Hi!
I am making a GPS localitation system using Ultimate GPS. I have about 10 of it, all with same hardware (Arduino + Ultimate GPS).
The system works fine if the object where I have attached is in movement, but if the speed is slow, about 0,5 Km/h the GPS starts to be not precisse with errors up 150 meters.
With the same hardware I have 2 that works perfect..
Someone had similar problem? or know a solution for it?
Ultimate GPS precission at low speeds
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Please be positive and constructive with your questions and comments.
- adafruit_support_rick
- Posts: 35092
- Joined: Tue Mar 15, 2011 11:42 am
Re: Ultimate GPS precission at low speeds
Please refer to page 13 of the command document. You can set the nav speed threshold ($PMTK397) for low-speed applications:
http://www.adafruit.com/datasheets/PMTK_A08.pdf
Also, see this thread:
http://forums.adafruit.com/viewtopic.ph ... ld#p279903
http://www.adafruit.com/datasheets/PMTK_A08.pdf
Also, see this thread:
http://forums.adafruit.com/viewtopic.ph ... ld#p279903
- jorge5a
- Posts: 14
- Joined: Tue Jun 03, 2014 11:40 am
Re: Ultimate GPS precission at low speeds
Dear admi:
I have this sentence at top of my code
$PMTK397,0.00*0D. But I have tested other same GPS and by default is with 0 (low speed)
It's possible I have Other Ultimates GPS with other configuration Threshold by default?
Thanks
I have this sentence at top of my code
$PMTK397,0.00*0D. But I have tested other same GPS and by default is with 0 (low speed)
It's possible I have Other Ultimates GPS with other configuration Threshold by default?
Thanks
- adafruit_support_rick
- Posts: 35092
- Joined: Tue Mar 15, 2011 11:42 am
Re: Ultimate GPS precission at low speeds
I would use the sentence exactly as specified in the user guide:
$PMTK397,0*23
However, if you think the threshold really is turned off, then you are at the limit of resolution of the GPS module itself.
$PMTK397,0*23
However, if you think the threshold really is turned off, then you are at the limit of resolution of the GPS module itself.
- jorge5a
- Posts: 14
- Joined: Tue Jun 03, 2014 11:40 am
Re: Ultimate GPS precission at low speeds
I have tested with $PMTK397,0*23 and I have error, about more 50 meters.
I must send any sentence (like +++) for put on command mode before send the $PMTK397,0*23 sentence?
The GPS is exactly when is stoped and about 3 hour after start, but with more time the GPS lost precision. The system run about 0,03 m/s
Do you have any idea, about I'm doing bad?
I must add or change another chip variable?
The same systems works fine in other places. The precission changes depending the place where the system is. But, I have ever good connection satellites, about 7-11 satellites.
Thanks a lot
I must send any sentence (like +++) for put on command mode before send the $PMTK397,0*23 sentence?
The GPS is exactly when is stoped and about 3 hour after start, but with more time the GPS lost precision. The system run about 0,03 m/s
Do you have any idea, about I'm doing bad?
I must add or change another chip variable?
The same systems works fine in other places. The precission changes depending the place where the system is. But, I have ever good connection satellites, about 7-11 satellites.
Thanks a lot
- adafruit_support_rick
- Posts: 35092
- Joined: Tue Mar 15, 2011 11:42 am
Re: Ultimate GPS precission at low speeds
No. Just send the $PMTK sentence.jorge5a wrote:I must send any sentence (like +++) for put on command mode before send the $PMTK397,0*23 sentence?
I think you're just at the limit of accuracy of the system.
- Barry914
- Posts: 448
- Joined: Sun Dec 08, 2013 1:26 pm
Re: Ultimate GPS precission at low speeds
Do you have WAAS enabled? There's a dramatic improvement in stability when I have it enabled.
- jorge5a
- Posts: 14
- Joined: Tue Jun 03, 2014 11:40 am
Re: Ultimate GPS precission at low speeds
If is not for default I have not it active.
Could you advice me what option to select with DGPS?
0’ = No DGPS source
‘1’ = RTCM
‘2’ = WAAS
And will be better activate or not SBAS?
Thanks a lot
Could you advice me what option to select with DGPS?
0’ = No DGPS source
‘1’ = RTCM
‘2’ = WAAS
And will be better activate or not SBAS?
Thanks a lot
- adafruit_support_rick
- Posts: 35092
- Joined: Tue Mar 15, 2011 11:42 am
Re: Ultimate GPS precission at low speeds
Which DGPS you activate depends on where in the world you are.
In North America, activate WAAS.
You want to activate SBAS.
In North America, activate WAAS.
You want to activate SBAS.
- jorge5a
- Posts: 14
- Joined: Tue Jun 03, 2014 11:40 am
Re: Ultimate GPS precission at low speeds
SOLVED!
Thanks a lot, I was using Arduino with SoftSerial library to chat with the GPS.
I have changed the sentence and all works fine :)
ss.wite("ss.println("$PMTK397,0*23\r\n")") -> Didn't work form
ss.println("$PMTK397,0*23")- > works fine
The mistake was ever on the threshold. The GPS module is perfect!
Thanks a lot, I was using Arduino with SoftSerial library to chat with the GPS.
I have changed the sentence and all works fine :)
ss.wite("ss.println("$PMTK397,0*23\r\n")") -> Didn't work form
ss.println("$PMTK397,0*23")- > works fine
The mistake was ever on the threshold. The GPS module is perfect!
Please be positive and constructive with your questions and comments.