I think the issue may be getting it to reliably output 5Hz. The phase lag in the log output above suggest to me that the update rate is likely 1Hz.
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Does this look like a Ardupilot issue (NMEA 5Hz)?
Dennis
No. It looks like a GPS module config issue.
Ok why the Lag from GPS.Lng to POS.Lng(about 1Sec.). Isn’t GPS.Lng direct from NMEA data?
Dennis
EKF estimates position between “truth data” updates. If data is updated infrequently, the EKF estimate may be imperfect (it’s using accel/gyro data, predominantly, which is a very imperfect source).
As with any filter, it takes time to converge to a solution. This prevents “step changes” in position, which, if unchecked, could lead to erratic behavior.
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Any correlation to what this poster was reporting? He doesn’t say which module it is. Last post.
NMEA GPS
It’s difficult to come to a conclusion with your data, since we don’t know what the true motion was. Ideally, the GPS would be stationary, and then to measure lag, you pull it in a certain direction rapidly. In the logs, you can then look at the moment the drone perceives an acceleration, and the moment the GPS perceives an increase in velocity.
But without exactly controlling the motion (flying the drone is not controlling the motion, if the drone is swaying uncontrollably), it is impossible to conclude on lag or accuracy of the GPS.
Indeed, I’m only making an educated guess based on the limited information presented.
It would be very easy to confirm my suspicions by directly observing serial output from the GPS.
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I think your observation that it’s not supplying any of this data and the unstable rate that the data is sent would lead one to believe the module protocol is problematic for Ardupilot:
While I do kind of expect that cheap hardware will produce cheap results, it’s a little early to write this one off entirely. I want to see more methodical configuration details and subsequently well controlled testing. If no one else achieves that, I may give it a try later this summer. I hesitate to take that on right now - my schedule is packed!
The GPA.HAcc - GPA.VAcc are all zeroi all the time.
I can post a link to the log file if you want?
Link to log file:
https://www.dropbox.com/scl/fi/w6i4ujupjblj6zpmthfxj/2024-05-28-08-14-28.bin?rlkey=vz31zzabm4ck3hgv95awj5vs2&st=a8pkitsp&dl=0
can you connect it to a different serial port, serial 6 can get funny with high speed serial data.
What we really need are the exact configuration details (of the GPS module, not ArduPilot) and confirmation that your 5Hz command actually took effect, along with timestamped serial output from something like RealTerm showing the NMEA sentences that are being sent (with good GPS lock).
Perhaps @Rolf could be of help with this as well.
Here is a set of commands that given to me to use that i used.
$PAIR003*39 → power off GNSS system
$PAIR512*3C clear data
$PQTMRESTOREPAR*13
$PAIR514*3A
$PAIR513*3D save file system
$PAIR023*3B reboot module
$PQTMGNSSSTOP*09
$PAIR007*3D → Full cold start will performs a cold start and clears system and user configurations
$PAIR023*3B reboot module
$PQTMGNSSSTOP*09
$PQTMCFGRCVRMODE,W,0*2B set receiver to unknown mode
$PAIR062,-1,1*13 (all Nmea sentences)
$PAIR063,-1*0F resp.: $PAIR063,-1,1,1,1,1,1,1*0F return NMEA output to default settings (all Nmea sentences)
$PAIR050,200*21 → set pos output interval to 200 ms 5 Hz
$PQTMCFGMSGRATE,W,PQTMEPE,1,2*1D how accurate is the obtained position
$PQTMCFGNMEADP,W,3,8,3,3,3,3*39 -->configure ALL to 3 decimals
$PQTMCFGMSGRATE,W,PQTMPVT,1,1*1C Outputs the PVT (GNSS only) result
$PAIR862,0,0,37*1E Set GNSS port data type configuration to nmea+command in & out only
$PAIR058,35*1D snr treshold to 35 if in open sky or $PAIR058,15*1F snr treshold to 15 if problem
$PAIR070,1*20 Sets the static navigation speed threshold to 1dm/s = 0.1m/s
$PAIR072,15*17 elev mask to 15°
$PAIR074,1*24 Enable active interference cancellation function
$PAIR080,5*2B Set navigation mode for drone
$PAIR391,1*2C enable jamming detection message output
$PAIR400,2*20 for sbas DGPS correction data source mode
$PQTMCFGMSGRATE,W,PQTMGEOFENCESTATUS,1,1*5C enable GEOFENCE outputs
$PAIR473,1*27 Enable EPO data aiding & limits saving the flash range to 80K.
$PAIR092,0*2D set **non static** mode
$PAIR753,1*26 enhance the PPS output timing accuracy
$PAIR513*3D save file system
$PQTMSAVEPAR*5A
$PAIR023*3B
Dennis
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Does the following command give a response?
$PQTMCFGFIXRATE,R*71
I would have done it already if I hadn’t fallen for the misleading advertising of one of the Aliexpress sellers (My module was advertised as a Quectel lc29hea with 10 Hz updaterate and these “Color”-choice has only the option of choosing a module with or without an antenna. What I get was an EC29HDA that only has a 1 Hz update rate ! I have written to the store asking what they suggest - before opening a Paypal case out of it)
I have ordered an EC29HEA from somewhere else, but it won’t arrive for about next week.
Rolf
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I just ordered one from presumably the same eBay listing as used above. I will likely not have time to test it for several weeks, even if it arrives quickly.
Yes
$PQTMCFGFIXRATE,OK,200*39
With the latest firmware it does 5Hz
As you see here:
$PQTMCFGFIXRATE,OK,200*39
It is shipped USPS! Thanks
Dennis