DSP Blockset

Changing Frame Status

The frame status of a signal refers to whether the signal is sample-based or frame-based. In a Simulink model, the frame status is symbolized by a single line, , for a sample-based signal and a double line, , for a frame-based signal.

In most cases, the appropriate way to convert a sample-based signal to a frame-based signal is by using the Buffer block, and the appropriate way to convert a frame-based signal to a sample-based signal is by using the Unbuffer block. See these sections for more information about these methods:

• Buffering Sample-Based and Frame-Based Signals
• Unbuffering a Frame-Based Signal into a Sample-Based Signal

On occasion it may be desirable to change the frame status of a signal without performing a buffering operation. You can do this by using the Frame Status Conversion block in the Signal Attributes library.

The Output signal parameter (or the signal at the optional Ref input port) determines the frame status of the output If the frame status of the input differs from the Output signal setting, then the frame status is altered as specified. If the frame status of the input is the same as that specified by the Output signal parameter, then no change is made to the signal.

The block's input and output port rates are the same, and because the block does not make any sample rate accommodation, the sample rate of the signal is generally not preserved under a change of frame status. (The exception to this rule occurs when a sample-based signal is converted to a frame-based signal with frame size 1, or vice versa.)

See the Frame Status Conversion block's reference page for complete information.

Example 2: Unintended Rate Conversion

Creating Signals