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Integrate and Dump

Integrate discrete-time signal, resetting to zero periodically

Library

Comm Filters

  • Integrate and Dump block

Description

The Integrate and Dump block creates a cumulative sum of the discrete-time input signal, while resetting the sum to zero according to a fixed schedule. When the simulation begins, the block discards the number of samples specified in theOffsetparameter. After this initial period, the block sums the input signal along columns and resets the sum to zero everyNinput samples, whereNis theIntegration periodparameter value. The reset occurs after the block produces its output at that time step.

Receiver models often use the integrate-and-dump operation when the system's transmitter uses a simple square-pulse model. Fiber optics and in spread-spectrum communication systems, such as CDMA (code division multiple access) applications, also use the operation.

This block accepts a scalar, column vector, or matrix input signal. When the input signal is not a scalar value, it must containk·Nrows for some positive integerk. For these input signals, the block processes each column independently.

Selecting输出中间值affects the contents, dimensions, and sample time as follows:

  • If you clear the check box, then the block outputs the cumulative sum at each reset time.

    • If the input is a scalar value, then the output sample time isNtimes the input sample time and the block experiences a delay whose duration is one output sample period. In this case, the output dimensions match the input dimensions.

    • If the input is a (k·N)-by-nmatrix, then the output isk-by-n. In this case, the block experiences no delay and the output period matches the input period.

  • If you select the check box, then the block outputs the cumulative sum at each time step. The output has the same sample time and the same matrix dimensions as the input.

Transients and Delays

A nonzero value in theOffsetparameter causes the block to output one or more zeros during the initial period while it discards input samples. If the input is a matrix withncolumns and theOffsetparameter is a length-nvector, then themthelement of theOffsetvector is the offset for themthcolumn of data. IfOffsetis a scalar, then the block applies the same offset to each column of data. The output of initial zeros due to a nonzeroOffsetvalue is a transient effect, not a persistent delay.

When you clear输出中间值, the block's output is delayed, relative to its input, throughout the simulation:

  • If the input is a scalar value, then the output is delayed by one sample after any transient effect is over. That is, after removing transients from the input and output, you can see the result of themthintegration period in the output sample indexed by m+1.

  • If the input is a column vector or matrix and theOffsetparameter is nonzero, then after the transient effect is over, the result of each integration period appears in the output frame corresponding to thelastinput sample of that integration period. This is one frame later than the output frame corresponding to the first input sample of that integration period, in cases where an integration period spans two input frames. For an example of this situation, seeExample of Transient and Delay.

Parameters

Integration period

重置之间的输入样本的数量。

Offset

A nonnegative integer vector or scalar specifying the number of input samples to discard from each column of input data at the beginning of the simulation.

输出中间值

Determines whether the block outputs the intermediate cumulative sums between successive resets.

Fixed-Point Signal Flow Diagram

Fixed-Point Attributes

The settings for the following parameters only apply when block inputs are fixed-point signals.

Rounding mode

Use this parameter to specify the rounding method to be used when the result of a fixed-point calculation does not map exactly to a number representable by the data type and scaling storing the result.

For more information, seeRounding ModesorRounding Mode: Simplest(Fixed-Point Designer).

Saturate on integer overflow

Use this parameter to specify the method to be used if the magnitude of a fixed-point calculation result does not fit into the range of the data type and scaling that stores the result:

  • Saturate represents positive overflows as the largest positive number in the range being used, and negative overflows as the largest negative number in the range being used.

  • Wrap uses modulo arithmetic to cast an overflow back into the representable range of the data type. SeeModulo Arithmetic(Fixed-Point Designer)for more information.

Accumulator-Mode

Use theAccumulator-Modeparameter to specify how you would like to designate the accumulator word and fraction lengths:

  • When you selectInherit via internal rule, the block automatically calculates the accumulator output word and fraction lengths.

  • When you selectSame as input, these characteristics match those of the input to the block.

  • When you selectBinary point scaling, you are able to enter the word length and the fraction length of the accumulator, in bits.

  • When you selectSlope and bias scaling, you are able to enter the word length, in bits, and the slope of the accumulator.

Output

Use theOutputparameter to choose how you specify the word length and fraction length of the output of the block:

  • When you selectSame as accumulator, these characteristics match those of the accumulator.

  • When you selectSame as input, these characteristics match those of the input to the block.

  • When you selectBinary point scaling, enter the word length and the fraction length of the output, in bits.

  • When you selectSlope and bias scaling, enter the word length, in bits, and the slope of the output.

关于参数pe的附加信息rtaining to fixed-point applications, seeSpecify Fixed-Point Attributes for Blocks.

Supported Data Type

Port Supported Data Types
In

  • Double-precision floating point

  • Single-precision floating point

  • Fixed-point
Out

  • Double-precision floating point

  • Single-precision floating point

  • Fixed-point

Examples

IfIntegration periodis4andOffsetis the scalar3, then the table below shows how the block treats the beginning of a ramp (1,2,3,4,...) in several situations. (The values shown in the table do not reflect vector sizes but merely indicate numerical values.)

输出中间值Check Box Input Signal Properties First Several Output Values
Cleared Scalar 0,0,4+5+6+7, and8+9+10+11, where one0is an initial transient value and the other0is a delay value that results from the cleared check box and scalar value input.
Cleared Column vector of length4 0,4+5+6+7, and8+9+10+11, where0is an initial delay value that results from the nonzero offset. The output is a scalar value.
Selected Scalar 0,0,0,4,4+5,4+5+6,4+5+6+7,8,8+9,8+9+10,8+9+10+11, and12, where the three0s are initial transient values.
Selected Column vector of length4 0,0,0,4,4+5,4+5+6,4+5+6+7,8,8+9,8+9+10,8+9+10+11, and12, where the three0s are initial transient values. The output is a column vector of length4.

In all cases, the block discards the first three input samples (1,2, and3).

Example of Transient and Delay

The figure below illustrates a situation in which the block exhibits both a transient effect for three output samples, as well as a one-sample delay in alternate subsequent output samples for the rest of the simulation. The figure also indicates how the input and output values are organized as column vectors. In each vector in the figure, the last sample of each integration period is underlined, discarded input samples are white, and transient zeros in the output are white.

The transient effect lasts forceil(13/5)output samples because the block discards13input samples and the integration period is5. The first output sample after the transient effect is over,80, corresponds to the sum14+15+16+17+18and appears at the time of the input sample18. The next output sample,105, corresponds to the sum19+20+21+22+23and appears at the time of the input sample23. Notice that the input sample23is one frame later than the input sample19; that is, this five-sample integration period spans two input frames. As a result, the output of105is delayed compared to the first input (19) that contributes to that sum.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

Version History

Introduced before R2006a

See Also

Blocks