| Communications Blockset | |
Digital Modulation Features of the Blockset
The figure below shows the modulation techniques that the Communications Blockset supports for digital data. All of the methods at the far right are implemented in both passband and baseband blocks. For a comparison of baseband simulation and passband simulation, see Comparing Baseband and Passband Simulation.
General and Specific Modulation Methods
Some digital modulation sublibraries contain blocks that implement special cases of a more general technique and are, in fact, special cases of a more general block. These special-case blocks use the same computational code that their general counterparts use, but provide an interface that is either simpler or more suitable for the special case. The table below lists special-case modulators, their general counterparts, and the conditions under which the two are equivalent. The situation is analogous for demodulators.
| General Modulator |
Specific Modulator |
Specific Conditions |
| General QAM Modulator Baseband, General QAM Modulator Passband |
Rectangular QAM Modulator Baseband, Rectangular QAM Modulator Passband |
Predefined constellation containing 2K points on a rectangular lattice |
| M-PSK Modulator Baseband | BPSK Modulator Baseband |
M-ary number parameter is 2. |
| QPSK Modulator Baseband |
M-ary number parameter is 4. |
|
| M-DPSK Modulator Baseband | DBPSK Modulator Baseband |
M-ary number parameter is 2. |
| DQPSK Modulator Baseband |
M-ary number parameter is 4. |
|
| CPM Modulator Baseband, CPM Modulator Passband | GMSK Modulator Baseband, GMSK Modulator Passband |
M-ary number parameter is 2, Frequency pulse shape parameter is Gaussian. |
| MSK Modulator Baseband, MSK Modulator Passband |
M-ary number parameter is 2, Frequency pulse shape parameter is Rectangular, Pulse length parameter is 1. |
|
| CPFSK Modulator Baseband, CPFSK Modulator Passband | Frequency pulse shape parameter is Rectangular, Pulse length parameter is 1. | |
Furthermore, the CPFSK Modulator Baseband and CPFSK Modulator Passband blocks are similar to the M-FSK Modulator Baseband and M-FSK Modulator Passband blocks, respectively, when the M-FSK blocks use continuous phase transitions. However, the M-FSK features of this blockset differ from the CPFSK features in their mask interfaces and in the demodulator implementations.
| | Accessing Digital Modulation Blocks | Representing Signals for Digital Modulation | |
