DVB-S2 Symbol Modulator

Modulate data bits to complex constellation symbols according to DVB-S2 standard

Since R2022b

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Libraries:
Wireless HDL Toolbox / Modulation

Description

The DVB-S2 Symbol Modulator block modulates data bits to complex data symbols based on the modulation types supported by the Digital Video Broadcast Satellite Second Generation (DVB-S2) standard [1]. The block accepts data bits and a valid signal and outputs modulated complex constellation symbols and a valid signal.

Each complex output symbol comprises a standard number of data bits based on the modulation type, as this table shows. If you provide input data bits with a nonmultiple of the number of data bits per symbol, the block ignores the output symbol with insufficient or excess bits.

Modulation Type	Number of Data Bits Per Symbol
π/2-BPSK	1
QPSK	2
8-PSK	3
16-APSK	4
32-APSK	5

The block provides an architecture suitable for HDL code generation and hardware deployment. You can use this block in the development of a DVB-S2 transmitter.

Examples

DVB-S2 Symbol Modulation of Data Bits

Modulate data bits to complex data symbols according to DVB-S2 standard.

• Open Script

Ports

Input

data — Data bits

Boolean scalar | real scalar

Input data bits, specified as a Boolean or real scalar. The block accepts Boolean or ufix1 data bits.

Data Types: Boolean | fixdt(0,1,0)

valid — Indication of whether input data is valid

0 | 1

Control signal that indicates whether the input data is valid. When this value is 1, the block accepts the values on the data input port. When this value is 0, the block ignores the values on the data input port.

Data Types: Boolean

modIdx — Modulation index

0 | 1 | 2 | 3 | 4

Modulation index, specified as 0, 1, 2, 3, or 4. Each value represents a specific modulation type, as table shows.

Modulation Index	Modulation Type
0	QPSK
1	8-PSK
2	16-APSK
3	32-APSK
4	π/2-BPSK

For HDL code generation, specify this value in fixdt(0,3,0) format.

If you specify a value other than one listed in this table, the block displays a warning message and:

• Applies QPSK modulation when load is 1.

• Continues with the current modulation when load is 0.

Dependencies

To enable this port, set the Modulation source parameter to Input port.

Data Types: single | double | fixdt(0,3,0)

codeRateIdx — Code rate index

5 | 6 | 7 | 8 | 9 | 10

Code rate index, specified as 5, 6, 7, 8, 9, or 10. Each value represents a specific code rate, as this table shows.

Code Rate Index	Code Rate
5	2/3
6	3/4
7	4/5
8	5/6
9	8/9
10	9/10

If you specify a value other than 5, 6, 7, 8, 9, or 10 for 16-APSK and other than 6, 7, 8, 9, or 10 for 32-APSK, the block displays a warning message and applies the code rate 3/4. For HDL code generation, specify this value in fixdt(0,4,0) format.

The code rates in this table apply to the modIdx input port values 2 and 3, which indicate 16-APSK and 32-APSK modulation, respectively. When you set the modIdx port value to 0, 1, or 4, the block ignores the codeRateIdx input port values.

Dependencies

To enable this port, set the Modulation source parameter to Input port.

Data Types: single | double | fixdt(0,4,0)

load — Modulation and code rate control

0 | 1

Modulation and code rate control, specified as a Boolean scalar.

When this value is 1, the block samples the modIdx and codeRateIdx values. When this value is 0, the block ignores any changes in the modIdx and codeRateIdx and continues with the current modulation index and code rate until load changes to 1.

If the load value changes to 1 during block operation, the block resynchronizes and restarts modulation using the current value of modIdx. This restart occurs regardless of whether the modIdx value changes.

If you do not specify the load value as 1 at the start of block operation, by default, the block operates with QPSK modulation.

Dependencies

To enable this port, set the Modulation source parameter to Input port.

Data Types: Boolean

Output

data — Modulated constellation data symbols

complex scalar

Modulated constellation data symbols, returned as a complex scalar.

The block supports double and single data types for simulation, but not for HDL code generation.

For HDL code generation, set the Output data type parameter to Custom and specify the word length.

Data Types: single | double | fixdt(1,wordlength,wordlength-2)
Complex Number Support: Yes

valid — Valid output data indication

0 | 1

Control signal that indicates whether the data from the data output port is valid. When this value is 1, the block returns valid data on the data output port. When this value is 0, the values on the data output port are not valid.

Data Types: Boolean

Parameters

Main

Modulation source — Source for modulation type

Property (default) | Input port

To specify the modulation type using the Modulation parameter, select Property. To specify the modulation using the modIdx port during run time, select Input port.

Modulation — Modulation type

QPSK (default) | 8-PSK | 16-APSK | 32-APSK | pi/2-BPSK

Select the modulation type.

Dependencies

To enable this parameter, set the Modulation source parameter to Property.

Code rate — Code rate

3/4 (default) | 2/3 | 4/5 | 5/6 | 8/9 | 9/10

Select the code rate.

Dependencies

To enable this parameter set the Modulation source parameter to Property and the Modulation parameter to 16-APSK or 32-APSK.

Unit average power — Spectral growth reduction

off (default) | on

Select this parameter to perform symbol modulation with a normalized constellation. Clear this parameter to perform symbol modulation using the constellation defined in the standard [1].

When you specify 0, 1, or 4 in the modIdx input port or set the Modulation parameter to QPSK, 8-PSK, or pi/2-BPSK, the block ignores this parameter during its operation.

Dependencies

To enable this parameter, set the Modulation source parameter to Input port or set the Modulation source to Property and the Modulation parameter to 16-APSK or 32-APSK.

Data Types

Output data type — Output data type

Custom (default) | double | single

Specify the data type for the output data.

The block supports double and single data types for simulation.

For simulation and HDL code generation, set this value to Custom.

Word length — Word length

16 (default) | integer in the range [3, 32]

Specify the output word length. This value must be an integer in the range [3, 32].

Dependencies

To enable this parameter, set the Output data type parameter to Custom.

Algorithms

Latency

The latency of the block is fixed to nine clock cycles.

This figure shows a Logic Analyzer waveform of the sample output and latency of the block for output data of type fixdt(1,16,14) when you set the Modulation source parameter to Input port and specify the modIdx input port value as 1 (8-PSK).

Performance

The performance of the synthesized HDL code varies with the target and synthesis options. The performance also varies based on the selected modulation type and the output data type.

This table shows the resource and performance data synthesis results of the block for different modulation types when you specify the Modulation source parameter as Property and an output word length of 16. The generated HDL code targets to an AMD^® Zynq^®- 7000 ZC706 Evaluation Board.

Modulation Type	Slice LUTs	Slice Registers	DSPs	Block RAM	Clock Frequency (MHz)
π/2-BPSK	33	40	0	0	837.52
QPSK	42	45	0	0	767.46
8-PSK	49	67	0	0	796.18
16-APSK	70	92	0	0	805.8
32-APSK	98	96	0	0	654.88

This table shows the resource and performance data synthesis results of the block when you specify the Modulation source parameter as Input port and an output word length of 16. The generated HDL code targets to a AMD Zynq- 7000 ZC706 Evaluation Board.

Slice LUTs	Slice Registers	DSPs	Block RAM	Clock Frequency (MHz)
341	284	0	0	501.5

References

[1] ETSI Standard EN 302 307 V1.4.1: Digital Video Broadcasting (DVB); Second generation framing structure, channel coding and modulation systems for Broadcasting, Interactive Services, News Gathering and other broadband satellite applications (DVB-S2), European Telecommunications Standards Institute, Valbonne, France, 2005-03.

[2] Viterbi, A.J. “An Intuitive Justification and a Simplified Implementation of the MAP Decoder for Convolutional Codes.” IEEE Journal on Selected Areas in Communications 16, no. 2 (February 1998): 260–64. https://doi.org/10.1109/49.661114.

[3] Sebesta, J. “Efficient Method for APSK Demodulation.” Selected Topics on Applied Mathematics, Circuits, Systems, and Signals (P. Pardalos, N. Mastorakis, V. Mladenov, and Z. Bojkovic, eds.). Vouliagmeni, Athens, Greece: WSEAS Press, 2009.

Extended Capabilities

C/C++ Code Generation

Generate C and C++ code using Simulink® Coder™.

This block supports C/C++ code generation for Simulink^® accelerator and rapid accelerator modes and for DPI component generation.

HDL Code Generation

Generate VHDL, Verilog and SystemVerilog code for FPGA and ASIC designs using HDL Coder™.

HDL Coder™ provides additional configuration options that affect HDL implementation and synthesized logic.

HDL Architecture

This block has one default HDL architecture.

HDL Block Properties

ConstrainedOutputPipeline	Number of registers to place at the outputs by moving existing delays within your design. Distributed pipelining does not redistribute these registers. The default is 0. For more details, see ConstrainedOutputPipeline (HDL Coder).
InputPipeline	Number of input pipeline stages to insert in the generated code. Distributed pipelining and constrained output pipelining can move these registers. The default is 0. For more details, see InputPipeline (HDL Coder).
OutputPipeline	Number of output pipeline stages to insert in the generated code. Distributed pipelining and constrained output pipelining can move these registers. The default is 0. For more details, see OutputPipeline (HDL Coder).

Restrictions

You cannot generate HDL for this block inside a Resettable Synchronous Subsystem (HDL Coder).

Version History

Introduced in R2022b

R2023b: Change in output data type default settings

The default value for Output data type parameter is now changed to Custom. To see this change, double-click the block and then click Data Types tab.