Multiband Combiner
Libraries:
Communications Toolbox /
RF Impairments and Components
Description
The Multiband Combiner block interpolates, shifts input signals to the specified frequency bands, and then combines them into a single signal. For more information, see the Algorithms section.
Examples
Combine QPSK and GMSK Signals Using Simulink
Combine two 60 KHz frequency bands adjacent to each other.
Run the model to explore how combining the frames affects the signals. The model frequency shifts and combines frames of QPSK and GMSK baseband modulated signals. A spectrum analyzer displays the individual and combined signals.
Extended Examples
Ports
Input
In — Input signals
N_{samp}byN_{chan}
matrix
Input signals, specified as an N_{samp}byN_{chan} matrix. N_{samp} is the number of input samples per channel and N_{chan} is the number of channels.
Data Types: double
 single
Complex Number Support: Yes
Output
Out — Output signal
N_{out}by1 vector
Output signal, returned as an N_{out}by1
vector of the same data type as input signal In
.
N_{out} is the number of output samples. The
Rate
options parameter specifies singlerate or multirate mode. For more
information, see Algorithms.
Parameters
To edit block parameters interactively, use the Property Inspector. From the Simulink^{®} Toolstrip, on the Simulation tab, in the Prepare gallery, select Property Inspector.
Input sample rate (Hz) — Input signal sample rate
1e6
(default)  positive scalar
Input signal sample rate in Hz, specified as a positive scalar.
Frequency offsets (Hz) — Frequency offsets
[0 1e6]
(default)  scalar  1byN_{chan} vector
Frequency offsets in Hz, specified as one of these options.
Scalar — Each channel of the input signal is frequencyshifted by this scalar value.
1byN_{chan} vector — Each channel of the input signal is frequencyshifted by the corresponding value in this vector. N_{chan} is the number of channels in the input signal
In
.
Rate options — Options for processing rate
Enforce singlerate processing
(default)  Allow multirate processing
Options for the processing rate, specified as one of these values.
Enforce singlerate processing
— The output sample rate must be an integer multiple of the input sample rate. The number of rows in the output is higher than or equal to the number of rows in the input signal. The output frame rate is equal to the input frame rate.Allow multirate processing
— The output has the same number of rows as the input. The output frame rate is higher than or equal to the input frame rate.
For more information, see the Algorithms section.
Output sample rate options — Options for output sample rate
Auto
(default)  Specify via property
Options for the output sample rate, specified as one of these values.
Auto
— The block interpolates the input signals to ensure that the resulting sample rate of the signals is sufficient to avoid distorting the frequency content of the original signals after they are frequencyshifted to produce the output signal.Specify via property
— Specify the output sample rate by using the Output sample rate (Hz) parameter.
Output sample rate (Hz) — Output signal sample rate
3e6
(default)  positive scalar
Output signal sample rate in Hz, specified as a positive scalar.
Tips
To avoid distortion, specify this value to be greater than or equal to the
automatically computed output sample rate. To determine the automatically computed
output sample rate, first run the block with the Output sample rate
options parameter set to Auto
.
Dependencies
To enable this parameter, set the Output sample rate
options parameter to Specify via property
.
Output delay (samples) — Output delay
36
(default)  positive scalar
This parameter is readonly.
Output delay in samples, specified as a positive scalar.
Block Characteristics
Data Types 

Multidimensional Signals 

VariableSize Signals 

Algorithms
Multiband Combiner
This figure shows how the multiband combiner algorithm processes input signal data.
When the output sample rate is greater than the input sample rate, the input signal is
interpolated to avoid distortion in the frequencyshifted signal. Each column of the input
signal is frequencyshifted by the corresponding value specified in the Frequency offsets
(Hz)
parameter. The frequencyshifted signals are then added together into a
single channel output signal. Each channel in the input must have the same number of
samples.
The Rate options
parameter enables operation of the block in singlerate mode or multirate mode. For
singlerate mode, the output frame rate equals the input frame rate. For multirate mode, the
output frame rate is increased by the ratio of the interpolation and decimation factors
(that is, by L/M). The interpolation and decimation
factors are computed as [L,M] = rat
(R_{O}/R_{I}).
When the algorithm is configured to automatically compute the output sample rate, the output sample rate is computed as R_{O} = R_{I} × L/M
R_{O} is the output sample rate specified in Output sample rate (Hz).
R_{I} is the input sample rate specified in Input sample rate (Hz).
L is the interpolation factor and is computed as L =
ceil
(2 × B_{max}/R_{I}).M is the decimation factor.
B_{max} is the maximum bandwidth and is computed as B_{max} =
max
(abs
(Frequency offsets (Hz))) + (R_{I}/2).
Multiband Combining Delay
Multiband combining introduces a delay computed as delay =
round
(length
(num)/2). The numerator coefficients, num, are computed as num = designMultirateFIR
(L,M), where L is the interpolation factor and
M is the decimation factor.
Extended Capabilities
C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.
Version History
Introduced in R2021b
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