LS Time System and Variety parameter

Nistorescu Sorin

Active Member
What could be the behavior of the LS plus GNSS receiver with four engine configuration and Variety, in the unlikely event like the one in January 2016, when a software upload to US GPS satellites induced a 13-microsecond misalignment? Also jamming or interference in the GPS L1 or L2 bands could make some trouble as well as other kind of "bad events" so, we need to put the actual quad constellations environment to a good use. It is all about the time and for the moment I think LS plus uses only GPS reference time with GLONASS time as (a difficult) alternative, as we can see:
LS plus Time System setup tab.png

Galileo System Time (GST) becomes essential for accurate positioning and it is determined using a set of active hydrogen maser atomic clocks. It is also required to be kept in strict agreement with the international reference time, Universal Time Coordinated (UTC). Current GPS to Galileo time offset (GGTO) needs to be passed to users through the navigation signal to an accuracy of 5 nanoseconds or less, as far as I know. Also BeiDou Time (BDT) is a continuous time scale synchronised with UTC.

User receivers must have alternatives for the continuity of operations, by complementing GPST or GLONASST with GST or BDT as time references and I think this could mean "true Variety" as a totally uncorrelated measurements parameter in the field. But probably it is very difficult to make a single receiver with four super engines, each engine calculating positions with separate signals/time scale provided by GPST, GST, BDT or GLONASST respectively, or a combination with up to three of them.

LS plus_4 engines with 1.3 Variety setup.png

Well, never say never at Javad GNSS.

Nistorescu Sorin

Active Member
It should work. Adding an atomic clock inside the receiver will help a lot in urban/forest canyons, also improving the time to get a fix from (fewer) satellites, anti-jam immunity, battery power consumption, etc. Someday, an atomic clock might even fit into our smartphones.

For the moment, we should be able to get some use of the Galileo and Beidou System Time into all Javad receivers as a backup for GPST. My (2500 EUR, homemade) GNSS receiver works with GST since the beginning of 2021.

Jim Campi

Active Member
What happens when my LS is traveling near the speed of light? It sounds like it's going to lose its way home.

I know, not funny.