The graph below shows the telemetry from the on-board GPS over three orbits. The bottom trace indicates a valid "lock"; the yellow trace the number of satellites tracked; and the top three traces the X,Y,Z position vectors.
In a perfectly circular orbit, the satellite velocity would be constant. In a near-circular orbit (as is the case with Sumbandila), the velocity fluctuates slightly between a minimum at Apogee and a maximum at Perigee. This effect is clearly visible in the measured velocity data from the GPS (see below). It shows a difference of 30m/s between Apogee and Perigee. Also note the very low level of "noise" on the measurement.