PPK: Pixhawk + simpleRTK2B + EXTINT + Antenna

Q&A forumPPK: Pixhawk + simpleRTK2B + EXTINT + Antenna
EarthImage asked 1 month ago

Howdy, I’m going to start trying to integrate a simpleRTK2B into one of my Pixhawk mapping drones for doing PPK surveys. I wish there was some documentation for this! Anyways, a few questions:

  1. Antenna – Is the new “Lightweight Helical Antenna” the best solution for either a copter or plane setup?
  2. Logging UBX – I’m wondering what the simplest method for logging raw data is? I have experimented with a Pi Zero W using str2str (RTKLib) and that works. I’m just wondering if there is a simpler way. I just need something that will start logging ubx when the gps boards is turned on.
  3. EXTINT Pin – Is this working reliably to embed timestamps equal to shutter events? I’m wondering about the message posted by gedizman (https://www.ardusimple.com/question/extint-inconsistent-timestamp/) and the response from ArduSimple that the length of the trigger cable might be causing issues (multiple timestamps for a single trigger event). Any suggestions for a good cable setup to get reliable timestamps?
  4.  Can the simpleRTKBlite be used to log raw data?

I’d be interested in knowing if anyone has successfully integrated a simpleRTK2B with a Pixhawk for conducting PPK surveys.
Thanks, Peter

Ardusimple Staff replied 1 month ago

1. It’s the lightest, but not the best performing. But might be enough for your project.
2. Easiest is openlog logger connected to serial port. We are working on a plug-and-play solution for datalogging, but will be available only in February.
3. Add an RC filter on your cable very close to the board. We are adding this filter by default in the upcoming simpleRTK2B.
4. Only if you connect to the bottom XBee header. The top xbee receptacle only supports NMEA and RTCM.

2 Answers
EarthImage answered 4 weeks ago

ArduSimple:
Can you provide some details on what type of RC filter should be added to the cable? What components would one need to make a filter?

Ardusimple Staff answered 4 weeks ago

Something like this, with R=100 ohm and C=0.1uF to have a characteristic time of 20uS. Vc connected to your trigger, Vi connected to simpleRTK2B board:
https://upload.wikimedia.org/wikipedia/commons/thumb/e/e0/RC_Series_Filter_%28with_V%26I_Labels%29.svg/1024px-RC_Series_Filter_%28with_V%26I_Labels%29.svg.png