Class InterSatellitesRange

  • All Implemented Interfaces:
    Comparable<ComparableMeasurement>, ComparableMeasurement, ObservedMeasurement<InterSatellitesRange>, TimeStamped, ParameterDriversProvider

    public class InterSatellitesRange
    extends AbstractMeasurement<InterSatellitesRange>
    One-way or two-way range measurements between two satellites.

    For one-way measurements, a signal is emitted by a remote satellite and received by local satellite. The measurement value is the elapsed time between emission and reception multiplied by c where c is the speed of light.

    For two-way measurements, a signal is emitted by local satellite, reflected on remote satellite, and received back by local satellite. The measurement value is the elapsed time between emission and reception multiplied by c/2 where c is the speed of light.

    Since 9.3, this class also uses the clock offsets of both satellites, which manage the value that must be added to each satellite reading of time to compute the real physical date. In this measurement, these offsets have two effects:

    • as measurement date is evaluated at reception time, the real physical date of the measurement is the observed date to which the local satellite clock offset is subtracted
    • as range is evaluated using the total signal time of flight, for one-way measurements the observed range is the real physical signal time of flight to which (Δtl - Δtr) ⨉ c is added, where Δtl (resp. Δtr) is the clock offset for the local satellite (resp. remote satellite). A similar effect exists in two-way measurements but it is computed as (Δtl - Δtl) ⨉ c / 2 as the local satellite clock is used for both initial emission and final reception and therefore it evaluates to zero.

    The motion of both satellites during the signal flight time is taken into account. The date of the measurement corresponds to the reception of the signal by satellite 1.

    Since:
    9.0
    Author:
    Luc Maisonobe