Hello All,
I am using the uBlox LEA-6 v1.1 I bought from 3DRobotics two years ago. It gets good lock in the open, but it can take over five minutes to get a lock in the woods, and most of my property is wooded. And the lock is very fragile as it looses lock quite often. I think I need a better unit.
Currently testing on a Traxxas Summit but will ultimately be used on a big, steel, 150 lb. skidsteer rover with (I'm sure) a huge EMF signature as it has two powerchair motors, 2x SLA batteries, 2x25 Sabertooth, 1.5W video TX, 433 Dragonlink RC control and 915 MHz telemetry.
I've looked at the alternatives and read about some new offerings but I'm not sure which would give me the most improvement for my situation.
1. Current 3DR uBlox offering
- u-blox NEO-7 module with compass (is this significantly better than the LEA-6 v1.1?)
- External compass may be an improvement
2. uBlox NEO-6M
- Is this at least as good as the NEO-7?
- Is this compatible with the APM 2.5?
3. uBlox NEO-M8N
- Is this the leading edge?
- Is this even available?
- Is this compatible with the APM 2.5?
I'd appreciate hearing from anyone that has experience with these other GPS units and can provide suggestions.
Falcon
Replies
I bought an LEA-6H and a NEO-M8N and tested both. I got the following results in my semi-open driveway:
Model HDOP SAT COUNT
Original LEA-6 v1.1 2.11 9
LEA-6H 1.36 11
NEO-M8N .96 14
Lower HDOP is, of course, better, but only with a dependable lock. I will continue to test the LEA-6H and NEO-M8N since they both have the external compass and are now plug-n-play. Eventually I'll upgrade to a Pixhawk if only for the option to run two GPS's.
Falcon
@Falcon,
Was the NEO-M8N programmed with the 3DR configuration file so that you are comparing apples to apples?
Because my M8Q far outdid the LEA-6 when programmed with the factory default configuration parameters, but when programmed with the 3DR configuration parameters, it hardly outdid the LEA-6.
Regards,
TCIII AVD
I did not change the firmware on the NEO-M8N. I changed only the baud rate.
Falcon
Thanks for the feedback.
Did 3DR sell the NEO-M8Q? How did you come by "3DR configuration parameters" for the M8Q? I assume only a uBlox GPS bought from 3DR would have 3DR parameters loaded. Otherwise it would come with the original default parameters.
The NEO-M8N I found was from EBay in the $40 range. Not sure where else to get one, or if this is counterfeit. The picture shows one 5-pin DF13 with 4 wires, and a 4-pin DF13 with 2 wires (and a <$25 version has one 6-pin DF13 with 4 wires, and a 4-pin DF13 with 2 wires). Not sure if either is 100% compatible with the APM 2.5. However I could easily change the DF13 connectors if need be.
I have the APM 2.5 so I don't think I have the option for a 2nd GPS. I hope to improve my lock with a better single unit.
My hobby pockets aren't deep enough for the Piksy. But the resolution is amazing.
Falcon
I've played with the Piksi and while its goal is amazing accuracy, its still in early beta. Frankly I haven't had much luck with it in less than perfect sky views. Since my rover is to be used in a known area like a backyard, my money (literally) is with the Pozyx. I'll have to figure out how to send fake GPS data to the Pixhawk from the Pozyx.
RoboBill
@Falcon,
I bought it from the GSCShop Guys in Europe.
I hooked up u-Center to the LEA-6 and downloaded the configuration file from it.
Then I had to hand load each applicable 3DR parameter into the M8Q because it would not accept the 3DR configuration file.
Regards,
TCIII AVD
@Falcon,
I have an M8Q with the smaller antenna than the N and I have it mounted on my test bench Pixhawk as the secondary GPS. I have found that when programmed with the 3DR configuration parameters, it is no better than the LEA-6. When I used it with U-center and set it up with its original default parameters it brought in more sats than the LEA-6 in the worst location in my house.
I presently run two LEA-6 GPSs each on my Pixhawk equipped rovers and have found that when one GPS drops out the other stays in lock and vice versa which helps in areas with large overhanging trees.
If you have deep pockets I would suggest a RTK type of GPS like the Piksy.
Regards,
TCIII AVD