I use ground control points and log events from the shutter output signal as well as PPK. My GCP’s are not as useful in the wetlands I fly since dry land access is extremely limited. In practice, not all of the events get logged to the Reach RTK for unknown reasons (perhaps the output pulse has issues). Because of that, I collect PPK data so that I then can match up the GPS times from the images to the sUAS path. We use a Micasense Rededge/Altum camera with their light sensor which geotags images using its own GPS.
Agree 100%. For most of our uses the single band has been excellent for terrestrial (land) surveys though we occupy a site for for approx. 10 minutes of static GPS logging while collecting other data. The general terrain of my study areas are pretty open (aside from canyons) and not a whole lot of tall vegetation to create problems (Utah is mostly desert).
If you already have a Here3 then I’d use it on board. I have a Here2 for nav because of cost and availability at the time I ordered parts. My previous build had a generic M8N which was also fine. Either version of the Here will work fine for logs and nav. You’ll have PPK from the EMLID which will be easier to work with than location data from a flight log. You could do a flight path comparison of the two, but ultimately it will come down to the processing software you use to create the final orthomosaics. If you have good coverage (overlap) then the precision/accuracy of the center of each image is less of an issue especially when you have GCP’s and good software.
I’d only use GCP’s with PPK to check the final orthomosaic or as a safety net if one of the two methods fails. If terrain/access is prohibitive regarding GCP’s, then PPK or RTK are really your only options.
Happy to take a look at your draft schematic, I could update and share mine now that wiring is complete. I like the idea of having power redundancy and not just a spare BEC because if the battery fails then it won’t matter. I am still on the fence in deciding to use the VTOL LiPo battery as a backup to the primary Li-Ion battery or keep it separate and just monitor the voltage/current. I need to look more closely at the battery failsafe parameters and wiring connections before I try it.
If you find any good info on common signal, let me know. I’ve seen chatter but not explicit details. This is the most detailed post regarding double battery (power) I have found thus far: "DoubleBat" Power Supply For Quadplanes - #29 by Rolf
If you have a proven airframe then it’s easy to add components to it to test (most of the time). Building a new airframe you still have to get to the point of airworthiness so maybe it comes down to cost of repairs if a test flight has an “unexpected landing” and needs fixing?
Cheers,
Christian