dGPS Questions

LEGO Mindstorms Navigation Sensors for LEGO
1

Hello,
I have a few quick questions about the dGPS:

  1. What units does the dGPS measure velocity in?
  2. Since the dGPS is completely open, what do you recommend using to protect it from static?
  3. I know your site just underwent a big move, and you’re probably still sorting things out; where can I download the dGPS EV3 block?

Thanks,
Kyle

2

Hey Kyle,

Thanks!

1. What units does the dGPS measure velocity in?

Meters per second.

2. Since the dGPS is completely open, what do you recommend using to protect it from static?

I would recommend cutting a hole in a very small piece of tupperware. It should not be metal or magnetic.

3. I know your site just underwent a big move, and you’re probably still sorting things out; where can I download the dGPS EV3 block?

Here’s the link: https://github.com/DexterInd/EV3_Dexter_Industries_Sensors

Also, you can find more information on this sensor in our manual for the dGPS here.

3

Thanks!

I have a few more questions for you!

  1. In what unit does the dGPS measure distance to a target (I would assume meters, but could you please clarify)?
  2. Could you please provide me with the URL’s for the dGPS Google Maps tutorial and the dGPS user guide (The link to the user guide you provided above returns the “404 error”).

Thanks again,
Kyle

4

Hey Kyle, should be here:

http://www.dexterindustries.com/manuals/dgps-2/

Some maintenance issues, thanks for your patience.

Velocity – Integer format in cm/s.

Best,

John

5

Hey, just a quick question,

I am currently doing a project in which I am programming a robot car (EV3) to travel to a set latitude and longitude, using my dGPS.
What is the difference between Relative Heading and Travel Heading?

Thanks and enjoy the new year!
Kyle

6

Hi Kyle,It’s been a while since I looked at these calls. But . . .

Travel Heading is a function that reads the GPS position and calculates the angle traveled since the function was last called. When used over distance, this function can serve as a more precise compass than the GPS output.
Calling the function intermittently over travel distances greater than 10 feet will give a more accurate compass reading.

The function works as follows:

  1. When the function is first called, the GPS coordinates are stored in the GPS chip. We will call the coordinates C1.
  2. When the function is called a second time, the coordinates at that point are stored (we’ll call them C2) and the angle between C1 and C2 is returned through the Angle of Travel Port.
  3. When the function is called a third time, the coordinates at that point are stored (C3), and the angle between C2 and C3 is returned through the Angle of Travel Port.

Relative travel calculates the angle you’re traveling vs the angle you’ve travelled (how far off you are from your heading).

7

Thanks again!

Now I have two more questions:

  1. What is the accuracy of the GPS’s “distance to destination?” The usual 3 meters?
  2. Does the dGPS have WAAS correction?

Thank you so much for your time and help!

8

I have two more answers back:

1). Definitely no more accurate than 3 meters.

2). No, it does not have WAAS correction. Just a really simple GPS receiver chipset.

Thank you for all the questions! Any time!

9

How does the dGPS calculate distance to destination? (If you could just give me the general gist).
And is the distance to destination measurement any more/less uncertain (or about the same) than just reading the GPS coordinates?

Thanks again for your time! Just in case you are wondering, the reason why I am asking so many questions is because I am doing a project for a very prestigious science fair, and I am using your dGPS for it; so I need to know enough info about the equipment I’m working with.

10

I think, if I remember correctly, it uses a set of math functions that calculates the distance between the most recent GPS coordinates, and the coordinates input as a destination. It returns the value of distance. Maybe you can tell me more about what exactly you’re looking for here, and I can frame the answer in a more specific way?

Uncertainty in distance to destination should just be the uncertainty introduced by the GPS module. No more or less I think.

Good luck on the science fair, that’s great! Please let us know how it goes!

John