Time Varying Gain

Time varying gain (TVG) control

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Libraries:
Phased Array System Toolbox / Detection

Description

The Time Varying Gain block applies a time-varying gain to input signals to compensate for geometric range loss at each range gate. Time varying gain (TVG) is sometimes called automatic gain control (AGC).

Examples

Simulating Test Signals for a Radar Receiver in Simulink

Model an end-to-end monostatic radar using Simulink®. A monostatic radar consists of a transmitter colocated with a receiver. The transmitter generates a pulse which hits the target and produces an echo received by the receiver. By measuring the time location of the echoes, you can estimate the range of the target. The first part of this example demonstrates how to detect the range of a single target using the equivalent of a single element antenna. The second part of the example will show how to build a monostatic radar with a 4-element uniform linear array (ULA) that detects the range of 4 targets.

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Ports

Input

Port_1 — Input signal

vector | matrix | array

Input signal, specified as a vector, matrix, or array.

The size of the first dimension of the input matrix can vary to simulate a changing signal length. A size change can occur, for example, in the case of a pulse waveform with variable pulse repetition frequency.

Data Types: double | single

Port_2 — Range loss

column vector

Range loss, specified as a column vector. The length of the vector must be equal to or greater than the number of rows in the input signal in Port_1.

The process equalizes power levels across all samples to match a given reference range. The gain is applied to each column in Port_1 independently. The number of rows in Port_1 cannot exceed the length of the loss vector specified in the Range losses (dB) parameter.

Dependencies

To enable this port, set Source of range losses parameter to Input port.

Data Types: double | single

Output

Port_1 — Range-compensated signal

vector | matrix | array

Range-compensated signal, returned as a vector, matrix, or array. The range-compensated signal has the same size as the input signal.

Data Types: double | single

Parameters

Source of range losses — Source of range loss

Property (default) | Input Port

Source of range loss, specified as Property or Input Port.

Property	Specify range losses using the Range loss (dB) parameter.
Input port	Specify range losses using the input port Port_2 .

Data Types: char | string

Range losses (dB) — Loss at each input sample range

0 (default) | vector

Loss at each input sample range, specified as a vector. Vector elements correspond to the samples in the input signal. Units are in dB.

Dependencies

To enable this parameter, set the Source of range losses parameter to Input port.

Data Types: double | single

Reference range loss (dB) — Loss at reference range

0 (default) | scalar

Loss at the given reference range, specified as a scalar. Units are in dB.

Data Types: double | single

Simulate using — Block simulation method

Interpreted Execution (default) | Code Generation

Block simulation, specified as Interpreted Execution or Code Generation. If you want your block to use the MATLAB^® interpreter, choose Interpreted Execution. If you want your block to run as compiled code, choose Code Generation. Compiled code requires time to compile but usually runs faster.

Interpreted execution is useful when you are developing and tuning a model. The block runs the underlying System object™ in MATLAB. You can change and execute your model quickly. When you are satisfied with your results, you can then run the block using Code Generation. Long simulations run faster with generated code than in interpreted execution. You can run repeated executions without recompiling, but if you change any block parameters, then the block automatically recompiles before execution.

This table shows how the Simulate using parameter affects the overall simulation behavior.

When the Simulink^® model is in Accelerator mode, the block mode specified using Simulate using overrides the simulation mode.

Acceleration Modes

Block Simulation	Simulation Behavior
	Normal	Accelerator	Rapid Accelerator
Interpreted Execution	The block executes using the MATLAB interpreter.	The block executes using the MATLAB interpreter.	Creates a standalone executable from the model.
Code Generation	The block is compiled.	All blocks in the model are compiled.

For more information, see Choosing a Simulation Mode (Simulink).

Programmatic Use

Block Parameter:SimulateUsing

Type:enum

Values:Interpreted Execution, Code Generation

Default:Interpreted Execution

Version History

Introduced in R2014b