Data Format and Scale

Format and Scale are display functions which can be selected for each plot to learn more about your measurement data.

Data Format

A data format is the way PLTS presents the measurement graphically. Select a data format appropriate to the information you want to learn about the device.

Each plot can have a different format.
All traces within the plot have the same format.

See the data formats that are available for:

Data format can NOT be selected for Eye Diagrams or Transmission Line Parameters.

How to select Data Format

Any of the following methods can be used to change the format for the plot.

Click Format
Select a format Icon from the Parameter bar.
Copy format and scale from a plot and paste in a different plot.

Frequency Domain Formats and Units

	Log Mag displays Cartesian logarithmic magnitude (no phase) in dB. Typical measurements are return loss and gain. This is the default format.
	Linear Mag displays positive values only in mU. Typical measurements are transmission, reflection coefficients, time domain transfer.
	Phase displays phase (no magnitude) in degrees. The trace 'wraps' every 180 degrees for easier scaling.
	Unwrapped Phase displays phase in a single, continuous, display. The phase is not reset every 180 degrees. This helps to see the minor changes from a linear phase response.
	Group Delay displays signal transmission (propagation) time through a device in nanoseconds (nS).
	Smith Chart displays an impedance plane that is mapped onto the polar plane. Every point on the Smith Chart represents a complex impedance made up of a real resistance (r) and an imaginary reactance (r + jX). The dotted circles represent constant resistance. The horizontal line through the middle is purely resistive (no reactive component). No units. To the far right, the value is zero ohms (short). To the far left, the value is infinite ohms (open). The dotted arcs represent constant reactance. The reactance arcs in the upper (positive) half of the circle represent inductive reactance (ZL = jwL). The reactance arcs in the lower (negative) half of the circle represent capacitive reactance (ZC = 1/jwC). Typical measurements: Impedance profile When in this format, the cursor bar allows you to choose the cursor value in either Mag + Phase or Inductance style. Refer to Frequency Domain Polar and Smith Chart Markers for additional information.
	Polar Chart plots the measurement result in a vector representation. No units. The magnitude at any point is determined by its displacement from the center (or zero value). Magnitude is scaled linearly, with the value of the outer circle set to a ratio value of 1. The radial lines scale the phase angle from 0 degrees to +180 degrees (counterclockwise) or -180 degrees (clockwise). When in this format, the cursor bar allows you to choose the cursor value in either Mag + Phase or Inductance style. Refer to Frequency Domain Polar and Smith Chart Markers for additional information.
	Real displays only the real (resistive) portion of the measured complex data in mUnits. Can show both positive and negative values. Typical measurement: time domain
	Imaginary displays only the imaginary (reactive) portion of the measured complex data in mUnits. Typical measurements are impedance for designing matching circuits.
	SWR Standing wave ratio. Displays reflection parameters calculated from the formula (1+r)/ (1-r) where r is reflection coefficient. Valid only for reflection measurements. Y axis: Unitless
	Impedance (Z) Real The rectilinear version of the same Real (resistive) data that is displayed on a Smith Chart.
	Impedance (Z) Imaginary The rectilinear version of the same Imaginary (reactive) data that is displayed on a Smith Chart.
	Impedance Magnitude displays the magnitude of impedance.
	Impedance Imaginary Magnitude displays the magnitude of the imaginary part of impedance.
	Impedance Angle
	Quality Factor
	Dissipation Factor

Time Domain Formats and Units

Stimulus - Type of the input to the DUT
	Impulse	inputs an impulse waveform as the stimulus.
	Step	inputs a step waveform as the stimulus. This is the default format.
Vertical Format - Units used on the vertical axis
	Volts	selects volts as the vertical unit of measure. This is the default format.
	Real	displays only the real (resistive) portion of the measured complex data. Real can show both positive and negative values. This is the default format.
	Log Mag	displays Cartesian logarithmic magnitude (no phase) in dB. Typical measurements are return loss and gain.
	Impedance	selects ohms as the vertical unit of measure. This choice is active only for reflection plots with a Step stimulus.
Horizontal Format - Units used on the horizontal axis
	ns	selects time units (in nanoseconds) for the horizontal format. This is the default format.
	cm	selects distance units (in centimeters) for the horizontal format.

Note: When opening measured DUT files in Time Domain to view in the Time format:

1. Go into the time domain/distance format and set your velocity factor accordingly (Example: Air VF=1.000, Surface traces VF=0.53146, Buried traces in a dielectric constant (er) ~ 4.3: VF=0.48795).

2. Select to view data in time, and then switch to view data in distance.

This triggers the correct computations to take place and you will now be able to set markers and measure device lengths and discontinuities accurately.

Note: When the horizontal units per division is changed, the Delay value is reset to zero.

Transmission Line Parameters

When the plot is inductance, the units are in Henrys
When the plot is resistive, the units are in Ohms.

Setting the Scale of a Plot

Note: Eye Diagrams do NOT allow the scale to be changed.

Use the following methods to make scaling changes:

Change Scale Manually

PLTS allows you to change the horizontal and vertical scale of plots using the Scaling Bar.

How to show or hide the Scaling Bar

Click View, then Toolbars, then Scaling Bar.

Click in any of the scale boxes. Then do one of the following to change the horizontal and vertical scale.

Click or hold the up/down arrow buttons to the right of each entry.
Use a mouse scroll wheel to increment or decrement values.
Type a new value. Units can also be entered, but defaults to the units currently displayed.
Change the step size of the Horizontal or Vertical settings as follows:

1. Click the right-arrow, shown in yellow shading in the above image.
2. Enter new step size.
3. Click left arrow to hide the Step Settings.

Click on the Vertical Scale Settings button to change between Ref Level-Units/Div to Min/Max mode. Min corresponds to the bottom of the vertical scale and Max to the top of the vertical scale.

Scale Notes

You can not extend the start and stop frequencies beyond the start and stop frequencies used in the measurement.
The horizontal scale may not be changed in Smith Chart and Polar formats.
Learn how to set the Time Domain Start and Stop values.

Autoscale

Autoscale changes the vertical scale of the active plot to allow the trace to occupy approximately 80% of the vertical axis of the display.

Note: You can select a User Preference to Autoscale each plot as it is created. Learn how.

Select the plot, then Right click on the plot to display the following menu.

Click Autoscale to change the vertical scale of the plot.
Click Autoscale All to change the vertical scale of ALL plots in the window.

Reset Scale

Reset Scale resets the vertical and horizontal scale of the active plot to the default settings. This is useful when you are adjusting the scale and the trace is moved off screen and can no longer be seen.

How to Reset the scale

Click Reset Scale to reset the vertical scale of the selected plot.
Click Reset Scale ALL to change the vertical scale for ALL plots in the window.

Click and Drag Zoom

Note: The zoom feature is not available for Eye Diagrams, Polar or Smith Chart plots.

To zoom in on an area of the active plot:

On the Plot toolbar, select the Zoom icon
Click within the plot and drag the mouse, creating a rectangle as the mouse is moved.
Release the mouse button to enclose the area of interest. The displayed plot now has new X-axis and Y-axis scales.
If necessary, right-click on the plot, then select Autoscale to set the Y-axis scale so that the data is better displayed.
To return the plot to the original horizontal and vertical settings, right-click on the plot and select Reset Scale.

Pan (traces)

Changes the scale for the X-axis and Y-axis to effectively move the traces within a plot.

On the Plot toolbar, select the Pan icon .
Click within the plot and drag the mouse.
Optionally, with the Plot icon selected, hold the shift key while clicking and dragging the mouse within the plot.
If necessary, right-click on the plot, then select Autoscale to sets the Y-axis scale so that the data is better displayed.
To return the plot to the original horizontal and vertical settings, right-click on the plot and select Reset Scale.

Copy and Paste Plot Format

You can change the plot format quickly using the Copy/Paste Plot Format functions. These functions are very useful when you are displaying several traces within a plot window.

To perform Copy/Paste Plot Format functions:

With your data plots displayed, make any changes in the format or scale of the plot to be copied. In this example, the format of TCC12 was changed from step to impulse and the vertical scale was changed.
With the cursor over the plot to be copied, right-click the mouse button, then click Copy Plot Format.
With the cursor over the plot to get the new format and scale, right-click mouse button, then click Paste Plot Format. The plot is now displayed with the new format and scale.

Last Modified:

15-Dec-2016	Added Min/Max vertical scaling
7-Jan-2013	Added Pan for 2013
15-Jun-2010	Updated scaling info