Inport

Convert Simulink input signal to RF Blockset signal

• Library:

• RF Blockset / Circuit Envelope / Utilities

• 

Description

The Inport block imports Simulink^® signals into the RF Blockset™ circuit envelope simulation environment. For an introduction to RF simulation, see the example, Simulate High Frequency Components.

Complex-valued input signals I_k(t) + j · Q_k(t) are the modulations at the frequencies {f_k} specified in the Carrier frequencies parameter of the block.

The input port converts the complex simulink input signals into an RF signal suitable for multicarrier simulation:

$$out=\mathrm{Re}al({\displaystyle \sum _{k=1}^N(I_k}(t)+j·Q_k(t))·e^{j2\pi f_{k}t})$$

The Source type parameter specifies the Simulink signal as either current, or voltage, or power source.

Parameters

Source type — Inport block interpretation of Simulink signal

Ideal voltage (default) | Ideal current | Power

Inport block interpretation of Simulink signal, specified as:

• Ideal voltage — The block outputs Simulink signals as voltage signals v(t) in the RF Blockset environment. When you choose an ideal voltage input port you need to manually add a series of source impedance to match the blocks connected to the input port. The following figure illustrates the internal configuration of the block.

  

• Ideal current — The block outputs Simulink signals as current signals i(t) in the RF Blockset environment. When you use an ideal current input port, you manually add a parallel source impedance to match the blocks connected to the input port. The following figure illustrates the internal configuration of the block.

  

• Power — The block interprets the Simulink signals, P_v(t), as available power and internally uses a voltage source, and series impedance. You use this option to import a 50 ohm environment or different reference impedance signals created using Communications Toolbox™. When you select this option, the input port automatically inserts a source impedance in your circuit as shown in the following figure.

  

  The voltage v(t) is a scaling of the Simulink signal v_SL(t):

  $$v(t)=2\sqrt{\text{Re}\left(Z_s\right)}{v}_{SL}(t)$$

  In the preceding equation, Z_s is the value of the Source impedance (ohms) parameter.

  The generator delivers real power to the load Z_l:

  $$P_{load}={\left|v(t)\right|}^2\frac{\mathrm{Re}(Z_s)}{\left|Z_s+Z_l\right|{\text{}}^2}$$

  When Z_l = Z_s^*, this generator delivers the available power |v_SL(t)|².

Source impedance (Ohm) — Source impedance for available power match

50 (default) | vector of positive integers

Source impedance for available power match, specified as a vector of positive integers in ohms

Dependencies

To enable this parameter, select Power in Source type.

Carrier frequencies — Carrier frequencies

0 Hz (default) | vector of positive integers

Carrier frequencies, specified as a vector of positive integers in Hz. In carrier frequencies, the elements are a combination of fundamental tones and corresponding harmonics in the Configuration block.

Ground and hide negative terminals — Ground RF circuit terminals

on (default) | off

Ground RF circuit terminals, specified as a on or off. Select this parameter to ground and hide the negative terminals. Clear the parameter to expose the negative terminals. By exposing these terminals, you can connect them to other parts of your model.

Model Examples

Attenuate Signal Power

Use the Attenuator block to attenuate a constant signal of 20 dB by 3 dB.

More About

Multi-Carrier Envelope Simulation

Using the Inport block you can specify the complex envelopes of your input signals and import them as RF signals for multi-carrier simulation.

The Configuration block automatically determines the fundamental tones specified in the input ports and proposes a suitable harmonic order to capture the non-linearity of the system. You can also manually specify the harmonic order for each fundamental tone in the simulation.

In the input port, you can specify as many carrier frequencies as you want. It is recommended that you trade off the simulation bandwidth (inversely proportional to the simulation time step) and the total number of simulation frequencies.

Algorithms

How to Use Inport Block

Physical Interpretation of Simulink Signals

The Inport block allows you to specify the complex envelopes of your input signals and import them as RF signals for multi-carrier simulation.

The power option automatically insert a source or load impedance in your network, and normalizes the signal power with respect to the specified impedance. You do not need to manually insert source and load terminations, and your signals are automatically scaled between RF Blockset and the Simulink environment that assumes an implicit 1 Ohm reference impedance.

When using voltage sources and sensors, manually add source and load terminations, otherwise there might be an undesired impedance mismatch in your network. When you measure the power of a voltage signal, make sure that you use a 50Ohm reference impedance.

If you use an ideal voltage source and add a source impedance, in perfectly matched conditions, the actual voltage applied to the first block of the RF chain is half of the value of the input Simulink signal. The source impedance and the input impedance of the first block of the RF chain form a voltage divider network.

Implicit Carrier for Complex Equivalent Baseband Signal

Input signal is a digital communication complex equivalent baseband signal (I,Q). You assume an implicit carrier for the system that is equal to the carrier frequency, Fc. You want to model RF effects such as amplifier nonlinearity and S-parameter filters using RF Blockset:

• Enter Fc in the Carrier Frequencies parameter.

• The simulation step size in the configuration block is the same as the sample time of the Simulink input signal, and it is not related to the carrier frequency.

• If the RF chain does not include any modulator or demodulator, use an Outport block at the end of the chain. You can use the Outport block to probe the complex equivalent signal centered on Fc.

No Carrier for Baseband Signal

Input signal is a digital communication complex input baseband signal (I,Q). You assume that no carrier is associated with the input signal. You want to upconvert the signal to Fc and model RF effects such as amplifier nonlinearity and S-parameter filters:

• Use to two Inport blocks for the I and Q components of the input signal. Set the Carrier Frequencies parameter of each Inport block to 0

• To upconvert the signal, use an IQ Modulator block. Set the Local oscillator frequency to Fc.

• The simulation step size in the configuration block is the same as the sample time of the Simulink input signal, and it is not related to the Local Oscillator frequency.

• Use an Outport block at the end of the chain. and probe the signal at Fc.

Upconvert Signal to IF and Then RF

Input signal is a digital communication complex equivalent baseband signal (I,Q). You want to first upconvert the signal to intermediate frequency (IF), then to RF, and model RF imperfections:

• Set the Carrier Frequencies parameter of each Inport block to IF.

• Use the Mixer block. Set the LO carrier frequency to RF-IF.

• Use an Outport block at the end of the chain. and probe the signal at RF.

Real Passband Signal

Input signal is a digital or analog real passband signal that is explicitly modulated to high frequency in Simulink domain:

• Set the Carrier Frequencies parameter of each Inport block to 0 and simulate RF effects.

• The simulation step size in the configuration block is the same as the sample time of the Simulink input signal, and it is proportional to the RF frequency.

• However there is no speed benefit in using RF Blockset for real-passband simulation. This option is not recommended