| Description: The Companding class describes whether or not data is or has had its bit depth reduced (for example conversion from 12 to 8 bits via a lookup table or bit scaling), the venue where it occurred (Software or Hardware), and the method used to complete the companding. The processing_algorithm attribute specifies how data was companded. Generally this will either be via a lookup table (such as a square root encoding), or by shifting bits to preserve the high order bits and discard the low order bits. The value of this keyword is mission specific but there are recommended values that should apply across missions when possible: NONE - no scaling. LUTn - use the numbered lookup table. Lookup tables are defined in the mission SIS. It is preferred for "n" to be a number but it could be a name, for example LUT_MMM_3 to indicate LUT 3 for the MMM instruments (on MSL). MSB_BITn - Shift to make bit "n" the most significant. Bits start numbering at 0 so MSB_BIT7 means no shift for a 12->8 bit companding, while MSB_BIT11 means to shift right 4 bits for a 12->8 bit companding. AUTOSHIFT - Data should be shifted to preserve the highest value. This value should only appear in a command echo; one of the MSB_BITn values should be used in downlinked data to specify what the actual shift was. |
| Namespace Id: img | Steward: img | Role: TBD_role | Status: Active |
| Class Hierarchy: Data_Processing :: Companding |
| Attribute(s) | Name | Cardinality | Value |
| | active_flag | 0..1 | None |
| | processing_venue | 0..1 | Ground, Ground Refined, None, Onboard, Onboard Both, Onboard Hardware, Onboard Software |
| | processing_algorithm | 0..1 | None |
| | sequence_number | 0..1 | None |
| | companding_state | 0..1 | Companded, Expanded, None |
| | early_scaling | 0..1 | None |
| Association(s) | Name | Cardinality | Class |
| | Companding_File | 0..1 | Companding_File |
| | Companding_Table | 0..1 | Companding_Table |
| Referenced from: Sampling |