the unit ready to ship tomorrow.

PM me you address to have it ready tomorrow.

I appreciate you help,

Alex,

So I just check the voltage of RX and TX pins using the same netduino.

RX = 2.65v
TX = 3.07v
By ezflyr
#134796
Hi Alex,

Sorry, I was really thinking about the supply voltage between pin 1 (GND) and pin 2 (+5V) on the GPS module. I was just thinking that maybe it wasn't really +5V?

Those other voltages are probably not too relevant if there is data activity on those lines!

Do you have the SiRF demo application? It's software that allows you to command and reconfigure a GPS using the SiRF chipset. Your module may just be in a 'weird' mode? I would probably use the software to reconfigure the module, and provide it with a 'known' position fix to help get it going!

John