GPS accuracy

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creolewalker
 
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GPS accuracy

Post by creolewalker »

Image of gps on map
Image of gps on map
gpslogerror.JPG (134.43 KiB) Viewed 573 times
Hi,

I have been testing the gps unit with a raspberry in a car, I get lots of data into my gpsdata file for later processing.

I have a problem, when doing the same circuit the gps is never the same. Please see example gpsfile and image of google.

How can I sort this problem ?
gpsdata.log
GPS Data Log file
(75.87 KiB) Downloaded 142 times
gpsdata.log
GPS Data Log file
(75.87 KiB) Downloaded 142 times

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adafruit_support_rick
 
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Re: GPS accuracy

Post by adafruit_support_rick »

GPS data is only good to 10 meters.

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creolewalker
 
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Re: GPS accuracy

Post by creolewalker »

adafruit_support_rick wrote:GPS data is only good to 10 meters.
Well that means the adafruit gps is of no use, so is really just a toy. The accuracy of the data as shown on map is well over 10 meters so the unit must be deficient.

Is there any way of increasing the accuracy of the data with this unit or is it just go an use another product that actually does what it is supposed to.
The car was on the track the whole time, more than 10 meters !!!!
The car was on the track the whole time, more than 10 meters !!!!
10meters.JPG (126.48 KiB) Viewed 516 times

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adafruit_support_rick
 
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Re: GPS accuracy

Post by adafruit_support_rick »

You might try enabling DGPS mode for WAAS. That may improve things.
Add this command to setup()

Code: Select all

  GPS.sendCommand("$PMTK301,2*2E\r\n");
Also, are you using an external antenna outside of the car?

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creolewalker
 
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Re: GPS accuracy

Post by creolewalker »

Thanks.

I have tried many variations of antenna, external and just the internal - both have the same problem.

I will try adding the DGPS mode for WAAS and let you know.

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creolewalker
 
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Re: GPS accuracy

Post by creolewalker »

adafruit_support_rick wrote:You might try enabling DGPS mode for WAAS. That may improve things.
Add this command to setup()

Code: Select all

  GPS.sendCommand("$PMTK301,2*2E\r\n");
Also, are you using an external antenna outside of the car?
How do I add this to setup() ?

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creolewalker
 
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Re: GPS accuracy

Post by creolewalker »

Also would a small drop in voltage cause problems

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adafruit_support_rick
 
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Re: GPS accuracy

Post by adafruit_support_rick »

Setup already has several calls to gps.sendCommand. You can add the line anyplace in there. Put it after to call to set the update rate, for instance:

Code: Select all

 // Set the update rate
  GPS.sendCommand(PMTK_SET_NMEA_UPDATE_1HZ);   // 1 Hz update rate
  // For the parsing code to work nicely and have time to sort thru the data, and
  // print it out we don't suggest using anything higher than 1 Hz

  GPS.sendCommand("$PMTK301,2*2E\r\n");
creolewalker wrote:Also would a small drop in voltage cause problems
How are you powering all this? Both the Arduino and the GPS have voltage regulators. Are you powering the GPS through the Arduino? What sort of voltage drop are we talking about?

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creolewalker
 
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Re: GPS accuracy

Post by creolewalker »

Hi, this is on a raspberry, connected to the GPIO, I noticed that I lost the fix when other components started (picamera, external hdd, usb webcam although the hdd and webcam are powered from external supply.

Just a thought !

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adafruit_support_rick
 
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Re: GPS accuracy

Post by adafruit_support_rick »

Ah - you did say that you were using a raspberry. Sorry - I missed that. See this post and this post for how to enable WAAS DGPS on the Raspberry.
So, you would use mcc's shell script, and execute gpssend '$PMTK313,1*2E' and gpssend '$PMTK301,2*2E'

You might need a larger power supply for the Pi. How many amps will yours supply?

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creolewalker
 
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Re: GPS accuracy

Post by creolewalker »

Thanks for the response, the unit is out on test for the next 2 days so I will let you know the results.

A quick test did show an improvement, so fingers crossed it will be ok.

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Kipling
 
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Re: GPS accuracy

Post by Kipling »

Hey,

Just wondering how the precision improved after enabling DGPS?

Cheers.

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creolewalker
 
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Re: GPS accuracy

Post by creolewalker »

Great improvement, we have now purchased 20 GPS units in total and they are all in our race cars gathering information and helping us record 2 video feeds GPS data directly on to the Pi and external USB drives simultaneously.

Thanks for all your help.

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funkytechmonkey
 
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Re: GPS accuracy

Post by funkytechmonkey »

Hey CreoleWalker, I am crazy interested in what you have going on with the Pi. You mind sharing your project with me? Do you have a writeup on it?

Laissez les bon temps rouler!!

Feel free to email me if you dont want to post it up here. [email protected]

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creolewalker
 
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Re: GPS accuracy

Post by creolewalker »

Hi,

FYI

I have developed using the pi, picamera and usb camera that records footage forwards (using the pi camera ) and internal towards the driver using the USB. Audio is recorded via the USB camera and the GPS using your module. The purpose is to give the footage to the driver on a USB memory stick after his 10 minute drive in either a Ferrari, BANNED, Aston Martin or other supercar (we have 20 available). The unit needs to record all information in real time onto the memory stick so at the end of the drive the customer can take it away with them. Each car does approx 30 drives per day, and there is little time between customers for post processing. The unit also has a main 64g memory card connected via USB that also records each drive in case of customer losing his memory stick data. The unit starts recording in 3 ways, 1 if a USB memory stick is inserted, 2 if the car moves at more than 5 mph or if the manual start button is pressed. There are commercial systems available that do this but at $3000 / unit we thought we would have a go at doing one with a Pi, each system costs @ $200.

This was my first project using a Pi or Python, so the code is a bit spaghetti but does the job. We have been using it for the past 3 months with only a few glitches, I have attached screen shots of video that is produced.
Track Video
Track Video
adafruit_img.JPG (57.89 KiB) Viewed 378 times
Track Video
Track Video
adafruit_img2.JPG (58.53 KiB) Viewed 378 times

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