Communications Blockset

Processing Frame-Based and Sample-Based Signals

All one-dimensional arrays are sample-based, but a matrix signal can be either frame-based or sample-based. A frame-based signal in the shape of an N-by-1 matrix represents a series of N successive samples from a single time series. The Communications Blockset processes some frame-based signals and is compatible with the DSP Blockset. However, the Communications Blockset omits some frame-based features, and many blocks are not specifically optimized for frame-based processing.

These rules indicate how most Communications Blockset blocks handle frame-based matrix signals:

• Most blocks do not process frame-based matrix signals that have more than one row and more than one column.
• Most blocks do not process frame-based row vectors and do not support multichannel functionality.
• Blocks that process continuous-time signals do not process frame-based inputs. Such blocks include the analog modulation blocks and the analog phase-locked loop blocks.
• Blocks for which a frame-based multichannel operation would make sense, even if the blocks do not currently support such operation, reject sample-based vectors because their interpretation is ambiguous.

• Frame-based vectors, however, have an unambiguous interpretation. Blocks interpret a frame-based row vector as multiple channels at a single instant of time, and interpret a frame-based column vector as multiple samples from a single time series (that is, a single channel).

• Some blocks, such as the digital baseband modulation blocks, can produce multiple output values for each value of a scalar input signal. In such cases, a frame-based 1-by-1 matrix input results in a frame-based column vector output. By contrast, a sample-based scalar input results in a sample-based scalar output with a smaller sample time.

Processing Matrices, Vectors, and Scalars

Communications Sources