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faq.md

@@ -62,8 +62,21 @@ cable. This system has been traveling through several metrology labs
 where it has been verified to be stable at the 1ns
 level.
 
-### What is the impact of the Ionosphere on the accuracy of the time transfer?  
-Geodetic receivers are able to decode the so-called ionosphere-free code (P3), which is transmitted over the L1 and L2 carriers. Notice that L1 and L2 are two different frequencies. As ionospheric delay changes affect differently L1 and L2, it is possible to calculate an additional correction to the ionospheric delay model. Additionally the common view technique helps reducing the impact of ionospheric delays on baselines at the 800 km level, by selecting satellites which are visible simultaneously by both base stations. On top of that, the use a cesium atomic clock allows for additional filtering of daily delay oscillations. Once all these techniques are applied the overall impact of ionospheric delays is inferior to 1ns. See [USE OF GEODETIC RECEIVERS FOR TAI](http://tycho.usno.navy.mil/ptti/ptti2001/paper35.pdf) by P. Defraigne, G. Petit and C. Bruyninx.
+### What is the impact of the Ionosphere on the accuracy of the time transfer?
+
+Geodetic receivers are able to decode the so-called ionosphere-free code
+(P3), which is transmitted over the L1 and L2 carriers. Notice that L1
+and L2 are two different frequencies. As ionospheric delay changes
+affect differently L1 and L2, it is possible to calculate an additional
+correction to the ionospheric delay model. Additionally the common view
+technique helps reducing the impact of ionospheric delays on baselines
+at the 800 km level, by selecting satellites which are visible
+simultaneously by both base stations. On top of that, the use a cesium
+atomic clock allows for additional filtering of daily delay
+oscillations. Once all these techniques are applied the overall impact
+of ionospheric delays is inferior to 1ns. See [USE OF GEODETIC RECEIVERS
+FOR TAI](http://tycho.usno.navy.mil/ptti/ptti2001/paper35.pdf) by P.
+Defraigne, G. Petit and C. Bruyninx.
 
 If needed, the time transfer could still be improved by adding a
 posteriori knowledge of the satellite orbits, atmospheric delays and GPS