Hi everyone! Another update from us:

As you may know, the goal of this project is to implement a SUPL-compatiable AGPS assistance server. Now, there are some unexpected technical challenges here that I felt were enough to announce here given that they are basically blocking a lot of testing and development:

  • SUPL uses ASN.1. This is okay, there are open-source ASN.1 toolchains, but the one we were using (python-asn1tools) seemingly does not properly decode some messages from modern devices. This is a problem, as any decoding errors are, from its perspective, fatal.
  • Most other ASN.1 toolchains are not featured enough to get close to properly being able to compile the ASN.1 specification for SUPL. There is asn1c, but it is old, and seemingly has problems compiling for me (that or I just couldn’t get it to work properly myself), and I would also personally rather use a programming language like python for things like this.
  • I wasted a lot of time trying to get the python library to work (I am not super experienced with ASN.1, so I was mostly trying stuff, hoping that it would start working), and a lot more time to being demotivated from it

This means we are (temporarily!) going to try something else: making our own assistance protocol. We already had ideas of doing this - ASN.1 may be standardized, but if someone wants to implement something using it, it can be a huge pain, compared to something like protobuf, or even JSON-encapsulated messages. Hopefully, I can wire something simple up soon, but don’t expect anything too quickly, since any protocol I hammer together will likely be based around the best way to sideload AGPS data into the testing devices I have (basically, a Fairphone 4, and a Volla 22), and I’ll need to look into how to best do that (any help with that is welcome, as always!).

If you are interested in potentially hosting a GPS base station - or are in a position to otherwise contribute GPS frame data - feel free to contact me, my contact info is on my GitLab page..

As always, any updates to code will be posted onto the OpenAGPS gitlab page..