As above said Satellite.IsActive is not set to True.
Yes, by commenting the below code in OnPaintOffScreen satellites are displayed.
//if (!satellite.IsActive && !DesignMode) // continue;
These lines are used in 3 locations in the same event.
Set the SatelliteView1.satellites in the nmeaInterpreter1_SatellitesChanged event.
Thanks for your inputs, helped me to achieve the requirement.