Rectangular QAM Modulator Baseband
Modulation using rectangular quadrature amplitude modulation.
blockType: RectangularQAMModulator
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Path in the library: |
Description
Block Rectangular QAM Modulator Baseband modulates the input signal using quadrature amplitude modulation with a constellation on a rectangular grid. The output is a basic representation of the modulated signal.
All power values assume a nominal impedance 1 Om.
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Ports
Input
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IN_1
—
Input signal
vector | scalar
Details
The input signal is in the form of a scalar or vector with the values of the elements in the range of values , where — modulation order, parameter value M-ary number.
| Data types |
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| Complex numbers support |
I don’t |
Output
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OUT_1
—
modulated signal
vector | scalar
Details
Rectangular modulated baseband signal.
The output will be of type ComplexF64 in any case, except when for the parameter M-ary number the value is set 2. In this case, the output will be data of the type Float64.
| Data types |
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| Complex numbers support |
Yes |
Parameters
Main
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M-ary number —
the order of modulation
Integer
Details
The modulation order is set as a positive integer equal to a power of two. The modulation order determines the number of points in the signal constellation.
| Default value |
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| Program usage name |
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| Tunable |
No |
| Evaluatable |
Yes |
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Input type —
input data type
Integer | Bit
Details
The input data type is specified as Integer or Bit to specify whether the input signal consists of integers or groups of bits:
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Integer— the input signal must consist of integers in the range , where — modulation order, parameter value M-ary number; -
Bit— the input signal must contain binary values, and the number of lines must be an integer multiple of .
| Values |
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| Default value |
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| Program usage name |
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| Tunable |
No |
| Evaluatable |
No |
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Constellation ordering —
the order in which characters are displayed
Gray | Binary
Details
Defines how the block maps each character to a group of output bits or an integer.
| Values |
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| Default value |
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| Program usage name |
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| Tunable |
No |
| Evaluatable |
No |
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Normalization method —
the scaling method for the constellation
Min. distance between symbols | Average power | Peak power
Details
The constellation scaling method, defined as Min. distance between symbols, Average power or Peak power.
| Values |
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| Default value |
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| Program usage name |
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| Tunable |
No |
| Evaluatable |
No |
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Minimum distance —
the distance between the two closest points of the constellation
Real number
Details
The distance between the two closest points of the constellation, given as a positive scalar.
Dependencies
To use this parameter, set for the parameter Normalization method meaning Min. distance between symbols.
| Default value |
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| Program usage name |
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| Tunable |
No |
| Evaluatable |
Yes |
# Average power, referenced to 1 ohm (watts) — average power
Details
The average power of the symbols in the constellation in watts, given as a positive scalar. The power values assume a nominal impedance 1 Om.
Dependencies
To use this parameter, set for the parameter Normalization method meaning Average power.
| Default value |
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| Program usage name |
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| Tunable |
No |
| Evaluatable |
Yes |
# Peak power, referenced to 1 ohm (watts) — Maximum power
Details
The maximum power of the symbols in the constellation in watts, given as a positive scalar. The power values assume a nominal impedance 1 Om.
Dependencies
To use this parameter, set for the parameter Normalization method meaning Average power or Peak power.
| Default value |
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| Program usage name |
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| Tunable |
No |
| Evaluatable |
Yes |
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Phase offset (rad) —
rotation of the signal constellation
Real number
Details
The rotation of the signal constellation, specified as a numeric scalar.
| Default value |
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| Program usage name |
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| Tunable |
No |
| Evaluatable |
Yes |
Algorithms
Signals with integer values and signals with binary values
Details
If set for the parameter Input type meaning Integer, the block accepts integer values in the range . — this is the modulation order specified by the block parameter M-ary number.
If for the parameter Input type the value is set Bit the block accepts binary values representing integers. The block collects binary-digit signals into groups by the bit where — the number of bits per character, and — the order of modulation.
The length of the input vector must be an integer multiple of . In this configuration, the block accepts a group of and maps it to the character at the output of the block. The block outputs one modulated symbol for each group of bits.
Parameter Constellation ordering specifies how the block assigns binary words to the points of the signal constellation. Such assignments are applied independently to the common-mode and quadrature components of the input signal.:
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If for the parameter Constellation ordering the value is set
Binarythe block uses a binary-encoded constellation. -
If for the parameter Constellation ordering the value is set
Grayand even, the block uses a constellation encoded by the Gray code. -
If for the parameter Constellation ordering the value is set
Grayand odd, the block encodes the constellation so that the pairs of closest points differ by one or two bits. The constellation has a cross-shaped shape, and the diagram below shows which pairs of points differ by two bits. The scheme uses , but the general case is assumed.
Since the common-mode and quadrature components are assigned independently, when the Gray code order and binary order are the same.
Constellation size and scaling
Details
The constellation of the signal consists of points where — parameter value M-ary number. it should have the form for some positive integer . The block scales the signal constellation depending on what value is set for the parameter. Normalization method.
| Parameter value Normalization method | Zoom condition |
|---|---|
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The nearest pair of points in the constellation is separated by the value of the parameter Minimum distance. |
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The average power of the symbols in the constellation is the value of the parameter Average power, referenced to 1 ohm (watts). |
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The maximum power of the symbols in the constellation is the value of the parameter Average power, referenced to 1 ohm (watts). |