Abstract: An inventive autonomous active manoeuvring method and system 1 for spinning spacecraft is provided having a capability to enhance the AOCMS performance of passive spinning satellites and to fulfil the emerging autonomy requirements applicable to new generation satellites. In broad terms, the invention resides in (a) the overall concept of providing autonomous execution of spin axis re-orientation manoeuvring for spinning spacecraft designed and executed autonomously on-board the spacecraft by the AOCMS and (b) in the proposed strategy set in place to execute the re-orientation manoeuvres with respect to the handling of residual nutation. Advantageously, the provision of coupling nutation avoidance manoeuvres with active nutation damping 8 on board the spacecraft reduces/minimises the manoeuvre settling time required to return the spacecraft to the steady state pointing performance, while not imposing constraints upon the particular spacecraft inertia sensor properties.

Abstract: In the signal acquisition system disclosed herein, frequency, phase and time uncertainties are resolved essentially simultaneously by including a preselected code group in the transmitted signal and by applying the received signal to a differential detector and then to a passive differential matched filter, the parameters of which are selected in correspondence with a code group, thereby to generate a corresponding series of complex match values. The absolute magnitude of the complex sum of the match values is maximized when the received signal is modulated by the preselected code group. When the presence of the code group in the received signal is detected, the phasing of the complex sum is detected thereby to determine carrier frequency offset. A directly detected version of the received signal is applied to a corresponding masking filter and the phase of a resultant sum signal is detected to determine carrier phase offset.