SPADE

SPADE (SCPC, PCM, Demand-assigned Equipment) is a demand-assigned satellite communications access technique developed for use in international satellite networks to provide efficient allocation of satellite channels for low-data-rate and intermittent traffic, particularly telephony.

In a SPADE system, each call or data circuit is assigned its own carrier for the duration of the connection. Channels are allocated dynamically on demand by a control system and released when no longer required, improving spectrum utilization compared with fixed-assigned SCPC systems. SPADE systems typically use digital modulation and PCM for voice transmission and are designed to operate with relatively small Earth stations.

SPADE was widely used in earlier Intelsat networks for international voice traffic before being largely superseded by more advanced multiple-access and packet-based techniques.