Raised Cosine Transmit Filter
The unit collapses the input signal with an impulse response, represented as a function of an elevated cosine.
blockType: SubSystem
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Description
Block Raised Cosine Transmit Filter increases sampling and filters the input signal using a conventional FIR filter with a raised cosine.
Filter Characteristics
Since the ideal cosine filter has an infinite impulse response, the block truncates the impulse response to the number of characters that the Filter span in symbols parameter specifies. The range of the filter in symbols, N, and the number of output samples per symbol, L, determine the length of the impulse response of the filter, which is equal to the filter range in characters .
The Rolloff factor parameter is the smoothing factor of the filter. It must be a real number from 0 to 1'. The smoothing coefficient of the filter determines the excess bandwidth of the filter. For example, a filter smoothing factor of `0.5 means that the filter bandwidth is 1.5 times the input sampling rate.
The unit normalizes the filter coefficients to a unit of energy. If you specified a linear amplitude filter gain other than 1, then the block scales the normalized filter coefficients using the gain value you specified.
Ports
Input
In — input signal
scalar | column vector | matrix
The input signal is in the form of a scalar, a column vector, or a matrix on , where — this is the number of input samples per signal channel, and — number of signal channels.
Data types: Float32, Float64, Fixed
Output
Out — output signal
scalar | column vector | matrix
The output signal is in the form of a scalar, a column vector, or a matrix on :
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.
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— number of signal channels.
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— the number of input samples per signal channel.
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— value of the Output samples per symbol parameter.
The block filters each channel by time and generates an output matrix on . The output signal has the same data type as the input.
Data types: Float32, Float64, Fixed
Parameters
Rolloff factor — pass smoothing factor:q[<br>] 0.2 (by default) | A real number between 0 and 1
Set the smoothing factor of the filter. Use a real number between 0 and `1'.
Filter span in symbols — filter length in pass characters:q[<br>] 10 (by default)
Specify the number of characters that the filter covers as an even, integer positive scalar. By default `10'. Since the ideal raised cosine filter has an infinite impulse response, the block truncates the impulse response to the number of characters that this parameter specifies.
Output samples per symbol — output samples per symbol
8 (by default)
Specify the number of output samples for each input character. By default, the value is `8'. This property takes an integer positive scalar value. The number of taps for the raised cosine filter is equal to the value of this parameter multiplied by the value of the Filter span in symbols parameter.
Linear amplitude filter gain — linear gain factor of the pass filter:q[<br>] 1.0 (by default)
The linear gain of the filter.