Low Cost, High Performance RTK Module from Tersus

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- Tazmoe > Darius Jack February 3, 2016 at 6:01pm
  
  Darius,
  
  My understanding of Ublox units is they are only L1 type systems to get to centimeter type measurements requires a L1, L2 GPS capable units. That is why I was recommending logging the positional information because this system is L1, L2 which should increase the ability to get higher accuracy positional data.
  
  Robert.
Tazmoe February 3, 2016 at 5:30pm

I would recommend that you support the RINEX format logging for your unit. (https://igscb.jpl.nasa.gov/igscb/data/format/rinex210.txt ) for the purpose of being able to get an exact fix of the unit used as a base station. Here in the US we have the OPUS service (http://www.ngs.noaa.gov/OPUS/) that will give precise coordinates from a log file that from a base station that has spent 2 to 3 hours on the same spot by post processing the logged data. With this ability your product could compete with much more expensive systems. Without this ability your system can't be used for real world problems that require the ability to obtain a precise position of the base station location after the mission has been flown. Such as getting volumetrics from quarry stock piles at locations that don't allow for surveyed control targets to be placed in the work environment.

Thanks,

Robert
- Tersus GNSS > Tazmoe February 4, 2016 at 3:02am
  
  Robert, Cioro
  
  It's great to know what requirements is critical for field operation. We are working on logging the rinex in PRECIS L1 and L2 observations. Currently we plan to support the PRECIS UART output soon, end user need to attach a device/ PC to receive/log the raw data.
  
  In our new L1 only platform PRECIS -2 board, we have 32G SD card on board . So it's easy to log the raw data for several days.
  
  Thanks,
  
  Winston
  
  Tersus-gnss Team
  - Cioro > Tersus GNSS February 4, 2016 at 3:54am
    
    @Winston
    
    Thank you for your feedback.
    
    Currently we're mapping some area with swamps using a multicopter. I think you can imagine what kind of effort we spend in getting the GCP's.
    
    So as soon as you get RINEX raw data out from your receiver and stored it on board, please make the announcement here or on your website.
    
    It is also important to store data on board (128 Mb is enough space to store 10-15 hours of observations at 0.5 sec recording interval) because RINEX raw data stream have to be perfectly continuous (even one missing epoch can affect the postprocessing). You can store the data directly in the onboard memory and the user can download the RINEX files after each landing through BT/USB cable/WiFi. Also please consider that in order to get a good carrier phase data you need a high quality antenna and good filtering (which can be acquired from the market).
    
    We are very close to hack a GPS Magellan Promark 500 to install it on multicopter but because of the considerable weight (>600g) we had to build another platform to support it so we postpone the project.
- Cioro > Tazmoe February 4, 2016 at 2:37am
  
  Totally agree with Robert, everyone is focusing to get RTK fix which is very important for navigation but for mapping what is very important is to get cm precision to the positions from where the pictures has been taken and this can be easely obtained if we have a GPS (even L1 GPS only is enough) that is logging RINEX data using a survey postprocessing software.
  
  Currently no GPS unit built for UAV's doesn't support onboard RINEX logging and to hack a few thousands $ survey grade GPS receiver (in order to reduce weight) doesn't look like a good choice.
  - Rick Hwang > Cioro February 4, 2016 at 4:29am
    
    Is there any advantage to logging in RINEX format directly by the RTK receiver than logging in more compact raw data binary format and later convert to RINEX on a laptop?
    - Cioro > Rick Hwang February 5, 2016 at 3:34am
      
      I didn't mean to store the raw text files directly, binary format is the way.
Ned Clark December 17, 2015 at 3:54pm

I would like more information on this please.
Ned
ark@netspace.net.au
- Hullam Nagy > Ned Clark December 18, 2015 at 1:23am
  
  Hi Ned,
  
  I have a Pixhawk and sincronised camera and Ublox GPS. The Pixhawk is connected to mobile phone with Android op. by BT.
  
  I plan to change the Ublox to a more precise GPS with RTK. (It would be good if I have an exact heading too.)
  
  On the phone with mobile net, I will have the RTCM data. How can I send it to the GPS on a simple way?
  
  (the mobile and the pixhawk is close to each other, so BT is a good way to communicate)
  
  Thanks,
  
  N Steve
Rick Hwang December 15, 2015 at 9:43pm

When using PRECIS-B01 in region where there is nearly no Beidou satellites, US for example, without GLONASS L2, would having 6 ~ 10 GPS L1/L2 + 5 ~ 9 GLONASS L1 satellites still achieve 1 minute RTK fix? If not, how would RTK fix time vary?

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Low Cost, High Performance RTK Module from Tersus

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