Main Site Documentation

GPS Megathread


#1

I have been getting into GPS lately with my GeoInfoSystems lb(s) and I thought I might post here to start a GPS megathread since it doesn’t appear as if we have one yet and also because I wanted to know what other community members are using.

So to start with a question: I am looking for the most accurate GPS I can get for under $150. Any suggestions?


#2

I have bought a LS20031
Havent done testing it yet but it its specs are

[quote]
MediaTek MT3318 solution
5Hz output
57600bps TTL serial interface
3.3V @ 41mA

32 Channel GPS
Fast TTFF at low signal level
Up to 5Hz update rate
Capable of SBAS (WAAS, EGNOS, MSAS)
Built-in micro battery to preserve system data for rapid satellite acquisition
LED indicator for fix or no fix
Documents: [/quote]

£34.00 which I thought was pretty good

Cheers Ian


#3

Woops, I forgot to mention, I have an LS20033.


#4

uBlox are probably the most accurate with a decent antenna. on the cheap end of the scale, it’s all about the antenna, not the unit itself - they all tend to use the same processors. You can get sub millimetre GPS units if you want something that weighs a couple of kilos and is $5k+ :stuck_out_tongue:

uBx have very good software though and tend to be paired with good antennas.


#5

This is the shortest “Megathread” that I have ever seen. :wink:


#6

Perhaps Chris should rename it to “GPS Microthread” until it can be upgraded to “GPS Thread” lol… then eventually we can progress to megathread!


#7

Just ordered a SUP500…

The RC car thread started out as small thread, didn’t it? Now it’s over 30 pages.


#8

I’m working with the module here:
http://www.ohararp.com/products.html

$25 + $7.5 for a break-out board. I haven’t done much with it yet but it quickly picked up a signal on my desk in my home office, 5 feet away from a single window. 10hz capable, 3.3v only.


#9

I just got two of these yesterday: http://store.diydrones.com/MediaTek_MT3329_GPS_10Hz_p/mt3329-01.htm

At 29 USD it’s basically the same thing andrejk has, but it has an alternative binary output protocol that claims to be an advantage over NMEA for some applications. Two breakboards are available for 9 and 20 USD; the more expensive model includes a backup battery with charging circuit.


#10

Seems like the MTK chipsets are better represented here. The main reason why I didn’t go with MTK was the available accuracy; I needed the best I could get, which was the 2.5 meters from the Venus chipset.

also, I will be posting my GeoInfoSystems API tonight, including…

  • GPS parser
  • Geo Coord API (distance/bearing with more calcs being added)

Chris


#11

MarkH,

You state in your first reply, “…it’s all about the antenna, not the unit itself…” Could you add a bit more for someone who is just starting to get into hooking a GPS to his Domino?


#12

Okay, I have a Domino sitting on a lawn mower that is moving and I want the Domino to make sure I am on track. First, any sub meter units or ways to get to submeter readings that won’t buy the land I am mowing? I know I can get geodetic differential data broadcast about 6 kilometers from the house, any available chip one would use with a Domino up accuracy or are we talking only post processing? What would be the minimum board you could use, just for the GPS information? Would I really need to go up the Cobra?

I a trying to get a sense of the current accuracy and processing power. Otherwise I will probably use vision processing and triangulation, hmmm, or maybe a stake and length of rope…

Oh, I have read the SparkFun writeup on GPS. For the more knowledgeable, is it current? is it an accurate representation?


#13

Yeah my first automated mower was a self pushing mower tied to a stake in the ground it would circle around. Worked fro a few weeks until the mower ran over the rope. Lets say that was a bad day for a 13 year old.

On topic though. I have ND-100 usb GPS and the same one as mooz on order. I have a few other laying around too. So I can test 4-5 chipsets with the code.


#14

The more testers on the GeoInfoSystems library the better. I’ll post SRC tonight…


#15

http://files.chrisseto.com/ZG5
Have fun guys… Report problems in this thread.


#16

Maybe I should have posted this (http://www.tinyclr.com/forum/7/871/#/10/) here… making major changes to the GPS linbrary. Looking forward to checking out Chris’ contributes from today as well.


#17

The GPS lib in this thread is meant as a very tiny GPS lib, but it’s core parsing code will always be in sync with MFGPs. As such, contributions to MFGPs benefit GeoInfosystems as well.


#18

Check the out SerialBuffer class I posted to that thread. It should be a lot faster than the buffering code you’re using now and give the GC a lot less work to do.


#19

It’s possible to connect the GPS to the 9dof, parse the whole data on the 9dof and transmit it via the binary ArduIMU protocol along with the IMU data. My parser is prepared for binary GPS data, it must only be implemented. This way a lot of GC intensive string parsing ninja would be swapped to another CPU.


#20

I was thinking about something like that when I saw the DYIDrones GPS that outputs in Binary format. I would add a ReadBinary method to the serial buffer class that would use a specific delimeter or fixed length to separate the messages.