Graph Types

This graph type calculates the power spectral density estimation of the waveform.

To create or open an IQ FFT plot settings,

1. Select any modulation schemes from the Modulation menu.
2. Click Graphics tab.
3. Select IQ FFT from the Measurements drop-down menu.
4. Click Regenerate Plot.

The resultant plot with default settings is as shown in the following figure.

The FFT measurement enables three controls under the Trace Controls menu:

Reset FFT

When zooming into specific time-based traces, such as IQ vs Time, or Frequency vs Time; the graphics page will show details of the zoomed region of the signal, which means that the FFT is performed only on specific regions of the signal. This can be seen by looking at the FFT details shown at the top right of the graph graticule. The Reset FFT control allows you to reset the FFT measurement so it applies to the entire signal.

Apply Window

This control allows you to control whether or not the incoming signal will be windowed as part of the FFT process. When selecting/unselecting this option, you will need to re-generate the signal to see the effects.

Display FFT Information

This will toggle the FFT information display is shown at the top right of the graph graticule.

To create or open a settings page,

1. Select any modulation schemes from the Modulation menu.
2. Click Graphics tab.
3. Select Vector from the Measurements drop-down menu.
4. Click Regenerate Plot.

The resultant plot with default settings is as shown in the following figure.

The IQ Vector measurement enables three controls under the Trace Controls menu:

Decimate Samples

This control allows to plot only a portion of the signal up to a maximum of 1500 points when a new signal is generated. While this can speed up the plotting process, it may cause spurious points to be shown when vector lines are enabled.

Show Vector Lines

This control allows you to turn on/off the lines that join the individual vector points. When this control is unselected, the individual points of the vector will be enlarged.

Reset Samples

When zooming into specific time-based traces, such as IQ vs. Time, or Frequency vs. Time, the graphics page will show details of the zoomed region of this signal, which means that the FFT is performed only on specific regions of the signal. This can be seen by looking at the FFT details shown at the top right of the graph graticule. The Reset Samples control allows you to reset the IQ Vector measurement, so it applies to the entire signal.

The in-phase(I) and quadrature(Q) components of a signal are shown as a function of time.

To create or open an IQ vs Time plot settings,

1. Select any modulation schemes from the Modulation menu.
2. Click Graphics tab.
3. Select IQ vs Time from the Measurements drop-down menu.
4. Click Regenerate Plot.

The resultant plot with default settings is as shown in the following figure.

The IQ vs Time measurement enables a few controls under the Trace Controls menu:

Decimate Samples

This control allows to plot only a portion of the signal up to a maximum of 1500 points when a new signal is generated. This can speed up the plotting process for large signals, but will cause some of the underlying I and Q data to be hidden.

Show I

Enables the I portion of the signal is shown on the trace.

Show Q

Enables the Q portion of the signal is shown on the trace.

This graph type displays the phase of the signal, as a function of time.

To create or open a settings page,

1. Select any modulation schemes from the Modulation menu.
2. Click Graphics tab.
3. Select Phase vs Time from the Measurements drop-down menu.
4. Click Regenerate Plot.

The resultant plot with default settings is as shown in the following figure.

The Phase vs Time measurement enables three controls under the Trace Controls menu:

Decimate Samples

This control allows to plot only a portion of the signal up to a maximum of 1500 points when a new signal is generated. This can speed up the plotting process for large signals but will cause some of the underlying I and Q data to be hidden.

This graph type displays the magnitude of the signal, in separate graphs, as a function of time.

To create or open a settings page,

1. Select any modulation schemes from the Modulation menu.
2. Click Graphics tab.
3. Select Phase vs Time from the Measurements drop-down menu.
4. Click Regenerate Plot.

The resultant plot with default settings is as shown in the following figure.

The Power vs Time measurement enables a few controls under the Trace Controls menu:

Decimate Samples

This control allows to plot only a portion of the signal up to a maximum of 1500 points when a new signal is generated. This can speed up the plotting process for large signals but will cause some of the underlying I and Q data to be hidden.

This graph type displays the instantaneous frequency of the signal as a function of time.

To create or open a settings page,

1. Select any modulation schemes from the Modulation menu.
2. Click Graphics tab.
3. Select Phase vs Time from the Measurements drop-down menu.
4. Click Regenerate Plot.

The resultant plot with default settings is as shown in the following figure.

The Frequency vs Time measurement enables Decimate Samples control under the Trace Controls menu:

Decimate Samples

This control allows to plot only a portion of the signal up to a maximum of 1500 points when a new signal is generated. This can speed up the plotting process for large signals but will cause some of the underlying I and Q data to be hidden.

This plot displays the wrap-round portion of a waveform. It shows the last samples of one cycle of the waveform followed by the first samples of the next, when the IQ source is continuously output.

A maximum of 100 samples from the end of the signal and 100 samples from the start is displayed. Use this plot to assess whether the transition between the start and the end of the file is smooth and contains no discontinuity. Discontinuities will result in spectral smear.

To create or open a settings page,

1. Select any modulation schemes from the Modulation menu.
2. Click Graphics tab.
3. Select IQ vs Time (wrapped) Plot from the Measurements drop-down menu.
4. Click Regenerate Plot.

The resultant plot with default settings is as shown in the following figure.

The IQ vs Time (Wrapped) measurement enables a few controls under the Trace Controls menu:

Show I

Enables the I portion of the signal is shown on the trace.

Show Q

Enables the Q portion of the signal is shown on the trace.

To create or open a settings page,

1. Select any modulation schemes from the Modulation menu.
2. Click Graphics tab.
3. Select Constellation from the Measurements drop-down menu.
4. Set the scaling properties. You can either select Auto Scaling or define your own values.
5. Click Regenerate Plot.

The resultant plot with default settings is as shown in the following figure.

The Constellation measurement enables Reset Samples control under the Trace Controls menu:

Reset Samples

When zooming into specific time-based traces, such as IQ vs Time, or Frequency vs Time; the graphics page will show details of the zoomed region of the signal, which means that the FFT is performed only on specific regions of the signal. This can be seen by looking at the FFT details shown at the top right of the graph graticule. The Reset FFT control allows you to reset the FFT measurement so it applies to the entire signal.

A Complementary Cumulative Distribution Function (CCDF) graph is a plot of relative power levels against probability. The graph shows the probability that the power is equal to or above a certain peak-to-average power ratio, for different probabilities and peak-to-average power ratios. Peak-to-average power is calculated for generated signal excluding OFF power period. The higher the peak-to-average power ratio, the lower the probability of reaching it. The x-axis represents the power level above the average power and the y-axis represents the percent of time the signal power is at or above the power specified by the x-axis. For example, at 10%, the corresponding peak-to-average power is 3.60 dB. This means the signal power exceeds the average by 1.88 dB for 10% of the time. The legend on the right-hand side identifies power levels associated with certain probabilities, except for Peak as this represents the crest factor of the curve.

Calculating CCDF

This is a 2-stage process, where the Probability Distribution Function (PDF) is used to compute the Cumulative Distribution Function (CDF) by computing the integral of the PDF. The CDF is then used to compute the CCDF by inverting the CDF result. The CCDF is plotted instead of CDF because a CCDF plot emphasizes peak amplitude excursions.

Create or open a settings page,

1. Select any modulation schemes from the Modulation menu.
2. Click Graphics tab.
3. Select CCDF from the Measurements drop-down menu.
4. Set the scaling properties. You can either select Auto Scaling from the Zoom drop-down menu or define your own values.
5. Click Regenerate Plot.

The resultant plot with default settings is as shown in the following figure.

The CCDF measurement enables few controls under the Trace Controls menu:

Reset Samples

When zooming into specific time-based traces, such as IQ vs Time, or Frequency vs Time; the graphics page will show details of the zoomed region of the signal, which means that the FFT is performed only on specific regions of the signal. This can be seen by looking at the FFT details shown at the top right of the graph graticule. The Reset FFT control allows you to reset the FFT measurement so it applies to the entire signal.

Display Annotation

This will toggle the CCDF information display shown at the top right of the graph graticule.

This graph type is currently only available for CDMA modulation schemes. This graph type shows all active channels in the code domain. The graph shows whether assigned code domains of different channels overlap; that is, whether a domain conflict occurs. The symbol rates of code channels are characterized by the color and widths of the corresponding bars. The information at the right of the graph indicates the colors used to represent symbol rates. The heights of the bars represent the channel codes’ power level.

To create or open a Code Domain plot settings,

1. Select CDMA2k from the Modulation menu.
2. Click the Graphics tab in the CDMA2k settings window.
3. Select Code Domain from the Measurements drop-down menu.
4. Click Regenerate Plot.