M-DPSK Modulator Baseband
Modulate using M-ary differential phase shift keying method
PM, in Digital Baseband sublibrary of Modulation
The M-DPSK Modulator Baseband block modulates using the M-ary differential phase shift keying method. The output is a baseband representation of the modulated signal. The M-ary number parameter, M, is the number of possible output symbols that can immediately follow a given output symbol.
The input must be a discrete-time signal. For integer inputs, the block can accept the
double. For bit inputs, the block
The input can be either bits or integers, which are binary-mapped or Gray-mapped into symbols.
This block accepts column vector input signals. For a bit input, the input width must be an integer multiple of the number of bits per symbol.
Integer-Valued Signals and Binary-Valued Signals
If you set the Input type parameter to
Integer, then valid input values are integers between
0 and M-1. In this case, the input can be either a scalar or a frame-based column
vector. If the first input is k1, then the modulated symbol
where θ represents the Phase rotation parameter. If a successive input is k, then the modulated symbol is
When you set the Input type parameter to
the block accepts binary-valued inputs that represent integers. The block collects
binary-valued signals into groups of K =
log2(M) bits, where K is the number of bits per symbol and
M is the modulation order.
The input vector length must be an integer multiple of K. In this configuration, the block accepts a group of K bits and maps that group onto a symbol at the block output. The block outputs one modulated symbol for each group of K bits.
The input can be a column vector with a length that is an integer multiple of K.
In binary input mode, the Constellation ordering parameter
indicates how the block maps a group of K input bits to a
corresponding phase difference. The
Binary option uses
binary-coded integer mapping, while the
Gray option uses
a Gray-coded assignment of phase differences. For example, the following table
indicates the assignment of phase difference to three-bit inputs, for both the
Gray options. θ
is the Phase rotation parameter. The phase difference is
between the previous symbol and the current symbol.
|Current Input||Binary-Coded Phase Difference||Gray-Coded Phase Difference|
|[0 0 0]||jθ||jθ|
|[0 0 1]||jθ + jπ/4||jθ + jπ/4|
|[0 1 0]||jθ + jπ2/4||jθ + jπ3/4|
|[0 1 1]||jθ + jπ3/4||jθ + jπ2/4|
|[1 0 0]||jθ + jπ4/4||jθ + jπ7/4|
|[1 0 1]||jθ + jπ5/4||jθ + jπ6/4|
|[1 1 0]||jθ + jπ6/4||jθ + jπ4/4|
|[1 1 1]||jθ + jπ7/4||jθ + jπ5/4|
For more details about the
Gray options, see the reference page for the M-PSK Modulator Baseband block. The signal constellation for that block
corresponds to the arrangement of phase differences for this block.
- M-ary number
The number of possible output symbols that can immediately follow a given output symbol.
- Input type
Indicates whether the input consists of integers or groups of bits. If this parameter is set to
Bit, then the M-ary number parameter must be 2K for some positive integer K.
- Constellation ordering
Determines how the block maps each group of input bits to a corresponding integer.
- Phase rotation (rad)
The phase difference between the previous and current modulated symbols when the input is zero.
- Output data type
The output data type can be either
double. By default, the block sets this to
Supported Data Types
|Port||Supported Data Types|
 Pawula, R. F., "On M-ary DPSK Transmission Over Terrestrial and Satellite Channels," IEEE Transactions on Communications, Vol. COM-32, July 1984, 752-761.
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