Frequency-shift and combine signals
Communications Toolbox / RF Impairments and Components
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.
In — Input signals
Input signals, specified as an Nsamp-by-Nchan matrix. Nsamp is the number of input samples per channel and Nchan is the number of channels.
Complex Number Support: Yes
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 | 1-by-Nchan vector
Frequency offsets in Hz, specified as one of these options.
Scalar — Each channel of the input signal is frequency-shifted by this scalar value.
1-by-Nchan vector — Each channel of the input signal is frequency-shifted by the corresponding value in this vector. Nchan is the number of channels in the input signal
Rate options — Options for processing rate
Enforce single-rate processing (default) |
Allow multirate processing
Options for the processing rate, specified as one of these values.
Enforce single-rate 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 frequency-shifted 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.
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
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 property is read-only.
Output delay in samples, specified as a positive scalar.
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 frequency-shifted signal. Each column of the input
signal is frequency-shifted by the corresponding value specified in the
(Hz) parameter. The frequency-shifted signals are then added together into a
single channel output signal. Each channel in the input must have the same number of
The Rate options
parameter enables operation of the block in single-rate mode or multirate mode. For
single-rate 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] =
When the algorithm is configured to automatically compute the output sample rate, the output sample rate is computed as RO = RI × L/M
RO is the output sample rate specified in Output sample rate (Hz).
RI is the input sample rate specified in Input sample rate (Hz).
L is the interpolation factor and is computed as L =
ceil(2 × Bmax/RI).
M is the decimation factor.
Bmax is the maximum bandwidth and is computed as Bmax =
abs(Frequency offsets (Hz))) + (RI/2).
Multiband Combining Delay
Multiband combining introduces a delay computed as delay =
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.