gr-satellites roadmap

In my talk at GRCon19 last week I presented the roadmap I have planned for gr-satellites for the next months and some longer term developments. The relevant slide can be seen below.

gr-satellites roadmap in my talk in GRCon19

Here I will describe the roadmap in more detail, including how certain things will be done (or how to find your way among the different releases and branches in the Github repository), in order to get feedback from the community.

Ephemeris quality during the Galileo outage

I have spoken about the Galileo incident that occurred in July in several posts already: here I took a look at the navigation message during the outage, here I used MGEX navigation RINEX files to look at the navigation message as the system was recovering, and here I did the same kind of study for the days preceding the outage. Other people, such as the NavSAS group from Politecnico di Torino, and Octavian Andrei from the Finnish Geospatial Research Institute, have made similar studies by looking at the \(\mathrm{IOD}_{\mathrm{nav}}\), data validity and health bits of the navigation message.

However, I haven’t seen any study about the quality of the ephemerides that were broadcast on the days surrounding the outage. The driving force of the studies has been whether the ephemerides were being updated or not, without taking care to check if the ephemerides that were broadcast were any good at all.

The NavSAS group commented seeing position errors of several hundreds of metres during the outage when using the broadcast ephemerides. That is to be expected, as the ephemerides were already many hours old (and indeed many receivers refused to use them, considering them expired). Here I will look at whether the ephemerides were valid (i.e., described the satellite orbit and clock accurately) in their time interval of applicability.

This post is an in-depth look written for a reader with a good GNSS background.

Measuring the ED4YAE 10GHz beacon

Last week, the 10GHz beacon ED4YAE on Alto del León was installed again after having been off the air for quite some time (I think a couple of years). The beacon uses a 10MHz OCXO and a 500mW power amplifier, and transmits CW on 10368.862MHz. The message transmitted by the beacon is DE ED4YAE ED4YAE ED4YAE IN70WR30HX, followed by a 5.8 second long tone.

On 2019-08-31, I went to the countryside just outside my city, Tres Cantos, to receive the beacon and do some measurements. The measurements were done around 10:00 UTC from locator IN80DO68TW. The receiving equipment was a 60cm offset dish from, an Avenger Ku band LNB, and a LimeSDR USB. Everything was locked to a 10MHz GPSDO. The dish was placed on a camera tripod at a height of approximately 1.5 metres above the ground.

In this post I show the results of my measurements.