constellation()
Generates the constellation diagram from Circuit Envelope, Transient, or Ptolemy simulation I and Q data
Syntax
Const = constellation(i_data, q_data, symbol_rate, delay)
Arguments
| Name | Description | Range | Type | Required |
|---|---|---|---|---|
| i_data | in-phase component of data versus time of a single complex voltage spectral component (for example, the fundamental) † | (-∞, ∞) | complex | yes |
| q_data | quadrature-phase component of data versus time of a single complex voltage spectral component (for example, the fundamental) † | (-∞, ∞) | real | yes |
| symbol_rate | symbol rate of the modulation signal | [0, ∞) | real | yes |
| delay | delay value † † | [0, ∞) | real | no |
| † this could be a baseband signal instead, but in either case it must be real-valued versus time. † † (if nonzero) throws away the first delay = N seconds of data from the constellation plot. It is also used to interpolate between simulation time points, which is necessary if the optimal symbol-sampling instant is not exactly at a simulation time point. Usually this parameter must be nonzero to generate a constellation diagram with the smallest grouping of sample points | ||||
Examples
Rotation = -0.21
Vfund = vOut[1] * exp(j * Rotation)
delay = 1/sym_rate[0, 0] - 0.5 * tstep[0, 0]
Vimag = imag(Vfund)
Vreal = real(Vfund)
Const = constellation(Vreal, Vimag, sym_rate[0, 0], delay)
where Rotation is a user-selectable parameter that rotates the constellation by that many radians, and vOut is the named connection at a node. The parameter delay can be a numeric value, or in this case an equation using sym_rate, the symbol rate of the modulated signal, and tstep, the time step of the simulation. If these equations are to be used in a Data Display window, sym_rate and tstep must be defined by means of a variable (VAR) component, and they must be passed into the dataset as follows: Make the parameter Other visible on the Envelope simulation component, and edit it so that,
Other = OutVar = sym_rate OutVar = tstep
In some cases, it may be necessary to experiment with the value of delay to get the constellation diagram with the tightest points.
 | Note vOut is a named connection on the schematic. Assuming that a Circuit Envelope simulation was run, vOut is output to the dataset as a two-dimensional matrix. The first dimension is time, and there is a value for each time point in the simulation. The second dimension is frequency, and there is a value for each fundamental frequency, each harmonic, and each mixing term in the analysis, as well as the baseband term. vOut[1] is the equivalent of vOut[::, 1], and specifies all time points at the lowest non-baseband frequency (the fundamental analysis frequency, unless a multitone analysis has been run and there are mixing products). For former MDS users, the notation "vOut[*, 2]" in MDS corresponds to the notation of "vOut[1]". |
Defined in
$HPEESOF_DIR/expressions/ael/digital_wireless_fun.ael
See Also
Notes/Equations
Used in Constellation diagram generation.
The I and Q data do not need to be baseband waveforms. For example, they could be the in-phase (real or I) and quadrature-phase (imaginary or Q) part of a modulated carrier. The user must supply the I and Q waveforms versus time, as well as the symbol rate. A delay parameter is optional. The i_data and q_data must be of the same dimension, and up to 5-dimensional data is supported.
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