Telecommand Encoder Shell
The Telecommand Encoder Shell package has more than 15 years of operational applications. It is a commercial off-the-shelf (COTS) software component that implements the ground based parts of a telecommand system, including the TC Space Data Link Protocol, the Communications Operation Procedure (COP-1) and the BCH channel coding.
It gives access through an API (Application Programming Interface) to the telecommand facilities using calls in ANSI-C. It is highly portable and easy to use for building into different kinds of spacecraft control systems.
The Telecommand Encoder Shell accepts packets and the other SDUs (service data units) defined for the TC Space Data Link Protocol. It delivers Communications Link Transmission Units (CLTUs) ready for serialisation and transmission. The Shell also accepts the Communications Link Control Words (CLCWs) which form the return part of the telecommand COP-1 protocol. CLCWs are extracted from the spacecraft telemetry.
The facilities and interfaces of the Telecommand Encoder Shell package are described further in the detailed description.
Security options for the Telecommand Encoder Shell
There are currently three versions of the Shell package:
- Telecommand Encoder Shell without security options
- Telecommand Encoder Shell with ESA Telecommand Authentication option
- Telecommand Encoder Shell with SLSI option.
The Shell can provide support for ESA Telecommand Authentication as an optional extra. When this option is selected, the Shell provides the sending-end processing for the ESA AU, including the addition of the authentication tail to telecommand segments.
The Shell can provide an interface for external implementation of security features such as authentication. The Segment Level Security Interface (SLSI) is an optional extra. When this option is selected, the Shell passes each segment to the interface for processing.
Addition of Space Data Link Security (SDLS): The September 2015
issue of the TC Space Data Link Protocol standard (CCSDS 232.0-B-3) includes the specification of the
interfaces between the TC protocol and the Space Data Link Security Protocol (SDLS).
We are currently updating the Telecommand Encoder Shell to include optional
interfaces to the SDLS protocol.
Please contact us for further information on technical questions or licensing conditions for the Telecommand Encoder Shell package.