DSP Blockset

Buffering with Preservation of the Signal.   There are various reasons that you may need to rebuffer a signal to a new frame size at some point in a model. For example, your data acquisition hardware may internally buffer the sampled signal to a frame size that is not optimal for the DSP algorithm in the model. In this case, you would want to rebuffer the signal to a frame size more appropriate for the intended operations, but without introducing any change to the data or sample rate.

There are two blocks in the Buffers library that can be used to change a signal's frame size without altering the signal itself:

• Buffer -- redistributes signal samples to a larger or smaller frame size
• Unbuffer -- unbuffers a frame-based signal to a sample-based signal (frame size = 1)

The Buffer block preserves the signal's data and sample period only when its Buffer overlap parameter is set to 0. The output frame period, T_fo, is

where T_fi is the input frame period, M_i is the input frame size, and M_o is the output frame size specified by the Buffer size parameter.

The Unbuffer block is specialized for completely unbuffering a frame-based signal to its sample-based equivalent, and always preserves the signal's data and sample period:

where T_fi and M_i are the period and size, respectively, of the frame-based input.

Both the Buffer and Unbuffer blocks preserve the sample period of the sequence in the conversion (T_so = T_si).

Example: Buffering with Preservation of the Signal.   In the model below, a signal with a sample period of 0.125 second is rebuffered from a frame size of 8 to a frame size of 16. This doubles the frame period from 1 to 2 seconds, but does not change the sample period of the signal (T_so = T_si = 0.125).

Frame Rebuffering

Buffering with Alteration of the Signal