GNSS Base Stations

RTK

The Astro and later versions of the Alta X come pre-integrated with a Freefly RTK unit. Just add a Freefly RTK GPS ground station (sold separately) to enable centimeter-level positioning data.

PPK

Generally, PPK can be performed with RINEX output from any GNSS base station that records at minimum L1 and L2 GPS observations (see Section 1.3 of the u-blox ZED-F9P datasheet). However, photo geotag accuracy after PPK corrections is limited to the accuracy to which the base's position is known. Therefore, it may be worth purchasing a base with additional capabilities (e.g. SIM for CORS RTK, receives more channels, advanced multipath processing, etc) when you cannot put the base on a pre-surveyed GCP.

For the base stations listed below, the settings and procedures provided will ensure output is compatible with the Precise Flight PPK app. The PPK workflow can be found here.

Emlid Reach RS2

Manufacturer's Page - Manual - Support

First time config

Configures output to be compatible with Astro.

• Follow Emlid's quickstart procedure.

• Install SIM card (optional).

• Open ReachView 3 app (iOS or Android). Connect to RS2. via wifi and open the Reach Panel (192.168.42.1)

• Logging > Raw Data > Settings:

  • RINEX 3.03

  • Satellite systems: check all

  • Logging Interval: 1s

  • This log is for OPUS: Checked

  • Measured height, m: [Height of your pole]

  • Automatically start recording when receiver is turned on: Optional. We use this.

• Logging > Position > Settings:

  • Automatically start recording when receiver is turned on: Optional. We use this.

• Logging > Base Correction > Settings:

  • Automatically start recording when receiver is turned on: Optional. We use this.

• Correction input (optional, requires network connection via wifi or cellular). This is not necessary for high accuracy results, but a live correction feed will allow another avenue of finding the GPS's position to high accuracy. With network corrections, the GPS absolute accuracy should increase to cm level.

  • Enter credentials.

Setup

Perform this procedure before flying Astro.

• Install Reach R2S on pole.

  • Optional: Position pole over GCP

• Power on RS2. Make sure booting is complete (LED status) takes about a minute. It will begin logging automatically.

RINEX Download

• Connect to RS2 via wifi

• Open EmlidView 3 app. Logging.

• stop logging if its running

• Download the RINEX file and the pos file if desired.

Trimble R2,10,12

Follow manual to enable recording either on boot or on demand. To download the data, stop recording, then go to the data store and select the correct file. Pick the option to convert and download and choose observables and ephermis, and RINEX 3.03 or 3.04 format.

(More details coming soon)

Known Issue: When you click Convert & Download, the Trimble crashes. You can only download without converting for now. Jeremy thinks it might be because of low storage space and reseting might help. Let's give it a shot.

Tersus Oscar

Use the NUWA app and connect to the Tersus Oscar. Go to SURVEY tab, and select static survey. Enter the duration to be max (1440 minx), interval 1hz, RINEX format 3.04, select mount type, and enter the antenna height on the given mount. Select start, and make sure the timer starts counting.

When done, reconnect with the NUWA app and go back to static survey, and then stop the recording. Use a USB-mini cable and plug into the bottom of the unit. Download the rinex files from the RECORD virtual USB drive that appears.

Internal GPS

Astro uses the uBlox F9P as its internal GPS unit.

Datasheet