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Convert SimRF signal to Simulink output signals
The Outport block outputs carrier modulation signals in the SimRF™ circuit envelope simulation environment as Simulink^{®} signal. For an introduction to RF simulation, see the example, Simulate High Frequency Components.
SimRF current and voltage signals consist of in-phase (I_{k}) and quadrature (Q_{k}) components at each frequency f_{k} specified in the Configuration block
The Sensor type parameter determines which signal the block measures, and the Output parameter defines the format of the Simulink signal.
Specify the type of signal measured by the sensor:
Ideal voltage — The block outputs the modulations of the voltage signal at the specified Carrier frequencies in the format specified by the Output parameter.
Ideal current — The block outputs the modulations of the current signal at the specified Carrier frequencies in the format specified by the Output parameter.
Power — The block outputs the modulations of the voltage signal
$$\frac{\sqrt{\text{Re}\left({Z}_{l}\right)}}{{Z}_{l}}v(t)$$
where Z_{l} is the value of the Load impedance (ohms) parameter, at the specified Carrier frequencies. Output parameter specifies the format of the signal.
If the Carrier frequencies parameter specifies more than one frequency, the block outputs a vector of signals. The kth output signal corresponds to the modulation of the kth carrier.
When Output is set to Power, the Outport loads the circuit with the specified impedance. When you use multiple Outport blocks as power sources at the same node in a given circuit, the resulting load is the parallel combination of the specified load impedances. By default, the impedance is 50.
Specify the format of the output signals:
Complex Baseband — The block outputs a vector of complex-valued signals I_{k}(t) + j · Q_{k}(t) at the port labeled SL. The kth element of the vector is the kth frequency specified by the Carrier frequencies parameter.
In-phase and Quadrature Baseband — The block outputs two vectors of real-valued signals I_{k}(t) and Q_{k}(t) at the I port and Q port, respectively. The signal at the I port contains the in-phase components, and the signal at the Q port contains the quadrature components. The kth element of the vector is the kth frequency specified by the Carrier frequencies parameter.
Magnitude and Angle Baseband — The block outputs two real-valued vectors, whose elements are the magnitude and phase angle of the modulation. The Mag port outputs |I_{k}(t) + j · Q_{k}(t)| and the Ang port outputs Arg[I_{k}(t) + j · Q_{k}(t)]. The kth element of the vector is the kth frequency specified by the Carrier frequencies parameter.
Real Passband — The block outputs real passband signals by combining envelope and carrier signals for all frequencies listed under Carrier frequencies.
You can use the following options to control passband output step size:
Select Automatically compute output step size to allow SimRF to determine the optimal time step to resolve the highest listed carrier frequency. The formula for the time step selected is:
where
$$\mathrm{min}(h,\text{\hspace{0.05em}}\text{\hspace{0.05em}}(\text{\hspace{0.05em}}(1/2\pi f)\xf78))$$
f is the largest listed carrier frequency.
h is the time step listed in Configuration block.
Clear the selection to enter a value for step size. By default, this option is selected.
Set Step size to -1 to inherit the time step specified from Step size in Configuration block.
Set Step size to a user specified time step. The step size should be small enough to resolve the fastest carrier signal. This helps to avoid passband output undersampling and aliasing effects.
The passband formula is defined by the Normalized carrier power option in the Configuration block:
When this option is selected, SimRF interprets complex envelope I+jQ signal for the k^{th} carrier as,
$${s}_{k}(t)=I(t)\sqrt{2}\mathrm{cos}(2\pi {f}_{k}t)\text{\hspace{0.17em}}-\text{\hspace{0.17em}}Q(t)\sqrt{2}\mathrm{sin}(2\pi {f}_{k}t)$$
When this option is not selected, the signal on the k^{th}
$${s}_{k}(t)=I(t)\mathrm{cos}(2\pi {f}_{k}t)\text{\hspace{0.17em}}-\text{\hspace{0.17em}}Q(t)\mathrm{sin}(2\pi {f}_{k}t)$$
In both cases, the signal for zero-frequency (DC) carrier is x( t ) = I( t ). The final output signal is computed as s(t) = sum( s_{k} )
Enter a vector of carrier frequencies whose elements are combinations of fundamental tones and corresponding harmonics in the Configuration block. Specify the units from the corresponding drop-down list. The default value of this parameter is 0 Hz.
Select this option to internally ground and hide the negative terminals. Clear this to expose the negative terminals. By exposing these terminals, you can connect them to other parts of your model.
By default, this option is selected.
The example, Passband Signal Representation in Circuit Envelope, shows how to set the step size value in the Outport block to avoid undersampling.
The example, Simulate High Frequency Components, compares the Real Passband and In-phase and Quadrature Baseband output options of the Outport block.
The example, Validating IP2/IP3 Using Complex Signals, shows how to use Outport blocks to probe RF systems in multiple locations.