piksi_multi_rtk_ros

[Daniel Reilly]

After some difficulty, I installed piksi_multi_rtk_ros from https://github.com/ethz-asl/ethz_piksi_ros.  At first it would not install.  I forget how I discovered it, but after I did a

$ cd swift_ws/src/ethz_piksi_ros
$ git checkout v1.11.0

I was able to get it to work... I think.

Does anyone understand the list of satellites that are displayed by the /piksi_multi_base_station/debug/receiver_state topic?

For example, after "sat" it displays an array of what I assume are satellite identification numbers, but the funny thing is that the same ID can appear multiple times in the list.  Can satellites have non-unique IDs?

I'm trying to figure out whether my base station sees enough of the same set of satellites as the rover.  

Thanks!

-- Dan

[Jeff Sampson]

Whoops!! That was supposed to go to everybody...

===========================

I haven't used Piksi Multi in several years, but...

I wouldn't start with a/the ROS driver. I used the "standard" ROS driver (whatever was supported by SwiftNav). Start with the bare receivers and the debug software provided by Swiftnav. Verify your base station is receiving satellites and giving you a single point fix. Then verify your rover is receiving satellites and giving you a single point fix. Then with your base powered up and transmitting over the radios (I assume you bought the complete kit from SwiftNav) verify your rover is receiving the correction data and providing an RTK fix. It should be holding within a few centimeters. If it is, then you can go to a ROS driver. If not then figure out why it is not working.

To your question "Does anyone understand the list of satellites that are displayed by the /piksi_multi_base_station/debug/receiver_state topic?

For example, after "sat" it displays an array of what I assume are satellite identification numbers, but the funny thing is that the same ID can appear multiple times in the list.  Can satellites have non-unique IDs?" I don't recall that ROS message. Maybe because we were using a different driver. 

But you can see a satellite listed more than once. A typical satellite, let's say there is one called GPS-3, it can be listed as GPS-3 L1, GPS-3 L2 and maybe GPS-3 L5. And Galeleo and Glonass can have several bands that they transmit on, so they can also be listed multiple times.

If you are questioning if the same satellites are being seen, you are probably chasing a different problem.

As long as both receivers are relatively close together and both have a clear view of the sky, then they should both be seeing mostly the same satellites.

You don't say where you are from but your email indicates you are in Illinois. You can check to see if you can get free correction data in your area. If nothing else, just as an alternate debug method. If you can get free correction data and you can feed that into your rover as a test.

https://duckduckgo.com/?q=cors+coorection+data+illinois&t=canonical&ia=web

I use free CORS correction data from Minnesota Department of Transportation on a ArduSimple F9P receiver.

- Jeff Sampson

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