First flight test with a ublox M8 GPS

[Peter Plischka]

Hi there,

attached a log file from a flight with a ublox M8 GPS and a 3DR ublox 6 GPS.

Between the houses a maximum of 13 Sats were achieved with the M8.
The ublox 6 had reached a maximum of 8 Sats.

The copter was very good in the air in hybrid mode.

The values ​​of ofsl ofsQ magl magQ look completely different than a ublox 6 

@ Paul
It was the version e924da4fec871ec5f0df4c786d9ef2d124f8e0b6  


regards Peter

[Julien Dubois]

Sounds great Peter!

From your log, the flight seems not very agressive and it would be interesting to see how the GPS module works in hard conditions
cf. Andrew's post here: http://diydrones.com/profiles/blogs/ublox-m8-series-gps-glonass-receiver-test

Still from you log, HDop was very bad at the beginning even with 8 sats.

Finally, Hybrid should be usefull to test GPS in hard condition as it's the more agressive flight mode that relies on GPS imo... so your choice for this test was the right one!

Where have you got the M8 module? Is it something like http://www.csgshop.com/product.php?id_product=170

Julien

[Peter Plischka]

Hello Julien.

It is this one:
http://www.csgshop.com/product.php?id_product=171

Unfortunately, here in front of the house is not enough space for a longer flight.
I'll try later on a larger area.

With enough Sats the accuracy is very good. Yesterday it was 15 Sats and HDOP of 1.16 

regards Peter

[john...@gmail.com]

A high number of satellites found is usually a indication of good GPS conditions, but does not automatically translate to a low HDOP value. It is the position of the locked satellites in relation to your GPS receiver that decided how good the horizontal resolution will be (triangulation). A high satellite count means that you have a strong lock and there is less chance you will lose the GPS solution during flight. And in practice it usually results in low HDOP, but there is no guarantee.

- JAB

[Cornel Fudulu]

I'm playing with an M8N myself, and I also saw more sattelites but worse HDOP around the house.

I'm waiting for a NEO-6 GPS with external LNA and SAW to swap the M8N module in, because I can't find a config option for the internal SAW filter.

[Paul Riseborough]

HDOP is supposed to represent the ratio of horizontal position error to range measurement error

http://en.wikipedia.org/wiki/Dilution_of_precision_%28GPS%29

and is not an absolute accuracy (for example two receivers could have the same HDOP, but one could have better range accuracy and therefore better positional accuracy). HDOP as reported by UBlox does not appear to conform to this convention.

There isn't much value comparing HDOP values between different models of receiver. A better test would be to put two receivers side by side in a static test (with the same level of  motion filtering selected) and compare the movement in their solutions over time.

[Randy Mackay]

 

     I wonder if it might help if MichaelO added the ability to graph the 2^nd GPS’s positions in the KMZ/KML files that the mission planner produces or when you click on the “show map” in the dataflash log viewer.  I’m not totally sure if it’s necessary or if it’s only something that developers really care about and it would just add complexity and confusion for normal users.

-Randy

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[Peter Plischka]

Hi Randy,

I think it's a good idea if we could graph information in the dataflash log viewer for both GPS Modules .

So then everyone has the opportunity two different GPS modules, or two identical modules in another location, easy to compare.
This function needs only in the advanced view available.  

 

regards Peter

[Peter Plischka]

Here are two logs with the M8 and a ublox-6 module.
Once a fast flight and then a longer loiter.

With Loiter 19 Sats were obtained with a HDOP of 1.19.
In fast flight there were 18 Sats with a HDOP of 1.06

The video shows that the hexa is very good over a period of 11 min on the spot.

 

https://www.youtube.com/watch?v=bN8JwNQk_a8

Compared to the flights with the ublox-6 module I am very satisfied.


regards Peter

[Julien Dubois]

Very good Peter, thanks for the test!

I've never got so many Sats netheir so low HDOP with my ublox-6. That sounds very promising as I had  compared the position hold on the APM + Ublox-6 VS Naza + DJI GPS and APM was >= even with strong wind.

So, now, if GPS is again better, that will push APM on top for sure!

Can't wait to try it and see how it behaves in the worst cases

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[Peter Plischka]

Julien,

I am looking forward to your test results.

 

The delivery from csgshop.com to Germany took only 4 days.
I'm going to order a few more for my other Copters.

regards Peter

[Tom Coyle]

Hi Peter,

Did you have to load this new uBlox GPS with the 3DR configuration firmware to get it to communicate correctly with your APM?

Regards,

Tom C ArduRover2 Developer 

[Peter Plischka]

Hi Tom,
No I have not. It is much easier to adjust the few values ​​manually.
I have:

PRT (ports)	UART 1
	Protocol out	UBX
	Baudrate	38400
RATE (Rates)	Measurement Period	200 ms
	Measurement Frequency	5 Hz
NAV5 (Navigation 5)	Dynamic Model	Airborn 4G
	Fix Mode	3 - Auto 2D/3D
	Min SV Elevation	10 Grad
	DGPS Timeout	120 sec
SBAS	Subsystem	Enabled
	PRN Codes	EGNOS (EUROPE)
		120, 124, 126, 131

 

regards Peter

[Tom Coyle]

Thanks for the response Peter, much appreciated.

Regards,

Tom C ArduRover2 Developer

[Peter Plischka]

No Problem Tom,

I am very happy with the M8. I get even in difficult situations (between trees and houses) more than 11 Sats. HDOP is between 100 and 200 cm.

With the ublox-6 I had only 6 Sats and was not as happy with the Loiter and Hybrid.
In an open area there are about 20 Sats.

Meanwhile, I have loaded all my copter with the M8, as the backup there is still a ublox-6 installed.

 

regards Peter

[Tom Coyle]

Hi Peter,

I am presently running a two GPS configuration (#DR uBlox LEA-6s) on my Pixhawk equipped Traxxas Slash rover.

I live in southern Florida, USA and typically can get 11 to 12 sats with an HDOP as low as 1.2 when I am at my parking lot test course.

I can get up to 10 sats and a HDOP of less than 2.0 inside my house in the afternoons:-)

We are using two GPSs mainly for redundancy since one GPS will usually maintain a lock if the other one momentarily goes out of lock.

I am hoping that the M8 will get the sat count up even higher and get the HDOP close to or less than 1.0.

Regards,

Tom C ArduRover2 Developer

[Peter Plischka]

Then yes you live in a good GPS area.
With the ublox-6 I've never had more than 9 Sats in the wild.
I usually fly in an area with houses and get to 5-6 Sats.

For me, the M8 is a great help.

I have ordered one with the helix antenna. and look forward to the comparison with the patch antenna.

Believed to be the helical antenna will not be as well suited for Copter or airplanes because of stronger directivity.

Could be interesting for your Rover.

 

regards Peter

[Julien Dubois]

100% OK with you Peter, helix has too narrow beam for copter/plane imo.

I had ordered the M8 with patch antenna you linked me but, Lucky as I am, it's been damaged during shipping (that's what answered CSGShop to explain why I've still received nothing).

So, I wonder if they are serious seller and if I'll get the item one day...

BTW, I get up to 12-13 sats with my Neo-6m single GPS with HDOP between 1,7 - 1,9. worst cases, 7 sats.

 

regards Peter

--

[Peter Plischka]

Hi Julien,

but that is a shame. The shop sents unfortunately only in a plain paper envelope.

Whether they are serious, I do not know. There is no Impressum in the shop and mails are not answered.

Another shop for the M8 I have not found it yet.

 

regards Peter

[Łukasz Wasik]

Peter how you configure that GPS? With 3DR configuration file?

[Peter Plischka]

Hello Lukasz, 

for the few values ​​you do not need a configuration file. 
You just have to change the following values: 

[Łukasz Wasik]

Thanks!

[Paul Riseborough]

With the extra satellites available with this receiver, it may be worth experimenting with a higher mask angle. There is an interesting paper which looks at the optimum mask angle and concludes that with the addition of Gallleo and GLONASS, the optimum angle is higher than it would be for just GPS.

http://gracegao.ae.illinois.edu/publications/conference/2013_ION%20GNSS_Liang_RFT%20mask%20angle.pdf

[Ben Nizette]

Huh, interesting. I've been doing some experiments with some
GPS/Beidou receivers and came to a similar (but far less rigorous!)
conclusion. In our case, dynamic maneuvers were putting low-elevation
satellites out of the FoV of the antenna, causing jumps in the
position solution. By increasing the software mask angle we can
simply ignore the SVs that are at highest risk of this and exclude
them from the solution entirely. Essentially we're sacrificing
accuracy for consistency but with enough sats, the trade-off seems
acceptable.

Ben.

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[Peter Plischka]

Thank you Paul and Ben,

The difference of 5 degrees to 10 degrees in practice, be very difficult to detect.
I'm about to read the Document from Paul.

regards Peter

[Andrew Tridgell]

Hi Paul,

> With the extra satellites available with this receiver, it may be worth
> experimenting with a higher mask angle.

makes sense, yes

We should add a GPS_ELEV_MASK parameter I think, with some reasonable
default (5 or 10 degrees maybe?). That would allow users to tune for
terrain too.

Cheers, Tridge

[Julien Dubois]

Hi Andrew,

and what about a real time autotune? the controller adjusts this mask value to get a decent accuracy with the highest mask value possible.
In worst case, the mask is limited to 5 (no change from current perf)
In other cases, we increase consistency while keeping the same accuracy we currently have.

Julien

[Peter Plischka]

That's fine, Andrew.

 

Due to the frequent plugging the GPS units, the DF-13 connectors are on PIXHAWK gotten loose.


regards Peter

[Łukasz Wasik]

Someone said that Airborn mode is better for fast planes. Pedestrian mode is better for copters. Is it true?

Setting NAV, NAV2 and NAV5 to Pedestrian mode cause better accuracy for position hold.

W dniu wtorek, 3 czerwca 2014 21:19:49 UTC+2 użytkownik Peter Plischka napisał:

[Peter Plischka]

It will be hard to see a difference.

 

You can even try out different settings and show us the difference. 

regards Peter

[Łukasz Wasik]

OK this is the best config. Max HDOP 1.3 on the 2nd of the 4-floor building, 3m from window!

[Ben Nizette]

On 6 June 2014 04:47, Łukasz Wasik <pankr...@gmail.com> wrote:
> Someone said that Airborn mode is better for fast planes. Pedestrian mode is
> better for copters. Is it true?

The defaults (used to be?) Plane used Airbourne 4G, 'Copter was
Airbourne 1 or 2G, Rover was Automotive. Tridge and I (mainly
Tridge!) did some testing 6 months ago and found that all three
probably should be using Airbourne 4G. 4G is the closest we've got to
telling the GPS not to filter at all. This is important for us
because 1) we have our own filters (INAV, recently EKF) that have more
information and can filter much more effectively than the GPS and 2)
because filtering inside the GPS introduces latency that degrades the
performance of our filters.

Things like "better accuracy for position hold" might be true if we
didn't have INAV (or if your frame vibrates heaps, in which case fix
that!), but in the general case it's best to just let INAV do its
thing.

Ben.

[Peter Plischka]

Ah, thank you Ben,

I had not considered that.

But we can still experiment with the Min SV Elevation Mask.
I would be glad if Andrew makes it a parameter.
That would help a lot.


regards Peter

[Ben Nizette]

Yep, for sure. It's only recently that the code's been changed to
allow parameters attached to GPS, it should be an easy-enough coding
task now.

Ben.

>>
>>
>> regards Peter

[Paul Riseborough]

Flew the M8 today on a 3DR quad with a combination of throwing it around in hybrid mode, auto and loiter. It got 14 to 15 satellites and during the 2x15min flights experienced no glitches. Unfortunately my Pixhawk did not log the 6H plugged into the serial 4/5 port, however I have never got more than 11 satellites using a 6H and I have never done two consecutive flights without a glitch of some sort so it appears to have outperfomed the 6H in that area.

Looking at the EKF data I think the latency on the M8 data (relative to the IMU)  is different to the 220msec value set by the EKF_POS_DELAY and EKF_VEL_DELAY parameters, which were optimised for the 6H. This is causing the GPS innovations to rise during manoeuvres. I will have a look at finding a better value for EKF_POS_DELAY and EKF_VEL_DELAY using the replay facility.

I was using a 10 degree mask angle, turned SBAS off (it can cause trouble in Australia) and was using the aircraft <4g motion filter setting.

[Craig Elder]

Thanks for the great news Paul

Did you have GPS_TYPE2 set to 1 or 2?

--

[Paul Riseborough]

I had rolled back to a previous set of params and forgot to check it. Looks like it was set to zero for those flights.

[Julien Dubois]

Great new... still waiting for mine, this seller is definitivelly not serious.

Could you compare perfs doing the same test with different mask angle?

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[Paul Riseborough]

Did another couple of flights with the 6H logging this time. This included some aggressive flying in hybrid mode. Observations from the logs are:

The M8 has ~100 msec less latency on the velocities than the 6H. I think I will reduce EKF_POS_DELAY and EKF_VEL_DELAY to 120 for subsequent flights.

Most importantly, the M8's velocity output never broke down under the aggressive flying, whereas the 6H did momentarily on three occasions. See attached plot showing one occurrence. Red is M8, green is 6H.

The M8 had slightly less velocity noise. 

The M8 averaged 17 and the 6H averaged 11 satellites (this is the maximum number I have seen with the 6H on this model during flight conditions)

So far, the performance of this receiver has been a noticeable improvement over the 6H in my environment (I don't get SBAS).

The wider band front end on the receiver required to cover the different satellite frequencies should theoretically make it more susceptible to RF interference, and I'm keeping it away from other equipment for the time being (its mounted out on one of the arms of the quad), so it's susceptibility to interference from the equipment typically fitted to our vehicles needs to be investigated.

[Paul Riseborough]

BTW, the backup battery on the back of the dev board, unless it is glued down, can fatigue its mounts and you lose backup power and go back to default settings. You can see the backup battery in this image:

http://www.csgshop.com/img/p/171-359-large.jpg

The battery is only supported by those thin tin leads. I had to bridge a broken track where the battery lead had lifted it and then glue the battery down to the board using CA. I would recommend a drop of CA between the backup battery and board.

[Julien Dubois]

From  this picture I see this is the mini GPS with small antenna. So I guess we could expect even better results with bigger antenna. 35*35 for example.

[gervais]

Am Samstag, 7. Juni 2014 13:12:38 UTC+2 schrieb Julien Dubois:

From  this picture I see this is the mini GPS with small antenna. So I guess we could expect even better results with bigger antenna. 35*35 for example.

The evaluation board with the bigger (but thinner ?) patch comes with a passive antenna, the smaller one with a different chip and active antenna. I would not bet, that the bigger one is better.
For such a small patch Peters (and others) results are amazing..even without an additional GP.

If you find a big active dual band antenna, please let us know. So far I did not.
 

[Julien Dubois]

The patch antenna built in the test module is a RCHP 24dB active antenna.
http://www.csgshop.com/product.php?id_product=138

The bigger the surface or volume of the antenna, the best it's performances.

So, I meants for example to replace this antenna by something like that
http://www.goodluckbuy.com/32db-high-gain-cirocomm-gps-active-built-in-ceramic-patch-antenna-38386mm.html
Same RHCP active, but more surface, more volume, more gain (here, 32dB)

http://www.goodluckbuy.com/32db-high-gain-cirocomm-gps-active-built-in-ceramic-patch-antenna-38386mm.html

Julien

[Loic B]

very interessing thread!

it could be great to have a ublox file to tune his own m8 with the best setting.

[jdennings]

I have a couple of Neo 7m modules with separate patch antennas with about an inch of wire, that I plan to dual use (second logged for now) on arducopter  (Something like these.)  Are there any pros or cons, electrical and signal quality wise, to soldering the antennas  at the edge of the pads instead of reflow soldering them on the boards with solder fully underneath? (The boards have four large pads at each corner). Hot glue/epoxy?

Also, is there any point in jacking up the update rate now with 10Hz on the 7M and up to 18Hz on the 8M? I know the accels and gyros can take care of it all in betweek refresh rates at 5Hz, but especially at high speeds (> 40ms, say), wouldn’t more frequent updates improve accuracy and be less error-prone?

 

[gervais]

Julien, the antennas you mentioned are single band GPS (center1575MHz) antennas and not designed for GLONASS.Bandwidth just 5MHz. Their bigger size doesn´t help.;-)

Active Dual band antennas mentioned in the u-blox hardware integration manual are heavy car types coming with an enclosure...

[Craig Elder]

John there is no point in going faster than 5hz unless you rewrite some of the control loops.
With the current setup you will gain more performance by increasing the precision of the GPS than you will by increasing the update rate.

On Jun 8, 2014 10:39 AM, "jdennings" <john.d...@live.com> wrote:

I have a couple of Neo 7m modules with separate patch antennas with about an inch of wire, that I plan to dual use (second logged for now) on arducopter  (Something like these.)  Are there any pros or cons, electrical and signal quality wise, to soldering the antennas  at the edge of the pads instead of reflow soldering them on the boards with solder fully underneath? (The boards have four large pads at each corner). Hot glue/epoxy?

Also, is there any point in jacking up the update rate now with 10Hz on the 7M and up to 18Hz on the 8M? I know the accels and gyros can take care of it all in betweek refresh rates at 5Hz, but especially at high speeds (> 40ms, say), wouldn’t more frequent updates improve accuracy and be less error-prone?

 

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[Ben Nizette]

.. or by reducing the latency. It might be interesting to see whether
changing the rate changes the latency (e.g. whether the unit
internally filters several successive samples if the output is not
requested at the solution rate) and if so, perform some hack along the
lines of dropping every second sample?

Ben.

[Julien Dubois]

Gervais,

the stock antenna installed with the M8 module is centered 1575MHz with only 10MHz bandwidth... so it doesn't no fit the Glonass Range neither:  1592.9525 MHz to 1610.485 MHz. It will be just a bit closer.
So, I was hoping extra gain would compensate it and give even better results.

But, anayways, now I have received the M8, I'll order the antenna I suggested and do some comparisons.

About dual-band, you're right, that would be ideal!
Julien

[gervais]

 Julien,

I did not receive mine yet. But I expected it to come with the CIROCOMM 605C which obviously looks different than the 1575MHz antenna of your first link.

Did you receive the antenna specs from CSG ?

CIROCOMM pages don´t reveal specs of the 605C type. 

Btw. I did experiments with a Navilock board which did not work well with a GPS patch for GLONASS. At that time I thought that this was due to GLONASS itself.  As far as I remember, Peter did as well. And according to his amazing results with the MAX-M8Q board, I just can´t believe that its equipped with a GPS single band antenna..

But if CSG told you,I have to. :-(

[Dom]

Hi

Sorry to add this here if it's not correct, but I thought it might be interesting to those following this thread.  I started flying my f450/pixhawk quad tonight with a Navspark-GL (GPS+Glasnoss) board as the primary GPS and the 3DR GPS/Compass as the secondary.  In the evening using the 3DR external gps/compass I usually get 8-10 satellites and often have to wait an hour or so for the HDOP to get down below 2.0 (sometimes it's good straight away and I usually get 1.8-2.0, sometimes I get 2.3-2.5 and have to wait a long time).  This is all in an open field.  This evening using the Navspark I got 21 satellites and an HDOP of 0.6.  I haven't worked out if/where the second GPS is logged to so can't see to compare in mission planner.  The Navspark cost $25 and weighs 2g (apparently, it doesn't register on my digital scales!), I power it with a tiny 300mah nanotech lipo that weighs 8g and cost less than a buck but could of course power it straight from the pixhawk gps socket.  I just like the fact that I can change main batteries and be ready to fly in seconds without having to wait for a cold start.  It also has quite a reasonable sparc cpu and lots of IO pins so has some interesting possibilities - I'm currently trying to port the taranis/x8r telemetry that is running on a teensy at the moment.

[Peter Plischka]

Hi there,

here is a quick comparison between a ublox M8N and a M8Q.
Both are mounted on a Hexa with PIXHAWK in the same amount.
GPS1 is M8N GPS2 is M8Q.

The N usually had two Sats more than Q.

    This will be due to the huge patch antenna  

.
I'm just flown between the houses.


regards Peter

[Craig Elder]

Peter

Have a look at the UBX1 and UBX2 messages in the dataflash log files.  Those two messages will give you the most information about the GPS.  You can find the details on how to interpret the messages in the ublox documnetation

--

[Craig Elder]

One more thing, you need to use the current Plane or Copter beta to have access to the messages.

Plane is nice because you don't need to arm the vehicle to have those messages logged.

[gervais]

Hi Dom,

looks great indeed. Did you use this antenna ?  http://navspark.mybigcommerce.com/internal-gps-glonass-active-antenna/

[Peter Plischka]

Thanks for the note, Craig. I'll be looking at the documentation.

I am a member of ArduCopter Tester Group and always fly the current master commit.

The M8N is certainly a great GPS.
Maybe Andrew can even view the log file. 


regards Peter

[Peter Plischka]

Craig.

 

I have today emailed with the Hannes Delago from the  ETH.
He is working on a driver rework for the PX4 Firmware . The M8 has a few other mesages.
His pull request can be found here:

https://github.com/PX4/Firmware/pull/1027

Maybe we could take over the.

At the moment ofsQ and magQ is not written in the log file.

regards Peter

[gervais]

Thx for comparing, Peter.

Obviously better.

Did you user the compass version of the M8N or the one without ?

BR

[Peter Plischka]

Kai, I have the version with the built-in Compass.

But I've been using the Honeywell HMC5983 on all Coptern with  better results than the Honeywell HMC5883L.

The M8N is has still a Honeywell HMC5883L installed.


regards Peter

[Craig Elder]

>>>At the moment ofsQ and magQ is not written in the log file. 

They are logged in the UBX2 message:

Please check 

https://github.com/diydrones/ardupilot/blob/master/libraries/AP_GPS/AP_GPS_UBLOX.cpp

static const struct LogStructure ubx_log_structures[] PROGMEM = {

    { LOG_MSG_UBX1, sizeof(log_Ubx1),

      "UBX1", "IBHBB",  "TimeMS,Instance,noisePerMS,jamInd,aPower" },

    { LOG_MSG_UBX2, sizeof(log_Ubx2),

      "UBX2", "IBbBbB", "TimeMS,Instance,ofsI,magI,ofsQ,magQ" }

};

--

[Peter Plischka]

Sorry, I have not seen it.
You're right, Craig .

regards Peter

[Randy Mackay]

Dom,

 

     The 2^nd GPS should appear in the GPS2 dataflash message.  It may not be available in AC3.1.5 though, you might need to move to AC3.2-rc2 which is available through the mission planner’s Beta Firmware’s link.

 

     The Navspark seems too good to be true (cheap, light and more accurate according to the hdop/num satellites).  My understanding is that the hdop is an estimate from the GPS itself so it may not be completely truthful or we at least may be comparing apples with oranges when we compare the ublox hdop with the navspark hdop.    Anyway, no need for me to be cynical too quickly, the proof will come when you’re able to compare the output more directly.

 

-Randy

--

[Xerr Avon]

Hi,

I just ordered 2 of the M8 GPS's I would like to use as a second GPS on my pixhawk but I am not finding any info on how to do it. Please if possible would someone point me to it if there is any?  I am guessing it goes in the serial port above the one labeled GPS on the pixhawk, is this correct?

I thought I remembered seeing some parameters for a second GPS but I just looked and do not see them now (running 3.2-RC2)  Will the parameters show up when a second GPS is connected?  do I need a different FW version?

thanks for any help,

John

On Saturday, May 17, 2014 10:03:37 AM UTC-5, Peter Plischka wrote:

Hi there,

attached a log file from a flight with a ublox M8 GPS and a 3DR ublox 6 GPS.

Between the houses a maximum of 13 Sats were achieved with the M8.
The ublox 6 had reached a maximum of 8 Sats.

The copter was very good in the air in hybrid mode.

The values ​​of ofsl ofsQ magl magQ look completely different than a ublox 6 

@ Paul
It was the version e924da4fec871ec5f0df4c786d9ef2d124f8e0b6  


regards Peter

[Randy Mackay]

Xerr,

 

     We currently only report the output from the 2^nd GPS in the dataflash logs, we don’t use it for navigation.

 

     We don’t have any documentation on how to plug in the 2^nd GPS but I think you’re right that it’s the Serial 4/5 port that should be used.  Also you should be able to use the standard DF13 6pin connector.  When it comes to figuring out which pins go where on the non-3dr M8 (‘cuz there isn’t a 3dr M8 yet), I have no idea, sorry!

 

-Randy

 

From: drones-...@googlegroups.com [mailto:drones-...@googlegroups.com] On Behalf Of Xerr Avon

Sent: June 13, 2014 9:33 AM
To: drones-...@googlegroups.com

--

[Jaime Machuca]

Hi, does anyone have a description of how the camera xml for Droidplanner works? I would like to add the GoPro to the list in Droidplanner.

Jaime Machuca Mercado

Sent from my iPhone

[Brandon Basso]

Hi Jamie,
The camera XML has sensor width and height in mm and number of horizontal and vertical pixels. We'll add a few of the GoPro models in the next release.

Brandon

[Xerr Avon]

Randy,

thanks for the info, I ordered the M8R, I think it is "R" the one with the compass so I will give it a try.   from the pic's the pinout is labeled on the board.

thanks again,

John

[Peter Plischka]

> We currently only report the output from the 2nd GPS in the dataflash logs, we do not use it for navigation.

Randy,

I think that's not true. As far as I know we switch to the second GPS when it has 2 Sats more than the first.

regards Peter

[Randy Mackay]

Peter,

 

     Yes, you’re absolutely right, sorry about that.

 

-Randy

 

From: drones-...@googlegroups.com [mailto:drones-...@googlegroups.com] On Behalf Of Peter Plischka
Sent: June 14, 2014 2:20 AM
To: drones-...@googlegroups.com
Subject: [drones-discuss] Re: First flight test with a ublox M8 GPS

 

> We currently only report the output from the 2nd GPS in the dataflash logs, we do not use it for navigation.

--

[Tom Coyle]

Hi Randy,

I have the second GPS (3DR uBlox LEA-6 v1.1) on my rover Pixhawk attached to Serial 4 using a DF13 connector/cable.

The rover firmware will presently use the GPS with the most number of satellites at any given time.

Regards,

Tom C ArduRover2 Developer

[Peter Plischka]

Here is a comparison of two M8 modules.
GPS1 is a M8N and GPS2 the M8Q.

The flight shows an autotune and fast flying.

The large M8N shows the best results.

By the way: The module with the helix antenna is not recommended.
Where the M8N gets 19 Sats, the helix modulegets gets only 5 Sats. Very poor.

regards Peter

[gervais]

Thx again for this comparison, and my saved bucks for the Helix, Peter.:-)

I have to order the M8N as well ;-), although the HDOP difference is not that big as I expected .

I was wondering, that the HDOP values of M8N are more inconsistent than than the slightly worser ones of the M8Q.

It might not matter (on that level), but did you notice this repeatedly ?

Did you choose the M8N without compass ?

BR,Kai

[Peter Plischka]

Hi Kai,

it was not a good day. We had high solar eruptions.
This was my second flight with the M8N. I'll be watching it.

regards Peter

[Ben Nizette]

Hi Peter,

I must admit that I haven't kept up with this thread but I have had a
quick look back through: Do you have a link to the particular M8N
module you're using? I presume that the M8Q module is the MAX-M8Q
module from CSGShop you linked to a while back?

I also just want to echo something Paul said ~60 messages ago, that
HDOP isn't necessarily a great thing to be comparing here. Strictly
speaking, HDOP is only a function of satellite position, it doesn't
have any measure of the absolute accuracy in it. If you've got two
modules looking at the same constellations at the same time then the
HDOP basically gives you no more information on relative performance
than the number of satellites does. Besides, once your HDOP is less
than two, and certainly less than 1.5, you've more or less won anyway
:)

It /might/ be better to actually look at the accuracy estimate fields
from the POS_{ECEF,LLH} messages as they should be the covariance
estimates from the internal filter, which is more or less what you
want. I haven't done or seen any characterisations to test their
reliability though, so YMMV!

Cheers,
Ben.

[Peter Plischka]

Hi Ben,

thanks for the info.

Both are Modeule of CSGShop.
http://www.csgshop.com/product.php?id_product=174

The POS_ {ECEF, LLH} message can I see only on the ground.
In the logfile it would be better.
The M8, however, is in any case an improvement.

On the same Place  the ublox 6 Module shows 7 Sats with HDOP 3.0 m.  

The  M8 shows 17 Sats with HDOP of 1.2 m.



regards Peter

[Ben Nizette]

Yes, the extra sats are a big deal, I was catching up on this thread
because I'm in China at the moment and the GPS geometry in this part
of the world is aweful. I'm going to order some M8's shortly for
exactly that reason.

OK cool, so you're running NEO-M8N and MAX-M8Q. I've actually have
interesting times comparing NEO and MAX before, quite apart from
whether they're flash or ROM memories. There seems to be some amount
of tradeoff in the RF front end integrity while packing in to the MAX
form factor (unsurprisingly!).

Anyway, thanks for the info, I'll order some soon!

Ben.

[Tom Coyle]

Hi All,

I received my M8Q GPS the night before I had to depart for the Sparkfun AVC in Boulder, CO so I was only able to see if I could talk to the GPS with the U-Center GUI.

I found that I had no problem communicating with the GPS and left additional testing to when I would return from the AVC.

I presently have the M8Q positioned about three feet from a small window in my town home, located in southern Florida, USA, and am experiencing an HDOP of 0.9 with 11 sats acquired.

The best that I have observed with my uBlox LEA-6s is an HDOP of 1.2 with 14 sats acquired.

I can just imagine an HDOP of <0.8 with probably around 18 sats acquired if I were outside.

I am presently using the uBlox default configuration file, but would like 3DR (Craig E) to come up with a configuration file to work with the Pixhawk.

Regards,

Tom C ArduRover2 Developer

On Saturday, May 17, 2014 11:03:37 AM UTC-4, Peter Plischka wrote:

[Alex]

same products available here on eBay.

the shipping is faster.

http://www.ebay.de/sch/csg_and_rc_extreme/m.html?_nkw=&_armrs=1&_ipg=&_from=

got the items within 3 days..

other question, regarding the configuration.. is it any reason to not using the default config? for now, its working fine on ground.

@peter: you wrote that only some settings are to be made in the config, but didnt find this settings, could you explain where this setting are to be made (ublox center / tab?)

many thanks!

Cheers,

Alex

[Roberto Navoni]

We have VRX GPS 8 available for pre order from tomorrow : )

https://plus.google.com/108932032205552825856/posts/UHLuQm7nhaY
best
Roberto

[Robert Lefebvre]

Does it have mag on board?

[Roberto Navoni]

Hi Robert,
sure have new magnetometer HMC5983 .. and support i2c and spi bus ...
so if you have a long cable ora have a lot of interference is not a
problem :)
best
Robeto

[Tom Coyle]

Hi All,

I have continued experimenting with the capabilities of the CSG M8Q and I may have identified a potential problem with the M8Q.

I have setup the M8Q with the following configuration parameters:

PRT (ports)	UART 1
	Protocol out	UBX
	Baudrate	38400
RATE (Rates)	Measurement Period	200 ms
	Measurement Frequency	5 Hz
NAV5 (Navigation 5)	Dynamic Model	Airborn 4G
	Fix Mode	3 - Auto 2D/3D
	Min SV Elevation	10 Grad
	DGPS Timeout	120 sec
SBAS	Subsystem	Enabled
	PRN Codes	EGNOS (EUROPE)
		120, 124, 126, 131

With the PRN Codes adjusted to "Other" and 120, 124,126,129, 133-134, 137-138 (3DR LEA-6 configuration file values)

Using this configuration there is definite glitching in the data stream being received by the U-Center as others on DIY Drones have reported Link

Changing the  Measurement Period back to 1000ms from 200ms cleared the data stream glitching.

Please be aware that I am doing my testing inside my house, but very close to a window with a view to the sky.

If the M8Q is not capable of operating at a Measurement Frequency of 5Hz, this may be a deal breaker in relation to using it with the Pixhawk.

Comments?

[Tom Coyle]

Hi All,

Since I am using U-Center, and not the MP connected to my Pixhawk which at boot up will send configuration parameters to the GPS, the reason for the data stream glitches, according to Craig Elder, is that the GPS is sending back unnecessary messages that are eliminated by the configuration parameters sent by the Pixhawk. The reduced number of required messages reduces the GPS transmission overhead thus eliminating the glitching.

Regards,

Tom C ArduRover2 Developer

[Tom Coyle]

Hi All,

It looks like I missed setting one configuration parameter that controls the messages sent by the GPS.

If you are using U-Center, you need to go to the Message View/MSG(Messages) and set UART1 On with a check in the box between "UART1" and "On" and put a 1 in the box to the right of "On"

I found this Message parameter setting in the 3DR LEA-6 configuration file.

The data stream appears to be pretty stable now in U-Center.

By the way, U-Center does not appear to convert UBX transmissions as far as HDOP and the number of sats.

Regards,

Tom C ArduRover2 Developer

[Jonathan Challinger]

1hz should be fine.

[Tom Coyle]

Hi Jonathan,

By setting the Message parameter to the same used by 3DR with the LEA-6 I was able to get the M8Q working smoothly, without data stream glitches, in either the NEMA or UBX (binary) mode at a Measurement Frequency of 5Hz.

Regards,

Tom C ArduRover2 Developer

[Roberto Navoni]

Hi Tom confirm , i'm using VRX GPS 8 with Ublox Neo M8 and i don't have problem ... all work fine no glitch and update at 5 hz 

[Xerr Avon]

Hi,

I just received the M8N with compass onboard. I am currently trying it on an APM25. I got the GPS working fine but the compass I am not having any luck with.

the header on the M8N is like the header on the 3dr GPS with compass (but no df13 connectors)  it is 5V, GND, SCL, SDA, RX, TX  I have the 5V, GND, RX and TX going to the GPS port  the I2C lines for compass I am just running SCL and SDA  to the I2C connector.

I know the 3DR GPS with compass, somehow handles the 3.3v for the I2C and works, so I thought this would work as well, but it does not seem to. 

does anyone know how to get this running on an APM25?  I havent tried on my pixhawk yet.

thanks,

John

[gervais]

Hi John,

PIXHAWK: CSG compass works with the PIXHAWK with SDA SCL only. (Since the 3.3V for the HMC are coming from an onboard LDO, it doesn´t need a sep. source)

APM: Since my M8 is already encapsulated, I can´t check the CSG board, but its sounds like there are pullups mounted on the output lines. Usually the APM level translator doesn´t get along with pullups (e.g.4.7k resistors) going from the output lines to 5V. If they are present, just remove them and it will work.

[Xerr Avon]

Thanks, I will check it out. I have it working on the apm with a separate compass board. I did get t working on the pixhawk with no problem.

On the Pixhawk with the compass on the  M8N the compass offsets are pretty high, higher than the 3dr gps compass in the same location and the magnetic interference is quite a bit lower. It is like it is not seeing the interference. 

In the same mounting location with a 4S the 3DR GPS was reding about 10% interference, the M8N was showing 0% or close to it.

**********************************************************

M8 compass
COMPASS_MOT_X,-0.02417866
COMPASS_MOT_Y,-0.06758815
COMPASS_MOT_Z,-0.03742902

COMPASS_OFS_X,-266.5963
COMPASS_OFS_Y,6.11928
COMPASS_OFS_Z,-257.6744

*********************************************
3DR GPS with compass
COMPASS_MOT_X,0.05558018
COMPASS_MOT_Y,-0.1073401
COMPASS_MOT_Z,-0.03237339

COMPASS_OFS_X,-33.80017
COMPASS_OFS_Y,33.18163
COMPASS_OFS_Z,58.92382



As far as the GPS, I am seeing much better results with the M8N, it loiters dead still, I had a little walking around with the 3dr GPS, I think it has a lot to do with the location. But still with the 3DR GPS I would usually get 11 sats (most I ever saw was 14, and just briefly) and was lucky to see  HDOP of 1.5.  with the M8N I am getting 17 or 18 sats right away and HDOP of 1.0 to 1.2.

John

[gervais]

Well, I am not able to compare compassmot results, since mine vary already @ slight changes, throttle input ...As long as the mast is high enough, I don´t really care. Concerning mag sensors..bought a lot which where DOA or didn´t work well, some are doing fine sort of cheap parts lottery. And I agree: The M8N works great, incredible fast fix, great reception, just a little big @ my  experimental  F450 ;-) Guess I´ll use the 3DR case with the tiny M8Q and sep. mag BOB.

http://s7.directupload.net/images/140706/hvb9nw3h.jpg

[Brian DeBusk]

Could someone please do a detailed walkthrough on where to get and how to configure the M8?  And does it have a version that comes with a compass (or does it come with a compass anyway?)

It would be a good starter exercise for me to learn how to integrate new hardware like this.

[Tom Coyle]

Hi Brian,

The CSG GPS comes in several different flavors:

M8Q which has an active antenna, but I have been told that the firmware is in ROM and is not updateable.

M8N which has a large passive antenna, but the firmware is updateable. The M8N appears to come with and without the compass.

I programmed my M8Q using U-Center and manually setting up the configuration based on looking at the 3DR configuration parameters downloaded from a 3DR GPS/compass module.

You will have to make custom cables to connect the GPS to an FTDI cable for programming and to mate the GPS to the 6pin DF13 cable for use with the Pixhawk Serial 4/5 port.

Regards,

Tom C ArduRover2 Developer

On Sunday, July 6, 2014 10:52:21 AM UTC-4, Brian DeBusk wrote:

[Brian DeBusk]

Perfect!

What do you think of this idea:

1) I order one of these:  http://www.csgshop.com/product.php?id_product=173

Question:  Do I need to order and antenna for it as well, or is it integrated into the module?  Am I ordering the right module?

2) Then I use the U-center software to configure the M8 to act like the 3DR GPS module.  Basically I'm not changing any of the Pixhawk code, but I am making the M8 act like the existing Pixhawk compass.

I have FTDI cables here at the house, so that part shouldn't be hard at all.

3) Then I cut a Pixhawk four-pin cable and connect it to the I2C port of the M8.  I'm guessing I'll need to configure the M8 to output the compass data on the I2C port.

4) Then I cut a Pixhawk six-pin serial cable and connect it to the M8's serial port.  I'm guessing the GPS location data is passed to the Pixhawk via the serial port.

Am I on the right track?

Thanks in advance,

Brian

[Brian DeBusk]

It looks like the module I referenced has a USB port on the side.  Does that mean it plugs into U-Center directly?  Will I even need a FTDI cable or will U-Center connect directly to the board?

[Tom Coyle]

Hi Brian,

Yes, you are on the right track.

No need to buy an antenna for the M8N as it is included on the GPS module. It is the white square in the middle of the module.

Regards,

Tom C ArduRover2 Developer