Digital Unit (4)
Camera Control Processor (CCP)
The CCP controls the entire camera system as its central processing unit. It interprets and executes the serial telecommands
and control data of the spacecraft. The CCP is based on a microprocessor (80C86), a boot PROM, a RAM for data handling and program execution,
and an EEPROM for application software. The EEPROM can be up and downloaded via normal telecommand / telemetry links for updating the software.
Data Compression Electronics (DCE)
The DCE consists of 4 Compression Units (CU) and the microcontroller (MC). The input buffers of the 4 CUs are directly linked to
the four signal chains of the Camera Head. Each CU works individually and uses a parameter table controlled JPEG compression algorithm. After compression,
an 80C31 microcontroller combines the data streams via multiplexing to a serial output.
Interface Electronics (IFE)
The IFE comprises two boards:
The IFE01 includes the low data rate interfaces between Camera Head, the Data Compression Electronics, spacecraft and the
Camera Control Processor.
The second board IFE02 includes the fast interface electronics used for the transfer of the scientific image data to the
spacecraft mass memory.
Power Supply Subsystem (PSS)
The PSS supplies the DU itself and the Camera Head. The power converter of the SRC is also located within the DU.
Heater Control Electronics (HCE)
The heater control system controls the thermal condition of the camera, which is thermally decoupled from the spacecraft.
The dissipated energy from the Camera Head is removed via cooling straps and an external radiator. Simultaneously
the camera is heated to a temperature of around 20°C via a system of 6 independent analogue heater control loops comprising thermistors and heaters on
the optical bench and inside the Front End Electronics. The heater control logic can be switched on independently from the camera electronics.